command guidance system tracks the
Cover Titan missile from its launching pad in the

Push-button telephone in top sketch was the fore-
runner of the rotary dial. In 1892, customers used
this key arrangement to send individually gen-
erated pulses to the first automatic exchange.

Today's version of the push-button telephone, now
being developed at Bell Laboratories, sends a pair
of distinct tones for each digit, and promises
fo make customer signaling easier and faster.

Push-button “dialing”—one of the most
important concepts in future telephone
service — has recently demonstrated

its customer appeal in two field trials.
Interestingly, many of the firm bases
for this very modern method of customer
signaling go back to early telephony.

For four months last year, 200 customers in
Hamden, Connecticut, and a similar number in
Elgin, Illinois, used telephones equipped with
push buttons instead of dials. This field trial
was, at least, a partial implementation of an
objective that has been sought over 60 years
of telephone development. For even in the very
early days of telephony, pioneer engineers recog-
nized the need for automatic switching systems
and, more importantly, for ways of easily and
economically directing such systems from the
calling station. Inventions aimed at the replace-
ment of the well-known telephone dial have crop-
ped up fairly regularly since before the turn of
the century. Now, with the development of newer
solid-state devices, a promising solution to simpli-
fied customer control of switching machinery
appears within reach.

The results of this important trial of push-
button signaling from the customer’s telephone
indicate that the development of push-button
station apparatus may become increasingly im-
portant. With this fact as its basis, this article
introduces some of the important concepts that
underlie push-button signaling.

Very early in its history, the tremendous po-
tential for growth of the Bell System became

evident to those who were guiding its develop-
ment. In his book, History of the Telephone,
published in 1910, Herbert N. Casson wrote:
“Already the Bell System has gone far in this
direction by organizing what might fairly be
called a ‘Foresight Department’... Even in the
city of New York, one half of the cable ducts
are empty, in expectation of the greater city
of eight million population which is scheduled to
arrive in 1928.” Telephone planners soon recog-
nized that if the number of telephones increased
at the expected rate, the problem of hiring and
training enough operators to handle traffic manu-
ally would be just about impossible.

There were many who opposed the proposed
solution to this problem—automatic switching
systems with “customer calling”. They predicted
that such systems would be too complicated, and
therefore unreliable and uneconomical; too ex-
pensive; and too inflexible, and therefore un-
adaptable to special services. Further, opposi-
tionists felt that automatic switching was wrong
from the customer’s viewpoint. “The public will
not tolerate doing its own operating,” they said.

In spite of these pessimistic predictions, the
first “step-by-step” system of automatic switch-
ing was put in service in La Porte, Indiana, in

1892. The stepping switches in this system were
actuated directly by pulses generated by the
customer at his station (progressive control).
By 1908, step-by-step exchanges were in use in
about 70 cities and towns in the United States.

Prior to 1896, customers on these automatic
systems called the desired number by pressing
push buttons. These buttons or more precisely,
keys, can be seen on the early instrument in the
sketch on page 82. On some versions of this early
telephone there were three buttons on the “call-
ing device,” as it was commonly called. The but-
ton on the left was labeled HUNDREDS, the
middle one TENS, and the one on the right
UNITS. To call 148, for example, the customer
would push the left-hand button once, the mid-
dle one four times, and the right-hand one three
times. Customers using this system made many
calling errors. Consequently, in 1896, a “con-
tact-making machine,” now commonly called a
dial, was substituted for the push buttons. These
governor-controlled dials were similar in prin-
ciple to those in use today.

Another important advance, in both automatic
switching and push-button signaling, came in
1910. This was the year the Western Electric
Company developed the panel system of auto-
matie switching. A semi-automatic system of 450
lines, the first switching system to use “common
control,” was set up for trial at what is now the
New York location of Bell Laboratories. In 1914,
a complete panel system of this type was installed
in Newark, New Jersey.

With the semi-automatic versions of panel, the
customer told the operator the number he wanted,
and she completed the call with push buttons.
Each operator’s position had five vertical rows,
each with ten push buttons, or “keys.” This ar-
rangement permitted the keying of decimal num-
bers up to five digits long.

In 1921, the first fully automatic panel system
was installed in Omaha, Nebraska. Here, the
customers were provided with dials. An “auto-
matic caller,” with five preset levers and an actu-
ating arm, was also used at this time.

The governor-controlled rotary dials devel-
oped for the early progressive-control systems
were well suited to the pulse-handling speed of
the stepping switches. Also, a rotary dial with
finger holes of adequate size requires only reason-
able and easily applied wind-up forces to gen-
erate the mechanical energy needed for con-
trolled-speed pulsing contacts.

On the contrary, it is difficult to generate this
energy mechanically with push buttons, because
the shorter stroke available requires rather high
mechanical forces. Suggestions for reducing the
mechanical loss due to the governor, or for using
escapement mechanisms and schemes other than
friction governors, have not borne fruit.

Dials were further suited to early switching
systems because the time required by the cus-
tomer to search for a following digit, plus the
time required to wind-up the dial preparatory

Mrs. Carole Rustako of the
Laboratories demonstrates the
first step in dialing SH-1, one
of the office codes used in the
Elgin trial. She is using an
exploratory model similar to
those used in the actual trials.

to pulsing, add up to a satisfactory interdigital
interval for activating stepping-type switches. Al-
though many improvements have been made in
dial mechanisms over the years, the basic design
adopted in 1896 has withstood the test of time
as the soundest method of manually applying the
energy to generate selected, timed pulses.

Things are changing in the Bell System, how-
ever, and the time has come to look seriously for
more effective methods for customer signaling.
There are now nearly 60,000,000 telephones in
the System and about 55,000,000 of these use
dials. Instead of restricting dialing to local calls,
the Bell System is rapidly extending the con-
venience of dialing by instituting customer dial-
ing of toll calls in many areas. The number of
digits to be dialed for some of these toll calls
may be as high as 14. Furthermore, the calling
rate, particularly on toll calls, has increased
materially.

New types of switching systems have also
been developed. Systems like No. 5 crossbar are
capable of establishing telephone connections at
speeds far greater than those of older systems.
The experimental electronic switching system
(ESS) (REcoRD, October, 1958), now called
the electronic central office (ECO), opens up even
greater potentials for high-speed calling devices.
These factors, along with the current flood of
push-button devices in other fields, conspire to
make this an appropriate time to consider the
introduction of push-button calling to Bell Sys-
tem customers.

Actually, Bell System toll operators have used
push-button calling,’ or key pulsing, for some
time. This system, using voice-frequency pulses,
was introduced in toll service in about 1940.
The arrangement uses a two-out-of-six frequency
code. But because they are all in the voice-fre-
quency band, the signaling frequencies can inad-
vertently be imitated by speech or other sounds
transmitted over the trunk. Therefore, special
operating procedures have been adopted to pre-
vent interference with the signaling process.
These special procedures cannot practically be
imposed on the customer, however, and a more
sophisticated system for protection against voice-
frequency interference had to be invented before
practical voice-frequency signaling could be in-
troduced to customers.

Efforts in this direction, using various signal-
ing schemes, have been tested and in some cases
commercially used, both in this country and
abroad. In Europe, push-button calling systems
have been developed, using de signals obtained
from combinations of polarity checks from the

Telephones used in the 1948 trials of push-button
calling. Pencil shows transducer that picks up
tones from plucked reeds (fixed to the base behind
the key levers). Note arrangement of buttons.

two sides of a telephone line to ground. This
method involves the use of diodes to maintain
proper signal direction. A trial installation, em-
ploying a modification of this principle was made
at the Laboratories in 1943. Because of the pos-
sible inductive effects from extraneous sources,
however, a grounded system of this kind is gen-
erally considered undesirable for the Bell System.

There have also been tests of a push-button
pulsing scheme based on the de voltage drop in
the customer’s loop. This system creates a prob-
lem in voltage regulation, and does not appear
well suited for use in a large and complex tele-
phone network. More recently, a pulse-position
code with six positions was suggested and eval-
uated by the Switching Research Department in
the early 1950’s (BSTJ, May, 1952).

Station devices for generating dial pulses in
a decimal code, similar to those produced by
existing rotary dials, have also been investigated.
Some of these devices were mechanical and some
were electronic. Such schemes require waiting
periods for both the transmission of the pulse
train and the inter-digital spacing, and thus
require self-discipline by the user. For high-speed
systems, this self-discipline might be tolerable,
but for the slower speeds demanded in current
step-by-step switches, waiting would undoubtedly
become a source of irritation to the customer.

The two-out-of-six frequency signaling sys-
tem currently used by operators for toll keying
is satisfactory from the standpoint of operating
speed, but it requires improved pulse-receiving
circuitry to guard against voice interference.
Such circuitry has been developed, but the pres-
ent analysis indicates that a new multifrequency
signaling system has many advantages.

This new system —a four-by-four frequency
scheme proposed by L. A. Meacham of the Sta-
tion Development Department — seems to attain
most of the objectives desirable in a push-button
calling system for customers (BSTJ, January,
1960). A complete explanation of this system
would itself take several articles. But briefly the
proposed system uses one frequency from each
of two bands (high and low) for each digit it
transmits. The frequencies that are used mini-
mize interference from harmonics. This permits
instantaneous limiting in both frequency bands,
and satisfactorily guards against possible voice
interference.

To this point, we have been primarily con-
cerned with the historical basis for push-button
signaling and with some of the experimental and
developmental efforts devoted to it. Because it
has been broad and brief, this background has
barely mentioned the most important parameter
in any telephone system — the customer. This
important consideration poses such questions as:
Will customers like push-button calling? Can
they learn to use it readily and accurately? Will
‘push buttoning” improve their service?

To make a start on getting answers to such
questions, Bell Laboratories in 1948 arranged a
small-scale trial of push-button calling, limited
to 35 employees of the Pennsylvania Bell Tele-
phone Company. The trial was held in Media,
Pennsylvania, the town in which the No. 5 Cross-
bar switching system was first introduced. This
switching system had, in its registers, receivers
that used the two-out-of-six multifrequency code.
Registers are the units that store and then spill
out the dialed digits as they are required by the
switching mechanisms. These receivers thus made
the No. 5 system very well suited to a trial of
customer signaling with push buttons.

For the trial, the customers were given a spe-
cial, mechanical push-button station mechanism.
The unit had mechanical linkages that plucked
two of six metal reeds, each tuned to resonate
at a desired frequency. When the customer pushed
any one of the ten buttons, two reeds would be
plucked and transmit the code for the desired
digit. A view of this mechanical arrangement
and the ‘external appearance of this experimen-
tal push-button telephone are shown on page 85.
The frequency pulses were generated in coils by
magnetic induction from the reeds. Although
this mechanism was not handy by present-day
standards for push buttons, the customers were
enthusiastic. Their performance was reasonably

adequate, according to both field and laboratory
studies. This trial established the desirability of
push-button signaling, from the customers’ view-
point. But the technical approach did not appear
attractive, so further work on this form of sig-
naling was deferred.

Recently, however, advances in technology,
particularly in the fields of transistors, ferrites,
and other solid-state electronic devices, have pro-
vided new tools for implementing the required
signaling circuitry at both the station and at
the central office. Furthermore, the conception of
the four-by-four frequency system has made pos-
sible a relatively simple mechanical structure at
the telephone set.

Concurrent with these electrical and mechanical
developments, human-factors engineers at the
Laboratories have made careful psycho-physical
studies of customer preference and performance
to determine the optimum arrangement, size, spac-
ing, stroke and operating force for push buttons.
These studies indicated that push buttons could
facilitate and speed up customer calling without
seriously increasing dialing irregularities. En-
couraged by the results of work in both of these
areas — solid-state technology and psycho-physi-
cal studies — the A.T.&T. Company and the Lab-
oratories decided to go ahead with a moderate-
sized field trial of push-button calling.

The main objective of the trial was to evalu-
ate the customers’ performance in using a mod-
ern push-button mechanism. A central-office re-
ceiver and converter were available in the form
of a “black box” device developed for another
purpose. Although not the ultimate in sophistica-
tion, this device would perform all of the nec-
essary central-office functions. The black boxes
were capable of repeating standard dial pulses,
receiving multi-frequency (MF) signals, and
converting MF signals to dial pulses for use by
the switching equipment.

In the step-by-step trial arrangement at Ham-
den, Connecticut, the receiver-converters were
installed between the first two elements in the
switching network —the line finder and the
first selector —in a segregated group of line
finders. In the No. 5 crossbar office at Elgin,
Illinois, they were put in between the trunk-link
and register circuits. About 170 individual and
two-rirty stations in each central-office area
were equipped with push-button sets. In addition
at each location about 30 key sets (telephones
with several lines selected by buttons) and an
attendant’s position on a PBX were so equipped.

Even though trouble rates were relatively high
due to the lack of refinement in apparatus de-

sign, customers in both areas were enthusiastic
about the service. Speed and ease of use were
the most frequently mentioned advantages. In a
relatively short period, the customers with push-
button sets were approaching the dialing accu-
racy they had achieved with regular dial tele-
phones. Laboratories’ engineers knew beforehand
that irregularities with push buttons tend to be
greater than those with the rotary dial — prob-
ably because of the ability of push buttons to
operate at higher speed. There is every indica-
tion that this small increase in errors will be
overcome with “learning,” as is the case when
a manual office is changed to dial.

The adjustment of an individual to the oper-
ational procedures of any new mechanical device
requires a period of learning. The graph oppo-
site compares learning curves, for speed of op-
eration, for the Elgin and Hamden trials. These
curves are also compared to an average rotary-
dialing-speed curve for both locations. One might
suppose, from a cursory look at the curves, that
people in Elgin are faster dialers, or button
pushers, than those in Hamden. It was found,
however, that a large proportion of the calls in
Elgin are to the local offices SH 1 and SH 2.
In the push-button configuration used on the trial
telephones (see photograph on page 84), the
buttons for dialing SH 1 are in bottom-to-top
sequence in a vertical row, an arrangement well
suited to fast operation. Dialing SH 2 is almost
as readily managed. The rate of learning, how-
ever, is about the same in both areas.

The curves show that several weeks were re-
quired for the customers to develop operating
skill approaching their potential end-point per-
formance. This is because most people make only
a few telephone calls a day, and therefore get
no concentrated practice. For a further compari-
son, a laboratory-measured learning curve is also
included. These data were obtained at the Labo-
ratories by testing twelve people who were asked
to dial ten, seven-digit numbers each day for
twelve days with the push-button set used in the
trial. The numbers used in these tests are com-
parable with those encountered in Hamden, and
no easily manipulated numbers such as those
found in Elgin are involved. The facility of oper-
ation these subjects attained in a few days equals
that attained by the Field-trial customers at Ham-
den in several weeks. Thus it is possible to get
approximate evaluations of customer perform-
ance in a relatively short time in the laboratory.
However, a full-scale trial of customer and equip-

Graph comparing speed of learning to dial with
push buttons with average rotary-dialing speed.
A laboratory-measured learning curve for ten
calls a day shows how fast skill in push-button
dialing can progress with more frequent practice.

ment performance in the field is required to evalu-
ate a new design fully.

From the customers’ point of view, push-but-
ton calling is easier and faster.than rotary dial-
ing. At the present state of the art, however,
the push-button station set is expected to cost
more. Also, rather costly additional central-office
equipment will be required in existing offices.

Why, then, is the Bell System interested in
the possibility of providing push-button calling?
One reason, of course, is that it is always inter-
ested in anything that provides better service
to the customer. Another reason is confidence its
ability to solve the technical and economic prob-
lems involved in this possible future service. Fi-
nally, a push-button device for voice-frequency
signaling provides the customer with a potential
(slow-speed) data transmitter.

The trials at Elgin and Hamden indicate that
customer approval of push-button dialing is ap-
preciable. The next step, which is already under
way, is to progress from the exploratory equip-
ment and apparatus designs used in these trials
to more sophisticated prototype models. These
models will then be used for additional larger
trials to evaluate the potential marketability of
push-button dialing and to explore in more detail
the technical and maintenance problems. Trials
of this type are scheduled for later this year.

The ubiquitous semiconductor ts enjoying
an ever-increasing popularity in electronics.
One reason designers are always

is that they know they can trust them.
This faith is attributable,
the reliability studies carried out by Bell

Designers of electronic equipment can gain
many important advantages from using semicon-
ductor devices such as transistors and diodes.
These small, lightweight components furnish low-
voltage operation, low power consumption, and a
mechanical ruggedness that surpasses that of
most other constituents of electronic equipment.
The design engineer, however, must first assure
himself of the feasibility of these devices by mak-
ing an important test. This is the test of reliabili-
ty — key to the successful use of semiconductors.

The concept of reliability has been increasingly
emphasized as engineering systems have become
more complex. Consider, for example, a table radio
with five tubes. If the radio is used ten per cent
of the time, and its tubes have a failure rate of
41% per cent per 1000 hours, only one will fail in
five years. Compare this record with a large com-
puter containing 300,000 transistors. If the com-
puter is to operate one week between breakdowns,
these transistors must have an average failure
rate of less than 0.002 per cent per 1000 hours.
In other words, the transistors must be over 2000
times more reliable than the tubes.

The more complex systems require a larger
number of devices which must have an increased

life expectancy roughly proportional to their in-
creased number. Furthermore, automatic assem-
bly of systems leads to constructing their parts in
packages, and the failure of any one device makes
the entire package unusable. This, of course, in-
creases the cost of a failure of the individual
device, and thus requires the newer devices to
have a reliability much greater than was expected
a few years ago. The rapid development of new
types of devices, and the rapid incorporation of
these devices into what we hope will be reliable
systems, means that we must find ways to demon-
strate their reliability in a much shorter inter-
val of time.

As the mean lifetimes of semiconductor devices
improve, it becomes either a larger or a longer
job to determine this life with the same confi-
dence. To illustrate, let us use the five-tube radio
set and the 300,000-transistor computer as before.
Fifty representative tubes life-tested for 1000
hours with no failures will verify with reasonable
confidence (90 per cent) that the radio will be
reliable. To verify with the same confidence that
the transistors will be satisfactory for use in the
computer, we must life test 110,000 of them for
1000 hours (or 12,000 for one year), again with

Semiconductor reliability testing equipment used
at the Allentown location. Pauline Holschwander
removes tray of devices from program panel.

no failures. This requirement, coupled with the
shorter development schedules for devices, makes
such evaluation a large-scale operation.

There are two methods of gathering informa-
tion about the life expectancy of devices required
to have long life. One source of information is the
field; the other source is the laboratory. The field
observation has the advantage of using more de-
vices than would be watched in the laboratory, as
well as the advantage of exposure to actual oper-
ating environments. On the other hand, the lab-
oratory trial has the advantages of closer control
of the environment and better observations of the
device behavior. Also, the cost of a failure in the
laboratory is much less than a corresponding fail-
ure in operating field equipment. A well-balanced
reliability program, of course, obtains data from
both sources.

Device designers generally gather data from
the field through cooperative effort with the sys-
tem designers. They acquire the information by
methods that vary widely from one field trial to
the next. The data from the laboratory experience,
however, can be obtained by well-designed statis-
tical, experimental plans. And most of these plans
require observations to be made at certain times
on the aging of devices.

Various tests can be set up in the laboratory to
check the reliability of transistors and diodes. For
example, if an engineer needs to know the relia-
bility of a device at the same time he is making
feasibility studies on it, he would use a type of
reliability test very different from one he would
use on devices in pilot production.

First of all, he would life test only a few de-
vices under a few conditions for a short time. In
a typical situation, forty diodes were fabricated.
One half of them were assembled by thermo-com-
pression bonding (RECORD, April, 1958) and the
other half by soldering. All of the devices were
life-tested at full power for about two months.
After that time both groups appeared to be simi-
lar, so the engineer concluded that the new tech-
nique of thermo-compression bonding was as
satisfactory as the old technique of soldering.

Since the reliabilities did not differ appreciably
between the two techniques, we chose thereafter
to use thermo-compression bonding because it
was less expensive. An experiment of this type
gathers preliminary information on the life ex-
pectancy of the device and uncovers its inherent
weaknesses. It may also indicate undesirable steps
in fabrication.

When the device is in pilot production, how-
ever, the reliability experiment would be made
on a much larger sample under a wider variety
of aging conditions. Also, we would need much
longer periods of time to gather information
about device behavior under conditions that might
be duplicated in the field. The knowledge gained
on this test would determine realistic ratings for
the device and guide the user of the device in its
reliable application. Various pertinent device
parameters would be measured during both of
these types of tests with little regard for what
might be defined as a success or failure.

Results of shelf-aging experiments of an experi-
mental n-p-n alloy germanium transistor. Note
effect of temperature on the collector current.

An experiment of the second type was _ per-
formed on a new type of click reducer. Formerly
a copper-oxide varistor, this “eardrum protect-
ing” device in the telephone handset was to be
made experimentally of diffused silicon. In the
experiment, 240 silicon varistors were divided
into ten groups, and each group was exposed to a
different set of conditions. One group was stored
at room temperature as a control while the other
nine were exposed to combinations of three ele-
vated temperatures (50, 80, and 110 degrees C)
and three powers (0.7, 7, and 70 milliwatts). The
test ran over eighteen months with measurements
at periodic intervals to determine the aging behav-
ior. The silicon varistor showed markedly less
aging than did the copper-oxide varistor it was
expected to replace and thus is considered to be
extremely reliable for telephone use.

The failure of a device is generally understood
to be its failure to perform satisfactorily in a
particular circuit in a particular system. Thus the
failure of a device is inexorably tied to the cir-
cuit in which it is used. The device designer
would employ a third type of experiment in a lab-
oratory to gather this type of information. This
experiment requires devices to be put into actual
circuits and allowed to operate while the circuits
are exposed to simulated changes in the surround-
ings similar to those expected to be encountered
in the field. In general, parameters of the device
would not be measured during the experiment.
But the experimenter would observe the time be-
tween each failure of the circuit and correlate
these failures with the devices.

In the proposed line concentrator for the No. 5
crossbar switching system, engineers assembled
in the laboratory a skeletonized system contain-
ing 127 germanium alloy transistors. They placed
this system in simulated operation while cycling
the temperature from room temperature to 60 de-
grees C. Alarm circuits were arranged to indicate
a failure of the system. In about a year they had
observed no failures due to transistors. The ex-
periment showed both the devices and their asso-
ciated circuits to have a reasonable reliability.

If the extreme values of the parameter of a
device that cause failure in the circuit are known
or can be found, the experiment with the pilot
models can be used to compute the results to be
expected of the “in-circuit” experiment. In gen-
eral, however, the results of an in-circuit experi-
ment cannot be applied to other uses of the de-
vices in other circuits and thus it is less useful
than the previous types.

When engineers suspect a weakness in the de-
sign of a device or actually detect one by the fore-

going tests, they can perform a ‘“‘mechanism”’ test
to verify the weakness and uncover its source. A
large variety of independent variables may be in-
troduced into this type of test. The device can be
exposed to mechanical, thermal, or electrical con-
ditions in an attempt to understand why the de-
vice behaves or misbehaves the way it does. For
instance, if engineers suspect that leaky seals are
causing abnormal aging, they can age groups
both in a deleterious, or wet, atmosphere and in
an inert atmosphere to verify leaks as a cause of
the unreliability.

The device designer performs another type of
test —the ‘accelerated” test —to gain insight
into the long-time behavior of a device by a short-
time test. This is applicable only after similar be-
havior data have been obtained by both a normal-
use life test and the system test. When the de-

These sketches show general trend of various
parameters of a group of 613 n-p-n germanium
alloy transistors given life tests. Information
from the thirty-week test indicates that currents
change in percentage more than voltage and trans-
fer characteristic over an extended period of time.

Margaret Perez, left, plugs de-
vice tray into furnace while
author adjusts power controls
on life rack. Reliability tests
are made at the Allentown
location of the Laboratories.

signer has determined the acceleration factors, he
then has a particularly useful test as a quality
control check on a manufacturer’s product.

Since a reliability program has life testing of
the devices as one of its purposes, one of the
types of equipment needed is a life rack. For this
reason, the Laboratories has designed a general-
purpose life rack for semiconductors. This piece
of equipment can impose bias and temperature
aging conditions on eight hundred devices at one
time. The diodes or transistors are placed in small
trays which are plugged into the life rack. The
trays are removed when measurements are re-
quired on the transistors. The measurements are
made by plugging the trays into an appropriate
measuring set.

The results of aging experiments can be plotted
in many ways. One way is shown in the curves
on page 90. In these curves, the average value of
a parameter, as well as its standard deviation, is
shown as a function of time. From this type of
presentation we can obtain an estimate of relia-
bility. In particular, we can detect unsatisfactory
behavior quite soon.

Shown in the figure are four parameters — I..,
(collector current), I,,, (emitter current), V.,,
(collector voltage), and alpha (a current transfer,

or gain, characteristic ) — for a group of 613 ger-
manium n-p-n alloy transistors made in 1956.
These transistors were life-tested at a tempera-
ture of 20 degrees C and dissipated 24 milliwatts
of power during the period of the test. The curves
indicate that the collector and emitter currents
were increased by about 40 per cent per year,
while the transfer characteristics and breakdown
voltage were changing by much smaller amounts.
Even smaller changes are observed on transistors
as presently constructed.

Changes are correspondingly small for groups
of germanium n-p-n grown-junction transistors
and germanium p-n-p alloy transistors. Extreme-
ly small changes of the parameters are also ob-
served for most diodes, such as the diffused and
alloy-silicon types.

The real usefulness of some of these tests be-
comes apparent when a group of experimental
devices, on life testing, indicates abnormal behav-
ior such as is shown in the curves of the second
figure. In this case, the leakage current increased
rather rapidly when the devices were aged at 60
degrees C, and increased very rapidly at 85 de-
grees C. A subsequent change in the manufactur-
ing process led to improved aging behavior.

Laboratory techniques can evaluate the aging
behavior of a device — the first step in determin-
ing its reliability. The usefulness of these tech-
niques lies in their ability to gain information
about aging behavior before the devices get into
large-scale use. Thus remedial action can be in-
stituted early to clear the difficulty. The proper
use and interpretation of these tests will result
in more reliable transistors in the field.

Vagnetic amplifiers are finding
increased popularity with designers ot
modern communications equipment,
Taking advantage of this art, Bell
Laboratories engineers have applied
the analog aspects of these devices to

An operator rotates a pointer to an arbitrary
position and simultaneously, a short distance
away, a small statue of The Huntress Diana turns
to aim an arrow in the same direction. This is a
typical scene at the Traveling Magnetic Amplifier
Display exhibited at several Bell Laboratories
locations. This particular demonstration is a sim-
ple illustration of remote positioning control—a
typical analog application of magnetic amplifiers.

Magnetic amplifiers obtain their amplifying
qualities from the non-linear characteristics of
saturable ferromagnetic cores. By virtue of their
construction and principle of operation, magnetic
amplifiers have many desirable characteristics.
Among these are: ruggedness, reliability, long
life, low maintenance, simplicity, small size, high
efficiency, no warm-up time, and great versatility.

In a large measure, the versatility of magnetic
‘amplifiers may be attributed to several features
not found in other amplifiers. These features in-

clude: (1) many possible types of operation, (2)
the availability of magnetic feedback in addition
to electrical feedback circuitry, and (3) the possi-
bility of using, on the same core, several signal
input windings, and these of arbitrarily chosen
numbers of turns.

On the other hand, since magnetic amplifier op-
eration depends on the saturation characteristics
of ferromagnetic cores, the output voltage of the
amplifier may be greatly affected by properties of
the magnetic core, voltage level, frequency and
wave shape of the power supply, and configura-
tions and parameters of the circuit. Therefore,
and this is also true of other types of amplifiers,
the relationship between amplifier output and
input is generally less precise than that required
in a closely engineered system.

To achieve more precision, magnetic amplifiers
use the technique of negative feedback. In analog
applications, negative feedback circuitry mini-

mizes deviations from ideal performance. Such
circuitry has the fundamental advantage that
proper “external” circuit behavior does not de-
pend upon precise “internal” performance. To
get this characteristic, the output of the ampli-
fier, transformed if necessary by a suitable feed-
back network, is compared to the circuit input.
The difference, or error, is the signal to the ampli-
fier. This error signal causes the amplifier output
to vary so as to reduce the error, maintaining
precisely the desired input-output relationship.

For example, in the display mentioned above,
the adjustable pointer is fastened to the shaft of
a potentiometer that provides the electrical input
to the circuit. The output, the position of the
statue, is transformed to an electrical signal by
a second potentiometer, serving as the feedback
network. The difference between the two potenti-
ometer voltages becomes the input to a magnetic
amplifier whose output signal drives the motor
that turns the statue. When the potentiometer
voltages are equal, at any value, the motor re-
ceives no power from the amplifier and remains
at rest. When the potentiometer voltages are
unequal, the amplifier drives the motor in the
proper direction to restore equality. Thus, the
circuit output is related to the input almost entire-
ly through the characteristics of the feedback
network, and is nearly independent of the charac-
teristics of the amplifier.

Where required, the input and output quanti-
ties might relate to many different forms of in-
formation. For example, the position of Diana
might be the position of a radar antenna, a con-
trol surface of an aircraft, or an instrument
pointer. Moreover, the output quantity may re-
late to some mathematical function or to a re-
sistor value, rather than to the control of a
mechanical quantity. The input, too, may have
different forms. It may be a voltage or current
obtained from a thermocouple, a pressure trans-
ducer or a standard reference source.

Thus, magnetic amplifiers employ non-linear
ferromagnetic cores with rather loosely controlled
characteristics. They can be used to advantage to
produce widely divergent, yet precisely controlled,
analog relationships. This can be demonstrated
by a few typical applications.

Consider as a quantitative illustration, the
problem of electrically positioning a rotary shaft
relative to a second shaft. Requirements may in-
clude angular accuracies of +5 minutes for rota-
tional speeds up to 10 degrees per second, and of
+10 minutes for rotational accelerations up to

A typical rectifier, regulated magnetically, used
in the “floating” storage battery. Here, the author
is adjusting the degree of line compounding.

100 degrees per second per second. This is rough-
ly the performance required of an automobile
driver who lines up the hood ornament with the
white center line of a road immediately in front
of the car and drives steadily at 100 miles an
hour. Following the road, including its curves,
he must not allow the ornament ever to go outside
the limits of the line. Practically, this positioning
problem arises in aircraft navigation when a
compass bearing must be inserted as a shaft posi-
tion into a navigational computer or autopilot
without disturbing operation of the compass.

A typical application of magnetic amplifiers to
this problem was made in the TRADIC bombing-
navigational computer (RECORD, April, 1955).
Here, the final circuit combines several magnetic
amplifiers and transistors to take advantage of
each type of device. In a small package, the main
ac transistor amplifier furnishes high gain and
responds rapidly — attributes typical of transis-
tor circuits. An input magnetic amplifier operates
stably and reliably at input-signal levels of power
below the capabilities of a transistor amplifier.
An output magnetic amplifier supplies the power
required to drive the shaft-positioning motor at
full speed.

In TRADIC, the input magnetic amplifier that
couples the input-signal network to the transistor
amplifier is of a type known as a “magnettor” or
second-harmonic modulator. This magnettor pro-
duces an ac output signal with a frequency twice
that of the power supply. Magnitude and polarity

of a net de signal of extremely low power de-
termine amplitude and phase, respectively, of the
magnettor output.

The device used here produces full output with
an input signal of one microampere at a power
level of 10~* watt. In addition, this amplifier
combines three input signals furnished to its
three input windings without the loss encountered
in conventional passive networks. The result is
an output specifically matched to the input re-
quirements of the ac transistor amplifier.

The output magnetic amplifier is of the “‘self-
saturating” type. It furnishes up to 2 watts of
400-cycle power to the reversible ac motor in re-
sponse to signals from the transistor amplifier.

The complete servo amplifier, from input shaft
to output shaft, has a bandwidth of approximate-
ly 14 cycles per second. This means that the out-
put shaft will assume its new position within ap-
proximately 0.02 second after the input shaft has
completed its move. The principal limitation of
this speed of response is the motor itself. This
application illustrates how magnetic amplifiers
may be used in conjunction with other conven-
tional elements — in this case transistors — to
produce a unified system. It exploits the comple-
mentary properties of both types of devices to
yield their best performance.

Another application of magnetic amplifiers is
in voltage stabilization of power supplies. The
objective is to maintain constant voltage out of

A computing amplifier before it is enclosed. With-
in this space, besides the magnetic cores and
windings, are various precision resistors, adjust-
ing potentiometers, and semi-conductor diodes.

the power supply regardless of changes in the line
voltage, load, ambient temperature and charac-
teristics of the circuit. Because of the differing
nature of their loads, various supplies may re-
quire devices that will control the peak, the root-
mean-square, or the average rectified value of an
ac line voltage. By fairly simple changes in cir-
cuitry, magnetic elements may be made to control
any one of the above characteristics.

In a power-supply arrangement developed at
the laboratories, for example, the de output volt-
age from the power supply was to be held con-
stant to within a few hundredths of a per cent.
Such a performance is obtained with a combina-
tion of magnetic and electron-tube amplifiers. The
magnetic amplifier provides the power-handling
capability to control the ac input to the power sup-
ply. The electron-tube amplifier provides sufficient
gain to furnish negative feedback signals to the
magnetic amplifier in response to error voltage
signals in the output. Since the output of this
power supply varies with changes in the average
rectified value of the ac input voltage, the mag-
netic amplifier reduces variations in this value
caused by changes in the line voltage independ-
ently of the action of the feedback amplifier. This
action is controlled by signals derived directly
from the ac line voltage — a technique known as
“line-voltage compounding.” Compounding re-
duces the effects of ten per cent line-voltage
changes to one per cent at the power supply. Such
circuitry lightens the burden on the feedback
amplifier and thus permit it to be smaller and
less critical in design. It also improves over-all
circuit performance.

Another special field where the Bell System
uses magnetic amplifiers to advantage is in the
application of “battery-float’” rectifiers. Here,
storage batteries are connected across a rectifier
output. They supply high load-current peaks in
excess of the rectifier rating and carry the full
load in case of an ac power failure. The rectifier
voltage, however, must be regulated so that the
batteries suffer neither overcharge nor net dis-
charge during normal operation. A regulated
rectifier does this with a magnetic amplifier
which controls the current into the rectifier in
response to negative feedback signals from an-
other magnetic amplifier in the feedback loop.

In addition to the normal error-voltage signal,
the feedback amplifier supplies what is called
“load compounding.” Here low resistance in
series with the de load yields a signal which
varies the input voltage of the rectifier to offset
fluctuations in the output voltage caused by
changes in the load current. However, the rectifier

Simple diagram of negative feedback system,
part a. Part b applies to servo amplifier used
in TRADIC, and shows interconnection of com-

current must be limited to a safe value upon ap-
plication of ac power after the batteries have been
discharged to any degree. This is done by design-
ing the feedback amplifier to “saturate” at ap-
proximately a 25-ampere load. Under these con-
ditions, despite increasing error-voltage and load-
compounding signals, output voltage drops off
to limit the short-circuit current to 45 amperes.

Magnetic amplifiers have also proven attrac-
tive in applications involving analog computa-
tions. Here, the magnetic amplifier itself is the
principal circuit element, and its output versus
input characteristic must be held to very close
limits. This is done by using the technique of
connecting a negative feedback loop around the
magnetic amplifier from output to input.

Operation of an analog computing circuit may
be best understood by considering a de voltage
amplifier of high linearity. Amplification is de-

ponents. Diagram c shows a voltage-stabilized
rectifier. The line-compounding signal and
error signal cooperate to control amplifier output.

termined by the feedback network over a dynamic
voltage range from a few millivolts to several
hundred volts. The output error is determined
principally by the accuracy of components in the
feedback network, and may be as little as +0.05
per cent.

Using the various possible types of feedback
connections, design engineers can make the input
and output resistances of the magnetic amplifier
high or low and can choose the input and output
polarities. The introduction of non-linear ele-
ments — such as diode-resistor networks — into
the feedback loop can be used to shape the charac-
teristic to produce almost any arbitrary function.
Such functions might be an output signal inde-
pendent of input polarity, or related by an ex-
ponential or trigonometric characteristic. Thus,
by converting input voltages to logarithmically
related currents and adding these currents alge-
braically, the output of an exponential amplifier
will be proportional to either the product or the
quotient of the input voltages.

Magnetic amplifiers are also particularly well
suited for dec meters used to measure currents
and voltages at high voltage levels. Cable engi-
neers have used magnetic amplifiers of the sat-
urable reactor type for metering in the terminal
equipment of submarine cables. Also, the ampli-
fiers are used for reliable operation of audible
and visible alarms in the event the voltage or
current varies sufficiently to endanger the elec-
tron tubes in the submerged amplifiers of the
cable. In addition to furnishing the high degree
of accuracy required, metering amplifiers elimi-
nate the need to carry high-voltage lines to the
location of the control and metering equipment.
Thereby, they also remove a hazard to operating
personnel.

In the saturable reactor circuit used for meter-
ing, the attributes of negative feedback circuits
again prevail, since all of the output current is
inherently effective as a negative magnetic feed-
back. Furthermore, the output is electrically iso-
lated from the signal input. Such an amplifier
acts as a true de current transformer whose ratio
equals that of the input-to-output turns on each
core.

These few, but diverse, types of magnetic
amplifier applications give some insight into the
adaptability of magnetic amplifiers. We can see
they perform a wide variety of highly precise
tasks, both alone and in conjunction with other
electrical or mechanical apparatus.

Diagram of an analog computing amplifier. With-
out feedback, amplifier has loosely controlled char-
acteristics, With feedback, amplifier has charac-
teristic precisely determined by feedback net-
work chosen, but requires larger input signal.

In sending still pictures over nationwide
telephoto networks, an appreciable change
in the transmission level of the circuits
can drastically affect the quality of the
received picture. Recently, transmission
engineers have devised a new technique
for rapidly detecting and localizing

A relatively unheralded forerunner of the
Laboratories historic transmission of moving
images —the first television broadcast — was
the long-distance transmission of a still picture.
This important communication medium — tele-
photography — was first used to send news pic-
tures of President Coolidge’s inauguration from
Washington to New York, San Francisco and
other major cities in March, 1925.

By the mid-1930’s, press associations had es-
tablished, over Bell System links, large networks
of private-line, telephoto facilities. These asso-
ciations, along with certain government agencies,
have continued to be the largest users of the
service. Press organizations use telephotography
to send up-to-the-minute news pictures as an ad-
junct to their standard, “wire-service” news cov-
erage over leased teletypewriter channels. An
outstanding example of how government agen-
cies use telephoto systems is the vast weather-
map network of the U. S. Air Force-Airways
Communication Service. This system, which cov-
ers the United States and portions of Canada,
transmits graphic meteorological information 24
hours a day, every day.

The rapid growth of such private-line tele-
photograph networks has complicated the tech-
niques for locating troubles in the transmission
circuits. And these techniques are of course vital
to offering the best possible service at a reason-
able cost. For example, some press and govern-
ment networks have over 300 stations and employ
as much as 25,000 miles of interconnected cable
and carrier-channel facilities. In such vast sys-
tems, it is important to locate troubles quickly,
because a transmission irregularity — specifical-
ly, a sudden change in the loss of the circuit —
may affect the quality of a picture being received
at many locations. In some cases, changes in the
level of the received picture signal due to changes
in loss may necessitate re-transmission of, say,
an entire photograph, and this takes time and
costs money.

instrumentation and techniques for rapid and
direct determinations of trouble locations.

Before we discuss the specific problems in-
volved in picture transmission, it would be well
to explain first some of the basic principles of
telephotography. At present, there are several
methods available for transmitting pictures over
common-carrier facilities. The most popular are
the “drum-type” and the “flat-bed” scanning sys-
tems. This discussion will be limited to the drum-
type system. However, application of the meas-
uring system is similar in the flat-bed scanning
technique.

The drum-type system works something like
this: At the sending station, a positive print of
the picture to be transmitted is attached to the
surface of a drum. As this drum rotates, an op-
tical arrangement scans the picture by slowly
traversing the length of the rotating drum. The
optical unit performs two functions: (1) it il-
luminates a small unit-area, or “element,” of
the picture; and (2) it detects the level of the
light reflected from this small area with a photo-
electric cell. In other words, the picture is scanned
helically, element-by-element.

During scanning, the analog electrical output
of the photocell is amplified and used to modulate
a carrier frequency in the audio range. Most
telephoto systems transmit an amplitude-modu-
lated signal, with either vestigial or double-side-
band transmission.

At the receiving end, the transmitted signal
is demodulated, amplified and then fed to a re-
ceiving optical system which converts the in-
tensity of the domodulated signal to a propor-
tional output of light. This light beam is fo-
cused on an elemental area of film on an enclosed,
light-tight, cylinder similar to the transmitting
drum. Thus, the received picture is exposed on
the film helically, element-by-element, just as it
was transmitted.

In a system of this type, the cylinders at both
the transmitting and receiving stations must ro-
tate at the same rate (about 100 rpm) to avoid
picture “skew.” It is also very important that
the receiving cylinder starts rotating at the same
point relative to the transmitting cylinder to
avoid reception of a “split” picture.

Since amplitude modulation is usually em-
ployed in the transmission of pictures, a change
in amplitude level corresponds to a change in the
density of the recorded picture. The result of a
change in level during picture transmission is
either a brightening or darkening of the portion
of the picture received following the change. The

The author using a prototype model of the new level appears as a steady indication on the db
measuring set at the telephoto test center in the meter on the test set. Mr. Benewicz reports read-
Long Lines building in New York City. Line ing to maintenance people along the network.

quality of the received picture, therefore, de-
pends very much on the stability of the trans-
mission facilities over which it is sent.

More specifically, present high-definition tele-
photographic systems are capable of detecting
sudden changes in amplitude level as small as
0.25 db. The resulting light or dark areas in the
picture copy depend on whether the change was
in a positive (increased gain) or negative (in-
creased loss) direction. Changes of 0.4 db or
greater will in most cases evoke a complaint
from the customer.

Bell System statistics indicate that over one-
half of the reported troubles associated with the
operation of long-distance press networks are
due to intermittent changes in the net loss of
the transmission circuits. Since many of these
networks are built up of tandem circuits, it is a
difficult and time-consuming procedure to locate
the particular link that is causing the intermit-
tent changes in the over-all level of the network.

Heretofore, testing these leased networks for
variations in level has been conducted largely
by the ‘“out-of-service” method. In this method,
maintenance people — sometimes with the coop-
eration of customer stations — approximate the
trouble location. Often this is a section of the
tandem facilities. A “patch” is established to
bypass the suspected section, and the out-of-serv-
ice circuits are then investigated with static
testing methods. For these level-variation in-
vestigations, maintenance people use graphic re-
corders to monitor a steady test tone applied to
the circuit. When a customer is receiving tele-
photographs, however, the detection of trouble
conditions is delayed from five minutes to an
hour. And this situation often results in addi-
tional impaired transmissions.

These, then, are some of the fundamental
problems involved in detecting and locating sud-
den changes in transmission level. In a few
words, the problem is one of making direct de-
terminations of the trouble locations in a mini-
mum time; preferably as they occur.

To help solve this problem, Bell Laboratories
has developed a Telephoto Transmission Meas-
uring Set (TPTMS) which automatically and
continuously indicates the amplitude level of the
telephoto circuits between a sending and receiv-
ing station. The new set does this by taking ad-
vantage of a hitherto unimportant part of picture
transmission — the “clamp-bar interval.”

Unlike video signals, which synchronize once
during each line, telephotograph systems gener-
ally remain in synchronism for the duration of
the entire picture transmission interval — ap-

Block diagram of the Telephoto Transmission
Measuring Set. Line signal enters the set at the
top and arrows indicate how signal is processed.

proximately eight minutes. After an initial phas-
ing, where the receiver scanning mechanism is
positioned to correspond with the transmitting
mechanism, only picture modulation signals are
transmitted. There is, however, a certain amount
of “dead-time” available during each scanning
line. This dead-time corresponds to the scanning
of the clamp-bar, a device which holds the picture
copy securely on the transmitting drum. Though
no clamp-bar is required in flat-bed systems, an
equivalent clamp-bar period is transmitted.
Since the clamp-bar interval represents re-
peatable dead-time, this time can be used for “in-
service’ measurements of the transmission level
of the system. This is done by inserting a special
signal at the transmitter during the dead period
and then detecting it at the receiving station. In

the new system, the inserted signal is a burst
of tone, with a frequency outside the band oc-
cupied by the modulated telephoto signals. This
pulse is separated from the telephoto signal by
a filter arrangement at the receiver, and then
is used to indicate line level.

One of the first steps in the development of
the measuring system was the design of a pulse
generator capable of inserting a burst of tone
during the clamp-bar interval. The diagram
below shows the general arrangement of this
generator. A small permanent magnet on the
drum of the telephoto transmitter passes the
pole-piece of a pickup coil at the same time the
optical system scans the clamp-bar. Thus, each
revolution of the drum induces a pulse in the
coil. This pulse is amplified, shaped, and made to
drive a modulator which gates a 1000-cycle os-
cillator. The resultant output signal is a 25-
millisecond burst of 1000-cycle tone during each
clamp-bar interval. This signal is combined with
the normal, amplitude-modulated telephoto trans-
mitter output, and yields a composite line signal
like the one shown on the opposite page.

The clamp-bar pulse is transmitted once per
revolution of the transmitting drum—a pulse
rate of from one to three per second, depending
on the telephoto system. Because these pulses
are so widely spaced in time, measuring them in
a way that would give a continuous display of the
network level posed a problem.

To meet this requirement, the designers of the
set developed a unique peak-discharge circuit.
This arrangement makes it possible to measure
the level of an individual clamp-bar pulse and
retain this reading until the next pulse is re-

ceived and its level recorded. The meter, there-
fore, displays a steady reading on transmission
facilities which do not exhibit level changes. -

The actual flow of a line signal through the
measuring set and the major circuits of the unit
are shown in block-diagram form on page 99.
A composite signal (picture signal and tone
burst) is taken off the line at the measuring-set
location by a four-way bridge. In the band-pass
amplifier, the clamp-bar signal is separated from
the composite line signal and amplified. A volt-
age measurement that corresponds to the level
of the clamp-bar signal is then displayed on a
peak-reading meter calibrated in decibels. The
discharge time-constant of this measuring cir-
cuit is longer than the time between clamp-bar
pulses, so the meter retains an indication that
does not change perceptibly during the picture
interval between pulses.

For a new measurement of network level to
be made during each clamp-bar interval, how-
ever, it is necessary to discharge the peak-read-
ing circuitry. To do this, a second output from
the band-pass amplifier feeds a series of pulse-
forming elements which derive a spiked pulse
corresponding in time to the beginning of the
clamp-bar signal. This pulse discharges the meter
circuitry, but immediately following discharge
it is recharged by the remainder of the clamp-
bar signal. This discharge-charge process occurs
in an interval of time so short that the mechani-
cal inertia of the meter prevents a noticeable de-
flection, provided the level of the clamp-bar signal
is the same as the preceding signal.

In addition to visual monitoring of the meter,
the measuring set may also be connected to an

A diagram showing the clamp-bar pulse generator. The pulses and line signals shown are idealized.

Typical line signal illustrating clamp-bar pulse.
Levels of picture signal are 4 db below maximum.

external graphic recorder to permit unattended
operation. The response of the measuring set is
such that it can indicate changes in level of from
+0.25 db to +10 db from pulse to pulse.

One point that has not been covered so far
is the exact method of inserting the clamp-bar
pulse signal. It appears advantageous that this
be done by the customer. Starting the pulse at
his station allows for an over-all measurement
of all of the facilities involved, including the
transmitting loop, the terminating key equip-
ment, and the telephoto transmitter. This also
simplifies the circuitry, since the regulated volt-
ages necessary to power the clamp-bar pulse
generator are in most cases available from the
customer’s transmitter. The frequency of the
clamp-bar signal can be simply derived by divid-
ing the carrier frequency by two.

A trial of the Telephotograph Transmission
Measuring Set has been conducted with six mod-
els, placed in service on one leg of a large tele-
photo network. Thirty additional production mod-
els will be completed and in service soon. A
prototype of these portable units is shown in use
in the photograph on page 98. Transmission
levels were monitored continuously through the
use of strip-chart recorders. Even with only one
sending station equipped with a pulse transmit-
ter, many irregularities were detected. Though
a majority of the level irregularities were of
small amplitude, a number of serious level changes
were also recorded. The set has also proven use-
ful in detecting excessive-noise conditions, and
some thought has been given to using the
clamp-bar signal for automatic gain control of
telephoto systems.

Universal application of the new level-measur-
ing system, through the cooperation of the Bell
System’s telephoto customers, will result in a
reduction of outage time on telephoto networks.
The new technique should likewise lead to con-
siderable economies in the operation of large
telephoto networks.

On February 3rd, the Army successfully test
fired a Nike-Zeus anti-missile missile at the White
Sands Missile Range, New Mexico. On the basis
of the initial data, the launch, boost, separation
and sustainer operations all were successful, the
Army said. All objectives of the test were
achieved.

The test was one of a series of preliminary
firings to evalute the aerodynamic characteristics
of the anti-intercontinental ballistic missile weap-
on now under development by the Army Ordance
Corps. Prime contractor for the system is the
Western Electric Company. System development
is the responsibility of Bell Laboratories, and the
missile and its handling equipment is in the
hands of Douglas Aircraft. The rocket motors
were produced by Grand Central Rocket Company
and Thiokol Chemical Corporation.

The firing was successful in all characteristics.
The Zeus traveled an unguided bailistic course.
To accomplish this the guidance fins were locked
in zero-degree position. Both the booster and the
sustainer motor were fired successfully. Devel-
oping 450,000 pounds of thrust, this booster is
the largest solid-propellant motor, using single-
grain fuel, ever fired.

Nike-Zeus will be an anti-missile missile cap-
able of intercepting enemy intercontinental bal-
listic missiles before they can reach their targets.

An early test model of the Nike Zeus anti-mis-
sile missile awaits take-off at White Sands, N. M.

fico new systemts are expected to het]
lhe increased de mand tor recorded

Recorded announcements have been serving
Bell System customers for many years. Since
1939, for example, residents of the New York
metropolitan area have been able to call a tele-
phone number and hear the current weather
forecast. More recently, Operating Telephone
Companies have added other recorded announce-
ment services. Sports news, highway traffic re-
ports and department-store sales bulletins are a
few of the announcements that are being made
available to the public through their regular
telephone facilities.

The success of these services prompted the
development of two new standard announcement
systems. One of these is designated the 8A An-
nouncement System and is intended for services
where the calling rate is relatively light, as in
announcing theater programs. The other is the
9A System (RECORD, February, 1959) for heavy-
traffic services—for example, the previously
mentioned weather-forecast announcements in
large cities.

Both systems were developed in two more or
less independent parts: the central-office ‘‘switch-

ing facilities’ and the ‘‘audio facilities,” of which
only the latter will be discussed in detail in this
article. The switching facilities include incoming
trunk circuits, alarm circuits and arrangements
for distributing the recorded announcement. Basi-
cally, the audio facilities consist of:

» a mechanism for recording the announcement
and playing it back; this is known as the
“recorder-reproducer” or “announcement ma-
chine” ;

» an amplifier used in both the recording and
the playback operations; and

» “remote control” apparatus that permits a
person at a distance from the announcement
machine to control the machine and to record
announcements.

The objectives of the work on these new audio
facilities were to incorporate improved recording
techniques, to simplify operating procedures, and
to provide a more integrated and therefore more
versatile recording-reproducing system.

mdio factlities have been designed
pinciude many ovemen4
table cucle ation thal
roth ol thre

To appreciate the nature of this new equip-
ment, it will be helpful to look at the announce-
ment service from the point of view of the ‘“spon-
sor’”’— which may be the Telephone Company
itself or another organization.

The sponsor uses the “remote control’ appa-
ratus to control the machine and to record the
announcements. This apparatus, shown on the
left in the diagram on the next page, consists of a
special handset, a small control unit, and a small
wall-mounted box. When the Telephone Company
is the sponsor, this apparatus will usually be at
a quiet location in the same building with the
announcement machine; otherwise, it can be miles
away on the premises of the sponsoring customer.

To dictate (record) an announcement, the spon-
sor uses the handset and the various switches and
keys on the control unit. The handset, although
it appears to be of conventional design, has a
dynamic (moving-coil) microphone in place of the
carbon-grain transmitter. This unit improves
both the speech quality and the intelligibility of
the announcement. The receiver, used to check
and monitor the recorded announcement, is the
U1 unit used in 500-type telephone sets.

All the manual controls required for operating
the announcement machine from the sponsor’s
premises are on the front panel of the control
unit. A speech-level indicator, with. a two-color
band for a scale, is also mounted on the front
panel. It serves as a simple talking-level guide
for the user.

W. Buckalew checking a dual-
channel set up; variable
length announcement—up to

A circuit in the wall-mounted box amplifies the
output of the handset. Gain is adequate for the
lowest talking level likely to be encountered, and
in addition, the circuit has an automatic loud-
ness-control action to equalize the recording level
of loud talkers with that of weaker talkers. This
“constant-loudness” feature, along with the indi-
cator in the control unit, aids the user consider-
ably in making a satisfactory recording on the
first try. Thus, the possible annoyance of re-
peated recording is greatly reduced.

From the remote-control apparatus, the speech
signals are sent to the announcement equipment
(see photograph below). This equipment, consist-
ing of the announcement machine, record-repro-
duce amplifier, coupling and distribution units,
will usually be located in a central office.

The speech signals go from the coupling unit
to the record-reproduce amplifier, where they are
amplified and combined with a high-frequency
“bias” signal. Bias current is needed so that when
the combined signal is applied to the recording
head, an undistorted pattern of residual magneti-
zation is produced in the recording medium.

The recording medium here is “magnetic rub-
ber,” made by combining an elastic, rubber-
like material (currently the commercial product
Hypalon, a polyethylene derivative) with mag-
netic iron oxide. The mixture is molded in the
form of a circular band and is then stretched
over a nonmagnetic, metal drum.

Only one announcement at a time can be placed
on the recording drum, but its duration may
range from a few seconds to 4 minutes. Further-
more, the machine automatically establishes a

playback cycle whose length corresponds closely
to the length of each new recording.

This feature, called ‘‘variable cycle,” is an im-
portant part of the new development. With “fixed
cycle” machines now in use, it is necessary to
“tailor” the lengths of announcements carefully
to make a satisfactory recording. If the length
falls short of the allotted time, undesirable ‘‘dead
time” results, during which the calling customers
hear nothing. If the length is excessive, of course,
the announcement will not be entirely recorded.

The block diagram below shows a single-chan-
nel and a dual-channel arrangement of the audio
facilities. In both cases, the speech and control
signals originate at the remote-control equipment
(left), and are sent to the announcement equip-
ment via telephone lines or, when the control
equipment is nearby, via conductors in a local cable.

The single-channel arrangement is obviously
the simpler of the two, and represents the mini-
mum amount of equipment. To avoid service in-
terruption during recording, the control circuitry
is arranged for “live dictate.” This means that
calling customers, instead of getting a busy signal
when a new announcement is being recorded, hear
the actual voice “live” as it is recorded.

The dual-channel arrangement is more sophis-
ticated. With it, the sponsor can check the newly

LOCAL
CABLE OR
TELEPHONE
LINES
3 LINES
SPONSOR'S CONTROL
-EQUIPMENT OR
16
CONDUCTORS

Both the single-channel and the dual-channel ar-
rangements for recorded announcements are rep-
resented in this drawing. Sponsor’s attendant

recorded announcement before it is made acces-
sible to callers. In addition, it ensures a higher
degree of service reliability. Parts of the an-
nouncement equipment are duplicated so that
there are two independent channels — one is con-
nected to the circuit, or line, outgoing to the
distribution and trunk circuits in the central
office, and the other is connected to the sponsor’s
recording apparatus. The latter is in a standby
status, ready for recording a new announcement
or for transferring to the line, in the event of
“on-line” channel failure.

As noted on the block diagram, the single-
channel arrangement requires two telephone lines
from the remote-control equipment, and the two-
channel version requires three lines. When the
remote-control position is nearby, nine and six-
teen conductors, respectively, in a local cable may
be used instead for the two arrangements. For
these cases, the remote-control portions of the
announcement equipment shown in the diagram
are not required. The “coupling unit” and “dis-
tribution unit,” also shown on the diagram,
connect the remote-control equipment and an-
nouncement equipment to the central-office cir-

ANNOUNCEMENT
“Bus” TO CALLING CUSTOMERS
VIA CENTRAL OFFICE
TRUNK CIRCUITS AND
SWITCHING FACILITIES

dictates announcement into handset of control
unit, left, and signal is carried over telephone
lines or local cable to announcement equipment.

Close-up of control unit showing various control
knobs. Here, attendant is depressing DICTATE key.
DICTATE light (above) lights when drum is “clean.”

cuits. In addition, the coupling units permit local
control of the announcement machines, so that
Operating Company personnel can record and
check announcements for maintenance and tests.
A switch on the coupling unit disconnects the
sponsor’s apparatus local operation.

A brief description of the recording procedure
for the dual-channel arrangement will illustrate
several of its advantages: The sponsor’s attend-
ant at the remote-control equipment can change
the announcement at will. To do this, she sets the
control unit to DICTATE (see photograph on this
page) and depresses a “dictate” key. This action
erases the old recording in the standby channel.
Erasure of the entire recording drum takes about
six seconds, after which the “dictate” lamp lights
on the control unit. The attendant then begins
talking (dictating) into the handset. The words
are recorded on the “clean” magnetic rubber of
the standby channel.

At the end of dictation, the attendant releases
the dictate key and sets the control unit to CHECK
to listen to a playback. If she detects a verbal
error or is dissatisfied with the announcement for
other reasons, she merely repeats the procedure
as many times as necessary. This does not inter-
fere with service, since she is recording on the
standby channel.

When she is satisfied with the announcement,
she operates a TRANSFER switch on the control
unit. As the on-line announcement in progress
ends, the newly recorded channel is automatically
transferred to the line. The channel with the old
announcement still recorded on it thus becomes
the standby.

with the old announcement still on the second
channel. At this point, however, the announce-
ment equipment automatically performs an addi-
tional important step. It causes the old announce-
ment to be erased from the standby channel and
the new one to be recorded in its place. Thus, as
a result of this “automatic dubbing” process,
identical announcements are on both channels
with no further action required of the attendant.
Then, if an electrical or mechanical failure should
occur in the on-line channel, the standby is au-
tomatically transferred to on-line operation. In-
terruption in service is thus very brief.

Other operational features are also designed
into both the single-channel and dual-channel
systems. For example, a “repeat dictate” lamp on
the control unit lights if the announcement being
recorded or the one just recorded is technically
unacceptable (because of low speech level or ex-
cessive length). The attendant then knows that
she must repeat the dictating procedure in a
satisfactory way.

In the dual-channel arrangement, another
lamp, the “transfer ready,” tells the attendant
whether her newly recorded announcement is
technically adequate and reminds her to transfer
this announcement to the line. She can also cancel
the “transfer” and “automatic dubbing” func-
tions if she finds it necessary to change the new
announcement at this time.

For longer-life service, the announcement ma-
chines will normally operate only on demand —
that is, the on-line machine will run only when
one or more calling customers are connected to
the system. The standby channel machine will
remain idle unless recording or checking is in
progress. As an optional feature, continuous oper-
ation of either or both channels is available.

Although these and other features of the
audio facilities add to the complexity of the cir-
cuitry, they simplify operating procedures. The
tasks of the user are reduced to a minimum con-
sistent with flexible and dependable operation
of the systems, and moreover, the user does not
have to develop special skills.

Since these audio facilities provide completely
integrated and independent recording and repro-
ducing, they are expected to find many applica-
tions in addition to the 8A and 9A Announcement
Systems. But what is also important, the 8A and
9A Systems, because of their improved perform-
ance and reliability, versatility and simplicity of
operation, are expected to promote the widespread
use of recorded announcements of many varieties.

Of the approximately 50 million telephones in
the Bell System served by dial central-office equip-
ment, about one million are of the pre-payment
coin type. Over the past few years, the Bell Sys-
tem has substantially improved non-coin custom-
er service by developing new switching and
charging features. Charging arrangements, such
as multiple registration and Automatic Message
Accounting, have greatly extended the areas
reached by direct dialing. However, these devel-
opments are not applicable for coin stations since
they make no provision for collecting the charges
at the time of the call.

Calls originated at dial coin stations and des-
tined for other stations within the minimum
charge local zone can be dialed directly and do
not require the assistance of an operator. In
some metropolitan areas, however, dial coin sta-
tions originate a substantial amount of multi-
unit (zone) traffic for points beyond the mini-

mum local zone. In New York City, for example,
an initial deposit of ten cents is required for
minimum-charge local calls. But there is a sub-
stantial amount of multi-unit traffic to offices in
other zones where the charge for the initial period
is 15, 20, 25 and 30 cents. A system of operation
permitting the customer to dial such calls is
known as coin zone dialing.

Originally, Laboratories engineers developed
coin zone dialing to permit completion of calls
from panel and No. 1 crossbar offices by way of
a panel-sender tandem office only. Later, they de-
veloped a way to permit completion by way of a
crossbar tandem office also. And recently, they
designed coin zone dialing for use with No. 5
crossbar. In this system, however, completion of
calls is not limited to a route through tandem
offices, but may go over direct trunks to the ter-
minating office.

initial deposit, just as he would for a local call.
Then he dials the call directly as though it were
originating at a non-coin phone. However, since
the call is to a point beyond the local zone, the
common-control switching equipment signals an
operator and indicates to her, by a distinctive
lamp, the amount of the charge for the initial
period. When she receives this lamp indication,
she plugs a cord into a corresponding jack in the
switchboard multiple and requests the customer
to make his deposit. When he deposits the money,
she withdraws the plug from the jack, permitting
the call to proceed. She need do no more unless
the call involves overtime.

If overtime is involved, and this occurs only
on a minority of the calls, a timing mechanism
in the trunk circuit again signals the operator,
this time by flashing the same lamp. She can
then time the overtime conversation, determine
the overtime charge, and supervise the deposit
for the overtime charge for that particular call.

Coins are collected in several ways. For ex-
ample, if the conversation extends to within one-
half minute of the end of the initial timing inter-
val, the coins deposited for that interval are

collected at this time. However, if an answered
call terminates before this time, the charge is
collected when the calling customer hangs up.
On the other hand, charges for the initial period
are returned automatically if the calling customer
hangs up before the call is answered. Also re-
funded automatically is any additional deposit
made during the last one-half minute interval
and up to the time an operator connects to the
circuit as a result of her receiving an overtime
signal.

As indicated in the block diagram (below)
the operators who supervise the initial deposit
and overtime on coin zone calls may be located in
the same building with the No. 5 crossbar equip-
ment or in a distant building. When they are lo-
cated in a distant building, the system might
make use of a concentrator — a device that “fun-
nels” the traffic of a relatively large group of
trunks to a group of fewer trunks to the switch-
board in the central office.

A maximum of eight “zones” can be indicated
for each trunk on lamps at the operator’s switch-
board. These lamps are controlled by polar duplex
signals applied to each of the two conductors of
the speech path. Nine combinations of signaling
are available in each direction, each independent
of the other direction. Signals from the switch-

In junctor operation, traffic from coin stations is
concentrated into one group of circuits and direct-

ed through the switching equipment for delivery
over non-coin routes, alleviating traffic problems.

M.C. Goddard with the labora-
tory model of the trunk frame
for switching arrangements
for coin telephone dialing.

board indicate operator’s actions — for example,
whether she has answered, or whether she has
operated a coin return, a coin collect, or a ring-
ing key.

Coin zone calls in No. 5 crossbar will ordinarily
be handled by junctor operation. This is a method
of concentrating the traffic for many destinations
into one group of coin zone circuits and then
directing the call through the line-link and trunk-
link frames to a non-coin route to the desired
destination. Since the periods of heavy coin traffic
during an average day are different from those
of heavy non-coin traffic, the same trunks can be
used in common for both services. There may
be cases, however, that justify direct coin-zone
trunks rather than junctor operation. In such
cases, direct trunks would avoid the need for ex-
tra channels through the No. 5 crossbar office
and for the common-control equipment inherent
in junctor operation.

Only multifrequency pulsing senders have been
arranged for coin zone operation. Their advan-
tage lies in their rapid outpulsing, or “delivery”
of the dialed digits. The operation of the sender
is affected in two ways in coin zone dialing: (1)

the connection toward the called party is delayed
until the operator has verified a proper coin de-
posit for the initial period, and (2) timing of the
call is cancelled while the operator is connected
to the circuit.

Long Beach, New York, on the south shore of
Long Island, was an early candidate for coin zone
dialing. Primarily a summer resort area, it has
a high proportion of transient visitors and short
term residents —a population situation result-
ing in a large volume of coin telephone traffic.
Moreover, Long Beach is fairly close to New
York City and, as a result, much of the traffic
is zone traffic.

At Long Beach, the New York Telephone Com-
pany has set up 80 coin zone circuits — 40 coin
zone junctors and 40 direct trunks to a crossbar
tandem office in Manhattan. Coin zone dialing
has been introduced in No. 5 crossbar offices in
several additional places in the New York City
area. Moreover, other metropolitan areas such
as Los Angeles and San Francisco are planning
to use this type of service.

Two Titan Missiles Successfully
Guided by Laboratories-Developed
Command Guidance System

In an important series of test
firings of the Titan ICBM (inter-
continental ballistic missile) from
Cape Canaveral, Florida, last
month, the command guidance
system developed at Bell Labora-
tories twice successfully guided
the huge missile. In the first of
these successful firings, on Febru-
ary 2, the second stage of the
Titan was steered on its prede-
termined trajectory over the At-
lantic Ocean.

This was the first guided test
flight of the over 90-foot, 110-ton
Titan missile. In previous flight
tests, only the first-stage rocket
engines were fired. The dummy
second stages were filled with
water. In one previous test (May
4, 1959), following a successful
launching and engine burnout
of the first stage, the second
stage was separated from the
first, but as in previous flights,
was not fired.

In the February 2 test, after
separation of the two stages, the
second-stage engine was fired and
continued to accelerate the vehicle
to the desired altitude and veloc-
ity under the control of the com-
mand guidance system. Then
commands were sent to cut off the
engine, and the missile followed
a ballistic trajectory to its se-
lected destination hundreds of
miles away.

In the second successful test
firing, on February 24, the mis-
sile’s reentry vehicle (nose cone)
was separated from the second
stage and landed in a preselected
target area in the Atlantic Mis-
sile Range. An instrumented data
capsule was ejected from the nose
cone and picked up by a waiting
Air Force recovery vessel.

Signals were sent from a
ground guidance station at the
launching site to the missile
(see cover) to steer it along a
desired trajectory. After separa-
tion from the second stage, the

reentry vehicle followed a ballis-
tic trajectory to its selected des-
tination, some 5,000 miles away.

Developed for the Air Force
Ballistic Missile Division, the
command guidance system for
the Titan was previously tried
out in a series of Thor Able II
test shots (REcorpD, May, 1959).
This highly accurate guidance
system helped the Air Force make
the first recovery of a nose cone
fired over an ICBM range. Teamed
with the Laboratories in the guid-
ance-system project is Remington
Rand-Univac, who developed and
produced the computer used in
the guidance system. The system
itself is produced by the Western
Electric Company.

The Titan missile, assembled
by the Martin Company, is de-
signed to fly at speeds of more
than 17,000 miles per hour with
a range of over 6,000 statute
miles. Insuring that it reaches its
desired target requires precise
control. For example, at the time
of cut-off of the second-stage en-
gine, when the missile may be
traveling about 25,000 feet per
second, a difference of one foot
per second in the desired speed
can cause a miss of one mile at
the target. Signals to control the
exact moment of engine cut-off
are a guidance-system function.

The Bell Laboratories command
guidance system, its accuracy
and reliability already tested,
is also scheduled for use _ in
forthcoming satellite launches and
space probes in other programs.

William W. Anderson, left, and Marion E.. Hines inspect laboratory
model of new traveling-wave solid-state amplifier. Device combines
negative resistance of Esaki diodes and one-way attenuation of fer-
rite strip transmission line arrangement for improved amplification.

Bell Laboratories announced a
new broadband microwave ampli-
fier using all solid-state devices
at the Solid-State Circuits Con-
ference held February 10 in Phila-
delphia. The device was described
in a paper by Marion E. Hines
and William W. Anderson of the
Solid-State Electronics Research
Department. The new amplifier
makes use of a property of the
Esaki, or “tunnel,” diode. This
property is “negative resistance”
—a decrease in current with an
increase in voltage. The device
also makes use of a ferrite prop-

erty — the ability to provide at-
tenuation for only one direction
of wave propagation. These two
properties help the amplifier
achieve a high amplification ratio
without self-oscillation.

The new amplifier can be used
to increase the strength of radio
signals over a broad band of fre-
quencies in the microwave range
above 1000 megacycles. Labora-
tories engineers expect it to have
applications in radar, microwave
radio relay, satellite communica-
tions, and waveguide transmis-
sion systems. They also expect

the low-powered device will cost
less and have greater reliability
than other methods of achieving
comparable amplification of sig-
nals.

The device is built on a travel-
ing-wave concept with a row of
Esaki diodes along the center of a
strip transmission line waveguide.
The negative resistance of the
diodes causes the power in a signal
wave to increase progressively as
it travels along the waveguide. By
including a magnet and a piece
of ferrite material in the struc-
ture, the designers have made the
device absorb waves traveling in
the undesired reverse direction
while it amplifies waves traveling
in the desired direction. This fea-
ture allows a large total ampli-
fication to be obtained with com-
plete stability by eliminating in-
ternal “feedback” —a_ phenome-
non that had previously caused
oscillations and other difficulties
in amplifiers of this type.

The active diode used in this
amplifier was discovered by Leo
Esaki of the Sony Corporation in
Japan. It has aroused consider-
able interest in the electronics in-
dustry because it is a simple semi-
conductor device which can con-
vert direct current into useful
alternating-current signals’ in
communications and computer cir-
cuits. The Esaki diode has only
two terminals and thus is easier
to construct than triode transis-
tors or vacuum tubes. Yet it can
do many of the same jobs.

Its most useful aspect is its
negative-resistance. This lets it
add to the power of signal waves
instead of absorbing the power as
a positive resistance does. Al-
though negative-resistance de-
vices have been known for many
years, the Esaki diode is superior
to previous types in its simplicity,
in its low-power requirements, in
the magnitude of its negative-
resistance effect, and in its ability
to operate at extremely high fre-
quencies.

Esaki diode by eliminating unde-
sired feedback —one of the major
difficulties in applying it as a sig-
nal amplifier. The model described
has operated most efficiently be-
tween 1200 and 1600 mec. Engi-
neers expect that the frequency
of operation of future models can
be extended to above 3000 me,
still using germanium diodes.
Much higher frequencies, perhaps
into the millimeter wavelength
range, should be possible with
diodes of indium  antimonide
which have been made by R. L.
Batdorf, also of the Solid-State
Electronics Research Department.

In fact, these methods have
worked for  indium-antimonide
diodes having speeds several times
faster. However, new models be-
ing devised by Robert L. Batdorf
and other members of the Solid-
State Electronics Research De-
partment are so fast that they
are beyond present stabilization
techniques. For example, one such
diode has switched a signal of a
quarter volt in less time than it

An Esaki diode (see item on
opposite page) is a semiconductor
device which exhibits a negative-
resistance region in its voltage-
current curve when biased in the
forward direction. In other words,
the current decreases as the volt-

age increases. This negative re-
sistance, multiplied by the junc-
tion capacitance of the diode, gives
a time constant indicating the
relative merit of the device. In
general, a smaller time constant
corresponds to a faster operating
device.

To make direct measurements
of the negative resistance and
junction capacitance, the engineer
must first stabilize the diode in
its negative-resistance region. He
can do this by shunting the diode
with a resistor made equal to or
smaller than the negative re-
sistance of the diode. Then if the
series inductance in the circuit
connecting the shunt to the diode
is small enough, the combined
diode and shunt will show a
voltage-current curve which is
stable and positive in slope over
the entire voltage range of the
diode and which, therefore, can be
plotted. If the engineer plots the
voltage-current characteristics of

the shunt resistance alone and
subtracts the shunt resistance
current manually from the total
current, he can obtain the cur-
rent characteristics of the diode.

Robert L. Batdorf, left, and Donald E. Thomas inspect voltage-
current curve of an Esaki diode just traced on new instrument.
Measuring instruments such as this one must be constantly im-
proved to keep up with the development of devices they measure.

Details were made public re-
cently of the major scientific and
technologicai effort being mus-
tered toward achieving the first
satellite-tracking and ground in-
strumentation system to encircle
the globe. This is a vital phase of
the National Aeronautics and
Space Administration’s Project
Mercury.

Construction on the network
has already begun. Eighteen sites
make up the world-wide chain of
ground stations. When completed
in 1961 they will provide com-
munications to America’s first
astronaut as he orbits the earth
in space at 18,000 miles per hour.

The world-wide complex essen-
tial to the success of the project
will have a computing and com-
munications center at the Goddard
Space Flight Center, Beltsville,
Md., and a control center at Cape
Canaveral, Florida. The 18 sta-
tions comprising the tracking and
ground instrumentation system
will include Cape Canaveral,
Grand Bahama Island, Grand
Turk Island, Bermuda, specially
equipped ships in the Atlantic and
Indian Oceans, the Canary Is-
lands, two sites in Africa, West
and South Australia, Canton
Island, Hawaii, two on the west
coast of North America, White
Sands, N. M., South Texas, and
Eglin Air Force Base, Fla.

For the project, Bell Labora-
tories will handle the basic sys-
tems engineering associated with
communications and visual pres-
entation and will provide con-
sultation in radar and communi-
cations. The Laboratories also
will study the compatibilities of
various equipments, and develop
operational plans to insure the
adequacy of the requirements for
the over-all system.

Western Electric will be respon-
sible for managing and directing
the activities of other team mem-
bers to see that the network is
built on time and that it has the
required capability and reliability
to perform as specified in the con-
tract. Western Electric is also
responsible for the design and
implementation of ground com-
munications required at site loca-
tions, for the study of, and the
lease arrangements for, suitable
communications among the 18
sites. The Company will also
train maintenance and _ opera-
tional personnel.

Pulse code modulation with mil-
limeter waves requires very nar-
row pulses that can appear and
retire very quickly. With this
new modulator, the designers have
achieved pulse “rise” and “decay”
times of less than 2 millimicro-
seconds at a repetition rate of 10
megacycles. The operation is car-

The device is essentially a
“switch,” that is, it effectively
turns the incoming radio-fre-
quency carrier signal on and off
at a desired frequency. It takes
advantage of the fact that the RF
impedance of the germanium di-
odes used with suitable wave-
guide mounts and tuning elements
can be varied from a nearly per-
fect absorber of radio waves to
a practically complete reflector.
This change can be made merely
by switching the bias signal on
the diode. Sending about 40 milli-
amps of current through the
diode in the forward direction
gives rise to the absorbing factor.
A reverse bias of 5 to 10 volts will
then cause the assembly to be a
nearly perfect reflector of radio
waves,

The modulator uses a pair of
diodes mounted in sections of
waveguide, combined with a hy-
brid junction. When the modula-
tor is “on,” the diodes reflect
essentially all of the incident en-
ergy, and the microwave signal is
transmitted with an attenuation
of only 1 or 2 db. When the
modulator is “off,” however, prac-
tically all of the energy to the
diodes is absorbed, and the trans-
mitted signal is attenuated 30 to
40 db. Engineers have used up
to one watt of power to success-
fully modulate at 35 kme, and
have used pulses as short as 5
millimicroseconds.

The diodes in this assembly are
formed inside the waveguide
structure, using techniques devel-
oped by A. E. Bakanowski, D. E.
Inglesias, and Mrs. M. S. Boyle,
all of the Transistor Development
Department. In the method, a
gold wire is attached to an n-type
germanium wafer by electrical
bonding. The bonding process is
carried out by passing three short
pulses of current through the con-
tact, giving a small, but secure,
bond area.

The point where a ballistic mis-
sile or re-entry vehicle hits the
surface of the ocean can now
be located by special underwater
detection systems. They have been
developed for the U. S. Navy by
Bell Laboratories and are being
installed by the Western Electric
Company at both the Atlantic
and Pacific ballistic missile
ranges. Now in operation at the
Atlantic Range, the underwater
detection systems are aiding re-
covery teams to find and retrieve
the nose cones of missiles that
have completed their space flights
(see page 109).

Two types of missile-impact lo-
cating systems (MILS) are used
in locating the missile-impact
point. One is a surface-impact
system and the other is a Sofar
(Sound Fixing and Ranging)
bomb method. Both rely on the
principles of transmission of
sound under water.

The surface-impact system de-
tects and locates the sound of a
missile actually striking the
ocean’s surface. This system uses
six hydrophones, or underwater
sound receivers, installed on the
ocean floor and connected by a
special cable to the shore station.
Five of the receivers are located
in the shape of a pentagon with
the sixth in the center. Informa-
tion from at least three of the six
hydrophones is needed to obtain
an acoustic “fix.”

In the Sofar method a bomb is
ejected from the missile and ex-
ploded under water in the vicinity
of the impact point. The sound
of the exploding bomb permits
the range and bearing to be meas-
ured to determine the area of
impact. With Sofar systems, de-
tection is possible at distances of
several thousand miles.

For the Sofar detection method,
a series of hydrophones, gener-
ally located in pairs, are spaced
about a large area and connected

to shore stations by submarine
cables. Electronic equipment at
the shore stations records the sig-
nals from the hydrophones when
they receive sound waves gen-
erated by the explosion of the
Sofar bomb. Trained operators at
the shore installations use the
time differences of the sound ar-
rivals at different hydrophones to
obtain the acoustic fix that es-
tablishes the spot where the
sound originated.

The operator obtains the time
of arrival of the signal at each
hydrophone of the various pairs
of hydrophones he has selected.
Subtraction gives him a time dif-
ference between any two hydro-
phones. Since the location of
the hydrophones and the velocity
of sound in water at each loca-
tion are known factors, the oper-
ator can convert time difference
into distance difference by mul-
tiplying the time difference by
the average velocity of sound for
the combination of two hydro-
phones. Then he determines the
acoustic fix by locating the inter-
section of two or more distance-
difference lines on previously pre-
pared charts.

To arrive at an acoustic fix,
operators must know the speed
with which sound travels through
water at the location of each
hydrophone. This velocity of
sound at any given point in the
ocean is a function of tempera-
ture, pressure and salinity. To
check velocity and other factors
in the Atlantic Ocean, last year
personnel from the Laboratories,
Western Electric Company and
the U. S. Navy conducted a three-
month calibration operation. Some
1,500 explosive charges were
dropped in the ocean range areas
to simulate the conditions of a
missile-locating operation. By
knowing the explosion time and
position of these charges, the sci-
entists checked the accuracy of
the underwater detection systems
and provided data for the oper-
ators’ use in determining acoustic
fixes.

as a navigation aid to recovery
vessels. Prior to a missile launch-
ing, a ship drops Sofar bombs.
The time of arrival of the signal
at the hydrophones determines its
exact position in relation to the
expected impact point of the mis-
sile.

Although an operator at the
MILS station plots the acoustic
fix on his charts, a more exact
calculation is obtained by using
a computer. Arrival time data
from the Atlantic shore stations
are sent to Patrick Air Force
Base, Florida, and relayed to
Winston-Salem, North Carolina,
where the information is fed into
a computer at the Western Elec-
tric plant there. This operation
furnishes precise determination
of the impact point.

Several MILS stations have
been established, including one on
the British island of Ascension.
Similar stations have been set up
or are being constructed on is-
lands in the Pacific for the Pa-
cific Missile Range.

The Underwater Systems De-
velopment Department of Bell
Laboratories developed the detec-
tion systems. Equipment for the
systems is furnished and installed
by the Western Electric Co. plant
in Winston-Salem, North Caro-
lina,

“The Universal,” latest addi-
tion to the Bell System’s family
of pay phone booths, is a versa-
tile new indoor-outdoor model, de-
signed by Bell Laboratories. It
will be available to the Operating
Companies early this year.

The Universal was developed
in answer to Operating Company
requests for a small, glass-walled
booth that could be placed in
either outdoor or indoor locations
— like sidewalks or stores —
where space is at a premium. It
also provides transparent booths
that can be arranged in neater-
looking compact groups.

R. Karl Honaman, Director of
Publication at Bell Laboratories,
retired on March 1 after more
than 40 years of Bell System serv-
ice. Since 1945 Mr. Honaman has
directed all public relations ac-
tivities of Bell Laboratories, in-
cluding press relations, employee
information, advertising, technical
and personnel magazines, tech-
nical libraries, and community re-
lations.

He began his telephone career
in 1919 with the Development and
Research Department of the
American Telephone and Tele-
graph Co. in New York. For the
next 20 years his work dealt
principally with the protection of
telephone circuits, and a number
of patents were granted to him
for inventions in this field. As
Assistant Protection Development
Engineer, he transferred with his
group to Bell Laboratories in
1934,

At the beginning of World War
Il, Mr. Honaman organized the
School for War Training to in-
struct military personnel in radar
and related developments, and
served as its director until 1945.
After the war, he was appointed
Director of Publication, with re-
sponsibility for all publication and
public relations programs of Bell
Laboratories.

From October 1954 to January
1956, Mr. Honaman was on leave
from Bell Laboratories to serve
with ‘‘\e Federat Government.
During the first part of this peri-
od he was Consultant to the Sec-
_wetary of Commerce, and organ-
ized and served as Director of the
Office of Strategic Information.
From April to December 1955, he
was Deputy Assistant Secretary
of Defense, with responsibility for
the public affairs activities of the
Defense Department.

Mr. Honaman is Chairman of
the Committee for Engineering
Information Services, an Engi-
neers Joint Council committee
for cooperation with the National
Science Foundation.

He is a Fellow of the American
Association for the Advancement
of Science and of the American
Institute of Electrical Engineers.
He is a Senior Member of the In-
stitute of Radio Engineers, and
past president of the New York
Electrical Society. He is also a
member of the American Manage-
ment Association, The Society for
the Advancement of Management,
Public Relations Society of Amer-
ica, Public Relations Society of
New York, The Commerce and In-
dustry Association of New York,
The New Jersey State Chamber
of Commerce, The American
Ordnance Association and _ the
Armed Forces Communications
and Electronics Association.

He is a director of the Rand De-
velopment Corporation, Cleveland,
Ohio, of Floating Floors, Ince.,
New York, and of the New Jersey
Council on Economic Education.

Mr. Honaman was a member of
a delegation which visited Moscow
in 1958 to discuss trade relations
with the Soviet Union. In 1959 he
visited a number of countries in
Western Europe, where he dis-
cussed industrial and_ techno-
logical problems.

A native of Lancaster, Pa., Mr.
Honaman received the B.S. and
M.S. degrees from Franklin and
Marshall College in 1916 and 1917,
respectively. He was awarded the
1956 Alumni Citation of Franklin
and Marshall College for “out-
standing contributions to the
greater community.” In 1958 he
received the Centennial Medal of
Seton Hall University.

George Griswold, Jr., Assistant
Director of Publication of the
Laboratories, has been named Di-
rector of Publication, effective
March 1, to sueceed Mr. Honaman.

Mr. Griswold joined the Labora-
tories in 1955. Previously he had
been associated with the Long
Lines Department of the Ameri-
can Telephone and _ Telegraph
Company and with Newsweek
magazine.

A native of New York City, he
is a graduate of Yale University.
He served in the U. S. Navy dur-
ing World War II and holds the
rank of Commander in the Naval
Reserve.

Mr. Griswold is a member of
the Overseas Press Club, The Pub-
lic Relations Society of America,
and the National Association of
Science Writers.

The 1960 Oliver E. Buckley
Solid-State Physics Prize was
awarded to Benjamin Lax, head
of the solid-state division of the
Massachusetts Institute of Tech-
nology’s Lincoln Laboratory in
Lexington, Mass. Dr. George B.
Kistiakowsky, President Eisen-
hower’s special assistant for sci-
ence and technology, spoke at the
presentation, which was sponsored
by the American Physical Society
and the American Association of
Physics Teachers.

The Buckley Award, which car-
ries a_ stipend of $1,000, was
established by Bell Laboratories
in honor of the retired chairman
of the board of the Laboratories
who died last year.

Edward E. David, Jr., Director
of Visual and Acoustics Research,
was presented the Ist annual Out-
standing Young Man-of-the-Year
Award by the Summit, New Jer-
sey Area Junior Chamber of
Commerce. The newly instituted
award, an engraved plaque, was
presented at the Jaycees’ annual
awards dinner on February 2.

Estill I. Green, Executive Vice
President of the Laboratories, and
John R. Pierce, Director of
Research - Communications Prin-
ciples, have been elected Fellows
of the Acoustical Society of
America.

Mr. Green was cited for “his
patents, publications and execu-
tive direction of the acoustics of
the telephone and transmission
media associated with telephony.”

Mr. Pierce was cited for “tech-
nical exploration for world-wide
speech communication by man-
produced satellites; for formula-
tion and lucid exposition of new
communication principles with
depth of understanding of the
roles of psychological, physiolog-
ical, and technological factors in
communication.”

Sanford B. Cousins, Vice Pres-
ident—Personnel Relations of the
A.T.&T. Co., and James E. Ding
man, Vice President and Chief
Engineer of A.T.&T., were elected
to the Board of Directors of Bell
Telephone Laboratories on Janu-
ary 25. At the same time, H.
Randolph Maddox, former A.T.
&T. Vice President, retired as a
Director.

Mr. Cousins was Vice President
and General Manager of the Lab-
oratories from 1950 to 1952 and
Mr. Dingman held the same post
from 1952 to 1956.

Mr. Maddox, who retired at his
own request from the A.T.&T. Co.
on December 31, was Vice Presi-
dent-Personnel Relations from
1954 until last October when he
became Vice President with re-
sponsibilities in the field of Man-
agement Development and Per-
sonnel Research. He had been in
the Bell System since 1921.

James W. McRae, a Vice Presi-
dent of A.T.&T. Co. and former
member of the Laboratories, died
suddenly on February 2. Mr. Me-
Rae was coordinator of defense
activities for the Bell System.

His career began in 1937 when
he joined Bell Laboratories where
his work included research on
transoceanic radio transmitters
and microwave techniques, both
for civilian and military applica-
tions.

In 1942, as a Major in the Sig-
nal Corps, he coordinated develop-
ment programs for airborne radar
equipment and radar counter-
measure devices. He was awarded
the Legion of Merit for his mili-
tary service. He was later chief
of the engineering staff of the
Signal Corps Engineering Labora-
tories at Bradley Beach, N. J.,
and subsequently Deputy Director
of the Engineering Division.

Mr. McRae returned to the
Laboratories in 1946 as Director
of Radio Projects and Television
Research. Early in 1949, he was
named Director of Apparatus De-

velopment, then Director of
Transmission Development. He
was appointed Vice President in
charge of Systems Development
in 1951. He was elected President
of Sandia and Vice President of
Western Electric in 1953.

Mr. McRae, a native of Van-
couver, British Columbia, received
his bachelor’s degree in electrical
engineering from the University
of British Columbia and his mas-
ter’s degree from the California
Institute of Technology. Heearned
his doctorate there in 1937.

He was a Fellow of the Insti-
tute of Radio Engineers and
served as President of the Na-
tional Society in 1953. He was
also a member of the American
Institute of Electrical Engineers
and Sigma Xi.

In October, 1959, the Army
awarded Mr. McRae the Distin-
guished Civilian Service Medal
for contributions toward develop-
ment of a series of small tactical
nuclear weapons while he was
president of the Sandia Corpora-
tion.

Ashkin, A., Louisell, W. H., and
Quate, C. F., Fast Wave Cou-
plers for Longitudinal Beam
Parametric Amplifiers, J. Elec-
tronics and Control, VII, 1, pp.
1-32, July, 1959.

Baker, W. O., and Hopkins, I. L.,
Stress Cracking of Polyethy-
lene, Kunststoffe, 49, pp. 621-
625, Nov., 1959.

Beck, A. C., and Rose, C. F. P.,
Waveguide for Circular Electric
Mode Transmission, Proc. Inst.
Elec. Engrs. Part B, Supple-
ment No. 13—Convention on
Long-Distance Transmission by
Waveguide, Jan., 1959, 106, pp.
159-162, Sept., 1959.

Brown, W. L., The Electron Van
de Graaff in Semiconductor Re-
search, Nuclear’ Instruments
and Methods, 5, pp. 234-241,
1959.

David, E. E., Jr., and van Berg-
eijk, W. A., Delayed Handwrit-
ing, Perceptual and Motor
Skills, 9, pp. 347-357, Dec. 4,
1959.

Davies, L. W., Recombination Ra-
diation from Hot Electrons in
Silicon, Phys. Rev. Letters, 4,
pp. 11-12, Jan. 1, 1960.

DeMonte, R. W., Synthesis of
Cable Simulation Networks,
Comm. & Electronics, 45, pp.
682-686, Nov., 1959.

Frisch, H. L., Hellman, M. Y.,
and Lundberg, J. L., Adsorp-
tion of Polymers: Polystyrene
on Carbon, J. Poly. Sci., 38,
pp. 441-449, 1959.

Grenander, U., Pollak, H. O., and
Slepian, D., The Distribution
of Quadratic Forms in Normal
Variates: A Small Sample The-
ory with Applications to Spec-
tural Analysis, J. Soc. Ind. &
Appl. Math., 7, pp. 374-401,
Dec., 1959,

Kac, M., and Slepian, D., Large
Excursions of Gaussian Proc-
esses, Annals Math. Stat., 30,
pp. 1215-1228, Dec., 1959.

Kaminisky, G., and Lee, C. A.,
Investigation of the Tempera-
ture Variation of Noise in Di-
ode and Transistor Structures,
J. Appl. Phys., 30, pp. 1849-
1855, Dec., 1959.

Kaminisky, G., and Lee, C. A.,
The Preparation aid Electrical
Properties of Alloyed p-n
Junctions of InSb, J. Appl.
Phys., 30, pp. 2021-2022, Dec.,
1959.

Logan, R. A., and Peters, A. J.,
Impurity Effects Upon Mobili-
ty in Silicon, J. Appl. Phys.,
31, pp. 122-124, Jan., 1960.

Matthias, B. T., and Suhl, H., A
Possible Explanation of the Co-
existence of Ferromagnetism
and Superconductivity, Phys.
Rev. Letters, 4, pp. 51-52, Jan.
15, 1960.

Moore, G. E., Dissociation of Sol-
id SrO by Impact of Slow Elec-
trons, J. Appl. Phys., 30, pp.
1086-1100, July, 1959.

D., Transmission Deviations in
Waveguide Due to Mode Con-
version: Theory and Experi-
ment, Proc. Institution of Elec-
trical Engineers, 106, pp. 30-
36, Sept., 1959.

Sinden, F. W., Mechanisms for
Linear Programs, J. Opera-
tions Res. Soc., 7, pp. 728-739,
Nov.-Dec., 1959.

Soder, R. R., Treuting, R. G.,
and Van Uitert, L. G., The
Fluorescent Emission and Tri-
boluminescene of Terbium Hexa-
Antipyrene Tri Iodide, J. Appl.
Phys., 30, p. 2017, Dec., 1959.

Thurmond, C. D., and Trumbore,
F. A., Heats of Solution from
the Temperature Dependence
of the Distribution Coefficient,
J. Phys. Chem., 63, pp. 2080-
2082, Dec., 1959.

White, L. D., Ammonia Maser
Work at Bell Telephone Labo-
ratories, Proc. Thirteenth An-
nual Symposium on Frequency
Control, pp. 596-602, May, 1959.

Windeler, A. S., Design of Poly-
ethylene Insulated Multipair
Telephone Cable, Elec. Engg.,
78, pp. 1030-1033, Oct., 1959.

Young, J. A., Resonant-Cavity
Measurements of Circular Elec-
tric Waveguide Characteristics,
Proc. Inst. Elec. Engrs. 106,
pp. 62-65, Sept., 1959.

Following is a list of the inventors, titles and patent numbers
issued to members of the Laboratories.

Nielsen, R. J.— Fabrication of
Grid Structures for Electron
Discharge Devices — 2,921,363.

Rosenthal, C. W.—Magnetie Core
Memory Circuits — 2,922,988.
Seovil, H. E. D. and Seidel, H. —
Power Saturable Wave Guide

ANNUAL MEETING OF THE IN-
STITUTE OF MATHEMATICAL
STATISTICS, Washington, D.C.

Gnanadesikan, R., On Certain Al-
ternative Hypotheses on Dis-
persion Matrices.

Gupta, S. S., On a Single Sample
Decision Procedure for Select-
ing a Subset Containing the
Population with the Largest
Mean and Some Extensions.

Gupta, S. S., On a Single Sample
Procedure for Selecting the
Population with the Smallest
Variance.

Barry, P. H., and Whitman, A. L.,
An Error-Detection System for
5-Unit-Code  Teletypewriter
Transmission, A.I.E.E. Fall
General Meeting, Chicago, Ill.

Batterman, B. W., X-Ray Intensi-
ty Measurements and the Dis-
tribution of Electrons in Iron
and Copper, Pittsburgh Diffrac-
tion Society, Pittsburgh, Pa.

Bender, W. G., Pulse Code Modu-
lation, Merrimack Valley Sub-
section, I.R.E., North Andover,
Mass.

Blumberg, W. E., Eisinger, J.,
and Shulman, R. G., Nuclear
Magnetization Distribution of
Two Mercury Isotopes from
Their Knight Shifts, A.P.S.
Meeting, Pasadena, Calif.

Bozorth, R. M., Magnetic Proper-
ties of Ferromagnetic Super-
conductors, A.L.E.E. Conference
on Magnetism and Magnetic
Materials, Detroit, Mich.

Buchsbaum, S. J., Jon Plasma
Resonance, A.P.S., Plasma Sym-
posium, Monterey, Calif.

Bulloch, W. D., New Develop-
ments and Things to Come in
Telephony, A.1.E.E., Jackson-
ville, Fla., Dec. 14; Miami, Fla.,
Dec. 15; Tampa, Fla., Dec. 17,
1959.

Cohen, B. G., What Are These
Things Called Compound Semi-
conductors?, Johns Hopkins
University, Baltimore, Md.

Cornell, W. A., and Schulte, H. J.,
Multi- Area Mobile Telephone
Systems, I.R.E. Prof. Gp. on
Vehicular Communications, St.
Petersburg, Fla.

Courtney-Pratt, J. S., Image Dis-
section Cameras, Soc. of Photo-
graphic Instrumentation Engi-
neers, Long Island, N. Y.

Cutler, C. C., Engineering Back-
ground for Communication in
Space, Montclair Soc. of Engi-
neers, Montclair, N. J.

David, E. E., Jr., Perception and
Coding of Speech, Philadelphia
Section I.R.E., University of
Pennsylvania, Philadelphia, Pa.

DeCoste, J. B., and Stiratelli, B.
A., Characterization of Poly
(Vinyl Chloride) Resins by the
Conductivity of the Water Ex-

Engelbrecht, R. S., and Mumford,
W. W., Parametric Amplifiers:
Historical Background and Re-
cent Results with UHF Travel-
ing Wave Amplifiers Using Di-
odes, Monmouth Subsection of
I.R.E., Little Silver, N. J.

Ferrell, E. B., Fundamental Con-
cepts of Statistical Analysis,
Alumni Association RCA _ In-
stitutes, N. Y. C.

Fitch, F. B., A Computer Program
for Basie Logic, Columbia Uni-
versity, Symbolic Logic Meet-
ing, N.. C;

Fu, C., and Jepson, J. W., Cri-
teria for Design of Foundations
for Precision Tracking Radars
Considering Dynamic Response,
A.S.M.E. Meeting, Atlantic
City, N. J.

Geschwind, S., Optical Detection
of Paramagnetic Resonance in
Metastable State of Ruby, New
York University, Jan. 12; Co-
lumbia University, Jan. 19,
1960,

Hammer, J. M., Low Noise C
Band Traveling Wave Tube,
I.R.E. Prof. Gp. on Electron
Devices, Washington, D.C.

Jacearino, V., Nuclear Magnetic
Resonance and Nuclear Quad-
rupole Resonance in Antifer-
romagnets, University of Cali-
fornia, Berkeley, Calif.

Jacearino, V., Temperature De-
pendence of the NMR in Fer-
romagnetic Cobalt, A.P.S. Meet-
ing, Pasadena, Calif.

King, J. C., Dislocation and Im-
purity Induced Defects in
Quartz, Thirteenth Annual
Symposium on Frequency Con-
trol, Asbury Park, N. J.

MeMillan, B., Statistics, Measure-
ment, and Information Theory,
University of Pennsylvania,
Philadelphia, Pa.

sociated with the Determination
of the Shock and Vibration En-
vironment of a Guided Missile
in Flight, Institute of Environ-
mental Sciences, N. Y. C.

Moore, E. F., Machine Models of
Self-Reproduction, Summit As-
sociation of Scientists, Summit,
N. J.

Murphy, R. B., Quality Assurance
and Reliability, Alumni Asso-
ciation RCA Institutes, N. Y. C.

Reed, E. D., The Variable-Capa-
citance Parametric Amplifier,
I.R.E./A.1.E.E. Meeting, Phila-
delphia, Pa.

Schimpf, L. G., The Application
of Semiconductors in an 860-
MC Radio Receiver, I.R.E. Prof.
Gp. on Vehicular Communica-
tions, St. Petersburg, Fla.

Scott, J. W., Designing for the
Shock and Vibration Environ-
ment, A.S.M.E., College of En-
gineering, Newark, N. J.

Schimmin, E. R., Vanderlippe, R.
A., and Whitman, A. L., A
Small Automatic Teletypewrit-
er Switching System, A.1.E.E.
General Meeting, Chicago, Il.

Slichter, W. P., Some Develop-
ments in Polymer Morphology,
University of Wisconsin, Dept.
of Chem., Madison, Wis.

Sundquist, M. R., Sampling Tech-
niques for Automatic Wave-
form Analysis, Elks Club, Win-
ston-Salem, N. C.

Wasserman, E., Thermochromism
and Linear Radicals, New York
University, Solid-State Physics
Group, N. Y. C.

Wasserman, E., Thermochromism
of Bianthrone, Princeton Uni-
versity, Princeton, N. J. -

Harris F. Hopkins, author of
“Push-Button ‘Dialing’” in this
issue, joined the Laboratories
(then the Engineering Depart-
ment of the Western Electric
Company) in 1920. Until 1949 he
Was concerned with the develop-
ment of special products, such as
the electrical stethoscope, equip-
ment for sound systems and
acoustical instruments. Since 1949
his efforts have been devoted to
the development of telephone sta-
tion apparatus. His present as-
signment — Station Instrumen-
talities Engineer — involves ex-
ploratory development and _ field
appraisal of station apparatus
and systems. Mr. Hopkins holds
the E.E. degree from the Poly-
technic Institute of Brooklyn.

Maynard C. Waltz is engaged
in development of electronic ap-
paratus at the Allentown loca-
tion of Bell Laboratories. His
particular work at present in-
volves silicon rectifier diodes. A
native of Damariscotta, Maine,
Mr. Waltz graduated from Colby
College in 1938 with a B.A. de-
gree in physics, and from Wes-
leyan University in 1940 with a
M.A. degree in physics. Prior to
joining the Laboratories in 1946,
he taught at Wesleyan, and also
engaged in microwave research
at the Radiation Laboratory at
M.I.T. Mr. Waltz is a member of
Phi Beta Kappa, Sigma Zi, and
Sigma Pi Sigma, as well as a
senior member of the I.R.E. In this
issue, he is the author of “Semi-
conductor Reliability Studies.”

T. G. Blanchard, who is a native
of Paterson, New Jersey, received
his M.E. and M.S. degrees from
Stevens Institute of Technology.
He joined the Laboratories in 1942
to work in the Transmission Ap-
paratus Development Department
on the design and development of
power transformers, reactors,
charging chokes and magnetic
voltage stabilizers. From 1950 to
1952, he engaged in fundamental
studies of the behavior of solid
and liquid dielettrics for use in
transformers and capacitors. In
1952, he was assigned to the then

newly formed magnetic amplifier
group. Mr. Blanchard is at pres-
ent in the Military Power Ap-
paratus Department, concerned
with the theory and design of
magnetic amplifiers and circuits
incorporating magnetic amplifiers.
He wrote the article, “Magnetic
Amplifiers: Analog Operation
and Applications,” in this issue.

C. M. Taris, a native of New
Jersey, received the B.S. degree in
Physics from Yale University in
1948. After about three years
with the audio-video engineering
department of the National
Broadcasting Company, he joined
Bell Laboratories in 1951. At the
Laboratories, Mr. Taris has been
engaged in the development of
telephone answering sets and re-
lated apparatus and recorded an-
nouncement equipment —the sub-
ject of his article, “New Audio
Facilities for Recorded Announce-
ments,” in this issue. He is a
member of the Audio Engineering
Society, the American Association
for the Advancement of Science,
Sigma Xi and Phi Beta Kappa.

T. F. Benewicez, a native of Fort
Lee, N. J., joined the American
Telephone & Telegraph Company
in 1947. He was temporarily as-
signed to the Systems Engineer-
ing Department at Bell Laborato-
ries in 1957, for the purpose of

studying and developing improved
telephoto testing and measuring
techniques. He formally trans-
ferred to the Laboratories in 1958,
as an Associate Member of Tech-
nical Staff. In 1959, he trans-
ferred to the Long Lines Depart-
ment of the AT&T Co., where he
is presently a Transmission Super-
visor in the telephoto section. Mr.
Benewicz is a member of the

I.R.E., where he is secretary of
the Committee on Facsimile. In
this issue, he is the author of
“Measuring Line Level on Tele-
photo Systems.”

M.C. Goddard, a native of Sid-
ney, Maine, graduated from
Worcester Polytechnic Institute in
1921 with the B.S. degree in Elec-
trical Engineering. He joined the
Engineering Department of the
Western Electric Company in
June of that year, and has since
been continuously with that or-
ganization and with Bell Labora-
tories. During his first nine years
in the Bell System, Mr. Goddard
was successively concerned with
maintenance and descriptive cir-
cuit information, with laboratory
testing of circuits, and with adap-
tation of standard circuitry to
special field conditions. From
1930 to 1942 he designed circuits
for the step-by-step system, and

during World War II he was a
member of the teaching staff on
the Laboratories School for War
Training, where he specialized in
airborne radar. Since World War
Il he has been concerned with the
development of the No. 5 crossbar
system. He is a member of A.I.E.E.
and is also a New York Licensed
Professional Engineer.

Chemist Jack Wright developed the use of this X-ray fluorescence
machine for testing the concentration of preservatives in wood. Here
he bombards a boring from a test telephone pole with X-rays.

This Bell Labs chemist is using a fast, new technique
for measuring the concentration of fungus-killing preserva-
tive in telephone poles.

A boring from a test pole is bombarded with X-rays.
The preservative—pentachlorophenol—converts some of
the incoming X-rays to new ones of different and charac-
teristic wave length. These new rays are isolated and sent
into a radiation counter which registers their intensity. The
intensity in turn reveals the concentration of preservative.

Bell Laboratories chemists must test thousands of wood
specimens annually in their research to make telephone
poles last longer. Seeking a faster test, they explored the
possibility of X-ray fluorescence—a technique developed
originally for metallurgy. For the first time, this technique
was applied to wood. Result: A wood specimen check in
just two minutes—at least 15 times faster than before possi-
ble with the conventional microchemical analysis.

Bell Labs scientists must remain alert to all ways of
improving telephone service. They must create radically
new technology or improve what already exists. Here, they
devised a way to speed research in one of telephony’s oldest
and most important arts—that of wood preservation.

Nature still grows the best telephone poles. There are over 21 million
wooden poles in the Bell System. They require no painting, scraping or
cleaning; can be nailed, drilled, cut, sawed and climbed like no other
material. Scientific wood preservation cuts telephone costs, conserves
valuable timber acres.

Bell Laboratories Record  1960-03: Vol 38 Iss 3