1、EIA 384 70 m 3234600 00bb70 2 m .- 4 EIA STANDARD m Time Division Multiplex Equipment 4 Standard For Nominal 4 kHz RS384 9 Y Channel Bandwidths Engineerng Department ELECTRONIC INDUSTRIES ASSOCIATION EIA 384 70 m 3234b00 00bb73 4 m NOTICE EIA engineering standards are designed to serve the public in
2、terest through eliminating mis- understandings between manufacturers and purchasers, facilitating interchangeability and improve- ment of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such standards shall
3、not in any respect pre- clude any member or non-member of EIA from manufacturing or selling products not conforming to such standards, nor shall the existence of such standards preclude their voluntary use by those other than EIA members whether the standard is to be used either domestically or inte
4、rnationally. Recommended standards are adopted by E1A without regard to whether or not their adoption may involve patents on articles, materials, or processes. By such action, ELA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the re
5、commended standards. Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street, N.W., Washington, D. C. 20006 Electronic Industries Association 1990 Ail rights reserved PRICE: $4.90 Printed in U.S.A. 22_ - . . . EIA 384 70 m 3234b00 00bb72 b m RS-384 Page 1 TIME DIVISION
6、MULTIPLEX EQUIPMENT STANDARD FOR NOMINAL 4 kHz CHANNEL BANDWIDTHS . (From Standards Proposals No . 1009. 1048. 1048.A. 1069 and 1079. formulated under the cognizance of EIA Subcommittee TR-14.2 on Multiplexing and Terminating Equipment.) TABLE OF CONTENTS PAGE Introduction and Scope . 2 Part I . Per
7、formance Specification 1 . Definition of Environmental Conditions . 3 3 . Relative Envelope Delay Distortion . 4 4 . AbsoluteEnvelopeDelay 4 5 . ImpedancesandLevels . 5 6 . Signal to Total Distortion Ratio . 7 7 . Single Frequency Distortion -8 8 . Longitudinal Balance 9 9 . IdleNoise 9 10 . Crossta
8、lk . 9 11 . Limiting . 12 12 . Level Stability . 12 13 . PhaseJitter . 12 14 . Level Tracking . 13 15 . Impulse Noise 13 2 . Attenuation Versus Frequency Characteristics . 4 Part II . 24 Channel Exchange Type PCM Introduction and Scope 15 Section A: Terminals 15 1 . -Fundamental Characteristics . 15
9、- 2 . System Design Characteristics . 18 Section B: Transmission Media Interface . 22 1 . LineRate 22 2 . Signal Format and Method of Timing Information . 22 3 . Code Restriction 23 4 . PulseShape . 23 5 . Impedance and Return Loss 23 7 . Frequency of Errors at the Receiving TMI 24 6 . Nature and Ma
10、gnitude of Timing Jitter at the Receiving TMI . 23 EIA 384 70 9 3234600 00bb973 8 ns.384 Page 2 INTRODUCTION AND SCOPE The standards contained in this document are intended to be used as performance and interface criteria. As such, these standards may find a typical application in the layout of a cq
11、mmunication system incorporating other types of equipment (such as cable or radio equipment). An added purpose of these standards, however, is to furnish a basis for the user to evaluate and specify TDM equipment on a terminal or back-to-back basis. It is recognized that the different requirements o
12、f systems result in more or less rigorous requirements for TDM equipment. It is one of the objectives of this document to assist the user in selecting the TDM equipment for his specific system needs. These standards apply to TDM equipment between the 4-wire audio frequency terminals and the terminal
13、s which interface with the transmission medium. The terminals which interface with the transmission medium are referred to in this standard as the TMI (Transmission Medium Interface) and represent the output of the highest level of time division multiplex. Wiring, signaling, and other office equipme
14、nts are specifically excluded from these standards. Where interconnects between TDM equipment of different types are not anticipated, it is only necessary to specify end-to-end performance and interface parameters at the audio and transmission medium terminals. These parameters are contained in PART
15、 I of this document. Where interconnects between different types of TDM equipment are planned, however, many additional parameters need to be considered. These parameters are contained in PART II of this document. Two types of multiplex equipments are considered in this standard. Class I mutiplex is
16、 intended primarily for use in multiple link (Built-up) circuits and/or long-haul circuits. Class II multiplex is intended for use in those applications which do not justify Class I equipment. Class II equipment may be used in tandem with Class I equipment but is not normally intended for use in tan
17、dem with more than one other set of Class II equipment. At present the following requirements apply to Class II equipment only. Requirements for Class I equipment will be added at a later date. PART I PERFORMANCE SPECIFICATION Part I of this specification is intended primarily for PCM and therefore
18、may not apply as well to other forms of pulse modulation. For example, with delta modulation techniques, the following performance characteristics may be different: Attenuation vs Frequency Characteristics Envelope Delay Distortion Signal to Total Distortion Ratio . o O O EIA 384 70 3234b00 00bb74 T
19、 W RS-384 Page 3 Signal Frequency Distortion Limiting Level Tracking 1. DEFINlTION OF ENVIRONMENTAL CONDITIONS For the purpose of these standards, environmental conditions are defined as follows: a. b. Relative humidity O-95%. Ambient temperature O“ to +5O“C. c. Elevation up to 15,000. d. The variat
20、ion of the applicable primary power source shall be within the followinglimitations: (1) 117V f 10% 60 f 2 Hz single phase (2) -48DC Nominal (-42 to -56 V DC), with a ripple and steady noise not exceeding 100 mv RMS measured unweighted with an instrument having a bandwidth at least equal to the base
21、band of the system. These ripple and steady noise figures apply with the multiplex equipment connected to the power source, as measured at the multiplex equipment. The impulse present on the primary power source shall not cause impulses in any channel to exceed the requirements of Paragraph 15. Wher
22、e the supplier of the multiplex equipment is not also the supplier of the primary power source, the multiplex equipment supplier shall state what impulse noise restrictions on the primary power source are necessary in order to meet the requirements of Paragraph 15. (3) -24V DC Nominal (-21 to -28V D
23、C), with a ripple and steady noise not exceeding 100 mv RMS measured unweighted with an instrument having a bandwidth at least equal to the baseband of the system. NOTE: (a) When the equipment is transported and stored according to the manufacturers instructions, it shall function according to the s
24、pecifications when operated within the environmental conditions stated above. (b) If the ambient temperature during operation exceeds the range of 1 .a., but is not outside the range -2OOC to +55“C, then the equipment shall function according to the specifications when the temperature returns to the
25、 range mentioned in 1.a above. EIA 384 70 m 3234600 0066975 L m RS-384 Page 4 2. ATTENUATION VERSUS FREQUENCY CHARACTERISTICS The attenuation versus frequency characteristic of any channel measured between the 4 wire VF transmit and the 4 wire VF receive points with the TDM terminals connected back-
26、to-back at the transmission medium terminals shall be within the following values: FREQUENCY BAND ATTENUATION RELATIVE TO 1020 Hz 600 - 2400 HZ I1.0dB 300 - 3400 HZ -1.0 dB, + 3 dB (Positive figures indicate a loss and negative figures a gain.) Outside the 300-3400 Hz band gain relative to 1 kHz sha
27、ll not exceed 1 dB. 3. RELATIVE ENVELOPE DELAY DISTORTION The relative envelope delay distortion of any channel measured between the 4 wire VF transmit and the 4 wire VF receive points, with the TDM terminals connected back-to-back at the transmission media terminals, shall not exceed the following
28、values: MAXIMUM DIFFERENCE IN MAXIMUM DELAY DISTORTION BETWEEN FREQUENCY BAND DELAY DISTORTION BEST AND WORST CHANNEL 1000 - 2600 HZ 160 psec 30 psec 800 - 2800 HZ 250 psec 50 ysec The above specification is the maximum allowable relative envelope delay distortion between any two frequencies in a gi
29、ven frequency range. Transmission of data over channels may require amplitude and delay equalization depending upon the type of data set used, the error rate and the signal-to-noise ratio. With the increasing use of higher speeds of data transmission, it is not practical to reduce the unequalized de
30、lay distortion value to meet all possible requirements for data transmission. Successful equalization depends more on uniformity of the attenuation and delay versus frequency characteristics from channel to channel and stability with time than on the actual values to be equalized. Therefore, it is i
31、mportant that the variance of the attenuation and delay distortion be kept low. 4. ABSOLUTE ENVELOPE DELAY 4.1 Standard The absolute envelope delay at 1020 Hz through a TDM channel with the multiplex terminals connected back-to-back at the transmission medium terminal shall not exceed 500 psec. EIA
32、384 70 m 3234600 00bb7b 3 RS-384 Page 5 i 4.2 Method of Measurement The absolute envelope delay may be determined as follows: (a) Measure the relative envelope delay with the test set(s) connected back-to-back (calibration). (b) Measure the relative envelope delay through the multiplex terminals. (c
33、) Subtract a) from b). 5. IMPEDANCES AND LEVELS (AT THE TDM INTERFACE TERMINALS) 5.1 Audio Impedance 5.1 . 1 Standard The 4-wire audio input and output impedances shall be balanced with respect to ground and shall have a nominal impedance of 600 ohms. The echo retum loss shall not be less than 21 dB
34、 when measured in accordance with figure 5.1.2. The minimum return loss against 600 ohms f 1/2% resistive at any frequency between 300 and 3400 Hz shall notbe less than 14 dB. NOTE: The echo return loss standard stated here will be sufficient to enable a terminating set connected to a 4-wire channel
35、 to meet a 27 dB echo return loss at the two-wire point, assuming a minimum of 3 dB loss between the 4-wire point of a channel and the four-wire point of the terminating set. This also assumes a minimum echo return loss of 33 dB at the 2-wire point of the terminating set with the 4-wire points termi
36、nated in 600 ohms I 1/2% resistive. 5.1.2 Method of Measurement The recommended method of measuring echo return loss is shown in Figure 5.1.2. The flat noise generator should feed through a speech weighting network as defmed in C.C.I.T.T. Blue Book, Volume III, 1965, pages 90-94 or equivalent to Wes
37、tern Electric 4SSB network. The noise meter should have psophometric or C-message weighting. With a 600 ohm f 1/2% precision resistor in place of the channel under test, the trans-hybrid loss should exceed 40 dB. Set the output from the noise generator to a level of -10 dBmO. Read the noise meter wi
38、th the channel connected and again with the hybrid terminals to the channel short circuited. The difference between the two readings is the echo return loss. 5.2 Audio Levels The nominal 4-wire levels shall be -16 dBm send and +7 dBm receive. The receive level shall be adjustable to within 0.25 dB b
39、etween +4 dBm and +8 db. RS-384 Page 6 o O W W L z: a o o EIA 384 70 M 3234600 00bb78 7 M h o RS-384 Page 7 - 7. MUX - MUX X 1 J 5.3 Transmission Medium Interface Impedances Because of the possibilities of use of TDM with a variety of transmission media (he-of-sight radio, cable systems, etc.), an e
40、xact standard for transmission medium interface (TMI) impedances is not recommended. However, to minimize unwanted reflections of the information crossing the transmission medium interface, the supplier of the TDM equipment shall specify return loss requirements to ensure satisfactory operation. 5.4
41、 Transmission Medium Interface Levels Because of the possibilities of use of TDM with a variety of transmission media (line-of-sight radio, cable systems, etc.) an exact standard for transmission medium interface (TMI). levels is not. recommended. As a guide to system and equipment designers, howeve
42、r, a transmit and receive level between .2 volt peak-to-peak and 20 volts peak-to-peak is offered as a recommendation. 6. SIGNAL TO TOTAL DISTORTION RATIO 6.1 Standard The signal to total C-message weighted distortion ratio of any channel measured between the 4-wire VF transmit and 4-wire VF receive
43、 points with the multiplex terminals connected back-to-back at the transmission medium interfaces shall not be less than the values in the following table: e TEST FREQUENCY 1020 Hz TEST TONE LEVEL +3 dBmO S/DIST. 30dB O dBmO RATIO 30dB -10 dBmO 26 dB -20 dBmO 25 dB -30 dBmO 26 dB -40 dBmO 22 dB 6.2
44、Method of Measurement The recommended test circuit is shown in Figure 6.2. 600 OHM OSCILLATOR -. STOP FILTER NOISE METER C-M ESSAGE WEIGHTED OR PSOPHOMETER FIGURE 6.2 - - EIA 384 70 = 3234b00 00bb979 9 A MUX o RS-384 Page 8 MUX - STOP FILTER SPECIFICATION: FREQUENCY RANGE 300 - 3400 HZ STOP BAND FRE
45、QUENCY RANGE STOP BAND ATTENUATION PASSBAND ATTENUATION RIPPLE 20 dB NOMINAL IMPEDANCE 600 ohms 1020 Hz f 30 Hz 50 dB min., with respect to passband PASSBAND FREQUENCY RANGE 300 - 800 HZ 1200 - 3400 HZ 7. SINGLE FREQUENCY DISTORTION 7.1 Definition Single frequency distortion consists of any undesire
46、d products at the output of a channel due to the application of a single frequency tone at the input of the channel, It includes harmonic distortion and fold-back distortion, both in and out of band, and sampling frequency leak. 7.2 Standard 7.2.1 With the multiplex terminal connected back-to-back a
47、t the TMI and with a O dBmO tone of any.frequency up to 12 kHz applied to the VF input, the output power at any other single frequency shall not exceed: Output Frequency Output Power, dBmO Any except 3700-4400 Hz 3700-4400 HZ -22 -16 7.2.2 With the multiplex terminal connected back-to-back at the TM
48、I and with a O dBmO, 1020 Hz tone applied to the VF input, the output power at any other single frequency in the 300-3400 Hz band shall not exceed -34 dBmO. 7.3 Method of Measurement The recommended test circuit is shown in Figure 7.3. 600 OHM OSC I L LATO R FIGURE 7.3 600 OHM SELECTIVE VOLT METER E
49、IA 384 70 3234600 0066980 5 W R5384 Page 9 8. LONGITUDINAL BALANCE 8.1 Standard The longitudinal balance as measured at either the 4 wire VF transmit point or 4 wire VF receive point shall not be less than 55 dB. This standard shall apply at any frequency between 300 and 3400 Hz. 8.2 Method of Measurement The recommended test circuit is shown in Figure 8.2. Longitudinal balance is equal to 20 loglo VI IV,. Balance should be measured with R1 + R2 equal to each of the values specified in order to assure that the standard is met regardless of whether the unbalance of the cha
