GB/T 15943-1995 Measurement methods for technical indicators of broadcast audio channels
Some standard content:
ICS33.160
National Standard of the People's Republic of China
GB/T15943—1995
Technical specification measuring method of broadcasting audio channel1995-12-21 Issued
State Administration of Technical Supervision
1996-08-01 Implementation
National Standard of the People's Republic of China
Technical specification measuring method of broadcasting audio channel1 Subject content and scope of application
This standard specifies the method for measuring the technical indicators of the audio channel of the broadcast control system. This standard applies to the measurement of the technical indicators of the broadcast audio channel. 2 Reference standards
GB1779.16.30mm Performance test method for broadcast recording tapes GB1779.26.30mm Minimum performance requirements for broadcast recording tapes Test tapes for broadcasting recorders
GB1780
GB1781
GB5440
GB9003
3 Terminology
Broadcast recording reference tape
Broadcast stereo recorders
Methods for measuring basic characteristics of mixing consoles
3.1 Broadcasting channel broadcasting channel The audio channel for transmitting broadcasting programs. Including live broadcast channel, recorded broadcast channel and live broadcast channel. 3.2 Direct broadcasting channel The broadcast channel from the microphone input end of the mixing console in the broadcasting room to the output end of the line amplifier. 3.3 live broadcast channel outsidebroadcastingchannel GB/T15943—1995
The broadcast channel from the microphone input of the mixer at the live broadcast point to the line amplifier output of the broadcast control center. 3.4 recorded broadcast channel recordedbroadcastingchannel The broadcast channel from the playback amplifier output of the player in the broadcast room, that is, the playback head, to the line amplifier output, and can be recorded at the same time.
3.5 recording channel recordingchannel
The audio channel for recording broadcast programs is the audio channel from the microphone input of the mixer to the recording and playback output of the recorder.
3.6 copy channel copyingchannel
The audio channel from the playback amplifier input of the player through the mixer to the output of the recorder. 3.7 operating recordedlevel The residual magnetic flux on the tape when the volume meter indicates 0VU scale. This standard recommends recording with reference frequency signals, and when the tape speed is 38.1cm/s and 19.05cm/s, 255nWb/m is used as the working magnetic level. 3.8 Maximum recorded magnetic level Approved by the State Administration of Technical Supervision on December 21, 1995 and implemented on August 1, 1996
GB/T15943—1995
Refers to the magnetic level when the harmonic distortion of the signal recorded on the tape reaches the specified value. This standard stipulates that when the tape speed is 38.1cm/s and 19.05cm/s and the signal frequency is 1000Hz, the third harmonic distortion reaches 3% as its specified value, that is, the maximum recording magnetic level.
3.9 Rated input level ratedinputlevel The input level of the audio equipment specified by the national standard or the manufacturer. 3.10 Normal operating level normaloperatinglevel The level when the volume meter of the audio equipment reaches the 0VU (100%) scale. 3.11 Normal operating status normal operating status Under specified test conditions, connect the rated signal source electromotive force of the reference frequency in series with the rated signal source impedance and then connect to the input terminal of the mixer. According to the level specified by the manufacturer, adjust the volume controller of the tested channel and the master volume controller to make the output level reach the normal operating level.
3.12 Normal playing status normal reproducing status Under specified test conditions, use the "working magnetic level" part of the playback calibration tape to play the sound, and adjust the gain of the playback amplifier of the recorder or player to make the output level reach the normal operating level. 3.13 Normal recording status normal recording status Under specified test conditions, when the rated input level signal of the reference frequency is input to the recording amplifier of the recorder, adjust the gain of the recording amplifier to make the output level reach the normal operating level. 4 Test conditions
4.1 Environmental conditions
Temperature: 15℃~35℃
Relative humidity: 45%~80%
Air pressure: 85kPa~105kPa
4.2 Power supply
Voltage: single-phase 220V±10V (AC)
Frequency: 50Hz±1Hz
4.3 Except for the tested channel, the volume controllers of each channel in the mixer are set to the minimum gain position. 4.4 Except for the tested live broadcast channel, the tone controllers of the mixer are set to the flat amplitude-frequency characteristic position. 4.5 Before the test, adjust the head azimuth angle and recording bias current of the player and recorder, and adjust the amplitude-frequency characteristic. 4.6 The connection between the devices in the tested channel and the load of the line amplifier output are tested according to the actual working conditions. 4.7 Test frequency and voltage of live and live broadcast channels: 4.7.1 The frequencies used to test the amplitude-frequency characteristics of the channel are: 31.5Hz, 40Hz, 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz6.3kHz, 8kHz, 12.5kHz, 14kHz, 16kHz, 18kHz and 20kHz, depending on the amplitude-frequency characteristics of the channel being tested.
Use the normal operating level of the 1000Hz signal as the reference value of the amplitude-frequency characteristics. 4.7.2 When testing the total harmonic distortion of the channel, it should be measured within the amplitude-frequency characteristics of the amplifier according to the preferred frequencies specified in 4.7.1. Generally, several frequencies can be selected for measurement, such as 31.5Hz (or 40Hz), 63Hz, 125Hz, 1kHz, 4kHz, 8kHz and 16kHz. The test level is 6dB higher than the normal output level.
4.7.3 When testing the level difference, phase difference and crosstalk attenuation of the stereo channels, the test frequency shall be selected in accordance with the provisions of 4.7.1. When testing the level difference and phase difference, the left and right channels are in normal working condition. When testing the crosstalk, the signal level is 6dB higher than the normal output level. 4.8 Test frequency and level of recording, recording and copying channels: 4.8.1 The technical requirements for the playback calibration tape for testing the playback part of a player or recorder are shown in Table 1. 2
Working magnetic level
Signal frequency, Hz
Magnetic level, nWb/m
Total harmonic distortion, %
Duration, s
Azimuth calibration
Signal frequency, Hz
Magnetic level, dB
Duration Time, $
Amplitude-frequency characteristics
Signal frequency, Hz
Frequency error
Signal frequency magnetic level, dB
Magnetic level error, dB
Duration time+s
GB/T15943—1995
1000±30
255(0dB)
16×10°±30 or 12.5×10°±30-6
1 ×108
16×10 or 12.5×103,
1×108
2×108
250500
10×103
14× 108
12.5×103
16×103 18×103
《±2%
f<10kHz, ±0.5
f>10kHz,<±1
19.05cm/s
1000±30
255(0dB)
12×10±30 or 10×10°±30
1×103||t t||12.5×108 or 10×10%
1252505001×103
2×103
10×10%
16×103
6.3×1038×108
4×108
12.5×103
14×108
f<10kHz, <±0.5
f>10kHz, <±1
4.8.2 When testing the amplitude-frequency characteristics of the recording and reproduction channels, the test shall be carried out according to the frequency and magnetic level used in the playback calibration test tape. 4.8.3 When testing the total harmonic distortion of the channel, several frequencies within the range of 40Hz to 6.3kHz shall be selected for measurement. Generally, three frequencies such as 125Hz, 1kHz and 4kHz can be selected for testing at 6dB higher than the working magnetic level. 4.8.4 The test frequency and magnetic level requirements of the distortion test tape used for the playback part are the same as those in 4.8.3. 4.8.5 Reference tape is a magnetic tape used as a reference for the measurement of the three electroacoustic properties of broadcast recording tapes (working bias magnetism, relative sensitivity and relative amplitude-frequency characteristics). This standard stipulates that reference tapes are used to test recording and playback channels. Note: When testing operating indicators, actual recording tapes can be used. 4.8.6 Test channel phase difference and level difference, measured using the frequency and magnetic level specified in 4.8.1. The frequency and magnetic level used when testing channel crosstalk attenuation are the same as in 4.8.3.
5 Technical requirements for measuring equipment
Should comply with the relevant provisions of GB5440.
6 Live channel test method
The instrument connection is shown in Figure 1.
6.1 Signal-to-noise ratio
GB/T15943—1995
Figure 1 Mono measurement diagram
The negative station
is Beijing Dufa
6.1.1 The mixer is placed in normal working state. Use the 1000Hz signal sent by the audio signal generator to adjust the volume controller of the line amplifier so that the channel output level N reaches the normal working level. 6.1.2 Disconnect the input wiring of the mixer and replace it with a well-shielded equivalent signal source impedance R., and measure the channel noise level at the output end of the line amplifier.
6.1.3 The difference between the normal working level of the channel and the channel noise level is the channel signal-to-noise ratio at the rated input level. 6.2 Amplitude-frequency characteristics
6.2.1 Same as 6.1.1.
6.2.2 According to the provisions of 4.7.1, change the frequency of the audio signal generator and keep its output level Nu1 unchanged. Measure the channel output level of each test frequency at the output end of the line amplifier. Subtract these levels from the output level of 1000Hz to obtain the channel amplitude-frequency characteristics. 6.3 Total harmonic distortion
6.3.1 Increase the output level Nu1 of the audio signal generator so that the channel output level is 6dB higher than the normal working level. Use a distortion meter to measure the channel total harmonic distortion of the 1000Hz signal at the output end of the line amplifier. 6.3.2 According to the provisions of 4.7.2, change the frequency of the audio signal generator and adjust the signal level N so that the channel output level is 6dB higher than the working level. Use a distortion meter to measure the channel total harmonic distortion of each test frequency at the output end of the line amplifier. The connection of the instrument for testing stereo channels is shown in Figure 2. N
Paired Guard Circuit
Figure 2 Stereo Channel Measurement Diagram
Use the 1000Hz signal sent by the audio signal generator to put the levels of the left and right channel devices into normal working state. 6.4 Level Difference
6.4.1 Same as 6.1.1.
6.4.2 Change the frequency of the audio signal generator according to 4.7.1, and keep its output level N unchanged. Measure the level value of each test frequency at the output end of the line amplifier of the two channels 4
GB/T15943—1995
, and subtract the output levels of the two channels to get the level difference. 6.5 Phase Difference
Use the method in 6.4 to measure the channel phase difference of each test frequency at the output end of the line amplifier with a phase meter. 6.6 Crosstalk attenuation
The signal sent by the audio signal generator enters one of the channels, and its frequency is changed according to the provisions of 4.7.1, and the signal level Na value is adjusted so that the output level of this channel is 6dB higher than the normal working value. A well-shielded equivalent resistor R is connected across the input end of the other channel, and the level of each test frequency is measured at the output end of the two channels using a frequency selection meter or a bandpass filter. The level measured at the output end is subtracted to obtain the crosstalk attenuation between the channels. 7 Live broadcast channel test method
The test instrument connection is shown in Figure 3.
Figure 3 Live broadcast channel measurement diagram
Low rate
Put the broadcast mixer at the live broadcast point in normal working state, adjust the tone controller of the mixer of the broadcast control system to a position where the channel amplitude-frequency characteristic reaches a flat position, and adjust the volume controller of the mixer and the amplifier to make the channel output level N reach the normal working level. 7.1 Signal-to-noise ratio
Test method refers to 6.1
7.2 Amplitude-frequency characteristic
Test method refers to 6.2.
7.3 Total harmonic distortion
Test method refers to 6.3.
7.4 Level difference
Test method refers to 6.4.
7.5 Phase difference
Test method refers to 6.5.
7.6 Crosstalk
Test method refers to 6.6.
Stereo channel measurement is shown in Figure 4.
8 Recording channel test method
Measurement instrument connection is shown in Figure 5.
As for the set
As for the practice
GB/T15943—1995
Figure 4 Stereo channel measurement diagram
Ketone station
Figure 5 Recording channel measurement diagram
Use the working magnetic level part of the playback calibration tape for testing, put the player in the normal playback state, adjust the volume controllers of the mixer and the line player to make their respective output levels reach the normal working level. 8.1 Signal-to-noise ratio
GB/T15943—1995
Pick up the tape from the playback head or use a non-magnetic tape to play, and measure the channel noise level at the output end of the line player. The difference between the normal working level of the channel and the channel noise level is the channel signal-to-noise ratio. 8.2 Amplitude-frequency characteristics
Use the frequency characteristic part of the playback calibration tape for playing, and measure the channel amplitude-frequency characteristics at the output end of the line player. 8.3 Total harmonic distortion
8.3.1 Play the sound with the distortion test tape, and measure the total harmonic distortion of each channel at the output end of the online player. 8.3.2 Connect the induction coil to the output end of the audio signal generator, and contact the coil to the playback head seam. Input the playback amplifier through induction. Change the frequency of the audio signal generator according to the provisions of 4.8.3, and adjust its level so that the output level of the playback amplifier is 6dB higher than the normal working level. Adjust the volume controller of the tested channel of the mixing console so that the channel output level is 6dB higher than the normal working level. Measure the total harmonic distortion of each channel at the test frequency with the distortion meter at the output end of the online player. 8.4 Jitter
Channel jitter, that is, the jitter of the recorder.
8.5 Level difference
8.5.1 The connection of the test instrument is shown in Figure 6.
Figure 6 Stereo Measurement Diagram
Use the working magnetic level part of the playback calibration tape to play the sound, and put the left and right channels of the player into normal playback state. Adjust the volume controllers of the mixer and the line amplifier to make the output levels of the left and right channels reach normal working values. 8.5.2 Use the amplitude-frequency characteristic part of the playback calibration tape to play the sound, and measure the level of each test frequency at the line amplifier output of the two channels. Subtract the output levels of the two channels to get the level difference. 8.6 Phase Difference
According to the method in 8.5, use a phase meter to measure the phase difference of the left and right channels at each test frequency at the line amplifier output of the two channels. 8.7 Crosstalk Attenuation
8.7.1 Use the crosstalk test tape to play the sound, and use a frequency selection meter or a bandpass filter to measure the crosstalk attenuation between channels at the line amplifier output of the two channels. 8.7.2 The signal sent by the audio signal generator enters one of the stereo heads of the player through a high-value series resistor. According to the provisions of 4.8.3, the frequency of the audio signal generator is changed, and the signal level is adjusted so that the output level of this channel is 6dB higher than the working level. No signal is added to the other channel. The level of each frequency is measured at the output end of the two channels using a frequency selection meter or a channel harmonic meter. The level measured at the output end is subtracted to obtain the channel crosstalk. 9 Recording channel test method
The test instrument connection is shown in Figure 7.
GB/T15943—1995
Base band
Figure? Recording channel measurement diagram
Installation resistance
Use the 1000Hz signal of the audio signal generator to set the mixer to normal working state, and adjust the recorder to normal playback state and normal recording state respectively, so that the channel output level reaches the normal working level. 9.1 Signal-to-Noise Ratio
9.1.1 Record the reference tape using a 1000 Hz signal at the working magnetic level through the recording and playback channel. 9.1.2 At the input end of the mixer, connect a well-shielded equivalent signal source resistor, demagnetize the recorded part of the reference tape, then play it back and measure the channel noise level at the output end of the amplifier. 9.1.3 The difference between the normal operating level of the channel and the channel noise level is the signal-to-noise ratio of the recording channel. 9.2 Amplitude-frequency characteristics
9.2.1 Record the reference tape through the recording and playback channel with a 1000Hz signal, reduce the output level Nal of the audio signal generator, and reduce the output level by 6dB.
9.2.2 Change the frequency of the audio signal generator according to 4.8.2, keep the output level N unchanged, record with the recording and playback channel test tape, replay the recorded part, and measure the channel amplitude-frequency characteristics. 9.3 Total harmonic distortion
9.3.1 Change the frequency of the audio signal generator according to the provisions of 4.8.3, record the reference tape through the recording and playback channel, adjust the signal generator output level Nu1, make the output level higher than the working level by 6dB, and measure the channel total harmonic distortion of each test frequency. 9.3.2 Increase the output level Nu1 of the audio signal generator, measure the output level when the channel total harmonic distortion of each test frequency signal reaches 3%, which is the highest output level of the recording channel. 9.3.3 Use the 10kHz sent by the audio signal generator to measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
9.4 Jitter
Channel jitter, that is, recorder jitter.
9.5 Level difference
9.5.1 The connection of the test instrument is shown in Figure 8. 8
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GB/T15943—1995
Figure 8 Stereo measurement diagram
Baseband
Phase meter
and frequency selection table
Use the 1000Hz signal of the audio signal generator to put the left and right channels of the mixer into normal working state, and adjust the left and right channels of the recorder to normal playback state and normal recording state respectively. 9.5.2 Adjust the 1000Hz signal level Nul sent by the audio signal generator to reduce the recording and playback output level by 6dB. 9.5.3 Change the frequency of the audio signal generator according to the provisions of 4.8.6, and keep the output level Nu unchanged, record the reference tape through the recording and playback channel, replay the recorded part, measure the left and right channel playback level of each test frequency, and subtract the two channel playback levels to get the level difference.
9.6 Phase difference
According to the method in 9.5, use a phase meter to measure the phase difference of the left and right channels at each test frequency at the output end of the playback part of the recorder. 9.7 Crosstalk attenuation
Use the 1000Hz signal sent by the audio signal generator to enter one of the channels, change its frequency according to the provisions of 4.8.6, and adjust the signal level Na value so that the output level of the recording and playback channel is 6dB higher than the normal working level, and connect a well-shielded equivalent resistor Rs across the input end of the other channel. Record the reference tape through the recording and playback channel, replay the recorded part, and use a frequency selection meter or a bandpass filter to measure the playback output level of the channel without signal. Subtract the levels measured on the two channels to get the crosstalk attenuation between the channels. 10 Copy channel test method
The connection of the test instrument is shown in Figure 9.
Figure 9 Reproduction Channel Measurement Diagram
Put the recorder in normal playback state, use the 1000Hz working magnetic level part of the playback calibration tape to play on the recorder, and adjust the volume controller of each device in the channel to make the respective output level reach the normal working value. 9
10.1 Signal-to-Noise Ratio
GB/T15943—1995
10.1.1 Use the 1000Hz working magnetic level part of the playback calibration tape to play, record the reference tape through the recording and playback channel, then pick up the tape from the playback head or non-magnetic tape on the recorder, demagnetize the recorded part, and play it back, and measure the channel noise level at the output end of the recorder's playback amplifier.
10.1.2 The difference between the normal playback output level of the recorder and the channel noise level is the channel signal-to-noise ratio. 10.2 Amplitude-frequency characteristics
Use the amplitude-frequency characteristics of the playback calibration tape to play on the player, record the reference tape through the recording channel, replay the recorded part, and measure the channel amplitude-frequency characteristics.
10.3 Total harmonic distortion
10.3.1 Use the distortion test tape to play on the player, use the recording channel test tape to record on the recorder, adjust the volume controller of the player so that the recorder's recording and playback output level is 6dB higher than the working level, rewind the recorded part and play it back, and measure the total harmonic distortion of each test frequency signal.
10.3.2 Connect an induction coil to the output end of the audio signal generator, input the signal into the playback amplifier of the player through induction, record the sound on the player with the recording channel test tape, change the frequency of the audio signal generator according to the provisions of 4.8.3, adjust its output level Na1, make the recording and playback output level of the recorder higher than the normal working level by 6dB, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.3 Amplify the output level Na1 of the audio signal generator, measure the output level when the channel harmonic distortion of each test frequency signal reaches 3%, which is the highest output level.
10.3.4 Record the 10kHz signal sent by the audio signal generator, and measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
10.4 Level difference
10.4.1 The connection of the test instrument is shown in Figure 10. BasebandbzxZ.net
Figure 10 Stereo Measurement Diagram
Phase Total
Put the recorder in normal playback mode, play the 1000Hz working tape part of the playback calibration tape on the recorder, and record with the recorder at the same time, adjust the volume controllers of the left and right channels of each device to make their respective output levels reach the normal working level. 10.4.2 Play the frequency characteristic part of the playback calibration tape on the recorder, record the reference tape through the recording channel, replay the recorded part, measure the level values of the left and right channels at each frequency at the output end of the playback part of the recorder, and subtract the two level values to obtain the level difference. 10.5 Phase Difference
Measure the phase difference of the left and right channels at each frequency at the output end of the playback part of the recorder according to the method in 10.4. 10.6 Crosstalk Attenuation
10.6.1 Play the crosstalk attenuation test tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level of each frequency at the left and right channel output ends of the playback part of the recorder, and the difference between the level values of the two channels is the crosstalk attenuation. 10
GB/T15943—1995
2 Use the 1000Hz signal sent by the audio signal generator to enter a winding in the stereo magnetic head of the player through a high-resistance series resistor, record the reference tape through the recording channel, and adjust the signal level so that the output level of the recorder is 6dB higher than the normal working level, and record the signals of each frequency separately according to the regulations. Then replay the recorded part, use a frequency selection meter or a bandpass filter to measure the recording and playback output level of the unsignaled channel, and the subtraction of the level values of the two channels is the crosstalk attenuation. Additional Notes:
This standard was proposed by the Ministry of Radio, Film and Television of the People's Republic of China. The Standardization Planning Institute of the Ministry of Radio, Film and Television is responsible for the technical coordination of this standard. This standard was drafted by Radio International. The main drafters of this standard are Shao Changyao and Wang Zexiang. 113 Use the 10kHz signal sent by the audio signal generator to measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
9.4 Jitter
Channel jitter, that is, recorder jitter.
9.5 Level difference
9.5.1 The connection of the test instrument is shown in Figure 8. 8
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GB/T15943—1995
Figure 8 Stereo measurement diagram
Baseband
Phase meter
and frequency selection table
Use the 1000Hz signal of the audio signal generator to put the left and right channels of the mixer into normal working state, and adjust the left and right channels of the recorder to normal playback state and normal recording state respectively. 9.5.2 Adjust the 1000Hz signal level Nul sent by the audio signal generator to reduce the recording and playback output level by 6dB. 9.5.3 Change the frequency of the audio signal generator according to 4.8.6, and keep the output level Nu unchanged. Record the reference tape through the recording and playback channel, replay the recorded part, measure the left and right channel playback levels of each test frequency, and subtract the playback levels of the two channels to get the level difference.
9.6 Phase difference
According to the method in 9.5, use a phase meter to measure the phase difference of the left and right channels of each test frequency at the output end of the playback part of the recorder. 9.7 Crosstalk attenuation
Use the 1000Hz signal sent by the audio signal generator to enter one of the channels, change its frequency according to 4.8.6, and adjust the signal level Na value so that the output level of the recording and playback channel is 6dB higher than the normal working level. Connect a well-shielded equivalent resistor Rs across the input end of the other channel. Record the reference tape through the recording and playback channel, replay the recorded part, use the frequency selection meter or bandpass filter to measure the playback output level of the channel without signal, subtract the levels measured in the two channels, and the crosstalk attenuation between the channels is obtained. 10 Copy channel test method
The connection of the test instrument is shown in Figure 9.
Figure 9 Copy channel measurement diagram
Put the recorder in the normal playback state, use the 1000Hz working magnetic level part of the playback calibration tape to play the sound on the player, and adjust the volume controller of each device in the channel so that the output level of each device reaches the normal working value. 9
10.1 Signal-to-noise ratio
GB/T15943—1995
10.1.1 Play the 1000Hz working magnetic level part of the playback calibration tape, record the reference tape through the recording and playback channel, then remove the tape from the playback head or non-magnetic tape on the player and play it, demagnetize the recorded part, and play it back, and measure the channel noise level at the output end of the playback amplifier of the recorder.
10.1.2 The difference between the normal playback output level of the recorder and the channel noise level is the channel signal-to-noise ratio. 10.2 Amplitude-frequency characteristics
Play the amplitude-frequency characteristic part of the playback calibration tape on the player, record the reference tape through the recording channel, replay the recorded part, and measure the channel amplitude-frequency characteristics.
10.3 Total harmonic distortion
10.3.1 Play the distortion test tape on the player, record the sound on the recorder with the recording channel test tape, adjust the volume controller of the player so that the recording and playback output level of the recorder is 6dB higher than the working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.2 Connect an induction coil to the output end of the audio signal generator, input the signal into the playback amplifier of the player through induction, record the sound on the music player with the recording channel test tape, change the frequency of the audio signal generator according to the provisions of 4.8.3, adjust its output level Na1 so that the recording and playback output level of the recorder is 6dB higher than the normal working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.3 Amplify the output level Nal of the audio signal generator and measure the output level when the channel harmonic distortion of each test frequency signal reaches 3%, which is the highest output level.
10.3.4 Record the 10kHz signal sent by the audio signal generator and measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
10.4 Level difference
10.4.1 The connection of the test instrument is shown in Figure 10. Base male tape
Figure 10 Stereo measurement diagram
Phase total
Put the recorder in normal playback state, play the 1000Hz working tape part of the playback calibration tape on the recorder, and record with the recorder at the same time, adjust the volume controllers of the left and right channels of each device to make their respective output levels reach the normal working level. 10.4.2 Play the frequency characteristic part of the playback calibration tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level values of the left and right channels at each frequency at the output end of the playback part of the recorder, and subtract the two level values to obtain the level difference. 10.5 Phase difference
Measure the phase difference of the left and right channels at each frequency at the output end of the playback part of the recorder according to the method in 10.4. 10.6 Crosstalk attenuation
10.6.1 Play the crosstalk attenuation test tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level values of each frequency at the output end of the left and right channels of the playback part of the recorder, and the difference between the level values of the two channels is the crosstalk attenuation. 10
GB/T15943—1995
2 The 1000Hz signal sent by the audio signal generator enters a winding in the stereo magnetic head of the recorder through a high-resistance series resistor. The reference tape is recorded through the recording channel, and the signal level is adjusted so that the output level of the recorder is 6dB higher than the normal working level. The signals of each frequency are recorded separately according to the regulations. Then the recorded part is replayed, and the output level of the recording and playback channel without signal channel is measured with a frequency selection meter or a bandpass filter. The subtraction of the level values of the two channels is the crosstalk attenuation. Additional remarks:
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. The Standardization Planning Institute of the Ministry of Radio, Film and Television is responsible for the technical coordination of this standard. This standard is drafted by Radio International. The main drafters of this standard are Shao Changyao and Wang Zexiang. 113 Use the 10kHz signal sent by the audio signal generator to measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
9.4 Jitter
Channel jitter, that is, recorder jitter.
9.5 Level difference
9.5.1 The connection of the test instrument is shown in Figure 8. 8
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GB/T15943—1995
Figure 8 Stereo measurement diagram
Baseband
Phase meter
and frequency selection table
Use the 1000Hz signal of the audio signal generator to put the left and right channels of the mixer into normal working state, and adjust the left and right channels of the recorder to normal playback state and normal recording state respectively. 9.5.2 Adjust the 1000Hz signal level Nul sent by the audio signal generator to reduce the recording and playback output level by 6dB. 9.5.3 Change the frequency of the audio signal generator according to 4.8.6, and keep the output level Nu unchanged. Record the reference tape through the recording and playback channel, replay the recorded part, measure the left and right channel playback levels of each test frequency, and subtract the playback levels of the two channels to get the level difference.
9.6 Phase difference
According to the method in 9.5, use a phase meter to measure the phase difference of the left and right channels of each test frequency at the output end of the playback part of the recorder. 9.7 Crosstalk attenuation
Use the 1000Hz signal sent by the audio signal generator to enter one of the channels, change its frequency according to 4.8.6, and adjust the signal level Na value so that the output level of the recording and playback channel is 6dB higher than the normal working level. Connect a well-shielded equivalent resistor Rs across the input end of the other channel. Record the reference tape through the recording and playback channel, replay the recorded part, use the frequency selection meter or bandpass filter to measure the playback output level of the channel without signal, subtract the levels measured in the two channels, and the crosstalk attenuation between the channels is obtained. 10 Copy channel test method
The connection of the test instrument is shown in Figure 9.
Figure 9 Copy channel measurement diagram
Put the recorder in the normal playback state, use the 1000Hz working magnetic level part of the playback calibration tape to play the sound on the player, and adjust the volume controller of each device in the channel so that the output level of each device reaches the normal working value. 9
10.1 Signal-to-noise ratio
GB/T15943—1995
10.1.1 Play the 1000Hz working magnetic level part of the playback calibration tape, record the reference tape through the recording and playback channel, then remove the tape from the playback head or non-magnetic tape on the player and play it, demagnetize the recorded part, and play it back, and measure the channel noise level at the output end of the playback amplifier of the recorder.
10.1.2 The difference between the normal playback output level of the recorder and the channel noise level is the channel signal-to-noise ratio. 10.2 Amplitude-frequency characteristics
Play the amplitude-frequency characteristic part of the playback calibration tape on the player, record the reference tape through the recording channel, replay the recorded part, and measure the channel amplitude-frequency characteristics.
10.3 Total harmonic distortion
10.3.1 Play the distortion test tape on the player, record the sound on the recorder with the recording channel test tape, adjust the volume controller of the player so that the recording and playback output level of the recorder is 6dB higher than the working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.2 Connect an induction coil to the output end of the audio signal generator, input the signal into the playback amplifier of the player through induction, record the sound on the music player with the recording channel test tape, change the frequency of the audio signal generator according to the provisions of 4.8.3, adjust its output level Na1 so that the recording and playback output level of the recorder is 6dB higher than the normal working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.3 Amplify the output level Nal of the audio signal generator and measure the output level when the channel harmonic distortion of each test frequency signal reaches 3%, which is the highest output level.
10.3.4 Record the 10kHz signal sent by the audio signal generator and measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
10.4 Level difference
10.4.1 The connection of the test instrument is shown in Figure 10. Base male tape
Figure 10 Stereo measurement diagram
Phase total
Put the recorder in normal playback state, play the 1000Hz working tape part of the playback calibration tape on the recorder, and record with the recorder at the same time, adjust the volume controllers of the left and right channels of each device to make their respective output levels reach the normal working level. 10.4.2 Play the frequency characteristic part of the playback calibration tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level values of the left and right channels at each frequency at the output end of the playback part of the recorder, and subtract the two level values to obtain the level difference. 10.5 Phase difference
Measure the phase difference of the left and right channels at each frequency at the output end of the playback part of the recorder according to the method in 10.4. 10.6 Crosstalk attenuation
10.6.1 Play the crosstalk attenuation test tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level values of each frequency at the output end of the left and right channels of the playback part of the recorder, and the difference between the level values of the two channels is the crosstalk attenuation. 10
GB/T15943—1995
2 The 1000Hz signal sent by the audio signal generator enters a winding in the stereo magnetic head of the recorder through a high-resistance series resistor. The reference tape is recorded through the recording channel, and the signal level is adjusted so that the output level of the recorder is 6dB higher than the normal working level. The signals of each frequency are recorded separately according to the regulations. Then the recorded part is replayed, and the output level of the recording and playback channel without signal channel is measured with a frequency selection meter or a bandpass filter. The subtraction of the level values of the two channels is the crosstalk attenuation. Additional remarks:
This standard is proposed by the Ministry of Radio, Film and Television of the People's Republic of China. The Standardization Planning Institute of the Ministry of Radio, Film and Television is responsible for the technical coordination of this standard. This standard is drafted by Radio International. The main drafters of this standard are Shao Changyao and Wang Zexiang. 112 The difference between the normal playback output level of the recorder and the channel noise level is the channel signal-to-noise ratio. 10.2 Amplitude-frequency characteristics
Use the amplitude-frequency characteristic part of the playback calibration tape to play on the recorder, record the reference tape through the recording channel, replay the recorded part, and measure the channel amplitude-frequency characteristics.
10.3 Total harmonic distortion
10.3.1 Use the distortion test tape to play on the recorder, use the recording channel test tape to record on the recorder, adjust the volume controller of the recorder so that the recorder's recording and playback output level is 6dB higher than the working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.2 Connect an induction coil to the output end of the audio signal generator, input the signal into the playback amplifier of the player through induction, record the sound on the player with the recording channel test tape, change the frequency of the audio signal generator according to the provisions of 4.8.3, adjust its output level Na1, make the recording and playback output level of the recorder higher than the normal working level by 6dB, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.3 Amplify the output level Na1 of the audio signal generator, measure the output level when the channel harmonic distortion of each test frequency signal reaches 3%, which is the highest output level.
10.3.4 Record the 10kHz signal sent by the audio signal generator, and measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
10.4 Level difference
10.4.1 The connection of the test instrument is shown in Figure 10. Baseband
Figure 10 Stereo Measurement Diagram
Phase Total
Put the recorder in normal playback mode, play the 1000Hz working tape part of the playback calibration tape on the recorder, and record with the recorder at the same time, adjust the volume controllers of the left and right channels of each device to make their respective output levels reach the normal working level. 10.4.2 Play the frequency characteristic part of the playback calibration tape on the recorder, record the reference tape through the recording channel, replay the recorded part, measure the level values of the left and right channels at each frequency at the output end of the playback part of the recorder, and subtract the two level values to obtain the level difference. 10.5 Phase Difference
Measure the phase difference of the left and right channels at each frequency at the output end of the playback part of the recorder according to the method in 10.4. 10.6 Crosstalk Attenuation
10.6.1 Play the crosstalk attenuation test tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level of each frequency at the left and right channel output ends of the playback part of the recorder, and the difference between the level values of the two channels is the crosstalk attenuation. 10
GB/T15943—1995
2 Use the 1000Hz signal sent by the audio signal generator to enter a winding in the stereo magnetic head of the player through a high-resistance series resistor, record the reference tape through the recording channel, and adjust the signal level so that the output level of the recorder is 6dB higher than the normal working level, and record the signals of each frequency separately according to the regulations. Then replay the recorded part, use a frequency selection meter or a bandpass filter to measure the recording and playback output level of the unsignaled channel, and the subtraction of the level values of the two channels is the crosstalk attenuation. Additional Notes:
This standard was proposed by the Ministry of Radio, Film and Television of the People's Republic of China. The Standardization Planning Institute of the Ministry of Radio, Film and Television is responsible for the technical coordination of this standard. This standard was drafted by Radio International. The main drafters of this standard are Shao Changyao and Wang Zexiang. 112 The difference between the normal playback output level of the recorder and the channel noise level is the channel signal-to-noise ratio. 10.2 Amplitude-frequency characteristics
Use the amplitude-frequency characteristic part of the playback calibration tape to play on the recorder, record the reference tape through the recording channel, replay the recorded part, and measure the channel amplitude-frequency characteristics.
10.3 Total harmonic distortion
10.3.1 Use the distortion test tape to play on the recorder, use the recording channel test tape to record on the recorder, adjust the volume controller of the recorder so that the recorder's recording and playback output level is 6dB higher than the working level, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.2 Connect an induction coil to the output end of the audio signal generator, input the signal into the playback amplifier of the player through induction, record the sound on the player with the recording channel test tape, change the frequency of the audio signal generator according to the provisions of 4.8.3, adjust its output level Na1, make the recording and playback output level of the recorder higher than the normal working level by 6dB, rewind the recorded part and measure the total harmonic distortion of each test frequency signal.
10.3.3 Amplify the output level Na1 of the audio signal generator, measure the output level when the channel harmonic distortion of each test frequency signal reaches 3%, which is the highest output level.
10.3.4 Record the 10kHz signal sent by the audio signal generator, and measure the recording and playback output level when the 10kHz signal reaches saturation, which is the high-frequency saturation output level.
10.4 Level difference
10.4.1 The connection of the test instrument is shown in Figure 10. Baseband
Figure 10 Stereo Measurement Diagram
Phase Total
Put the recorder in normal playback mode, play the 1000Hz working tape part of the playback calibration tape on the recorder, and record with the recorder at the same time, adjust the volume controllers of the left and right channels of each device to make their respective output levels reach the normal working level. 10.4.2 Play the frequency characteristic part of the playback calibration tape on the recorder, record the reference tape through the recording channel, replay the recorded part, measure the level values of the left and right channels at each frequency at the output end of the playback part of the recorder, and subtract the two level values to obtain the level difference. 10.5 Phase Difference
Measure the phase difference of the left and right channels at each frequency at the output end of the playback part of the recorder according to the method in 10.4. 10.6 Crosstalk Attenuation
10.6.1 Play the crosstalk attenuation test tape on the player, record the reference tape through the recording channel, replay the recorded part, measure the level of each frequency at the left and right channel output ends of the playback part of the recorder, and the difference between the level values of the two channels is the crosstalk attenuation. 10
GB/T15943—1995
2 Use the 1000Hz signal sent by the audio signal generator to enter a winding in the stereo magnetic head of the player through a high-resistance series resistor, record the reference tape through the recording channel, and adjust the signal level so that the output level of the recorder is 6dB higher than the normal working level, and record the signals of each frequency separately according to the regulations. Then replay the recorded part, use a frequency selection meter or a bandpass filter to measure the recording and playback output level of the unsignaled channel, and the subtraction of the level values of the two channels is the crosstalk attenuation. Additional Notes:
This standard was proposed by the Ministry of Radio, Film and Television of the People's Republic of China. The Standardization Planning Institute of the Ministry of Radio, Film and Television is responsible for the technical coordination of this standard. This standard was drafted by Radio International. The main drafters of this standard are Shao Changyao and Wang Zexiang. 11
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