GB/T 3971.3-1983 Test methods for technical indicators of multi-frequency recorder signals in automatic telephone exchange network
Some standard content:
National Standard of the People's Republic of China
GB/T3971.3—1983
The test methods for the technical specifications ofmulti-frequency register signalling fortelephone automatic switching network1983-12-15Published
National Bureau of Standards
1984-10-01Implementation
National Standard of the People's Republic of China
The test methods for the technical specifications ofmulti-frequency register signalling fortelephone automatic switching network621.395.66
:621.391.8
621. 317. 08www.bzxz.net
GB/T3971.3-1983
This test method is based on GB3377-1982 "Signal Mode of Multi-frequency Recorder in Automatic Switching Telephone Network". Test contents include*: a.
Multi-frequency equipment impedance;
Multi-frequency transmission frequency;
Multi-frequency transmission level, leakage level, harmonic distortion and intermodulation distortion d.
Multi-frequency receiving action range, no action and no recognition requirements; e.
Multi-frequency mutual control period.
1 Impedance measurement of multi-frequency equipment
1.1 Indicators
At the point of connection with the circuit, the nominal impedance value of the multi-frequency equipment is 6002 pure resistance, and its impedance in the frequency band of 300~3400Hz should meet: 600+Z.
201g/600=≥10 dB
In the frequency bands of 520~1160Hz and 1360~2000Hz, it should meet 20g1016aB
Where Z is impedance.
1.2 Measurement method
Use the general comparison method-reflection attenuation measurement method. In this bureau, simulate the actual occupation process to occupy the multi-frequency equipment under test, disconnect the multi-frequency equipment from the circuit at the point of connection with the circuit, and connect the multi-frequency equipment under test to B and D at the disconnection point as shown in Figure 1. The sound source side of the sending branch of the multi-frequency equipment should be terminated with a 600Q resistor. For the multi-frequency equipment currently in use, which is converted into two lines through a directional filter and then into four lines through a hybrid coil, when measuring the output impedance of the sending branch, the receiving branch circuit side should be terminated with a 600Q resistor; when measuring the input impedance of the receiving branch, the sending branch circuit side should be terminated with a 600Q resistor. The output signal frequency of the audio oscillator E is 300, 400, 520, 600, 800, 1000, 1160, 1360, 1500, 1800, 2000, *This standard does not include the working condition test method. It is not appropriate to conduct power supply deviation and environmental condition tests on equipment that has been put into use, but when conducting the various tests specified in this standard, the on-site environmental temperature, humidity and actual power supply voltage should be recorded. For equipment that has not been put into use, the power supply deviation and environmental condition tests shall be carried out according to the general methods for telecommunications equipment.
**For example, in domestic JT801 long-distance switching equipment, the multi-frequency equipment is connected to the circuit at the switching point; in domestic HJ921 and HJ941 local telephone switching equipment, the multi-frequency transmitter is connected to the circuit at the cable line, and the receiver is connected to the circuit at the input repeater. If there is only a wire with a contact between the multi-frequency equipment and the circuit connection point, the impact on the impedance can be ignored, and the impedance of the multi-frequency equipment can be directly measured at the second-line side of the two-wire multi-frequency equipment, the sending output end, and the receiving input end of the four-wire multi-frequency equipment. National Bureau of Standards issued on December 15, 1983
Implementation on October 1, 1984
GB/T3971.3—1983
2400, 2800, 3400Hz, the level of each frequency signal oscillator output to the bridge A and B points is +1dBm and -29dBm respectively. Under the above-mentioned input signal conditions of each frequency and level, first connect LM to points 1 and 2 for frequency selection, remember the sensitivity switch and the meter pointer position (the pointer position can be adjusted to a position that is easy to read and remember), then connect LM to points 3 and 4, adjust the attenuation value of the balanced variable attenuator, make the sensitivity switch position and the meter pointer position the same as at points 1 and 2, and record the ATT attenuation value b, then: 600+z
201ogl600-z
New rate meter
(balanced product)
1.3 Instrument devices and requirements
As shown in Figure 1, among which:
Block diagram of impedance measurement of multi-frequency equipment
E: audio oscillator, balanced output, output frequency range: 20Hz~10kHz or above, output level range: -40~+20dB, output impedance 02.
LM: Audio frequency selection level meter, balanced input, high impedance greater than 10kΩ, frequency range: 50Hz～10kHz or above, measurement level range: -70～+20dB.
ATT: Balanced variable attenuator, characteristic impedance 600Ω, variable attenuation range 0～50dB or above. Frequency meter: Measurement frequency range 200Hz～10kHz or above, counting error ±1Hz. KK2: Double-pole double-throw switch.
R: Two equal value resistors, resistance 60012 or 300±10. Z: Impedance of the multi-frequency device under test.
Test bridge ABCD: When the impedance Z of the multi-frequency device under test is replaced by a pure resistance of 600±1Ω, the attenuation of the opposite end of the bridge AB-CD measured by the circuit in Figure 1 should not be less than 50dB.
2 Multi-frequency transmission frequency measurement
2.1 Indicators
Forward transmission signal nominal frequency:
1380, 1500, 1620, 1740, 1860.1980Hz, backward transmission signal nominal frequency:
1140, 1020, 900, 780Hz.
Frequency allowable deviation: ±5Hz.
2.2 Measurement method
GB/T3971.3-1983
The measurement method of multi-frequency transmission frequency is the same as the measurement method of ordinary sine wave signal oscillation frequency. The measurement point can be selected according to the use conditions of the measurement frequency meter used (such as input signal level, etc.). The reading error of the measurement frequency meter used should not exceed ±1Hz. 3 Measurement of multi-frequency signal transmission level, signal frequency leakage level, harmonic distortion and intermodulation distortion 3.1 Indicators
3.1.1 Signal transmission level
The level of the unmodulated single-frequency signal (i.e. the signal of each single frequency) at the 0 relative level point (600Q terminal of the main distribution frame of the originating office in the case of real-line relay of local telephone) is -8dBm, and the allowable deviation is ±1dB. The difference in the transmission level of the two frequencies that make up a signal is not greater than 1dB. 3.1.2 Signal frequency leakage level
Under the condition of not sending multi-frequency signals, the total power level of the leakage current sent to the circuit should be at least 50dB lower than the nominal single-frequency signal level. Under the condition of sending multi-frequency signals, the level of any single-frequency leakage signal should be at least 34dB lower than the level of any frequency signal in the sent dual-frequency. 3.1.3 Harmonic distortion and intermodulation distortion
The total power level in the 300~3400Hz band that may be sent to the circuit due to harmonic distortion and intermodulation distortion should be at least 37dB lower than the level of any single-frequency signal in the dual-frequency signal sent. 3.2 Measurement method
Use the general direct reading frequency selection level measurement method. The measurement point of two-wire multi-frequency equipment is at the main distribution frame*, and the measurement point of four-wire multi-frequency equipment is at the switching point*.
3.2.1 To measure the two-wire multi-frequency equipment, the office should simulate the actual occupation process to occupy the multi-frequency equipment, establish and maintain the connection between the multi-frequency equipment under test and the main distribution frame, disconnect the external line and connect a balanced 600Q audio frequency selection level meter for measurement, as shown in Figure 2. Anji Xinsa
<60u)
3.2.2. To measure the four-wire multi-frequency equipment, the office should simulate the actual occupation process to occupy the multi-frequency equipment, establish and maintain the connection between the multi-frequency equipment under test and the exchange point, disconnect the circuit at the exchange point, terminate the multi-frequency receiving branch with a 600Q resistor, and connect the balanced 600Q audio frequency selection level meter to the multi-frequency sending branch for measurement, as shown in Figure 3. If the level on the sending side of the exchange point is PaBr, the single-frequency unmodulated signal level measured at the exchange point should be within the range of -8+PaBr±1dBm. * Under the premise of knowing the attenuation from the sending end of the two-wire multi-frequency equipment (the two-wire side of the directional filter) to the main distribution frame, it can be measured directly at the sending end for convenience and then converted to the main distribution frame.
** Under the premise of knowing the attenuation from the sending end of the four-wire multi-frequency equipment (such as the sending end on the circuit side of the hybrid coil of the current long-distance multi-frequency equipment) to the exchange point, it can be measured directly at the sending end for convenience and then converted to the exchange point. 3
Glue without modification
GB/T3971.3—1983
Resource exchange point
3.2.3 After the measurement circuit is connected, first use the frequency selection meter to select the leakage level of each signal frequency without sending the dual-frequency signal, and calculate the total leakage according to the power addition. Then manually send various dual-frequency combinations, and use the frequency selection meter to select the main signal level, signal frequency single-frequency leakage level, harmonic distortion and intermodulation distortion frequency signal level*. Calculate the total power level of harmonic distortion and intermodulation distortion according to the power addition. 3.3 Instruments and requirements to be used
As shown in Figures 2 and 3, among which:
LM: audio frequency selection level meter, balanced input, input impedance 600Q. Frequency range 50Hz~10kHz and above, measurement level range -70~+20dB, the self-distortion attenuation in the machine should be greater than 80dB. 4 Multi-frequency receiving technical index test
4.1 Index
4.1.1 Action range
The maximum change range of the input signal frequency is allowed to be ±10Hz; a.
The absolute power level range of the single-frequency signal input is -b.
c. The level difference of the two frequencies that make up a signal: adjacent frequencies are not greater than 5dB, and non-adjacent frequencies are not greater than 7dB.
4.1.2 Inaction and non-recognition requirements
In the frequency band of 300~3400Hz, for any single-frequency or dual-frequency sine wave, the absolute power level of each single frequency is not greater than -42dBm, and the receiving equipment should not act.
b: When the level difference of the two frequencies that make up a signal is more than 20dB, the receiving equipment should not recognize it as a signal. c. For dual-frequency combinations within the frequency band of 1300-3400Hz, the backward signal receiving equipment should not operate if the power level of each single frequency is 5dBm; for dual-frequency combinations within the frequency bands of 330-1150Hz and 2130-3400Hz, the forward signal receiving equipment should not operate if the power level of each single frequency is 5dBm. d. Within the passband receiving limit level range, the receiving equipment does not recognize the dual-frequency signal with a duration of no more than 7ms as a signal; when the receiving equipment is already in operation, the receiving equipment should not release the signal for a signal interruption of no more than 7ms. e. In the case of dual-frequency signal input, the total power level of a single frequency or a combination of multiple other signal frequencies is higher than that of any of the input dual frequencies. *If there is no low-distortion frequency selection meter, the frequency selection meter can be used to measure the harmonic distortion, intermodulation distortion and single-frequency leakage signal level after filtering out the main signal. 4
GB/T3971.3—1983
The single-frequency signal level is 20dB lower and should not cause malfunction of the receiving equipment. 4.2 Test method
4.2.1 Connect the test circuit according to Figure 4. When dual-frequency input is connected, E1 and E2 are used as dual-frequency signal sources, and the output frequencies are f1 and f2 respectively (at this time, Es in Figure 4 is not connected to FG). When testing the third-frequency interference prevention, E1, E2, and E3 are connected, and the output frequencies are f1, f2, and fs respectively. E1 and E2 are used as the main dual-frequency signal sources, and E: is used as the third-frequency signal source. To ensure the correct test signal, the audio frequency selection table and frequency meter should be used to monitor the signal level and frequency at points A and B before connecting K.
New rate meter
Figure 4 Multi-frequency receiving test block diagram
4.2.2 The multi-frequency receiving test signal should be input from the "exchange point". Before the test, the actual occupancy process should be simulated in this office to establish and maintain the connection between the exchange point and the multi-frequency equipment under test, and the corresponding multi-frequency transmitting equipment should simulate the state of the actual receiving process**. For four-wire multi-frequency equipment, the transmitting branch side should be terminated with a 6002 resistor. 4.2.3 For the forward signal receiving equipment, the frequencies of f1 and f2 take the forward "6 out of 2", and fs takes the forward nominal frequency other than f1 and f2; for the backward signal receiving equipment, f1.f2 take the backward "4 out of 2", and f: takes the backward nominal frequency other than f1.f2. a. Under the frequency and level combination signals listed in Table 1, the switch K is continuously turned on and off, and the receiving equipment should operate and release reliably without malfunction. Among them, When there is a third frequency, the third frequency should not operate, and the main dual frequencies should operate reliably. * Under the premise of knowing the attenuation from the exchange point to the receiving end of the multi-frequency equipment (the two-line side of the directional filter of the two-wire multi-frequency equipment, and the receiving end of the hybrid coil circuit side of the long-distance four-wire multi-frequency equipment), for convenience, the test signal can be directly input at the receiving end after conversion. **For example, when measuring the forward signal receiving device, the corresponding backward sending device does not send any backward signal before the input signal. Before the input signal is cut off, a group of backward signals should be sent to observe whether it can be released normally. For example, when measuring the backward signal receiving device, the corresponding forward signal sending device should send a group of forward signals before the input signal.
Signal combination
GB/T3971.3—1983
Table 1 List of receiving equipment action signal combinations P(f1)=P(f2):-5 dBm
P(f1)=P(f2):—35dBm
P(fi±10Hz):—5dBm
P(f2±10Hz):—12dBm||tt ||P(fi±10Hz):-12dBm
P(f2±10Hz):—5dBm
P(fi±10Hz):—5dBm
P(f2±10 Hz):10 dBm
P(fi±10Hz)：—10dBm
P(f2±10Hz):—5dBm
P(f1±10H z):—28dBm
P(f2±10Hz):—35dBm
P(fi±10Hz):35dBm
P( f2±10Hz):—28dBm
P(fi±10Hz)—30dBm
P(f2±10Hz):35dBm||t t||P(fi±10Hz):-35dBm
P(f2±10Hz):30dBm
P(f1)=P(f2):-5d Bm
P(fs):-25dBm
P(f1)=P(f2):-15dBm
P(fs)35dBm
(f1, f2 are not adjacent)
(f1f2 are not adjacent)
(f1, f2 are adjacent)
(f1, f2 are adjacent)
(f1, f2 are adjacent)
(f1f2 are not adjacent)
(fif2 are adjacent)
(f1, f2 are adjacent)
Note: The (f1(2)±10Hz) in the table refers to the maximum frequency variation. For example, when fi=1380Hz, (f1±10Hz) is 1390Hz or 1370Hz. Under the signal combination of P(f1)=P(f2):-42dBm, switch K is continuously turned on and off, and the receiving device should not be reliably operated. b.
Under the signal combination of P(f1):-5dBm, P(f2):-25dBmP(f1):-15dBm, P(f2):-35dBm, switch K is continuously turned on and off, and the receiving device should not recognize it as a signal. When the receiving device is not operated, for the signal of P(f1)=P(f2):-5dBm, the control switch K is turned on for 7d.
, and the receiving device should not be operated reliably; when the receiving device has been operated, the control switch K is turned off for 7°ms, and the receiving device should not be released. For each test, the interval between two consecutive tests should be much greater than 7ms. 4.2.4 For the forward signal receiving equipment, f1f2 takes any dual-frequency combination within the frequency band of 330~1150Hz and 12130~3400Hz\, P(f1)=P(f2): -5dBm, for the backward signal receiving equipment, fi, f2 takes any dual-frequency combination within the frequency band of 1300~3400Hz*, P(fi)=P(f2)-5dBm. Continuously turn on and off the switch K, and the receiving equipment should be reliable and not operate. 4.3 Instruments and requirements to be used
As shown in Figure 4, among which:
E1, E2, Es: audio oscillator, balanced output, frequency range 300Hz～10kHz, level range -35dB～+20dB, output impedance 600Ω. For the convenience of testing, E1 and E2 should try to use oscillators that can change the frequency by Hz (such as audio variable resistance oscillator), E: can choose a continuously variable frequency oscillator.
LM: audio frequency selection level meter, balanced input, input impedance 600Ω. Frequency range 50Hz～10kHz or above, measurement level range -70～+20dB, the internal self-distortion attenuation should be greater than 80dB. Frequency meter: frequency range 300～10kHz or above, counting error within ±1Hz. The total distortion of E1, E2 together with the two bridges in the frequency band of 300-3400Hz, that is, the total distortion measured at points A and B should be at least 37dB lower than the level of any single-frequency signal in the dual-frequency sent to that point by E1 and E2. *There are many actual dual-frequency combinations. Generally, the sensitive frequency points of the receiving equipment can be specifically analyzed to select the sensitive frequency combination. Or, one signal source is fixed to a certain signal frequency in the specified frequency band, and the other signal source continuously changes the signal frequency in the specified frequency band. 6
5 Multi-frequency mutual control cycle test
5.1 Index
GB/T3971.3—1983
Under the condition of reliable signal transmission, the multi-frequency mutual control cycle should be as short as possible. Excluding the signal propagation time, the mutual control cycle, that is, the duration of sending and receiving one digital number, should not exceed 250ms.
5.2 Measurement method*
Use a general measurement time method, the time range is from tens of milliseconds to tens of seconds. As shown in Figure 5, use the idle make contact of the code sending program relay or the idle make contact of other relays with the same beat to lead out the ground potential signal at the corresponding beat of the code sending process (Figure 5 is when FB and Fc are closed), and shape it into a signal that meets the needs of the measuring instrument used. According to the logic trigger and cut-off timing, the timing duration is one bit of mutual control cycle (Figure 5 is B bit). The test can be carried out by self-loop calling method, and the signal propagation time can be ignored. The attenuation of the self-loop trunk line of two-wire multi-frequency equipment to 800Hz should be 14dB, or it can be simulated by a false line. The self-loop test of four-wire multi-frequency equipment can be based on the level configuration of the office where the equipment under test is located. The attenuator is inserted between the outgoing repeater and the incoming repeater. The attenuator attenuation value should ensure that the minimum signal level received by the receiving branch exchange point is -35dBm. The test should be based on the characteristics of the specific equipment, excluding non-multi-frequency mutual control time such as waiting for connection. Shape
Low heart
Figure 5 Schematic diagram of mutual control cycle measurement
Note: The figure takes the measurement of B-position mutual control cycle as an example; the time test instrument takes the QB307 frequency counter as an example; FA, FB, Fc are the idle contact points of the code transmission program relay; other time measurement instruments should be connected according to the instrument requirements. Additional notes:
This standard was drafted by the Telecommunications Transmission Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Huang Shiliang.
This measurement method mainly takes the relay receiving and sending code circuit as an example to explain the logical beats that should be included in the measurement of the mutual control cycle. The electronic receiving and sending code circuit can refer to the corresponding beats and use methods suitable for the characteristics of the equipment for measurement. 7
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