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89e7acbbf7c885a99263890058a04f00 | 101 870 | 5 Site characterization | To validate the exposure at an antenna site the following three methods are proposed. NOTE: The benefits of protective clothing, if any, should be taken into account. |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1 Method 1: Field monitor | Method 1 is based on the principle that field strength levels are unknown. This means that no calculations need to be carried out before entering a site. A field probe or monitor should always be used. This method covers the situation where a site has either not been defined or has been defined but it is not certain if... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.1 Types of field monitors | |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.1.1 Personal monitors | Personal monitors provide a means of continuously monitoring the RF field to which an individual is actually exposed. They provide broadband coverage of a range of frequencies. More than one monitor could be required to cover all the frequencies present at multi-user locations for example, where Microwave, Cellular Tel... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.1.2 Area monitors | RF field strength can be continuously measured by an unattended area monitor linked to an alarm system. |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.1.3 Survey instruments | Survey instruments measure the electrical or magnetic components of RF fields. They can be used to pinpoint RF leakage from feeder cables and other sources, using probes that permit measurements in relatively inaccessible places. They also allow the detector to be physically separated and, if necessary, electrically de... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.2 Assessment by field monitors | The personal monitors described in clause 5.1.1.1 could be used to establish the RF field strength at a site. The equipment must be selected to give adequate coverage of the required range of power levels, frequencies, etc. As there will generally be no locally available alternative method for cross-checking the result... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.1.2.1 Exposure assessment | a) If field strengths are known but Limit Distances have not been calculated field strength values must be checked against the Relevant Recommendations. If values are judged by the EM worker to be below the Relevant Recommendations, work may proceed without taking any exposure precautions. For borderline values a perso... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.2 Method 2: Limit distances | Method 2 is based on limit distances. The company responsible of each antenna at a site should provide the limit distance for the relevant configuration. The limit distance information should be available on the site, this may be provided by signs. If the information is not available at the site it should be obtained b... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.3 Method 3: By zoning | The concept of a "Zone" is used to simplify the treatment of EMF and clarify the potential exposure when entering a particular area. Zoning is achieved by comparing the measured values to the limits and categorizing the values according to the safety aspects that need to be adhered to. These different categories are de... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.3.1 Zone definition based on exposure levels (SAR, (S), E, and (H)-field) | Zone A: Total or Partial body exposure values exceed the Relevant Recommendations for workers. Zone B: Total or Partial body exposure values exceed the Relevant Recommendations for workers at some point in space and time but when averaged out (e.g. six-minute rule by spatial moving) levels do not exceed the Relevant <R... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 5.3.2 Site access classification | A site may consist of a number of discrete "sub-sites". Each sub-site will be allocated what is termed an "access level". The objective of assigning an access level to the various sub-sites is to clearly define who is allowed to enter and under what conditions. Four different access levels have been defined. The defini... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6 Access management | |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.1 On-site information | The main purpose of the on-site information is to give information about the characterization of the site. When following one of the three methods defined in clause 5, at least the following on site information should be provided: • Contact information of the company responsible for each antenna at a site. • Signage of... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.2 General Access Conditions | 1) If zoning information is available, the EM workers must make use of the different Zones and Access Levels when working at a site or before accompanying a non-EM Worker. 2) In situations where no valid zoning information is available or it is thought to be out of date no entry is allowed into an area without a field ... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3 Access conditions related to the assessment method | |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.1 Access condition by using a Field monitor (Method 1) | EM workers may only enter those areas where the field monitor indicates that the Relevant Recommendations for workers have not been exceeded. Non-EM Workers are only allowed to access a site using a field monitor under the instruction and supervision of an EM worker. |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.2 Access condition by using limit distances (Method 2) | • When limit distance for workers (see clause 5.2) falls within the equipment enclosure of the antenna then there are no restrictions. • Workers are not allowed to have access to the area defined by the limit distances for workers. |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.3 Access condition by using zones and access levels (Method 3) | |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.3.1 Access conditions for areas with access level 3 | 1) No entry is allowed to Zones A without taking precautionary measures (e.g. protective clothing, power reduction). Such precautionary measures must ensure that exposure above the Relevant Recommendations for workers does not occur. 2) Entrance is allowed to a Zone B under the condition that the EM worker follows the ... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.3.2 Access conditions for areas with access level 2 | 1) Entrance is allowed to a Zone B under the condition that the EM worker follows the on-site specific instructions in order to remain below the basic restrictions of the Relevant Recommendations. These instructions related to spatial or time averaging rules are defined by the company responsible for the site (e.g. kee... |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.3.3 Access conditions for areas with access level 1 | Workers have no access restrictions. |
89e7acbbf7c885a99263890058a04f00 | 101 870 | 6.3.3.4 Access conditions for areas with access level 0 | No condition apply. ETSI ETSI TR 101 870 V1.1.1 (2001-11) 15 History Document history V1.1.1 November 2001 Publication |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 1 Scope | The purpose of the present document is to assist the public network operators and public service providers in producing interface publications according to Article 4.2 of Directive 1999/5/EC [1]. The present document lists the parameters of the analogue interface to the public telecommunications network which could be ... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • Fo... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 3 Definitions and abbreviations | |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: A-wire: one of the wires used in the 2-wire local loop to provide connection to the NTP B-wire: one of the wires used in the 2-wire local loop to provide connection to the NTP Carrier Selection Code (CSC): part of the dialling procedur... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply: AHGC Ad hoc group C, one of the groups set up by the European Commission to preliminarily study the implementation of Directive 1999/5/EC [1], group C was given the task of studying the operator's obligation to publish interface specifications... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 4 Applicability of parameters to interface types | The parameters described in the present document are applicable to various types of analogue access to the public telecommunications network. Indirect access to telecommunications networks is also considered, the most common scenarios are described in table 1. Table 1: Methods of indirect access to PNO Scenario Who Pub... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8 Dialling | X X X X 5.9 Ringing X X X |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.10 Register Recall | X X X 5.11 Answer Signal X X X 5.12 Charge Information X X X 5.13 Supplementary services X X X 5.14 PSTN Display services X X X ETSI ETSI TR 101 730 V1.1.1 (2000-01) 9 |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5 Parameters to be specified | Where a terminal equipment standard exists which would ensure an appropriate level of functionality when connected to the network, these standards may be referenced as additional information. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.1 Connection method | The mechanical and contact assignments of the Network Termination Point (NTP) should be described in detail. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.2 Wiring Arrangements and driving capability | ETSI Guide EG 201 120 [3] describes how terminal manufacturers should calculate the loading factor of a terminal based on the parameters which are affected by parallel or series connection. The driving capabilities of the NTP should be specified based on the parameters in EG 201 120 [3], guidance on this may be found i... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.3 DC Voltages and feed conditions | |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.3.1 DC Voltage - On Hook | The DC voltage conditions should be described in such a manner that the terminal manufacturer can anticipate the minimum and maximum DC voltage that a terminal could find on the network in the on hook state, this should include voltages applied during line testing. It is recommended that these voltages be specified int... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.3.2 Polarity | Information should be given as to whether the network maintains a specific polarity on one wire of the line with respect to the other. If polarity reversal occurs then this should be stated along with its purpose. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.3.3 Line current | The DC current available on the line should be specified for both maximum and minimum possible feed currents. In cases where DC feeding conditions change during a call or call attempt then this should also be specified. As the network operator will not know what resistance the terminal will present at the NTP, it is re... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.3.4 Park condition | In cases where the network applies a park condition at the NTP, this should be specified in the same way as stated in subclauses 5.3.1 and 5.3.3. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.4 Seizure | |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.4.1 Conditions at the NTP not recognized as a seizure | The conditions presented at the NTP, which will not be recognized as a seizure condition, should be stated. It is recommended that this should be expressed as the minimum resistance value which can be placed across the A-wire and B-wire at the NTP. ETSI ETSI TR 101 730 V1.1.1 (2000-01) 10 It should be noted that where ... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.4.2 Conditions at the NTP to facilitate line testing | Many network operators perform automatic line testing to permit them to make early detection of line faults. The resistance required at the NTP would normally need to be higher than that specified in subclause 5.4.1. The minimum resistance across the A-wire and B-wire required at the NTP in order to facilitate automati... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.4.3 Conditions at the NTP which will be interpreted as a seize signal | The conditions presented at the NTP, which will be recognized as a seizure, should be specified. It is recommended that this be expressed in terms of maximum resistance value and the resultant DC current that would flow when placed across the A-wire and B-wire at the NTP, which will be recognized as a seizure signal. A... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.4.4 Time required for seizure signal to be recognized | The minimum time during which the seizure condition is applied across the A-wire and B-wire in order to be interpreted as a seizure condition should be stated and also the maximum time during which the seizure condition may be applied without the network interpreting it as a seizure condition. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5 Transmission | The relative level is assumed to be 0 dBr on the digital side of the analogue/digital conversion point in the local network. See figure 1. D D A A Digital Digital 0 dBr 0 dBr NTP Li dBr Lo dBr Line loss: L dB R dB T dB Li = (T + L) dBr Lo = -(R + L) dBr Network equipment delivering the NTP Figure 1: Relative Levels |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.1 Frequency Band | The frequency band available should be specified. The worst case frequency response for frequencies within this band within the network of the PNO should also be specified. ETSI ETSI TR 101 730 V1.1.1 (2000-01) 11 |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.2 Relative Level | For interfaces providing analogue access to the PSTN the input and output relative levels should be specified at a reference frequency within the band specified in subclause 5.5.1. It is recommended that figures be given for best and worst case scenarios. Nominal recommended send and receive loudness ratings for voice ... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.3 Input Impedance | The input impedance for frequencies within the band specified in subclause 5.5.1 should be specified. It is recommended that this be done by: • specifying a nominal network reference impedance and specifying worst case return loss figures for the frequency range in question; or • specifying the terminating impedance(s)... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.4 Longitudinal Conversion Loss | Minimum longitudinal conversion loss for signals within the frequency range specified in subclause 5.5.1 should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.5 Coding Law | Where other than A-law conversion according to ITU-T Recommendation G.711 [8] is used, this should be stated. NOTE: The use of digital pads within the network can reduce the performance of some types of terminal equipment e.g. V90 modems. In such instances their characteristics should be stated by the PNO. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.5.6 Noise | The maximum level of noise introduced by the network when the line is terminated by a reference impedance should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.6 Acceptable signal levels at the NTP | The maximum signal level acceptable at the NTP should be specified for signals within the frequency band referred to at subclause 5.5.1 using the following parameters: • The maximum mean signal level. • Maximum peak voltage. For frequencies outside that band the maximum acceptable level should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.7 Supervisory tones | Supervisory tones such as dial tone, progress tone, busy tone, congestion tone, call waiting tone and ringing tone should be specified in terms frequency including tolerance, cadence including tolerances and maximum and minimum signal levels possible at the NTP. Where verbal announcements are used this should also be s... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8.1 Dialling type | It should be stated if the network supports DTMF and/or Loop disconnect dialling. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8.2 Reception of first digit | The time period following line seizure where the network will accept the first digit should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8.3 Number and timing of call attempts | The maximum frequency of call attempts acceptable by the network should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8.4 DTMF Dialling | ETR 206 [4] specifies the DTMF receiver in the local exchange, however the acceptable level of DTMF tones at the NTP should be additionally specified. In cases where DTMF receivers do not conform to ETR 206 [4] then the following information should be published: • Tone combinations and tolerances acceptable for each di... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.8.5 Loop Disconnect Dialling | Where networks accept loop disconnect dialling the following parameters should be specified: • Coding. • Acceptable frequency range. • Acceptable range of make period duration. • Acceptable range of break period duration. • Minimum acceptable make period current. • Maximum acceptable break period current. • Acceptable ... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.9 Ringing Signals | The ringing signals used on the network should be specified using the following parameters: • Frequency range and waveform of ringing signal. • Maximum and minimum ringing voltages possible at the NTP, it is recommended that these be specified into a fixed impedance. ETSI ETSI TR 101 730 V1.1.1 (2000-01) 13 • Maximum d... |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.10.1 Timed break recall | Where timed break recall is used to signal register recall the acceptable range of duration of the break in the loop current should be specified along with the maximum acceptable residual current during the break period. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.11 Answer signal | Where an answer signal is applied by the network to the calling party at the NTP this should be specified |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.12 Charge information | Where charging information is applied by the network at the NTP this should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.12.1 Meter Pulses | Where meter pulses are used to deliver charge information the following parameters should at a minimum be specified. • The frequency used including tolerances. • The maximum and minimum duration of the pulse. • The maximum and minimum level of meter pulses possible at the NTP. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.13 Clearing signal from the network | When a call is cleared by the network, any signals sent to the terminal equipment should be specified. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.14 Signalling for supplementary services | Where supplementary services such as call diversion, call hold, call retrieve and call conference are available, the necessary signalling methods, codes and protocols should be defined. NOTE: An ETSI register of supplementary service codes is listed in TR 102 083. |
6e2f5ef4541d2040ede21595aa63016a | 101 730 | 5.15 Signalling for PSTN display services | EN 300 659-1 [5] and EN 300 659-2 [6] specify possible signalling methods which may be used to deliver display services over the PSTN, these standards contain options, PNOs should publish which options are implemented and which coding parameters are implemented. Where display services are implemented using methods othe... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 1 Scope | The present document establishes the results of an investigation into existing standards and approval documents dealing with acoustic safety (including acoustic shock) requirements for telecommunications terminal equipment, together with other relevant background information. The present document has been produced in o... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 2 References | The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • Fo... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 3 Definitions and abbreviations | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 3.1 Definitions | For the purposes of the present document, the following terms and definitions apply: noise induced permanent threshold shift: amount of permanent threshold shift remaining in a population after subtracting the threshold shift that would occur "normally" from causes other than from occupational noise [41] recruitment: c... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 3.2 Abbreviations | For the purposes of the present document, the following abbreviations apply: CHABA National Academy of Science Research Council Committee on Hearing Bioacoustics and Biomechanics DRP Eardrum Reference Point ERP Ear Reference Point FDA Food and Drugs Administration (of America) HATS Head And Torso Simulator NIH National... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4 Acoustic shock | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4.1 General | Damage may be caused to hearing either by long-term exposure to high levels of sound or by high levels of acoustic shock. Acoustic shock is defined by the ITU-T [1] and by ETSI [2] as "any temporary or permanent disturbance of the functioning of the ear, or of the nervous system, which may be caused to the user of a te... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4.2 Noise induced hearing loss | The American National Institute of Health (NIH) [6] states that sounds of sufficient intensity will damage the ear and result in temporary or permanent hearing loss. The hearing loss may range from mild to profound and may also result in tinnitus. The effect of repeated sound overstimulation is cumulative over a lifeti... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4.3 Assessment of NIHL | The same NIH statement [6] explains that hearing loss is measured by determining auditory thresholds (sensitivity) at various frequencies (pure-tone audiometry). Pure-tone audiometry is also used in industrial hearing conservation programs to determine whether adequate protection against hazardous sound levels is provi... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4.4 What sounds can damage hearing? | The NIH [6] points out that some sounds are so weak physically that they are not heard. Some sounds are audible but do not have any temporary or permanent after-effects. Some sounds are strong enough to produce a temporary hearing loss from which there may appear to be complete recovery. Damaging sounds are those that ... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 4.5 Telephone speech levels | At a distance of 1 metre, French and Steinberg [8] quoted the intensity of speech integrated over the entire spectrum to be 65 dB relative to 10-16 watt/cm2. This figure was measured using a telephone testing crew and is equivalent to a sound pressure of 65 dB SPL. Barnes [9] quotes a nominal speech level of 63,9 dB SP... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5 Legislation | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.1 European legislation | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.1.1 The RTTE Directive (1999/5/EC) | This Directive 1999/5/EC [11] establishes a regulatory framework for the placing on the market, free movement and putting into service in the Community of radio equipment and telecommunications terminal equipment. In Article 3.1(a), "the protection of health and the safety of the user and any other person, including th... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.1.2 Low voltage Directive (73/23/EEC) | This Directive 73/23/EEC [12] is a "total harmonization" Directive so that the measures it contains replace national rules in the field in question. It applies to all telecommunications terminal equipment through the RTTE Directive. It specifies that equipment "may be placed on the market only if, having been construct... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.1.5 Draft Physical agents Directive | In 1994, The European Commission proposed in a draft Physical Agents Directive [16] that 75 dB(A) should be a threshold level for noise exposure at which workers should be informed on risks. It also proposed that at 80 dB(A) or a peak pressure of 112 Pa (equivalent to 135 dBPa), workers should have a right to hearing s... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.2 American legislation | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.2.1 Walsh-Healey Act of 1969 | The American National Institute for Occupational Safety and Health (NIOSH), in its paper entitled "Occupational noise and hearing conservation, selected issues" [17] has set out a critical history of the current United States legislation on noise mandated by the Walsh-Healey Act. It states that: "In 1965 the National A... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.2.2 National Institute for Occupational Safety and Health | Arising from a requirements of the Occupational Safety and Health Act of 1970, the US department of Health and Human Services in 1998 published a National Institute for Occupational Safety and Health (NIOSH) document [23] revising earlier recommendations for criteria for a recommended standard on occupational exposure ... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 5.2.3 Federal Communications Commission | Part 68 of the Rules of the Federal Communications Commission requires that since the 1st January 2000, all telephones, including cordless telephones, manufactured in the United States (other than for export) or imported for use in the United States, "must be hearing compatible" by having a volume control feature consi... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6 Standardization | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.1 International Standardization | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.1.1 Activities in the ITU | The original CCITT recommendation dealing with acoustic shock was CCITT Recommendation K.7 [24] (adopted in Geneva 1964). This recommended that when a voltage surge occurred on a telephone line that caused the protective device to operate, the amplitude of the sound pressure caused by the diaphragm of the receiver shou... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.1.2.1 IEC 950 | A proposal for a new work item on the control of acoustic levels was proposed by IEC/TC74 WG 7 in July 1991. The first draft amendment was based on rather poor rewording of CCITT Recommendation P.36 [28] and at voting in early 1993 received a number of negative comments, mainly from European countries. A fresh draft wa... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.2 European Standardization | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.2.1 Activities in CENELEC | The work of CENELEC paralleled the IEC work on the unsuccessful amendment to IEC Publication 950 [38]. Since then a proposal has been made by the UK that CENELEC should commence work on "Acoustic power limitation for the safe use of telecommunications receiving transducers intended for application to the human ear". A ... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.2.2 Activities in ETSI | The 19 ETSI documents, which make reference to acoustic shock, are listed in clause A.1. The listing also gives extracts indicating the requirements. Early documents (e.g. ETSI ETS 300 085 [60] on ISDN handset terminals) specified limits of 24 dBPa rms (equivalent to 118 dB rel 20 µPa) measured at the Ear Reference Poi... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.3 National specifications | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.3.1 European telephone specifications - summary | Clause A.2 gives details of the acoustic shock requirements set out in approval requirements for telephone apparatus from many European Countries. Of the 11 countries for which specifications are available, four (Belgium, Denmark, Finland and the Netherlands) set a limit of 120 dB SPL for sinusoidal signals. Switzerlan... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.3.2 American telephone specifications - summary | Clause A.3 gives acoustic shock requirements taken from American specifications. EIA-470-A (dated 1987) applies a surge to the telephone line and requires that the peak acoustic pressure in the artificial ear shall not exceed 130 dB SPL (36 dBPa). EIA-470-B [101] (dated 1995) retained the same peak limit but added a re... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.3.3 Other countries - summary | Of the three other specifications available, one asks for click suppression to prevent "damage to the ear", a second asks for conformance "to the relevant CCITT Recommendations" and the third requires the level through the earpiece not to exceed 24 dBPa when the incoming call indication is provided on the handset. ETSI... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.3.4 European noise exposure standards | Hassel and Zaveri [42] in 1979 quoted the brief summary of some limits for occupational noise exposure in national standards that are reproduced in table 1. Table 1: National Standards on Occupational Noise Exposure limits EEC member state Steady noise level (dB(A)) Time exposure (h) Halving rate Overriding limit Impul... |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.4 Other relevant standards | |
3e44a52a33a6dfb0c8fe1f15a080e7a9 | 101 800 | 6.4.1 BS 5330 | This standard describes a method of test for estimating the risk of hearing handicap due to noise exposure. When it was published in 1976 it differed substantially from the then current version of ISO Publication 1999 [33]. It still differs substantially from the 1990 version of that standard in that it deems handicap ... |
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