GB/T 4312.3-1987 Technical parameters and measurement methods for FM broadcast transmitters Dual program
Some standard content:
National Standard of the People's Republic of China
GB/T4312.3—1987
Technical parameters and measuring methods for FM broadcasting transmitters of dual programmes
Technical parameters and measuring methods for FM broadcasting transmitters of dual programmes Issued on March 12, 1987
National Bureau of Standards
Implementation on November 1, 1987
National Standard of the People's Republic of China
Technical parameters and measuring methods for FM broadcasting transmitters of dual programmes UDC621.396.61
:621.317.08
GB/T4312.3—1987
This standard applies to dual-program FM broadcasting transmitters. Its contents include the main technical parameters and measuring methods from the audio input terminal to the high-frequency output terminal of the transmitter.
1 Explanation of terms
1.1 Crosstalk between main and sub-channels
The mutual leakage between the main and sub-channels is called the crosstalk between the main channel and the sub-channel or the crosstalk between the sub-channel and the main channel. The mathematical expression is as follows:
C(main→sub)-201g sub-signal output level (dB)Crosstalk level between sub-channel and main
C.(sub→main)-201g main output level (dB)Where: Cmain→sub
C(sub→main)-Crosstalk between sub-channel and main.Crosstalk level between main and sub-channel: The audio fundamental wave output level measured at the output end of the sub-channel when the transmitter only has the main channel input audio signal (frequency deviation is 52.5kHz).
Crosstalk level from auxiliary to main: The audio fundamental wave output level measured at the main channel output end when the transmitter has only auxiliary channel input audio signal (frequency deviation is 8kHz).
1.2 Residual wave radiation intensity
refers to the permissible value of the radiation power of harmonic radiation, parasitic radiation, and intermodulation products generated by mutual modulation other than fundamental wave radiation, expressed in decibels, milliwatts, or microwatts.
2 Technical parameters
The technical parameters of dual-program FM broadcast transmitter shall comply with the provisions of Table 1. Table 1 Technical parameters of dual-program FM broadcast transmitter Serial number
Frequency range
Permissible deviation of carrier frequency
Load impedance
Residual wave radiation intensity
Approved by the National Bureau of Standards on March 12, 1987
Same as GB4312.1-84 "Technical parameters and measurement methods of FM broadcast transmitters - mono and stereo"
Same as GB4312.1
Same as GB4312.1
Same as GB4312.1
Implementation on November 1, 1987
Pre-emphasis time constant
Maximum modulation frequency deviation
GB/T/ T4312.3—1987
Continued Table 1
Main channel: 50μs
Sub-channel: 75μs
±75.0kHz
Main channel signal modulates the maximum frequency deviation of the main carrier Sub-carrier modulates the frequency deviation of the main carrier
Sub-channel signal modulates the maximum frequency deviation of the sub-carrier Audio input impedance
Audio input level
Composite signal input level
Frequency response
Signal-to-noise ratio
Parasitic AM noise
Output power tolerance
Harmonic distortion
Main and sub-channel crosstalk
3 Test methods for main technical indicators
3.1 Test conditions
Same as those specified in GB4312.1.
The technical requirements of the test instrument shall comply with the provisions of Table 2. 3.2
±52.5kHz
±22.5kHz
Same as GB4312.1
Same as GB4312.1
600Q unbalanced
Main channel: 40~15000Hz±1.0dB
Sub-channel: 50~10000Hz±2.5dB (including compression and expansion deviation)Main channel: greater than or equal to 60dB
Sub-channel: greater than or equal to 65dB
Same as GB4312.1
+10%(5 0Q impedance)
Main channel: 40~15000Hz less than or equal to 1.5%Auxiliary channel: 50~10000Hz less than or equal to 2.5%Auxiliary series main: 50~10000Hz better than -63dB
Main series auxiliary: 40~15000Hz better than -70dB
Table 2 Technical requirements for test instruments and equipment
Audio signal generator
a. Frequency range: 0.02~20kHz
b: Frequency error: less than or equal to ±1%: ±1Hzc, amplitude error : less than or equal to ±0.1dBd. Harmonic distortion: less than or equal to 0.05%
e. Output impedance: 600Q balanced
f. Maximum output level: not less than 12dBm
GB/T/T4312.3—1987
Continued Table 2
Modulation tester (frequency deviation meter and amplitude modulation
degree tester)
Distortion meter
Dual program decoder
Frequency selection level meter
Spectrum analyzer
8. Frequency range: Covering the measured The entire band of the measurement b. Frequency deviation range: 0~150kHz (frequency deviation accuracy: full scale ±3%) c. Distortion: 100% modulation 0.04~100kHz less than 0.25% d. Signal-to-noise ratio: better than 65dB
e. Frequency response: 0.04~100kHz less than ±0.1dB f. With a low-pass filter greater than or equal to 120kHz g. Can be used for FM, AM testing, output voltage greater than 500mV a. Range: 0.05%~100%
b. Frequency range: 0.02~200kHz|| tt||c. Measurement error: less than or equal to ±5%~10%d. Voltage range: 100μV~30V
a. Subcarrier operating frequency: 67kHz
b. Subchannel frequency deviation range: greater than 10kHz (frequency deviation measurement accuracy: ±5% of full scale)
c. Input level: 300mV~1V
d. Input impedance: 10kΩ
e. Frequency response:
Main channel: 40~15000Hz
Subchannel: 50~10000Hz|| tt||f. Distortion
Main channel: 40~15000Hz
Sub-channel: 50~10000Hz
g. Crosstalk between main and sub-channel:
Sub-channel to main: 50~10000Hz
±2.0dB (including expansion deviation)
Less than 0.5%
Less than 2.0% (including expander)
Better than -66dB
Main channel to sub: 40~15000Hz
Better than -73dB
Signal-to-noise ratio:|| tt||Main channel: greater than or equal to 65dB
Sub-channel: greater than or equal to 70dB
1. De-emphasis time constant:
Main channel: 50us
Sub-channel: 75μs
j. Output impedance: 600Q balanced, unbalanced k. Output level: greater than 10dBm
1. Expansion ratio: 1·2 (dB) Expansion deviation is less than or equal to ±1.5dB
a. Frequency range: 20~20000Hz
b. Input impedance: 6002 balanced
c. Frequency selection level measurement range: -100~+40dBd. Frequency response: 40~20000Hz±0.2dBe. Internal noise: less than or equal to -120dB (frequency selection)a. Frequency range: upper limit greater than or equal to 1000MHzb. Level dynamic range: greater than or equal to 80dB3
3.3 Test precautions:
GB/T/T4312.3—1987
Before testing, adjust the transmitter to normal working state and measure without various external interferences. Before measuring, check and calibrate the instrument and use it only after it passes the test. 3.4 Test methods for main technical indicators
3.4.1 Signal-to-noise ratio
3.4.1.1 Test block diagram is shown in Figure 1.
The dual-program encoder has pre-emphasis and compressor, and the dual-program decoder has de-emphasis and expander. 「
Audio source number
High test
3.4.1.2 Test method
3.4.1.2.1 Main channel signal-to-noise ratio
a When there is no subcarrier, the audio signal generator sends a 1kHz signal to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz.
b. Use a level meter to measure the main channel output level (dB value) at the main channel output end of the dual-program decoder as the reference level. c. Remove the 1kHz modulation signal. At this time, the level measured at the main channel output end of the dual-program decoder is the output noise level (dB value). The difference between this level and the reference level is the main channel signal-to-noise ratio 3.4.1.2.2 Sub-channel signal-to-noise ratio
Audio signal The signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, and the sub-channel output of the dual-program decoder a.
is connected to the level meter.
b. The frequency deviation indication of the frequency deviation meter of the dual-program decoder (hereinafter referred to as the frequency deviation meter) is 8kHz. At this time, the reading of the level meter is the reference level (dB value).
c: Remove the 1kHz modulation signal. At this time, the sub-channel output level of the dual-program decoder is the output noise level (dB value). The difference between this level and the reference level is the sub-channel signal-to-noise ratio. 3.4.2 Frequency response
3.4.2.1 The test block diagram is the same as Figure 1.
The dual-program encoder has no pre-emphasis or compressor, and the dual-program decoder has no de-emphasis or expander. 3.4.2.2 Test Method
3.4.2.2.1 Main channel frequency response
When there is no subcarrier, the audio signal generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the frequency deviation indication of the modulation tester a.
is 52.5kHz.
b. The main channel output of the dual program decoder is read to the level meter (dB value), which is the reference level of the frequency response. Keep the output level of the audio signal generator at each test frequency point of 0.04, 0.1, 1, 3, 5, 7, 10, 12, and 15kHz unchanged, and record the main channel output level (dB value) of the dual program decoder at the corresponding test frequency point at Ct
. The difference between this level and the reference level is the main channel frequency response. || tt||3.4.2.2.2 Sub-channel frequency response
GB/T/T4312.3—1987
The audio signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
The sub-channel output of the dual-program decoder is sent to the level meter. At this time, the level meter reading (dB value) is the reference level of the frequency response. b.
Keep the output level of the audio signal generator at each test frequency point of 0.05.0.1, 1, 3, 5, 7, and 10kHz unchanged, and record the sub-channel output level (dB value) of the dual-program decoder at the corresponding test frequency point at this time. c.
The difference between this level and the reference level is the sub-channel frequency response.
3.4.3 Pre-emphasis characteristics
3.4.3.1 Test block diagram is the same as Figure 1
3.4.3.2 Test method
3.4.3.2.1 Main channel pre-emphasis characteristics
The main channel of the dual-program encoder has 50us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. When there is no subcarrier, the audio signal generator sends a 15kHz signal to the main channel input of the dual-program encoder, so that the modulation index tester frequency deviation indication is 52.5kHz, and the main channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 12, 10, 7, 5, 3, 1, 0.1, and 0.04kHz signals to the main channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the main channel output of the dual-program decoder. c. Measure the output level corresponding to each frequency point and make a 50us pre-emphasis curve. 3.4.3.2.2 Sub-channel pre-emphasis characteristics
The sub-channel of the dual-program encoder uses 75us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. The audio signal generator sends a 10kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation indicator of the frequency deviation table is 8kHz and the sub-channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 7, 53, 1, 0.1, and 0.04kHz signals to the sub-channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the sub-channel output of the dual-program decoder. c. The output level corresponding to each frequency point is measured to make a 75μs pre-emphasis curve. Appendix: 50, 75μus pre-emphasis characteristic theoretical value frequency
3.4.4 Harmonic distortion
3.4.4.1 The test block diagram is shown in Figure 2.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has no de-emphasis and has an expander. E
Audio signal
Kawatakema
3.4.4.2 Test method
3.4.4.2.1 Main channel distortion
GB/T/T4312.3—1987
&. When there is no subcarrier, the audio signal generator sends the signal of each test frequency point of the main channel to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz. b. The main channel output of the dual-program decoder is sent to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.4.2.2 Sub-channel distortion
The audio signal generator sends the signal of each test frequency point of the sub-channel to the sub-channel input end of the dual-program encoder, so that the frequency deviation indication of the frequency deviation meter is 8kHz.
b. The sub-channel output of the dual-program decoder is fed to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.5 Main and sub-channel crosstalk
3.4.5.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, while the dual-program decoder has a de-emphasis and an expander. Audio tube number
Optimum measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.2 Sub-channel signal-to-noise ratio
The audio signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, and the sub-channel output of the dual-program decoder a.
is connected to the level meter.
b. The frequency deviation indication of the frequency deviation meter of the dual-program decoder (hereinafter referred to as the frequency deviation meter) is 8kHz, and the reading of the level meter is the reference level (dB value).
c: Remove the 1kHz modulation signal, and the sub-channel output level of the dual-program decoder is the output noise level (dB value). The difference between this level and the reference level is the sub-channel signal-to-noise ratio. 3.4.2 Frequency response
3.4.2.1 The test block diagram is the same as Figure 1.
The dual-program encoder has no pre-emphasis and compressor, and the dual-program decoder has no de-emphasis and expander. 3.4.2.2 Test method
3.4.2.2.1 Main channel frequency response
When there is no subcarrier, the audio signal generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the frequency deviation indication of the modulation tester a.
is 52.5kHz.
b. The main channel output of the dual program decoder is read to the level meter (dB value), which is the reference level of the frequency response. Keep the output level of the audio signal generator at each test frequency point of 0.04, 0.1, 1, 3, 5, 7, 10, 12, and 15kHz unchanged, and record the main channel output level (dB value) of the dual program decoder at the corresponding test frequency point at Ct
. The difference between this level and the reference level is the main channel frequency response.
3.4.2.2.2 Sub-channel frequency response
GB/T/T4312.3—1987
The audio signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
The sub-channel output of the dual-program decoder is sent to the level meter. At this time, the level meter reading (dB value) is the reference level of the frequency response. b.
Keep the output level of the audio signal generator at each test frequency point of 0.05.0.1, 1, 3, 5, 7, and 10kHz unchanged, and record the sub-channel output level (dB value) of the dual-program decoder at the corresponding test frequency point at this time. c.
The difference between this level and the reference level is the sub-channel frequency response.
3.4.3 Pre-emphasis characteristics
3.4.3.1 Test block diagram is the same as Figure 1
3.4.3.2 Test method
3.4.3.2.1 Main channel pre-emphasis characteristics
The main channel of the dual-program encoder has 50us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. When there is no subcarrier, the audio signal generator sends a 15kHz signal to the main channel input of the dual-program encoder, so that the modulation index tester frequency deviation indication is 52.5kHz, and the main channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 12, 10, 7, 5, 3, 1, 0.1, and 0.04kHz signals to the main channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the main channel output of the dual-program decoder. c. Measure the output level corresponding to each frequency point and make a 50us pre-emphasis curve. 3.4.3.2.2 Sub-channel pre-emphasis characteristics
The sub-channel of the dual-program encoder uses 75us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. The audio signal generator sends a 10kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation indicator of the frequency deviation table is 8kHz and the sub-channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 7, 53, 1, 0.1, and 0.04kHz signals to the sub-channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the sub-channel output of the dual-program decoder. c. The output level corresponding to each frequency point is measured to make a 75μs pre-emphasis curve. Appendix: 50, 75μus pre-emphasis characteristic theoretical value frequency
3.4.4 Harmonic distortion
3.4.4.1 The test block diagram is shown in Figure 2.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has no de-emphasis and has an expander. E
Audio signal
Kawatakema
3.4.4.2 Test method
3.4.4.2.1 Main channel distortion
GB/T/T4312.3—1987
&. When there is no subcarrier, the audio signal generator sends the signal of each test frequency point of the main channel to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz. b. The main channel output of the dual-program decoder is sent to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.4.2.2 Sub-channel distortion
The audio signal generator sends the signal of each test frequency point of the sub-channel to the sub-channel input end of the dual-program encoder, so that the frequency deviation indication of the frequency deviation meter is 8kHz.
b. The sub-channel output of the dual-program decoder is fed to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.5 Main and sub-channel crosstalk
3.4.5.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, while the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.2 Sub-channel signal-to-noise ratio
The audio signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, and the sub-channel output of the dual-program decoder a.
is connected to the level meter.
b. The frequency deviation indication of the frequency deviation meter of the dual-program decoder (hereinafter referred to as the frequency deviation meter) is 8kHz, and the reading of the level meter is the reference level (dB value).
c: Remove the 1kHz modulation signal, and the sub-channel output level of the dual-program decoder is the output noise level (dB value). The difference between this level and the reference level is the sub-channel signal-to-noise ratio. 3.4.2 Frequency response
3.4.2.1 The test block diagram is the same as Figure 1.
The dual-program encoder has no pre-emphasis and compressor, and the dual-program decoder has no de-emphasis and expander. 3.4.2.2 Test method
3.4.2.2.1 Main channel frequency response
When there is no subcarrier, the audio signal generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the frequency deviation indication of the modulation tester a.
is 52.5kHz.
b. The main channel output of the dual program decoder is read to the level meter (dB value), which is the reference level of the frequency response. Keep the output level of the audio signal generator at each test frequency point of 0.04, 0.1, 1, 3, 5, 7, 10, 12, and 15kHz unchanged, and record the main channel output level (dB value) of the dual program decoder at the corresponding test frequency point at Ct
. The difference between this level and the reference level is the main channel frequency response.
3.4.2.2.2 Sub-channel frequency response
GB/T/T4312.3—1987
The audio signal generator sends a 1kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
The sub-channel output of the dual-program decoder is sent to the level meter. At this time, the level meter reading (dB value) is the reference level of the frequency response. b.
Keep the output level of the audio signal generator at each test frequency point of 0.05.0.1, 1, 3, 5, 7, and 10kHz unchanged, and record the sub-channel output level (dB value) of the dual-program decoder at the corresponding test frequency point at this time. c.
The difference between this level and the reference level is the sub-channel frequency response.
3.4.3 Pre-emphasis characteristics
3.4.3.1 Test block diagram is the same as Figure 1
3.4.3.2 Test method
3.4.3.2.1 Main channel pre-emphasis characteristics
The main channel of the dual-program encoder has 50us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. When there is no subcarrier, the audio signal generator sends a 15kHz signal to the main channel input of the dual-program encoder, so that the modulation index tester frequency deviation indication is 52.5kHz, and the main channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 12, 10, 7, 5, 3, 1, 0.1, and 0.04kHz signals to the main channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the main channel output of the dual-program decoder. c. Measure the output level corresponding to each frequency point and make a 50us pre-emphasis curve. 3.4.3.2.2 Sub-channel pre-emphasis characteristics
The sub-channel of the dual-program encoder uses 75us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. The audio signal generator sends a 10kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation indicator of the frequency deviation table is 8kHz and the sub-channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 7, 53, 1, 0.1, and 0.04kHz signals to the sub-channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the sub-channel output of the dual-program decoder. c. The output level corresponding to each frequency point is measured to make a 75μs pre-emphasis curve. Appendix: 50, 75μus pre-emphasis characteristic theoretical value frequency
3.4.4 Harmonic distortion
3.4.4.1 The test block diagram is shown in Figure 2.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has no de-emphasis and has an expander. E
Audio signal
Kawatakema
3.4.4.2 Test method
3.4.4.2.1 Main channel distortion
GB/T/T4312.3—1987
&. When there is no subcarrier, the audio signal generator sends the signal of each test frequency point of the main channel to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz. b. The main channel output of the dual-program decoder is sent to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.4.2.2 Sub-channel distortion
The audio signal generator sends the signal of each test frequency point of the sub-channel to the sub-channel input end of the dual-program encoder, so that the frequency deviation indication of the frequency deviation meter is 8kHz.
b. The sub-channel output of the dual-program decoder is fed to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.5 Main and sub-channel crosstalk
3.4.5.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, while the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.3—1987
The audio signal generator sends a 1kHz signal to the subchannel input of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
The subchannel of the dual-program decoder is output to the level meter. At this time, the level meter reading (dB value) is the reference level of the frequency response. b.
Keep the output level of the audio signal generator at each test frequency point of 0.05.0.1, 1, 3, 5, 7, and 10kHz unchanged, and record the subchannel output level (dB value) of the dual-program decoder at the corresponding test frequency point at this time. c.
The difference between this level and the reference level is the subchannel frequency response.
3.4.3 Pre-emphasis characteristics
3.4.3.1 Test block diagram is the same as Figure 1
3.4.3.2 Test method
3.4.3.2.1 Main channel pre-emphasis characteristics
The main channel of the dual-program encoder has 50us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. When there is no subcarrier, the audio signal generator sends a 15kHz signal to the main channel input of the dual-program encoder, so that the modulation index tester frequency deviation indication is 52.5kHz, and the main channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 12, 10, 7, 5, 3, 1, 0.1, and 0.04kHz signals to the main channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the main channel output of the dual-program decoder. c. Measure the output level corresponding to each frequency point and make a 50us pre-emphasis curve. 3.4.3.2.2 Sub-channel pre-emphasis characteristics
The sub-channel of the dual-program encoder uses 75us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. The audio signal generator sends a 10kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation indicator of the frequency deviation table is 8kHz and the sub-channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 7, 53, 1, 0.1, and 0.04kHz signals to the sub-channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the sub-channel output of the dual-program decoder. c. The output level corresponding to each frequency point is measured to make a 75μs pre-emphasis curve. Appendix: 50, 75μus pre-emphasis characteristic theoretical value frequency
3.4.4 Harmonic distortion
3.4.4.1 The test block diagram is shown in Figure 2.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has no de-emphasis and has an expander. E
Audio signal
Kawatakema
3.4.4.2 Test method
3.4.4.2.1 Main channel distortion
GB/T/T4312.3—1987
&. When there is no subcarrier, the audio signal generator sends the signal of each test frequency point of the main channel to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz. b. The main channel output of the dual-program decoder is sent to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.4.2.2 Sub-channel distortion
The audio signal generator sends the signal of each test frequency point of the sub-channel to the sub-channel input end of the dual-program encoder, so that the frequency deviation indication of the frequency deviation meter is 8kHz.
b. The sub-channel output of the dual-program decoder is fed to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.5 Main and sub-channel crosstalk
3.4.5.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, while the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.3—1987
The audio signal generator sends a 1kHz signal to the subchannel input of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
The subchannel of the dual-program decoder is output to the level meter. At this time, the level meter reading (dB value) is the reference level of the frequency response. b.
Keep the output level of the audio signal generator at each test frequency point of 0.05.0.1, 1, 3, 5, 7, and 10kHz unchanged, and record the subchannel output level (dB value) of the dual-program decoder at the corresponding test frequency point at this time. c.
The difference between this level and the reference level is the subchannel frequency response.
3.4.3 Pre-emphasis characteristics
3.4.3.1 Test block diagram is the same as Figure 1
3.4.3.2 Test method
3.4.3.2.1 Main channel pre-emphasis characteristics
The main channel of the dual-program encoder has 50us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. When there is no subcarrier, the audio signal generator sends a 15kHz signal to the main channel input of the dual-program encoder, so that the modulation index tester frequency deviation indication is 52.5kHz, and the main channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 12, 10, 7, 5, 3, 1, 0.1, and 0.04kHz signals to the main channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the main channel output of the dual-program decoder. c. Measure the output level corresponding to each frequency point and make a 50us pre-emphasis curve. 3.4.3.2.2 Sub-channel pre-emphasis characteristics
The sub-channel of the dual-program encoder uses 75us pre-emphasis and no compressor, and the dual-program decoder has no de-emphasis and no expander. a. The audio signal generator sends a 10kHz signal to the sub-channel input of the dual-program encoder, so that the frequency deviation indicator of the frequency deviation table is 8kHz and the sub-channel output level of the dual-program decoder is recorded. b. The audio signal generator sends 7, 53, 1, 0.1, and 0.04kHz signals to the sub-channel input of the dual-program encoder respectively, keeps the input level unchanged, and reads the output level of each corresponding frequency at the sub-channel output of the dual-program decoder. c. The output level corresponding to each frequency point is measured to make a 75μs pre-emphasis curve. Appendix: 50, 75μus pre-emphasis characteristic theoretical value frequency
3.4.4 Harmonic distortion
3.4.4.1 The test block diagram is shown in Figure 2.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has no de-emphasis and has an expander. E
Audio signal
Kawatakema
3.4.4.2 Test method
3.4.4.2.1 Main channel distortion
GB/T/T4312.3—1987
&. When there is no subcarrier, the audio signal generator sends the signal of each test frequency point of the main channel to the main channel input end of the dual-program encoder, so that the frequency deviation indication of the modulation tester is 52.5kHz. b. The main channel output of the dual-program decoder is sent to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.4.2.2 Sub-channel distortion
The audio signal generator sends the signal of each test frequency point of the sub-channel to the sub-channel input end of the dual-program encoder, so that the frequency deviation indication of the frequency deviation meter is 8kHz. bzxz.net
b. The sub-channel output of the dual-program decoder is fed to the distortion meter. c. Measure the nonlinear distortion of each corresponding test frequency point. 3.4.5 Main and sub-channel crosstalk
3.4.5.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, while the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.1 The test block diagram is shown in Figure 3.
The dual-program encoder has no pre-emphasis and has a compressor, and the dual-program decoder has a de-emphasis and an expander. Audio tube number
Excellent measurement
3.4.5.2 Test method
3.4.5.2.1 "Main-to-sub" crosstalk
The audio signal generator sends a 1kHz signal to the input end of the sub-channel of the dual-program encoder, so that the frequency deviation meter indicates 8kHz. a.
b. The sub-channel of the dual-program decoder is output to the frequency-selective level meter to read the reference level (dB value). c. When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter at the output end of the sub-channel to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. 3.4.5.2.2 "Sub-to-main" crosstalk
When there is no subcarrier, the audio signal generator sends each test frequency point signal to the main channel of the dual-program encoder, so that the modulation index tester indicates a frequency deviation of 52.5kHz. Add a subcarrier, remove the audio input signal of the sub-channel, and use the frequency-selective level meter to measure the fundamental wave level (dB value) of the signal at each test frequency point sent by the main channel at the output end of the sub-channel. The difference between each level and the reference level is the "main-to-sub" crosstalk of the frequency. The generator sends a 1kHz signal to the main channel input of the dual program encoder, so that the modulation tester frequency deviation indicates 52.5kHz. The main channel output of the dual program decoder is sent to the frequency selection level meter to read the reference level (dB value). b.
c. Remove the audio input signal of the main channel, and the audio signal generator sends each test frequency point signal to the sub-channel of the dual program encoder, so that the frequency deviation meter indicates 8kHz. At this time, the main channel output uses the frequency selection level meter to measure the fundamental wave level (dB value) of each test frequency point signal sent by the sub-channel. The difference between each level and the reference level is the "sub-main" crosstalk of the frequency. 6
Additional instructions:
GB/T/T4312.3—1987
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is drafted by the equipment manufacturer of the Ministry of Radio, Film and Television. The main drafter of this standard is Chen Beijun.
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