The Direct-Line Emergency "eporting System
4A and 4M CAMA: Routing Arrangements

The Navy’s New Defense Against Air Attacks H.W. Augustadt
Sixteen-Channel Banks for Submarine Cables — R.S. Tucker
Transistorized Carrier System for TV L.G. Schimpf

The Direct-Line Emergency Reporting System F. M. Pearsall, Jr.
Power Supply for TJ Repeaters = R. H. Small

be held in the hand, semiconductor
Lovel components make it capable of trans-

The USS Canberra—one of two naval ships on of the Mark 65 equipment for direction of gun
which are presently installed operational versions and guided-missile fire against attacking aircraft.

Revising military tactics to improve
them is no small undertaking. Thus
Bell Laboratories devoted a great deal
of time and effort to finding for the
United States Navy a completely new

During the short period at the close of World
War II in which the Japanese launched their
kamikaze attacks, the United States Navy lost
more of its fleet than it had in all the sea actions
of the war. The success of these suicide missions
pointed up an immediate need for the Navy to
revise its philosophy of defense against air
attack. Accordingly, in 1945 Bell Laboratories
was asked to study the problem and to recom-
mend a course of development. The _ project
eventually came to be known as the “Mark 65
Program.”

The war itself had brought forth the first evi-
dence that the evolution of adequate air defense
was seriously lagging that of new offensive
weapons. For example, as the war progressed
dive and torpedo bombers greatly increased their
speed and maneuverability. But during the same
period, impreved methods came more slowly for
detecting, tracking, and destroying targets.

“An antiaircraft system is like a jigsaw
puzzle; the pieces are all related to one an-
other in a very specific, though complex way:
Before starting to put this puzzle together,
it is well to study the pieces. A good way to
proceed is then to lay down all the corners
and edges of the puzzle: these are the bound-
aries beyond which the designer knows no
pieces will lie.”

Studying the pieces and laying down the cor-
ners and edges first required an information-
gathering survey to define clearly the elements
needed to fight off an air attack. This survey
was begun by investigations of the characteris-
tics of such shipboard elements as the surveil-
lance systems—search radars as well as lookouts

To understand how the Navy’s air defense
system was revised requires first a brief descrip-
tion of the methods it had been using. On a
typical ship, long-range “search” radars scanned
the skies for targets. Those that appeared on
a radar oscilloscope were identified, electronically,
as “friendly” or “unfriendly.” Unfriendly targets
were then evaluated manually as to their poten-
tial threat. When these reached a certain range,
they were “designated’”’ to more precise radars
associated with the guns—the “fire-control”
radars.

These radars acquired and automatically
tracked the targets until they reached a range
where the guns could effectively open fire. Infor-
mation on the continuously changing range and
bearing went from the fire-control radars to a
computer, and thence to the gun machinery. The
ultimate aim, of course, was to point the guns in
the appropriate direction.

This defense was coordinated by a ship’s
organization, formed during World War II, known
as the Combat Information Center. But CIC was
poorly equipped for this job. Most of the threat
evaluation and target tracking from search-radar
data was done as grease-pencil notations on a
glass screen. Targets were designated by talkers
to gun directors over a sound-powered telephone
circuit between CIC, far below the main deck,
and an officer in the fire-control director, four or
five decks above, and as much as 400 feet away.

The Laboratories study indicated that CIC,
although equipped to control interception of
threatening targets with fighter aircraft, did not
effectively handle the defense with the ship’s own
weapons. Basically, CIC had no way to give the
fire-control radars precise information on the
position of the targets they should acquire and
track.

This weakness in coordination was one of the
major problems to be solved. Therefore, the
Laboratories recommended development of a con-
trol system to perform this function. The activ-
ities to be coordinated included air surveillance,
evaluation of the threat of the target, assign-
ment of fire-control radars to targets, assignment
of weapons to targets, and assessment of target
kill.

As an aid in achieving this coordination, the
Laboratories recommended that the new control

system include a display of the tactical situation.
This would show: (1) the positions of threatening
targets about the ship as detected by the search
radars; (2) targets being tracked by the fire-
control radars; and (3) targets under fire by guns
or missiles. Through such a display, the ship’s
gunnery officer would be able to use his weapons
most effectively.

The study also considered new developments
both in weapons for offense, such as faster
attacking aircraft, and in weapons for defense,
such as guided missiles. These, the engineers
foresaw, would require quicker threat evaluation
and decision making when the ship was under air
attack.

For these reasons, the Laboratories study team
made a second major recommendation—automat-
ing the tools of defense. This meant automatic
operation, such as had been used by fire-control
computers and tracking radars, was to be ex-
tended to the decision-making equipment. There
was a conviction that many of the processes and
techniques developed through years of Labora-
tories work on telephone switching systems would
apply in the design of automatic decision-mak-
ing equipment.

In putting forth these ideas,
engineers realized they were suggesting new
doctrines for the conduct of antiaircraft warfare.
The basic ideas resulted from detailed consid-
eration of the sequence of events as portrayed in
the illustration on the facing page. The situation
is somewhat analogous to a_ telephone traffic
problem in which the number of customers
(attacking aircraft) exceeds the number of avail-
able trunks (radars and guns). Thus, the system
was designed to provide automatic processing of
information to insure that the highest priority
customers (the most threatening targets) would
be given first call on the available trunks (the
radars and the guns).

Convinced these proposals were sound, the
Navy accepted them, and requested that the Lab-
oratories begin to build the control equipment
and study and analyze in detail the various
approaches that might be used. Realizing the
difficulties and expense of conducting actual field
trials, the engineers decided to test their ideas
by simulation.

For this purpose, they built a device to simu-
late an attack on a ship by a number of aircraft.
This “air-attack” simulator made it possible to
conduct “war games” against a ship, based on
programmed air raids, by different numbers of
aircraft and different methods of attack. From

this, the engineers could assess the effectiveness
of their proposed control equipment. Equipment
with automatic decision-making functions was
also designed and tested with the air-attack
simulator. This automatic simulation equipment,
primarily relay circuitry, was called the ATEWA,
or Automatic Target Evaluator and Weapon
Assignor.

During a simulated engagement, ATEWA
would determine the threat of approaching ‘“‘tar-
gets” and assign a priority to each. From this
priority, the targets were then automatically
“designated” by ATEWA to the fire-control
radars. After a fire-control radar had acquired
the target, gun groups were automatically as-
signed to the radar. ATEWA also made this
decision, based on the priority of a target and
the ability of the guns to bear on it.

Ships’ personnel need displays that present
tactical information clearly. Many human factors
are involved in assessing a tactical situation
because the information characterizing it is so
extremely diverse. For example, the “blips” on
a search-radar oscilloscope indicate the positions
of both friendly and enemy planes. Hence an
operator must have some way of distinguishing
between them. Also, targets seen on the radars
and those picked up by lookouts with binoculars
must be correlated. Furthermore, the positions
of targets being tracked by the fire-control radars
must be precisely known so that when friendly
fighters are in the area, fire is directed at enemy
planes only. Finally, the status of missile
launchers—whether ready to fire or not—must be
known at all times.

In addition to the human factors, development
of a tactical display required a study of what
should be presented, and how. The important
objective here was proper interpretation, espe-
cially under many confusing situations. Also
associated with this work was a way to phys-
ically present the selected information to the fire-
control operators.

At first, the enginesrs used optical projectors
to display tactical information. But subsequently,
they developed cathode-ray tube equipment with
much more versatility. An example is illustrated

A weapon-direction equipment operates to filter
progressively the incoming enemy traffic to make
sure the ship's defensive equipment—guns or mis-
siles—fire first on the most threatening targets.

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in the figure below. This is a ‘‘north-oriented”
plot of the positions of targets attacking the ship.
These positions are obtained by tracking the
targets on the search or fire-control radars. In
the illustration, the targets tracked by search
radars are represented by alphabetical letters.
Those tracked by fire-control radars are rep-
resented by numerals. Letters to show
the positions of targets being tracked by the
lookouts with binoculars. And numerals next to
letters show fire-control radars in the process of
acquiring targets designated to them from the
search radars.

Displays are one of the many devices used for
feedback information—an important function for
both manual control and supervision of an air
attack. As an example, the activity of each fire-
control radar is displayed continuously and auto-
matically, making it possible to monitor the
position in space where the radar is scanning or
tracking a target. Therefore, when a radar is
assigned to a target, operators can observe it
“slewing” to position by the motion of its numeral
toward the letter location representing the tar-
get. Subsequent field experience confirmed the
importance of feedback of information. This
provision has been praised by the operating
people in the fleet who use the equipment.

Plot of targets attacking a ship (top of figure is
true north). Letters are targets acquired by search
radars; numerals those acquired by fire-control
radars. Letters next to numerals show targets
“passing” from search to fire-control radars.

Laboratories engineers realized early that they
had to consider the growth of the air-defense
system to meet future developments in air war-
fare. This is particularly important because usu-
ally four to six years elapse between a develop-
ment and the introduction of equipment in the
field. In weapon system developments, this time
lapse may prove crucial unless plans are made
with a great deal of foresight.

Thus, early in the development program the
Laboratories directed its study toward concepts
that would be applicable when guided-missile
systems materialized. As a result, the rapid de-
cline of the gun and its replacement by the
guided missile has not outmoded the concepts
developed under the Mark 65 Program nor mate-
rially affected the equipment it uses.

Normally, a new weapon system would not be
considered for shipboard use until it had been
subjected to a test on land. However, the world
political situation in the early 1950's indicated
that every effort should be made to put the equip-
ment on board ships as soon as possible. Accord-
ingly, the Laboratories bypassed the land test
and immediately constructed control equipment
for the USS Northampton a naval command
ship with gun armament. This equipment incor-
porated the ATEWA to test the effectiveness of
the automatic decision-making equipment under
actual field conditions.

The Laboratories and the Navy evaluated the
installation aboard the Northampton by planning
and executing a number of war games in which
the Northampton was placed under simulated air
attack by actual aircraft. Precise methods of
assessing the success of the defense had to be
devised because the “kills,” of course, could be
only simulated.

During the evaluations, which lasted about six
months, aircraft flew approximately 1500 “raids”
against the ship. In some of these raids, as many
as 25 aircraft were employed simultaneously.
U. S. Navy personnel operated the equipment
throughout this period, and Bell Laboratories
engineers on board helped make up test plans
and observed and assessed the operation of the
equipment. The evaluation indicated that the
recommendations of the study were valid and,
specifically, that a centralized control system
would greatly increase the effectiveness of the
defenses of a ship under air attack. These con-
clusions were wholeheartedly endorsed by the
ship’s personnel.

Naval and Marine Corps personnel intensively
studied equipment during evaluation period. This

Prior to completion of the evaluation, the Navy
requested new equipment of the type adapted
to control guided-missile fire to be installed on
the first guided-missile ships—The USS Boston
and the USS Canberra. The changes in design
required for this new weapon equipment were
made expeditiously—a tribute to the versatility
of those conducting the program. Today, the
equipment aboard the Boston and the Canberra
directs, under tactical conditions, the fire of
eleven gun groups and two guided-missile launch-
ers employing the Terrier missile.

Because of the results of the experimental
system aboard the Northampton and the working
equipment aboard the Canberra and Boston, the
Navy requested the Laboratories to develop, and
the Western Electric Company to supply, a sub-
stantial number of weapon-direction systems for
the fleet. This equipment will be used primarily
on destroyers, cruisers, and aircraft carriers for

officer is monitoring a typical display of tactical
information on enemy and on defense status.

direction of guided-missile fire of the Navy’s
Terrier or Tartar missiles.

The widespread acceptance of the philosophy
and concepts developed under this program proved
its basic soundness. Subsequently, other defense
activities have been organized on the pattern
developed from Bell Laboratories work in this
field. Representative concepts from this program
are found in missile-control systems for the Army
and the Air Force, as well as the Navy.

To show its appreciation for the success of
this program, the Navy awarded the Laboratories
a citation. In part, this citation reads:

“Bell Telephone Laboratories brought to
completion a highly complex family of de-
vices which permit full utilization of anti-
aircraft armament of the Navy’s guided
missile ships. Reports from Fleet Commands
attested to the remarkable performance of
designation equipment Mark 7 and the high
calibre of the development program.”

In 1937, H. A. Affel, then Director of Toll
Transmission Development at Bell Laboratories,
described to an international meeting in Paris
the Bell System plans for the frequency range of
circuits in broad-band carrier systems for long-
distance telephony (BSTJ, October, 1937). These
plans were so well-conceived that they are still the
standard for American and European countries.
Affel’s concept specified individual telephone chan-
nels with a frequency band from somewhat
below 200 to about 3500 cycles per second. Twelve
of these channels are stacked side by side in
the carrier frequency band from 60 to 108 kilo-
cycles, with each channel allotted a total space
of 4000 cycles.

Spacing, stacking and modulating on the chan-
nel-carrier frequencies are done by the transmit-
ting part of a “channel bank’”—the network of
filters and modulators at each end of the carrier
system. The receiving part of the channel bank
accepts the group of 12 channels after it has
been transmitted over the carrier line and divides

it into 12 separate audio channels for forwarding
to listening customers.

These same channel banks have been used with
submarine-cable telephone systems (RECORD, Feb-
ruary, 1957). But for these systems a change is
now in the making. The increase in telephone
traffic with Europe since 1956, when the first
transatlantic cable system was opened for service,
has been so great that the demand for circuits
will shortly outrun the supply, even though a
second 36-channel cable system to Europe went
into service last September (RECORD, November,
1959).

Because of the demand for these circuits and
because of their high cost—about one million
dollars per channel—engineers at Bell Labora-
tories and in Europe have for many years been
working on ways of getting more telephone con-
versations on the existing cable systems. Actually,
research on this general problem started long
before the advent of undersea voice transmission,
but the transatlantic cables are only now justify-

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One method of increasing the number of cir-
cuits is TASI (REcoRD, March, 1959). This sys-
tem makes more efficient use of the cable’s
channels by very careful time-assignment of even

Bell Laboratories engineers have been working
with the British to make this 16-channel system
suitable for transatlantic use, and for use with
TASI. As usual, it turns out that other changes
in the plant are needed to make the whole system
(including land lines to White Plains and London)
workable on the basis of 3-ke transmission in the

Sha undersea portion. On the first transatlantic sys-
‘ tem, this part of the job has been divided between
the British and American partners.

In terms of telephone channels, the new chan-
nel banks will increase the capacity of the trans-
atlantic cable from 36 two-way voice paths to 48.
This increase is in the same proportion as 3 ke—
the new channel spacing—is to the original 4-ke
spacing. The principal trick used to achieve this
increase in channels lies in the double-modulation
scheme. Double modulation—the principle of twice
transposing the original frequency position of
an audio channel before transmitting it—is used
in many Bell System carrier systems. But this
new system is the first one in the Bell System
that will double modulate with a single bank.

The channels of this new double-modulation
bank have an audio pass-band extending from
approximately 200 to 3050 cycles. It is interest-
ing to see how this is possible with a gross
bandwidth of only 3000 cycles per channel. The
diagram on this page shows the frequency plan
of modulation. The slightly clipped triangle on
the top line represents the audio band, with the
lower part of the triangle starting at about 200
cycles. In the first step of modulation, four of

This diagram shows the frequency plan of modu-
lation for the new 16-channel banks. Frequency-

band triangles are sloped to indicate lower and
higher audio frequencies, hence their sideband,

these audio channels are individually shifted to
higher frequency ranges on the four channel
carriers in the second line. Alternate lower side-
bands and upper sidebands are selected from the
products of this modulation, and the results are
combined to form the “subgroup” that appears
in the third line.

As this line of the diagram shows, this close
“stacking” of channels is accomplished by using
carriers that are each shifted by 150 cycles from
multiples of 3000 cycles. For example, carrier A,
at 15.15 ke, is modulated with audio channel
A, and the lower sideband—12.10 to 14.95 ke—
becomes carrier channel A in the subgroup.

The diagram also shows that the carrier of
channel A—if the triangle were completed—
would fall within the sideband of channel B, and
vice versa. Therefore, the “carrier leak’? must
be cleaned out very thoroughly before channels A

W. G. Simpson, left, and H. B. Law, both of the
British Post Office, examine one of the plug-in
channel packages of a prototype 16-channel bank.

and B are combined. If this were not done, each
channel would have an unwanted 300-cycle tone
in it.

One can also see from the subgroup diagram
that the band edges of the adjacent channels are
very close to each other. For example, the edges
of channels A and B are separated by only 100
cycles, and the edges of channels B and C are only
200 cycles apart. To make such close spacing
practical, it is necessary to have very “‘steep,” or
sharp-cutoff, filters so that the channels do not
spill over into each other.

The subgroup formed from channels A, B, C
and D in the band from 12 to 24 ke is then
modulated to its final position in the “group”
frequency band by the second stage of modula-
tion. Carriers used for this step are shown on
the fourth line of the chart. In this step, the
lower sideband is used in all cases.

The resulting “stack” of channels in the group
frequency band, namely 60 to 108 kc, appears
in the bottom line of the diagram. Here, we see
that the individual channels are alternately lower
sideband and upper sideband as they are applied
to the high-frequency line, and that high audio-
channel frequencies are adjacent to the lower
(60 ke) and upper (108 kc) edges of the group
frequency band.

This double-modulation scheme makes it pos-
sible to use about 95 per cent of the gross fre-
quency band. To achieve such high efficiency,
it is necessary to: (1) offset, or shift, the first-
stage carrier frequencies by a small amount (150
cycles) from a multiple of the specified 3-kilocycle
spacing, as explained above; (2) allocate losses
due to filters carefully between the audio filters
and the various carrier-frequency filters; and (3)
pay close attention to other details of the design,
such as the impedance relationships of points
within the equipment where channels or sub-
groups are paralleled.

A block schematic on the next page illustrates
the equipment used to implement this efficient
double-modulation plan. Following the “audio
input” at the upper left, we see an ‘amplitude
limiter” that protects the system from very high
input powers, and then an “audio filter,’”’ which
passes the frequency band from about 200 to
3050 cycles. This block is actually made up of a
steep-sided, high-pass filter and a steep-sided,
low-pass filter in tandem.

Then comes the “channel modulator,” which
performs the first step of modulation. The dia-

The components of the 16-channel, 3-ke banks de-
veloped by the British Post Office. Audio signals
are twice modulated by the transmitting com-

gram shows the 15.15-ke carrier supply for
channel A. Following the channel modulator is
a bandpass filter that passes the appropriate
sideband and a stop filter that eliminates the
15.15-ke carrier leak. Channels are combined
with the aid of hybrid coils, which, along with
other elements like attenuators, have been omitted
to simplify the diagram.

After the four channels have been combined,
they are translated to their final position in the
group band by a second stage of modulation in
the subgroup modulator. The carrier—in this
case for subgroup No. 4—is 84 ke. The lower
sideband of this carrier passes through the “‘sub-
group filter’ in the range from 60 to 72 ke, and
is then combined with the three other subgroups
to give the complete 60- to 108-ke band. In this
illustration, the channels are numbered from 1A
to 4D as an aid to understanding the modulation
The numbers 1 to 16 will be used in
practice, to conform with the numbering method
for 4-kec channels. In the bottom portion of the
diagram, the transmitted audio signals are de-
modulated and separated into 16
they move to the left.

Two British firms provided channel banks of
this type for installation late in 1959. One set
is in use on the Florida-Puerto Rico cable and
the other set on the first transatlantic cable.
These installations have an audio band extend-
ing from 300 to 3150 cycles, with corresponding

ponents, left to right in the top line, and demodu-
lated by receiving components. Each subgroup,
such as 4A through 4D, contains four channels.

differences in the frequency plan shown in the
first illustration. A photograph of the proto-
type of the first set of channel banks is shown
on page 250. Later models will use the 200-to
3050-cycle allocation, and the first (present) in-
stallations may later be changed to this type.
For the second transatlantic cable system, French
engineers are designing similar 200- to 3050-
cycle banks. These are to be installed this sum-
mer at both the French and American terminals.

Although this double-modulation method makes
efficient use of the available bandwidth, there is
a transmission penalty exacted for the use of the
3-ke system. Subjective tests at the Laboratories
indicate that the transmission impairment, due
to loss in speech quality and naturalness, on a
single link of the 200- to 3050-cycle channel, as
compared to thé channel obtained from a 4-ke
bank, would be equivalent to about a 2-db loss
in power. For the 300- to 3150-cycle channel, it
would be somewhat over 3 db. Two or more links
in tandem would tend to increase the impairment,
although not in direct proportion to the number
of links.

The major part of the impairment on the 300-
to 3150-cycle channel is caused by the loss of
low frequencies. It is for this reason that the
change to 200 to 3050 cycles is being made.

This new type of channel bank is designed
for submarine cables and is not recommended for
use on other broadband systems in the United
States. There are three general reasons for
this. First, the 2-db impairment from a single
link is by no means negligible, in view of the
constant effort being made to improve over-all
Bell System transmission. How much the impair-
ment might increase with several such links in
tandem is not yet known.

Part of this problem is the effect of transients.
The sharp cutoff of the filters necessary to realize
a useful band covering 95 per cent of the gross
bandwidth inevitably produces delay distortion
near the edges of the pass-band. This creates
some transients in the received speech. Listening
tests have indicated that with two 3-ke links in
tandem the effect is not objectionable to most
people. But what the effect would be like with
several such links is questionable. In the future,
as more and more submarine cables are installed,
it may be possible that several 3-kc systems will
be linked in tandem.

A second important reason for not using the
double-modulation banks generally in the Bell
System is that they are inherently more costly
than the standard single-modulation banks.

The third reason for not generally adopting
3-ke channels is that when a 4-ke system is

SYDNEY MINES PENMARCH
NEW YORK NOVA SCOTIA FRANCE PARIS
|
12-CHANNEL BANK WITH 16-CHANNEL BANK
4KC CHANNEL SPACING 1KC CHANNEL SPA

Four 4-ke, 12-channel banks on the land line por-
tion of the system will work into three 3-ke,
16-channel banks on the undersea link between.

transmission plan besides the channel banks must
also be changed. Prominent among these are
“pilot frequencies” and unwanted carrier-fre-
quency “tones.”

Pilot frequencies for the type-K cable-carrier
system, for example, are 60, 64, 92, and 108 ke,
when expressed in terms of equivalent frequencies
in the 60- to 108-kec band. Two of these—64
and 92 ke—would fall within 3-ke channels, as
can be seen by a close look at the bottom line
in the frequency-plan diagram. The pilot fre-
quency would cause a single-frequency tone in
the channel, and the pilot filters would cause a
slot of transmission loss in the channel. This slot
would be near 1000 cycles for both the 64-ke and the
92-ke pilots. The 92-ke pilot is used in all Bell Sys-
tem broadband, long-distance transmission sys-
tems except type-J open-wire carrier, and would
produce noise and a slot of loss in one of the 3-ke
channels if such voice channels were generally
applied.

By the same token, tones would appear in
various 3-ke channels because of carrier leaks
or modulation products at frequencies that are
multiples of 4 ke but not of 3 ke. Such tones
exist in present transmission systems, but do
no harm since they fall between 4-ke channels.
Many of them, however, would fall within 3-ke
channels and produce unwanted tones. A large-
scale clean-up effort would be needed to remove
them from the present land telephone system.

In the transatlantic systems, which are actu-
ally a mixture of land plant and undersea plant,
these three reasons, and other difficulties in the
land plant, have led to the decision that 3-ke
channels will be used only in the submarine sec-
tions. Standard 4-ke channels will continue to
be used on land. A simplified schematic of how
this combination of the two schemes will work
on the White Plains-to-Paris system when it is
converted is shown on this page.

The engineering of these new channel banks
to fit into the over-all transatlantic system,
including TASI, and other work on the complete
3-ke system (not described in this article), have
required close cooperation among telephone engi-
neers in the three countries most directly in-
volved: Great Britain, the United States and
France. A firm background for this cooperation
among the three countries was well established in
the course of the joint work on the engineering,
development and installation of the submarine-
cable systems themselves,

Since the advent of television, Bell Labora-
tories and has been vitally concerned with tele-
vision transmission and is constantly striving to
improve this important service. In recent years,
the application of solid-state devices in experi-
mental television circuitry has reduced the size
of such TV apparatus and decreased the amount
of power needed to generate and transmit high-
quality television signals.

This article explains how transistors are used
to transmit television signals over the coaxial-
cable portion of a TV transmission system. More
specifically, it discusses the advantages of tran-
sistors and. some of the engineering factors in-
volved in designing a transistorized system for
short-distance transmission.

The system used for these experiments is an
experimental hook-up between the Holmdel, New
Jersey, and Murray Hill, New Jersey, locations
of Bell Laboratories. This transmission system
consists of a transmitting terminal at Holmdel
connected by three miles of coaxial cable to a
microwave terminal on Crawford’s Hill which

beams a signal to a microwave tower and receiv-
ing terminal at Murray Hill. The output of this
microwave receiver is connected to the TV termi-
nal in the Murray Hill laboratory by one-half
mile of coaxial cable. As shown in the upper por-
tion of the system diagram on page 255, a tran-
sistorized repeater is spliced into the coaxial
line midway between Holmdel’s transmitter and
its microwave terminal. Transistors are also used
in the terminal equipment at both ends of the
system, as shown by the shaded blocks on the
diagram.

There are two major advantages of this ex-
perimental system over present commercial equip-
ment: (1) the apparatus is much smaller, and
(2) power requirements are considerably re-
duced. It achieves these advantages chiefly
through the use of simple transistorized ampli-
fiers (see cover). The amplifier circuit for this
system is less complex than those employed in
long-distance television transmission, principally
because of relaxed transmission requirements for
closed loop service.

Low power requirements eliminate the need
for a local power supply and permit the operating
power for the amplifiers to be transmitted over
the cable. This results in a small amplifier that
can be mounted on poles or installed underground
without complex housings. A pole-mounted am-
plifier is shown below. In light of their low
power requirements and adaptability, transistor-
ized repeaters may be particularly applicable to
closed-loop television service in the future
(RECORD, January, 1960).

The most common method of sending television
signals over short spans of coaxial cable is to
transmit a baseband video signal—a direct elec-
trical analog of the picture information—with-
out altering it in any way. The frequency band
for such a signal ranges from 30 cps to 4.5 me.
Although the transistors for transmitting a
baseband video signal are comparatively inex-
pensive and easily procured, the very low (30-cps )
frequency cutoff requires large transformers.

Further, because the attenuation characteristics
of the cable change drastically over such a wide
range of frequencies, the equalizer design for a
baseband system is quite complicated. For these
and lesser reasons, a carrier system rather than

The housing mounted on the telephone pole above
contains a pair of transistorized repeaters
(shown in inset). These repeaters are part of
the experimental Holmdel-to-Murray Hill system.

Both double-sideband and _ vestigial-sideband
‘arrier systems were considered. A double-side-
band system requires about twice the bandwidth
of a vestigial system. However, the distances in-
volved in closed-loop and local transmission sys-
tems are usually short. This means that the ter-
minal equipment constitutes a large part of the
cost. To simplify the terminal equipment and con-
sequently reduce this cost, the designers chose a
double-sideband system.

In double-sideband transmission, picture infor-
mation is sent on both sides of the carrier fre-
quency, allowing the use of simple modulators
and detectors. This method also eliminates spe-
cial filters and shaping networks, which are an
essential part of a vestigial-sideband carrier sys-
tem. Video signals carried by the double-sideband
system are recovered at the receiving terminal
by passing them through a rectifier (detector)
and a low-pass filter. These units and the other
elements of the Holmdel-to-Murray Hill system
are shown in the lower portion of the diagram
opposite.

Having selected the double-sideband system,
the designers had to consider several factors be-
fore deciding on the carrier frequency. In carrier
transmission, lower carrier frequency means low-
er cable loss; this allows repeaters to be widely
spaced and consequently reduces the cost of the
system. At the same time, the carrier frequency
must be high enough to prevent the lower side-
band from overlapping the baseband video input.
A baseband signal of 5 mc therefore requires a
minimum carrier frequency of 10 me. And to
provide a “guard channel,” which prevents this
type of interference, the carrier frequency should
be a little higher. To meet these demands, a 15-me
‘arrier frequency with an ultimate bandwidth
of 10 to 20 me was chosen. Although the loss is
greater, this higher carrier frequency has an
advantage in that it results in a simpler equa-
lizer design.

To this point, we have discussed the advantages
of the transistorized transmission system and
some of the engineering considerations in its
design. Now, with the help of the lower portion
of the block diagram on page 255, let us see how
a television signal is transmitted through the
system, and consider some of the interesting fac-
tors underlying the behavior of the components.

The carrier frequency is generated at the trans-
mitting terminal by a crystal-controlled transistor
oscillator. The output is modulated by passing
the video signal through a modulator designed

Holmdel-to-Murray Hill transistorized TV system
is represented in the upper portion. The black

with semiconductor components. A low-pass filter
prevents interference products from entering the
input circuit. As shown in the diagram, the signal
then passes through a de isolation circuit before
being fed to the cable. The isolation circuit per-
mits de power to be applied to the repeaters
without short-circuiting the ac carrier signal.
After passing through a length of coaxial cable,
the signal is amplified by a transistorized re-
peater. The repeater gain characteristic compen-
sates for the electrical losses in the cable.

At the receiving terminal, the signal is passed
through another repeater. This repeater makes
up for the loss in the final section of cable and
amplifies the signal so that it may directly oper-
ate a detector which demodulates the video signal.
A low-pass filter following the detector removes
the carrier from the video output. From this
point, the signal is passed through the video
amplifier to the television monitor.

Repeaters are designed on the basis of loss
characteristics through the system. In other
words, the repeater must compensate precisely
for the attenuation of the signal as it passes
through a given length of cable. The required
gain is obtained by using a two-section feedback
amplifier designed to have a flat frequency char-
acteristic. An equalizer between the two sections
of the amplifier compensates for the attenuation
characteristic of the cable. Miniature inductors
and transformers, 0.25 inch in diameter, are used
in the repeaters. Ferrite cores in these compo-
nents result in a desirable frequency character-
istic in the 10-to-20 me range.

The crystal-controlled, transistorized oscillator
supplies the carrier power. <A_ diffused-base

blocks in the lower part of the diagram indicate
sections of the system that contain transistors.

transistor connected in a common-base circuit is
the only active element of the oscillator. A minia-
ture transformer, similar to one used in the re-
peater, makes possible the efficient transfer of 5
milliwatts of carrier power from the oscillator
to the modulator.

A balanced modulator, consisting of four gold-
bonded diodes, is used to eliminate some unwanted
signals in the output. Since this also balances
out the carrier, it is necessary to feed some
‘arrier-frequency power from the oscillator di-
rectly into the output to obtain double-sideband
operation. This modulator circuit is arranged so
that the video frequencies need not be transmitted
through the transformers. Carrier level is ad-
justed to give a favorable signal-to-noise ratio
and a minimum of distortion. The peak-power
level at the output of the modulator is about 1
milliwatt.

For demonstration purposes, a 6-mile experi-
mental system over coils of coaxial cable was set
up at the Murray Hill location of the Labora-
tories. The three general circuit classifications
for this hookup were the transmitting terminal,
the cable repeaters, and the receiving terminal. A
monitor was arranged so that it could be con-
nected to either the input or the output of the
system. Most observers watching the screen could
not tell the difference between a television signal
sent directly from the input and a signal sent
through the 6-mile link. In fact, the video re-
sponse of the 6-mile system was down by less
than 2 db at 6 me. These results, plus the opera-
tional reliability of the Murray Hill-to-Holmdel
system, represent the successful application of
the solid-state art to television transmission.

15 MC POWER REPEATER DETECTOR | OUTP
TO AMD MICROWAVE LINK EQUALIZER LOW-PASS | AMPLIFIER
e

In an emergency, our first thought is
hre tele} rove. io make eniergencyu
elephones available to the general public,

va It is an axiom in fire fighting that the first few
: minutes of a fire are of paramount importance.
‘4 More lives and property are saved by the prompt

action of trained firemen than by the number of
men and quantity of equipment that ultimately
get to the fire. Actually, this is a truism in all
' types of emergencies where dangerous conditions
or serious injuries endanger life and property. If
precious moments are lost in communicating with
the civil authorities equipped to handle emergen-

cies, tragedy may result.
Because speed is so essential, many communi-
ties have found that a convenient, easily recogniz-
able, fast and reliable communication system is a
necessity for adequately safeguarding life and
2 property. In many towns and cities across the
country, the Bell System provides such a system,
based on the most familiar means of communica-
tion known to the public—the telephone. This sys-

Fundamentally, the reporting system consists
of telephone sets (570-type) mounted in metal,
weather-proof boxes that are conspicuously
marked and placed at convenient public locations.
Each of these telephone sets is connected by a
pair of conductors to emergency headquarters.
Here, the telephone circuit terminates in both
jack and key appearances at a PBX switchboard
(520-type). So far, this description is similar, in
some respects, to a telephone private branch ex-
change (PBX).

When dealing with emergencies, however, safe-
guards are also necessary, even in a relatively

Headquarters attendant answers call at switchboard
of direct-line installation at North Bergen, N. J.

Diagram shows the principal circuits of the direct-
line reporting system and some of the details of

simple manual telephone system. These safety, or
reliability, features are the distinctive character-
istics of the emergency system, and their purpose
and implementation will be the principal concern
of this article. But before describing these safe-
guards in detail, it would be well to outline first
the general operation of the direct-line system.

Let us assume that a fire has been discovered
in the vicinity of emergency box 0101. This box
and the basic circuits of a direct-line emergency
system are shown in the diagram on this page.
When a caller lifts the telephone handset, a path
is closed, through the line and delay circuits, from
an interrupted battery source in the flashing cir-
cuit to the lamp associated with line 0101 on the
switchboard at emergency headquarters. In con-
cert with the flashing lamp, an audible alarm (not
shown) signifies the arrival of an emergency call.
No dialing or signaling is required.

The headquarters attendant can answer the call
by two methods. Normally, he momentarily presses
the “answer” key, which connects the attendant’s
telephone circuit to the calling line. The attend-
ant may also insert the plug of an answer cord in

the dual appearances at the switchboard. The
answer keys light, as do colored indicator lamps.

a jack, and then operate the associated “talk”
key to converse. This method is usually used only
when it is necessary to “extend” incoming calls.
In either case, the attendant’s answer changes the
flashing lamp to a steady light. This light then
remains as an indication of which box is calling
until the attendant releases the call. By answer-
ing the call, the attendant restores the flashing
circuit to normal, and makes it available for sub-
sequent calls.

Direct communication with the person at the
scene of the emergency allows the attendant to
get valuable information regarding the type of
fire and its exact location. With such informa-
tion, he can dispatch the most efficient aid in the
speediest manner. When the person reporting
hangs up, either the supervisory lamp associated
with the answer cord, if cord answered, or the
“position-release” lamp, if key answered, lights
as a visual signal to the attendant. The attendant
can disconnect either by removing the cord or
by operating the “position-release” key. A typical
emergency switchboard installation is shown in
the photograph on page 257.

Each line from an emergency telephone has two
terminations in the switchboard, one in each sec-
tion. This arrangement—‘“dual-line appearances”
— is one of the important safety features of the
system. Each appearance has its own line lamp
as protection against the failure of a single lamp.
A single attendant still has two methods of an-
swering a call at his disposal: namely, by key
or jack.

As an extension of the dual-circuit protection
feature, two position circuits and two attendant’s
telephones are furnished, and both are under the
control of a “position-release” key. Normally, one
position circuit and one telephone circuit are in
use with the left section of the switchboard and
one of each with the right position. By moving
the release key to the left or right, however, a
single attendant can put all lines under the con-
trol of his position and telephone circuits.

Some emergency telephone sets are in isolated
locations. In such situations, the danger of dam-
age by accident or vandalism always exists. Since
such damage could result in inoperative lines, it
is imperative that the condition be detected im-
mediately. To ensure this, each line is constantly
monitored electrically.

For line-monitoring, a “loop-open” relay is
added in the line circuit of each telephone. This
relay releases if the line is opened or grounded,
and causes a red alarm signal to light at the line
appearance on the headquarters switchboard. The
attendant can then place a guard at the defective
telephone set immediately, and repairs can be
made subsequently by a
maintenance crew.

Each line of the system also has a “lock-in”
feature to compensate for the often unpredictable
actions of excited people. In emergency situa-
tions, it is inevitable that someone will lift the
handset, shout “fire” or “police,” and then hang
up before the operator has had time to acknowl-
edge the call. In regular telephone systems, this
would be an abandoned call and the circuits in-
volved would release immediately. Here, however,
the calling signal is locked-in, or held, to ensure
that the attendant can identify the telephone set
and take proper action. He may ring back to the
telephone set, send an investigative team to the
scene or both.

The system also includes a “signal-delay” fea-
ture that minimizes the effects of electrical dis-
turbances of short duration — often called “hits”
or surges — which occur occasionally on telephone
lines. This feature delays signals on their way to

the switchboard long enough to cover the surge
interval but not long enough to interfere with
the lock-in arrangement. A simplified schematic
of this circuit appears on the first drawing.

The signal-delay circuit uses the negative-
resistance characteristic of a thermistor to delay
the operation of a relay long enough to cover
surge times. During this delay, a second relay
removes battery from the emergency-reporting
relay, which releases. When the thermistor-de-
layed relay operates, battery is reapplied. If the
initial action of the emergency-reporting relay
was a legitimate call and not a hit, ground will
still be present and the relay will operate. On
hit-initiated action, no ground is available, and
the emergency-reporting relay and the circuits
restore to normal.

In some communities, it is desirable to have
separate headquarters for emergency reporting
and for police reporting, both routine and emer-
gency. For such arrangements, the emergency
telephones can serve a dual-purpose and eliminate
the duplication of these outside telephones and
their cable conductors. A nonlocking key in the
570 set and a “‘selective-routing” circuit located
at the central office provide the transfer feature
required to direct calls to fire or police headquar-
ters. The schematic on page 261 shows such a
selective-routing arrangement, as
Indianapolis.

A double-wound line relay, whose windings are
in the line loop, is the important element in the
selective-routing circuit. Both of its windings
have equal turns, but since they oppose one an-
other, normal loop current creates no effective
ampere turns to operate the relay. With the selec-
tive-routing relay unoperated, calls are directed
to emergency (fire) headquarters.

Now, suppose a policeman wishes to call police
headquarters. Before lifting the telephone, he
presses the “police” key, which is part of the
emergency telephone set. This sends current
through only the secondary winding of a selec-
tive-routing relay, which operates, and in turn
operates the transfer relay. This relay transfers
the line loop to police headquarters and at the
same time connects the two windings of the
selective-routing relay in “series-aiding.”’

With the windings series-aiding, the selective-
routing relay remains operated when the tele-
phone is off hook and the police key can be re-
leased. A relay in the police line circuit operates
and initiates the lamp signal to the police switch-
board. The signal-delay circuit prevents alerting
the primary emergency headquarters.

continuously monitored at only the primary emer-
gency headquarters. Consequently, an important
part of the function of the transfer relay is to
prevent the loop-open, or line-monitoring, relay
from releasing when a call is routed to police
headquarters. Such action would falsely alarm the
primary emergency headquarters.

The police headquarters switchboard also has
dual line lamps, and is equipped for both key and
jack answering. Since all calls to this switchboard
are originated by trained personnel, the lines do
not require the lock-in feature. Also, the flash
delay and loop-open alarm features are not pro-
vided at police headquarters, because no hits or
loop-open signals can be transmitted to the
switchboard with the circuit “normal.”

Emergency-reporting systems also have two
“external” reliability features to ensure against
the loss of valuable, though sometimes hastily
given, information in an emergency. Both of
these, which are basically recording methods, can
be appended to any switchboard of the 520 type.

The first is voice recording. Where desired,
the emergency-reporting system can be easily ar-
ranged to record conversations automatically by
a tape recorder. The recorder is normally con-
nected across the position circuit at the switch-
board. Answering a call automatically starts the
recorder, while disconnecting stops it. At each
position, there is a key which disconnects the
recorder when held in the operated position.

In the other recording feature, a printed rec-
ord is made of each call. This records line iden-
tity, date, and time-of-day. The printed record
is made by either a 1A ticketer or a teletype-
writer. A typical printed record for a call is
shown below.

The reporting systems also offer other versatile
communication services needed in emergencies.
For example, the headquarters attendant can alert
any fire house or police station, any group of
these, or all such locations at once, through a
“paging” circuit. A “paging-line’” key connects
the attendant’s position to the associated fire
house or police station. When he operates the
“paging-tone” key, an alerting tone is trans-
mitted. If the attendant wants to page all sta-
tions at once, he operates another key. To release
the paged lines, he momentarily presses the
“paging-release” key.

On some occasions, connection to the paging
facilities may be requested by the fire chief, po-
lice chief, or some other authority calling head-

quarters from an outside location. In such cases,
the attendant answers the incoming call with the
answering cord and uses the calling cord to plug
into the paging jack. This cuts off the attendant’s
position, but completes the transmission path to
the paged location.

Trunk circuits are provided to give the emer-
gency-reporting system access to the telephone
central office. Through these, incoming calls can
be received from, or outgoing calls can be origi-
nated to, any telephone destination. The central-
office trunk circuits also have dual appearances
and may be answered by either jack or key.

On key-answered calls, arriving on one of these
trunk circuits, it may be convenient, or even nec-
essary, to maintain a regular connection while
the attendant handles an emergency-reporting
line, so a hold key is provided for each central-
office trunk circuit. Momentary operation of this
key disconnects the attendant’s talking circuit,
but holds the connection to the calling party. This
puts a distinctive “winking” signal on the trunk
lamp as an indication that the trunk is being
held. The attendant can re-establish the connec-
tion by momentarily operating the trunk key.

The headquarters attendant, in addition to be-
ing the focal point for emergency information, is
always faced with the problem of knowing the
whereabouts of the various pieces of emergency
equipment at his disposal. This can become a
rather complex problem when serious fires occur
and fire-fighting equipment is dispersed over sev-
eral areas. To ease the attendant’s problem, the

The printed record of a call to emergency head-
quarters, along with the meaning of the printed
numbers. This record was printed bya 1A ticketer.

Diagram of a typical selective-
routing arrangement. All lines
go through the central office,
and calls are routed to police

its associated red lamp is lighted at the
indicator by a signal that may be automatically
initiated by the movement of the equipment. As
long as this light remains, the equipment is not
available, and if necessary, some other fire house
must be called upon to answer a fire call.

When equipment is ready to return to its sta-
tion, the information is radioed to headquarters,
and its associated status key is pulled out. This
lights a green lamp and the combination of lighted
red and green lamps is a visual indication that
the fire-fighting apparatus is enroute to its regu-
lar location. When it arrives the red lamp is
extinguished, signifying that the station is again
“ready.” The attendant then returns the status
key to “normal” and this extinguishes the green
lamp.

The emergency attendant also receives visible
and audible alarm signals for various trouble
conditions. These include: circuit-fuse operation,
line open, ringing-power failure, time-of-day or
ticketer-motor power failure, or time-of-day or
ticketer-motor fuse operation. If the ticketer is
used to record calls, a lamp lights if the paper
supply drops below a pre-selected minimum value.
The same lamp also lights when a trouble occurs
in the teletypewriter and control circuit if a tele-
typewriter is used.

There are cutoff keys for silencing both the
audible alarm and call signals. Since the latter
is the signal given whenever an emergency ¢all
is received, an amber lamp is provided as a warn-
ing that the audible signal is “cut off.” The
switchboard can also be equipped with a “dead-
man” alarm. With this feature, if a specific call
is not answered for three minutes, an audible and
visual alarm is initiated.

The Emergency Reporting System can be read-
ily expanded or contracted with population shifts
or zoning changes. The public emergency tele-
phone sets can be easily moved or added because
of the extensive cabling network of the Telephone
Companies. The Companies also assume respon-
sibility for maintenance.

The Bell System’s fire and police reporting
system offers versatility, reliability and simplic-
ity of operation and maintenance. Principally,
however, it furnishes the essentials of emergency
reporting: calling-telephone identification; direct
communication with those reporting the emer-
gency for determining its exact location and
nature; line-identity recording; and where de-
sired, voice recording. The system was designed
with the strict specifications of the fire under-
writers in mind, and installation often results in
a reduction in fire-insurance rates on both mu-
nicipal and individual properties.

Solid-state devices are used extensively
in the power supplies for TJ Radio.

By employing silicon junction diodes and
magnetic amplifiers, designers have

The microwave radio-relay system used by
the Bell System for telephone and _ television
transmission in the 11,000 megacycle band is
called TJ Radio (RECORD, April, 1959). The
greatest use for TJ radio is as a short-haul, low-
density system capable of transmitting 240 tele-
phone circuits or a television program over dis-
tances of 100 to 250 miles. .

For flexibility each transmitter-receiver bay
needs a separate power supply to convert the
primary ac power to several regulated de and ac
voltages. The power supply designed for TJ
radio represents the results of several new ap-
proaches to design of power supplies.

The major design objectives were long-term
reliability and a minimum over-all cost for man-
ufacture and maintenance. Included in these ob-
jectives are efficiency, accurate regulation, long
life, safety, ease of operation, ease of mainte-
nance, compactness and attractive appearance.

Equipment in the TJ system is supplied by
four regulated de outputs: 600, 400, 200 and
—400 volts, with three independent ac filament
voltages. These outputs are all furnished by the

new power supply. In addition, metering net-
works are supplied on the de outputs to monitor
important voltages and currents.

There are only four electron tubes in the en-
tire power supply. These are long-life types, ap-
plied conservatively within their ratings. The
shortest expected life is about five years.

Among the examples of new design techniques
used in these power supplies is the extensive use
of solid-state devices. The main regulator is a
magnetic amplifier and all the rectifying de-
vices are silicon junction diodes. The magnetic
amplifier and silicon diodes regulate and rectify
with higher efficiency than comparable electron-
tube units. The TJ power supply is the first pro-
duction power supply to use silicon rectifiers for
high-voltage rectification.

Rectifier circuits produce a pulsating de volt-
age that always possesses the same polarity. But
this voltage isn’t as useful as a de supply for
electron tubes because it causes pulsations in
amplitude, or “ripple,” of the output voltage.
These pulsations must be smoothed out by filter
networks made up of inductor coils and capac-

itors. The supply was designed to take advantage
of the constant-current nature of the loads, and
the averaging characteristics of the filters.

As long as the current from a rectifier is kept
flowing by the series input choke of the ripple
filter, the de of the output follows the half-cyclic
average value of the ac input. Thus one needs
only monitor the output of one of the supplies

This method of regulating the outputs is
shown in the accompanying block diagram. Be-
cause the load is constant, the feedback regula-
tor maintains the half-cyclic average of the ac
voltage at a constant value, and all the de output
voltages are maintained constant. The feedback
amplifier controls the magnetic amplifier, and
thereby regulates the power to the rectifiers.

The 3A magnetic amplifier regulates ac volt-
age by absorbing area (volt-seconds) from the
ac wave presented to it. For a given combination
of bias and control currents, a magnetic core
absorbs a given amount of the ac wave; indicated
by area A in the diagram on page 264. Then the
core saturates, and the magnetic amplifier presents
a very low impedance to current flow. Volt-time
area B is then applied to the rest of the circuit.
On the next half-cycle of voltage, the other core

absorbs area C and passes area D. The resulting
waveform looks rather chopped up, and requires
somewhat more filtering than a wave from a
conventional full-wave rectifier.

Author shown testing the TJ
power supply unit. Approxi-
mately 160 pounds of compo-
nents and wiring are packed
into 21 by 19 by 101% inches.

Variations in ac line voltage are regulated by
varying the volt-time area absorbed in the mag-
netic amplifier cores. This is done by changing
the bias and control currents. The bias current
is supplied from the unregulated ac and applied
through a network to the bias winding of the
magnetic amplifier. An increase in the unregu-
lated voltage increases the bias current and tends
to correct the regulated output.

Finally, an electron-tube circuit in the feed-
back amplifier adjusts the control current to
maintain the —400 volt output exactly at —400
volts. In the process of maintaining the —400 volt
output constant, the average ac voltage to all the
other outputs is also maintained constant. The
wave diagram shows how, by varying the total
area absorbed (A+C), the average output passed
(areas B+D) is kept constant.

When the input line voltage varies, and the
average value of the regulated voltage is main-
tained constant, the parameters of the wave-
form vary, however. The peak voltage is the same
as the input peak voltage, because the magnetic
amplifier in this circuit always begins to con-
duct before the peak occurs. But the root-mean-
square (rms) voltage, which is pertinent when
heating effects are considered, does vary with
line voltage. In the range of operation of the
TJ power supply, a 10 per cent variation in line
voltage, with a constant regulated voltage, pro-
duces 5 per cent variation in rms voltage.

For the separate filament supplies, the regu-
lated ac voltage is stepped down by a filament
transformer and supplied to the three filament
outputs. The filaments of various tubes in the
TJ system are heated by the rms or “effective”
voltage applied to them, and thus these supplies
are regulated within about +5 per cent.
Several features were included in the TJ pow-
er supply to assure safety for all personnel in-
volved in operation and maintenance. In the first
place, electrical circuits are covered when the
equipment is in the operating position. The cover,
which has a recessed control panel, forms the
front of the power supply. Pin jacks are avail-
able for making pertinent measurements, but the
circuitry can be reached only by a thin probe.
It also has current-limiting resistors in series
with all pin jacks more than 150 volts off ground.
When the equipment must be opened for access
during maintenance, an interlock circuit re-
moves power from the circuit. The few parts of
the circuit not de-energized by the interlock are
covered by transparent plastic covers and sleev-
ing to avoid contact by maintenance personnel.
Long-term reliability involves working well
under normal conditions; it also involves the
ability to withstand many kinds of abnormal con-
ditions and the ability to work well when condi-
tions return to normal. TJ equipment is protected
against external short circuits and overloads
by a circuit breaker and fuses within each power
supply. The circuit breaker, besides acting as an
on-off switch, will also trip and turn off the input
power in the event of an internal short circuit.
The silicon rectifying elements are very sen-
sitive to excess inverse voltages. During a field
trial, Laboratories engineers traced failures of
diodes to lightning-voltage surges. Customary
lightning protection for power service consists
of diodes and carbon blocks that can limit surge
voltages at the equipment to less than 1000 volts.

However, for this supply such protection 1s not
sufficient. The TJ power supply is designed to
operate from a 117-volt power line, and the
maximum peak voltage from this — even with a
line voltage 10 per cent higher —is only 183
volts. A safety factor of about 4% times normal
on all the rectifiers would be expensive, so the
designers incorporated a lightning-voltage lim-
iter in the production models. This limiter con-
sists simply of two rectifiers and two capacitors.

During normal operation, the capacitors
charge to the peak ac voltage of the input line.
When a lightning surge tries to raise the volt-
age beyond the recurrent peak of the ac, the rec-
tifier takes energy from the surge and charges
the capacitor. For a 1000-volt surge, the capaci-
tor, typically, may charge about 20 volts above
its normal peak voltage of 165. Thus, the 1000-
volt surge is held to 185 volts.

Lightning is infrequent, and a light bleeder
current easily discharges the excess voltage be-
fore another surge occurs. A model was tried
with this surge protector, and was hit with re-
peated 1000-volt surges from a lightning-surge
simulator. After 50 simulated lightning hits,
the power supply continued to operate.

This new power supply also includes a sensi-
tive relay to protect the klystrons (which gen-
erate microwaves in the transmitter and_re-
ceiver) from the application of “resonator” volt-
age before “repeller” bias voltage is available.
Briefly, the resonator voltage in a klystron ac-
celerates its electron beam. If the repeller unit
has no bias, the accelerated electrons from the
resonator can stream into the repeller at full
speed, melting it in a matter of milliseconds. The
sensitive relay operates only when voltage is
present on the —400V output (repeller supply) ;
the positive voltages (including resonator volt-

The 3A magnetic amplifier regulates ac voltage
by absorbing area (volt-seconds) from the ac
wave presented to it. Two magnetic cores absorb

areas (A or C) from alternate half cycles. Areas
B and D, constant with varying input, go to
the rectifiers and their waveforms are filtered.

Block diagram of the operation of the power sup-
ply circuit showing how outputs are regulated.

The power supply for TJ radio is an exam-
ple of good packaging for maximum economical
use of space. It weighs 160 pounds, mounts on
a 19-inch-wide relay rack, and is 21-inches high.
Full accessibility is required, although the TJ
bay must be mounted against a wall so that only
the front is available for such access.

One part of the answer to full accessibility
is to use the full depth allowed. Components
are mounted on both sides of the backplate and
on the inside of the cover. All wiring is placed
on the front of the backplate and the inside of
the cover. The cover has a hinge at the bot-
tom and, when released by two. twistlock
fasteners, swings open to expose all the wires
and connections This is. sufficient for ad-
justments, trouble shooting and replacement of
most components. The backplate divides into
two parts, with the upper part also hinged to
swing forward. This permits access to the back
of the backplate so that even the filter capacitors,
transformers and other coils can be replaced
from the front of the power supply. The general
arrangements made for front access can be seen
in the accompanying photograph.

The cover presents a smooth, attractive appear-
ance and serves its utilitarian functions of sup-
porting components and protecting personnel
from contact with live electrical parts. A recessed
panel holds the necessary controls and test jacks
in a convenient position with no protruding parts
to catch clothing or to break off accidentally.
When the cover is opened, its weight is counter-
balanced by sash pulleys—one on each side—
which allow easy movement. The sash pulleys —
visible in the photograph in the upper corners
of the open power supply—hold the cover open
in a horizontal position.

The photograph also shows the arrangement of
circuits in the supply. Mounted inside the cover
are: (in addition to the front-panel controls)
the directly regulated -—400 volt supply; the
auxiliary plate-voltage supply; and, on the shelf
in the corner, the voltage-reference tube and
feedback amplifier. The magnetic amplifier is
mounted on the upper-left corner of the back-
plate, which is vertical in the photograph. Posi-
tive supplies are lined up vertically on the upper
section of the backplate, and the filament supply,
relays and external connections are in the lower
section.

Because this power supply is the first in the
Bell System to use silicon diodes in a high-volt-
age rectifier application, the rectifier-bridge cir-
cuits have been changed several times to keep
pace with advances in the state of the art. For
example, the tool-made sample shown in the pho-
tograph had more than one hundred 200-volt
diodes mounted on card assemblies. Successive
improvements in the diode section of the supply
include: omission of bridging resistors, reduc-
tion to five 400-volt diodes in the production
sample, and now that 2000-volt units are avail-
able, reduction to a single 2000-volt diode per arm.
When only four 2000-volt diodes are needed for a
rectifier bridge, they can be mounted on tall
standoffs (directly from the back panel) to save
the equipment and assembly expense of the recti-
fier-bridge card assemblies used initially.

One final feature of the TJ power supply is
that all 42 connections to transmitter, receiver,
IF amplifiers, metering panels, AFC and blower
motors — the whole TJ repeater bay — are made
through connectors, which merely plug into the
power supply.

The use of connectors facilitates installation
and helps to assure that everything necessary is
plugged in before the power-supply interlock
circuit is closed. Also a connector takes less
room for a given number of leads than a ter-
minal strip, and once wired correctly assures the
right connections throughout the long life of
the equipment.

Customer dialing of toll calls will take a
major step forward with the application
of Centralized Automatic Message
iccounting (CAMA) to the 4A and 1M
Toll Systems. These changes have brought
about a need for new considerations in

For nationwide customer dialing, the dialing
instructions must be uniform for all central
offices in clearly recognizable numbering plan
areas. In telephone language, a numbering plan
area consists of a particular geographical terri-
tory in the United States and Canada. Each
numbering plan area is represented by a dis-
tinctive 3-digit code, with either a 1 or 0 as a
middle digit. Each such area will generally con-
tain some 500 or fewer local central offices, each
of which will be assigned a distinctive 3-digit
office code.

Thus, each telephone will have, for distance-
dialing purposes, a unique identity—a 3-digit
area code, an office code of three digits that may
include one or two letters, and a station number
of four digits. Under this plan a customer will
dial seven digits to reach another customer in
the same numbering area, and ten digits to reach
a customer in a different numbering area. (In
addition to the 7- or 10-digit codes, a directing
code will be necessary in some instances.)

With the introduction of centralized automatic
message accounting (CAMA) facilities for the
No. 4A and 4M toll crossbar systems, direct dis-
tance dialing (DDD) will be available to many
customers for the first time. To further imple-
ment direct distance dialing, the No. 4-type sys-
tems are also arranged to furnish CAMA facili-
ties for customers in two areas adjacent to the
area in which the No. 4 CAMA office is located.

The map opposite illustrates a geographical loca-
tion where the 4A CAMA office serves customers
in area 206 and its home area 503. Suppose a
customer from OXford 3 in Vancouver calls a
customer in ATwater 2, Seattle, and his call is
routed via the Portland 4A CAMA toll office.
OXford 3 and ATwater 2 are in area 206, and
therefore the customer will dial the 7-digit AT2
number 282-XXXX. There is also a 282 (ATlan-
tic 2) office in Portland, so to be able to route
this call back to the originating area — even
though the area code 206 is not received — the
4A CAMA office in Portland must know the area

from which the call originated. This is done by
using an area of origin mark from the trunk cir-
cuit to generate the correct area code, which is
then prefixed to the dialed code to make possible
the correct translation.

The area of origin of the incoming trunk used
on a customer-dialed call is indicated by the trunk
class translator frame (RECORD, June, 1960).
When the call originates in the home area, the
area of origin mark ‘“‘zero” is received. Area of
origin marks “Al” or “‘A2” are received for calls
originating from the two adjacent areas. In the
‘ase of the call from a customer in OXford 3,
(see map) to a customer in ATwater 2, the area
mark ‘‘Al” will indicate that the call is originat-
ing from area 206. However, before action can be
taken by the decoder with this mark, it must
know whether an area code was dialed.

This is determined by the CAMA sender, which
indicates by a 7D mark that seven digits were
received. With these two marks — the area mark
“Al” from the trunk class translator and the
“7D” mark from the sender — the decoder pro-
ceeds to steer the call to the proper card trans-
lator, prefixes the area code 206 in the first 3-digit
position of the code leads, and transfers the re-
ceived office code 282 to the second 3-digit posi-

Area code numbers in Northwestern United States.
Western Washington code is 206; Oregon code is
503. Middle digits of all codes are “zero” or “one”.

tion of the code leads. This simulating of a dialed
area code and shifting of the code leads permit
the 6-digit card (code 206-282) to be selected in
the right card translator. The translator in turn
gives proper routing instructions for call com-
pletion.

A slightly different situation exists on a call
from OXford 3 to the ATlantic 2 office in Port-
land. Here the area mark “Al” received by the
decoder from the trunk class translator again in-
dicates that the call originates from area 206.
The CAMA sender associated with this call re-
veals to the decoder that it has received ten digits
503-282 XXXX. The home area code is “recog-
nized” by the decoder which proceeds to delete it
and then shifts the office code to the A, B and C
digit positions. The decoder goes on to complete
the call by selecting the ATlantic 2 card 282 in
the home translator.

If the Oxford customer had dialed a call for
BUckminster 2 in New York City, instead of
ATlantic 2 in Portland, the decoder would again
have examined the area code and determined now
that it is not the home area but some distant area
212. With this information, the decoder will pro-
ceed to select the New York area code card (212)
in the home translator and complete the call in
the regular manner — that is, without code shift-
ing or deletions.

Customers served by 4A CAMA may uninten-
tionally dial calls using codes which are irregular
or unauthorized, such as the use of two area
codes, or special “operator only’’ codes. These
calls, which require detection and special routing
arrangements, all involve the digits ‘‘zero” or
“one” in the D or E positions. The sender, upon
recognizing this condition, stops the progress of
the call, and signals the decoder to set this call
up so that the customer reaches a special operator
or a particular trunk group which gives a ma-
chine announcement suggesting that he consult
the directory for correct dialing information.

The decoder, in conjunction with the routing
‘ard in the 4A system, continues the screening
process on those codes which the CAMA sender
cannot detect. For example, codes such as 121-
XXXX must be screened by the decoder because
CAMA customers may inadvertently call an in-
ward operator (code 121). To detect routings of
this nature, the 121 route card will indicate
“UCR” (Unauthorized for CAMA Routing). This
indication causes the decoder to route the call to
a machine announcement instead of the regular
121 inward operator. The machine announcement
will suggest that the customer consult his direc-
tory to avoid subsequent incorrect dialing. If

Author points out 503 area on nationwide dialing map. Other three-digit numbers are also area codes.

this same 121 code is used by an operator on a non-
CAMA eall, the “UCR” indication is disregarded
and the connection to the 121 inward operator is
permitted in the regular manner. The “UCR”
indication can therefore permit discrimination
on any code route in the 4A system. For example,
all arbitrary codes used by operators on non-
CAMA ealls, or unauthorized area codes, will
have the “UCR” indication to prevent their use
by CAMA customers.

Furthermore, by using the “UCR” indication,
customers would be prevented from unintention-
ally dialing any route involving 6-digit transla-
tion. To safeguard this arrangement, all per-
missible routings for both CAMA and non-CAMA
customers will be coded “ACR” (Authorized Code
Routing). The 4A CAMA system checks each
routing for one or the other (“UCR” or “ACR’’)
indication, and warns if neither or both occur on
any call.

Customers, after becoming acquainted with
CAMA dialing facilities, may attempt to route

local calls through the 4A toll system after they
have tried and failed to complete them through
the regular local telephone plant. For example, if
a customer in the OXford 4 office (see page 267)
is unsuccessful in completing a call to a customer
in OXford 5 office, he may try to complete the
same call by first dialing a directing code which
routes the call to the 4A CAMA office. Then, fol-
lowing this code he would dial OX5 plus four
digits. If these calls were allowed to be completed
through the toll system, the trunk group between
Vancouver and Portland would be overtaxed un-
necessarily. All misrouted calls of this type are
screened by the CAMA equipment and routed to
a machine announcement.

Facilities are available at the 4A system main-
tenance center for initiating calls with all pos-
sible code routings so that these new features
may be tested for proper operation. In this man-
ner, satisfactory performance of the CAMA fea-
tures in the 4A and 4M toll switching system will
be verified.

The discovery that zinc oxide and cadmium
sulfide are strongly piezoelectric was recently re-
vealed by A. R. Hutson of the Semiconductor Re-
search Department. He reported his finding in
the May issue of Physical Review Letters, a
publication of the American Physical Society.

In piezoelectric materials, the application of
a mechanical stress generates an electrostatic
charge. Conversely, an electrical field applied to
such a crystal changes the crystal’s physical
shape according to the way it is
cut. An electrical signal at a radio
Semiconductor frequency can thus be applied to

Research a piezoelectric crystal to generate
mechanical vibrations the
same frequency as the signal. This property is
known as electromechanical coupling. The best
electromechanical transducers of this type are
made from materials which are strongly piezo-
electric, and such materials exhibit a large elec-
tromechanical-coupling constant.

To demonstrate the piezoelectricity in zine
oxide, it first had to be “doped” with lithium to
neutralize the excess conductivity. The degree
of piezoelectricity exhibited by doped zinc oxide
is about four times as great as that of quartz;
cadmium sulfide is twice as great. Mr. Hutson
made confirming measurements on single crystals
of zine oxide grown both by vapor techniques and
from a flux, or molten salt. The cadmium-sulfide

Both zine oxide and cadmium sulfide are recog-
nized as “n-type’”’ semiconductors. For example,
zine oxide usually shows a room temperature re-
sistivity less than 10* ohm-cm—a figure denoting
a good semiconductor, This relatively low re-

sistivity has heretofore effectively hidden all
direct experimental evidence of piezoelectricity.
Mr. Hutson decided to investigate the piezoelec-
tric constants of these materials while studying
some of their unusual conductivity properties. A
large piezoelectric constant seemed to explain
these anomalies theoretically, but it had never
been observed experimentally.

The conductivity of the zine oxide was
“quenched” by diffusing lithium atoms into the
material. These acted to “neutralize” the excess
electrons which were contributing to the con-
ductivity. When this was done, the resistivity
of the material was raised from 10° to 10!
ohm-cm at room temperature.

Both electrical and mechanical measurements
were made on vapor-grown needles and _ flux-
grown platelets of zinc oxide, and on the vapor-
grown cadmium sulfide. With dielectric constants
of 8.2 and 9 for zine oxide and cadmium sulfide,
respectively, Mr. Hutson calculated the electro-
mechanical coupling constants to be approxi-
mately 0.4 for zinc oxide and 0.2 for cadmium
sulfide, compared with 0.095 for quartz.

A psychoacoustic phenomenon called the ‘“Cock-
tail-Party Effect” has recently been duplicated
electronically by a group of investigators at
Bell Laboratories. The name of this phenome-
non comes from the fact that the human listener
-an concentrate his attention on a specific voice in
which he is interested, and thereby “‘enhance’’ it
from the surrounding babble of voices or other
noise. This is true even though the voice of inter-
est may be no louder than the surrounding noise.

News of tener can enhance the effective
Acoustics intensity of the desired voice by
Research 5 to 15 decibels by “suppressing”

J. F. Kaiser, left, and E. E.
David with equipment used to
duplicate electronically a hear-
ing phenomenon. E frect studied
is one permitting listener to
pick out one conversation from
a cacophonous background.

Similarly, a remote listener auditing with a tele-
phone transmitter, or any single microphone, is
unable to suppress spurious noises in the originat-
ing environment. Thus, background noise inter-
feres much more with a transmitted voice than
the same noise would if the two-eared listener
were standing in the same room with the talker.

The advantage achieved by the ear and brain in
the cocktail party effect is more than would be ex-
pected through linear addition of the two aural
inputs. Therefore, the investigators used non-
linear techniques in the attempts to duplicate
the effect electronically. In one technique, the
output of two microphones are compared automat-
ically to generate a gating wave, which controls
the volume of the combined output of the two
microphones. This gating raises the intensity of
the combined signal only when energy from the
desired voice arrives simultaneously at the micro-
phones. Otherwise, the gate suppresses the com-
bined signal. Noise or interfering speech signals
will pass through the gate only if they occur simul-
taneously with the desired speech signals. How-
ever, this simultaneity is rare, and the pattern, or
continuity, of the undesired signal is disrupted,
greatly reducing its interfering qualities.

In subjective tests, enhancements of 9 db in
effective signal level were achieved against a
background of one interfering talker and 5 db
was found with two extra talkers. While the data
reported are preliminary, they suggest that hu-
man-attention mechanisms may be simulated.

The Army demonstrated early last month how
an improved version of its Nike Hercules can
meet short-range ballistic missile threats when a
Hercules missile destroyed a Corporal missile at
White Sands Missile Range, New Mexico. The
spectacular engagement between the two missiles
was carried out many miles above the desert and
miles from the defended area.

The photographs below show Nike Hercules,
left, which is a surface-to-air guided missile and
Corporal, right, the U.S. first operational ballis-
tic missile. Center sequence shows, top to bottom,
the actual missile intercept and the complete de-
struction of the Corporal target. Hercules is on
top with Corporal directly below.

In the test, an operational Army Corporal with
a warhead was fired at a target near the Nike
Hercules site. As soon as the Corporal emerged
above the intervening mountains it was detected,
tracked and destroyed considerably short of its
target by the Hercules missile. The firing was
carried out by Army personnel and Bell Labora-
tories and Douglas Aircraft Company engineers.

Nike Hercules, now extensively deployed in de-
fense of the U. S. and vital overseas installations,
has previously demonstrated its ability to engage
and destroy supersonic, high-performance air-
craft, which pose a threat today. The inherent
growth potential of the system has permitted
Bell Laboratories to design an improved version
by modifying already deployed Nike Hercules
systems. This modified system is designated the
Improved Nike Hercules. These field modifica-
tions are supplied by the Western Electric Com-
pany, prime contractor for the Nike Hercules
system, and one of its principal subcontractors,
the General Electric Company.

The Improved Nike Hercules has a defense
capability against ballistic missiles of the field
artillery type, such as the Corporal and also
against air-to-ground missiles. In addition, ad-
vanced radar designs insure high performance
despite attempts at sophisticated electronic jam-
ming that could be a threat to our defense during
the forthcoming decade. The improved Nike Her-
cules system can use both Ajax and Hercules
missiles. No modifications to Nike Hercules
launching areas are required.

Under direction of U. S. Army Rocket and
Guided Missile Agency, Hercules was designed by
Bell Laboratories and Douglas Aircraft Company.
The same Army-Industry team responsible for
Nike Hercules is also working on Nike Zeus,
America’s only system now under development to
defend against the threat of
ballistic missiles.

In high-speed, short-pulse studies, engineers
can obtain a great deal of information by using
oscilloscopes to observe repeti-
tive pulse patterns. However,
several new devices, such as
the microwave transistor re-
cently announced by Bell Lab-
oratories (RECORD, April, 1960)
and Esaki diodes (RECORD, March, 1960), operate
too rapidly for conventional oscilloscopes to fol-
low. Standard practice with typical broadband
amplifier oscilloscopes is to “trade” sensitivity
for fast rise time. In other words, fast rise
time and high sensitivity are usually mutually
exclusive in these instruments.

This restriction does not apply to an electrical
stroboscope, however. Here, the rise time is pri-
marily a function of the bandwidth of the
sampling circuits, and sensitivity depends only
on the gain of the amplifier in the low-frequency
portion of the oscilloscope. But a penalty is paid
for these advantages in the time required for
integration. The principle involved in the opera-
tion of an electrical stroboscope is similar to that
of a light stroboscope, which appears to slow

In the electrical device, when the signal pulse
and the strobe pulse occur at the same rate, the
stroboscope continues to look at the same part of
the electrical signal, comparable in a sense to a
light stroboscope freezing the motion of a rotating
shaft. If the two frequencies differ slightly, the
signal interval is scanned repetitively. Here, the
analogy to the light stroboscope is the way that a
moving part appears to move slowly when the
light frequency differs slightly from rotational
frequency.

The designers are using the new instrument,
which has a sensitivity of 2 mv/cm, in studies of
binary pulses in the range of 1,000 megabits, or
a billion bits per second. They have produced
oscillograms of 160-mc square waves, and of 640
million pulses per second, with a rise time for
the wave forms of as fast as 2x10~!° seconds.
Further tests conducted at the Laboratories indi-
cate that rise times at least as short as 10~!° see-
onds can be displayed satisfactorily.

j ly j j
is one of Great advantag
State ete iii thre pul Sli
fast operation of thety experunentai evices.
3 4

Epitaxial Film Technique
Brings Major Improvements
In Diffused-Base Transistor

Research at Bell Laboratories has _ recently
brought about major improvements in the dif-
fused-base transistor through use of the epitaxial
film technique. The improvements include large
reductions both in switching time and in the
resistance of the collector region of the tran-
sistor. The achievement was recently revealed in
a paper authored by H. H. Loar, H. Christensen
and J. J. Kleimac of the Transistor Development
Department and H. C. Theuerer of the Metallur-
gical Research Department.

Epitaxial films are those formed on the surface of
a crystal which are identical to the crystal in struc-
ture of the lattice. These films have made possible
silicon transistors whose switching times are less

implications in both the fabrication and applica-
tion of semiconductor devices.

Diffused-base transistors require a collector
region with relatively high resistivity to attain
low capacitance and high voltage breakdown.
Heretofore, for ease of fabrication, this region
has been much thicker than required electrically.
The excess thickness increases the collector re-
sistance and, through storage of the electrical
carriers, the switching time.

Ideally, the thickness of the collector region,
lightly doped with impurities, should be in the
neighborhood of 0.1 mil, which is about one thir-
tieth as thin as normally used. Semiconductor
wafers prepared by conventional methods become
extremely difficult, if not impossible, to handle
as they approach this desired thinness. Now, this
problem can be solved with the epitaxial film
techniques. In this method, lightly doped, high-
resistivity, epitaxial films are grown on and sup-
ported by a heavily doped, low-resistivity ‘“‘sub-
trate,” giving the desired combination of elec-
trical properties and mechanical strength.

The Laboratories has made diffused-base tran-
sistors on epitaxial layers of both germanium and
silicon which have exhibited the improvements
predicted theoretically. For example, in two simi-
lar silicon transistor structures, one conventional
and the other using the epitaxial material,
switching time in a typical circuit has been re-

duced from 200 to 20 millimicroseconds. Further- ;
more, the series resistance of the collector in the
epitaxial transistor was reduced by a factor of
more than 10 and was comparable to the resist-
ance of conventional devices 15 times larger. Ex-
periments with germanium indicate that epi-
taxial layers will extend the frequency response
of such transistors well beyond that of a 2-kme
device recently announced at the Laboratories.

The new technique involves modification of the
“starting” material. The device can then be made
by existing production facilities for diffused-base 3
devices. In the process, single-crystal wafers of
heavily doped material are first cut and polished.
A lightly doped thin film (about 0.1 mil) of the
same type of conductivity is then deposited epi-
taxially on the wafer surface (see accompanying
illustration). This film provides the desired thin,
lightly doped, collector region. From this point
on, manufacturers will use standard diffused-
base techniques.

Epitaxial material in diffused-base transistors
not only results in major improvements in switch-
ing time and collector resistance, but also simpli-
fies the design and understanding of transistor
devices and brings them closer to ideal forms.
Furthermore, the addition of the epitaxial film
technique to the well established diffusion tech-
nology gives the device engineer an extra degree
of freedom in design which should result in new
devices, formerly difficult or impossible to achieve.

THICK, LIGHTLY
DOPED, HIGH-
RESISTIVITY
COLLECTOR REGION |
RQ ur
b EMITTER COLLECTOR

Essential differences between conventional and
epitaxially grown transistors. Thickness of col-
lector region in (a) results in high resistance.
Epitaxial construction of region in (b) permits
it to be thinner, hence have less resistance.

Three men—Gordon N. Thayer,
vice president, S. Whitney Landon,
assistant to president and secre-
tary of the Company, and Pres-
cott C. Mabon, assistant to the
president were involved in recent
organization changes at the
A.T.&T. Company.

Mr. Landon and Mr. Mabon
were elected vice presidents of the
Company, and Mr. Thayer, since
last October vice president in

charge of the marketing depart-
ment, was appointed operations
vice president. Mr. Landon will
continue as secretary of the Com-
pany, a post he has held since
1952. Mr. Mabon has been assist-
ant to the president since 1949.

Mr. Thayer, who joined the
technical staff of Bell
tories in 1930, was named trans-
mission development engineer in
1948. The following year he be-
came assistant director of trans-
mission development and in 1951
he was named director of trans-
mission development.

Mr. Thayer was elected vice
president of the Laboratories in
1952 and was in charge of the

Laboratories military develop-
ment program. Later, for about
two years, he was in charge of
engineering and development
work for the Bell System.

Company in 1934 as an attorney.
Three years later he became gen-
eral attorney in charge of the
legal department of the Long
Lines Department. He was named
assistant vice president and as-
sistant secretary, Secretary’s De-
partment, in 1951. The next year
he was elected secretary of the
Company and appointed assistant
to president.

Mr. Mabon joined the General
Information Department of the
Southern New England  Tele-
phone Company in 1934. In 1939
he joined the A.T.&T. Information
Department. He was appointed
information manager the next
vear, in 1944 was named assistant
vice president, and in 1949 became
assistant to the president.

At its 206th Commencement
Exercises held on June 1, Colum-
bia University awarded Dr. J. B.
Fisk the honorary Doctorate of
Science.

Others who received honorary
degrees from Columbia at the
same ceremonies were: Vice Ad-
miral Hyman G. Rickover, chief
of the Navy Bureau of Ships and
authority on nuclear-powered sub-
marines; Albert J. McConnell,
Provost of Trinity College, Dublin,
Eire; Lawrence M. Gould, Presi-
dent of Carleton College, North-
field, Minnesota; Bishop Horace
W. B. Donegan, Episcopal Diocese
of New York; Allan Nevins, Pro-
fessor Emeritus of American His-
tory at Columbia; Mark Van
Doren, Columbia Professor Emer-
itus of English; Frank Pace, Jr.,
Board Chairman of General Dy-
namics Corp.; U.S. Comptroller-
General Joseph Campbell; U.S.
Senator Lister Hill (D-Ala.); and
Henry Cabot Lodge, Jr., U.S. Am-
bassador to the United Nations.

Following is a list of speakers, titles and places of presentation
for recent talks presented by members of Bell Laboratories.

(YIG) at Low Temperatures. Procedure to Improve DC Char- Trumbore, F. A., Effect of p-Type
Donovan, P. F., Foreman, B. M., acteristics of Oxide Film Ca- Germanium Arsenide Occlu-

Jr., and Miller, G. L., Nuclear
Radiation Spectrometry Using
Semiconductor Detectors.

Feher, G., Gere, E. A., and Wil-
son, D. K., Anisotropy of the
Direct Phonon Relaxation Proc-
ess of Donor Electrons in Sili-
con,

Frisch, H. L., Helfand, E., Lebo-
witz, J. L., and Reiss, H.,
Scaled Particle Theory of
Fluids.

Waves in Yttrium Iron Garnet:
Part I Frequency Dependence.
Miller, G. L., see Donovan, P. F.
Nielsen, J. W., see Dillon, J. F.
Nielsen, J. W., see Geschwind, S.
Reiss, H., see Frisch, H. L.
Spencer, E. G., Spin-Lattice Re-
laxation of Low k-Number Spin
Waves in Yttrium Iron Garnet:
Part Il Temperature Depend-
ence.
Stillinger, F. H., Approximations
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Matthias, B. T., Ferromagnetic
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Northern Valley
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Moore, E. F.,
Relay Decoding Networks, Com-
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Pierce, J. R., Satellite Systems for
Commercial Communications,
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I.R.E., Bell Telephone Labora-
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Space, International Scientific
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Device Fabri-
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Anderson, O. L., Andreatch, P.
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Method and Apparatus’ for
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H. W. Augustadt received the
B.S.E.E. degree from the Uni-
versity of North Dakota in 1928
and the M.S. degree in Physics
from Columbia University in 1941.
He joined Bell Laboratories in
July, 1928. During his first four
years with the Laboratories Mr.
Augustadt engaged in network
development and design. From
1932 until 1940 he engaged in the
development of a variety of sound
reproduction systems including
sound picture apparatus, public ad-
dress, speech input and Navy

Newby, N. D.—Means for De-
tecting Marking and By-Pass-
ing Defective Areas in a Mag-

battle announcement systems for
battleships, cruisers and aircraft
carriers. During World War II
he worked on Navy fire control
systems and designed the auto-
matic radar ranging and angle
tracking systems used in the
Mark 12 and Mark 25 radars. In
1955 he was assigned responsibil-
ity for the Mark 65 program for
the Navy, the subject of his ar-
ticle in this issue of the REcorpD.
Subsequently he supervised the
development of the Navy’s cur-
rent series of guided-missile,
weapon-direction equipments for
cruisers and frigates.

Rexford S. Tucker was born in
Jamestown, N. Y., and received
an A.B. degree from Harvard Col-
lege in 1918 and an S.B. from
Harvard Engineering School in
1922. He joined the Development
and Research Department of the
A.T.&T. Company in 1923 and
transferred with that group to
the Laboratories in 1934. His
early work was on noise and cross-
talk prevention. During World
War II he was engaged in various

Younker, E. L.—High Speed
Switching Circuits Employing
Slow Acting Components—2,-
936,117.

military projects and was co-
editor of the Signal Corps Tech-
nical Manual on Electrical Com-
munications Systems Engineering.
After the war he worked on
mobile-radio systems engineering
and is presently engaged in similar
work on transoceanic cables. Mr.
Tucker is a member of I.R.E., the
Acoustical Society of America,
A.I.E.E., the Harvard Engineer-
ing Society, and Phi Beta Kappa.
He is the author of “Sixteen-
Channel Banks for Submarine
Cables,” in this issue.

L. G. Schimpf (“Transistor-
ized Carrier System for TV’)
was born in New Washington,
Ohio, and received a B.E.E. de-
gree from Ohio State University
in 1937. He joined the research
department of the Bell Labora-
tories the same year and began
work on the application of elec-
tronic devices to switching func-
tions. With the outbreak of World
War II, he turned his attention
to research and development work
on military projects. After the
war, he specialized in transmis-
sion research studies of local sub-
scriber station circuits. Since 1952,
he has been engaged in transistor
circuit research. His chief interest
in this area has been the applica-
tion of transistors to wideband
and high-frequency transmission
circuits. Mr. Schimpf, who holds
several patents in the field of
electronic switching, is a member

of the Institute of Radio Engi-
neers, the Acoustical Society of
America, Eta Kappa Nu, and
Tau Beta Pi.

I’. M. Pearsall, Jr., a native of
Brooklyn, joined the Laboratories
in 1929. He conducted fundamen-
tal pulsing studies for step-by-
step and worked on the No. 4
During World
War II, he designed test circuits

for electrical gun directors and
operational flight trainers for the
Navy. Subsequently, he tested the
performance and outlined require-
ments for the trouble recorder and
card translator. After working on
the Nike project, Mr. Pearsall did
some preliminary investigation of
the flying-spot store for the semi-
permanent memory for ECO and
designed the translator-shift regis-
ter circuit for the magnetic-drum
sender. Most recently, he has been
concerned with the development
of CAMA trunks and the design
of the emergency reporting sys-
tem. He received a B.E.E. degree
from Brooklyn Polytechnic Insti-
tute in 1943 and is a member of
Eta Kappa Nu, A.I.E.E., and the
New York State Society of Pro-
fessional
author of “The Direct-Line Emer-
gency Reporting System.”

R.H. Small was raised in Mich-
igan and received his B.S. degree
at Michigan State College (now
Michigan State University). He
joined the technical staff of Bell
Laboratories in 1953. Upon com-
pletion of the Communications
Development Training program,
he attended Newark College of
Engineering, receiving his M.S.
degree in Electrical Engineering
in 1958. In 1957, Mr. Small
became a member of the Power
Development Department, where
he was engaged in the develop-
ment of unregulated and regu-
lated rectifiers. He resigned from
the Laboratories in August, 1959.
Mr. Small wrote, “Power Supply
for TJ Repeaters.”

Edward Jacobitti, author of the
article on 4A CAMA routing ar-
rangements, is a native of New-
ark, N. J. He joined the Engineer-
ing Department of the Western
Electric Co. in 1919, serving that
organization and its
Bell Laboratories, ever
In his early years, Mr. Jacobitti

designed local panel and _ local
No. 1 systems. Dur-
ing the second World War, he did
the fundamental and

practical
design for relay digital computers
and other military projects. Fol-
lowing the war, he designed de-
coders, markers, and translators
used in the nationwide dialing toll-
switching system project. More
recently he has been concerned
with the design of the SC2 Super-
visory Control system for private-
service use and with the applica-
tion of automatic
message accounting (CAMA) to
the 4A and 4M toll systems.

Can you guide a 110-ton Air Force Titan missile
far up into the sky, to bring its nuclear warhead
down with pinpoint accuracy on a target one-
fourth the way around the globe—a target you not
only can’t see but which continually
moves with the spinning earth?

This was the problem in missile
guidance the Air Force presented
to Bell Telephone Laboratories and
its manufacturing partner, West-
ern Electric. The answer was the
development of a command guid-
ance system which steers the Titan
with high accuracy.

Unlike self-contained systems
which demand complex guidance
equipment in the missile itself, Bell
Laboratories Command Guidance

System keeps its master control equipment on the
ground where it can be used over and over again.
Thus a minimum of equipment is carried in the
missile, and the ground station has full control
of the missile during its guided
flight. Techniques drawn from the
communications art render the sys-
tem immune to radio jamming.
Bell Laboratories scientists and
engineers designed the trans-
mission and switching systems for
the world’s most versatile telephone
network, developed much of our
nation’s radar, and pioneered in
missile systems. From their vast
storehouse of knowledge and ex-
perience comes the guidance system
for the Titan.

Bell Laboratories Record  1960-07: Vol 38 Iss 7