GB/T 9039-1988 Technical requirements for 10KHZ~18.6MHZ transmission tester
Some standard content:
National Standard of the People's Republic of China
10kHz～18.6MHz Transmission Tester
Technical Condition for Transmissionmeasuring Set 10kHz to 18. 6MHzUDC 621.317
GB 9039-88
This standard applies to 10kHz～18.6MHz level oscillator and 10kHz~18.6MHz frequency-selective level meter and similar products. 10kHz～18.6MHz level oscillator and 10kHz～18.6MHz frequency-selective level meter can be used together or separately, and are mainly applicable to the manufacture, installation, maintenance and system testing of carrier and other analog communication equipment, and can also be used for other tests with equivalent frequency range.
1 Technical Requirements
1.1 The warm-up time for the instrument to reach the working characteristics shall not exceed 30 min. 1.2 Main working characteristics:
The main working characteristics are divided into three levels according to the surface quality list. The characteristics of each level are shown in Table 1 and Table 2. Table 1. Main technical indicators of 10kHz~18.6MHz level oscillator Angstrom
(!) Frequency range
(2) Resolution
(3) Frequency accuracy
(1) Output voltage half
(1) Output level
(2\Zero level accuracy
at 100 kHz:
1c kliz-~ 18. 6 MHz
106 Hz or 10 Hz
12X10 $:1 academic
level meter synchronous oscillator or oscillator
synchronous meter
70~ 0 B -60 ~+
10 dRm) each step 10 dB, continuously adjustable
Approximate minimum adjustable level
--80 B (70 dBm)
Under reference conditions: 0 dB (dBm)
: 0-1 d
0~40 ℃, ± 0. 2 dB
Approved by the Ministry of Posts and Telecommunications of the People's Republic of China on 1987-12-02
10 kHz~18. 6 MHz
250 Hz
After calibration
When locked: ±1×105=300 Hz
Continuous: ±3×10-*Hz±30kHz
Level meter synchronized with oscillator or vibrator
Synchronized level meter
70~0dB-60~-
10dBm) 10B per step, continuously adjustable
About 11 dB Minimum adjustable level
80 dB(-70 dB)
Under reference conditions: with 0 dB(dBm)
0~-40 C: ±0. 25 dB
10 kHz~18. 6 MHs
After calibration
When locked: ±1×10-5±450 Hz
Continuous: ±3×10-*Hz±30kHz
Level meter synchronized with oscillator or oscillator
Synchronized level meter
70~0dB, 10B continuous step
Adjustable about 11 dB Minimum adjustable level
Under reference conditions: based on 0 dB
0~-40C: ±0. 3 dB
10B8-10-01 implementation
(3) Attenuator accuracy
At 100 kHz
(4) Frequency response
Based on 100 kHz, 0 dB
3 first true attenuation
At 0 dB, secondary,
tertiary waves
clutter suppression (including full load)
at B
5Output impedance
(1)Nominal value
(2)Reflection reduction
---70--: - 10 dB
Mean time between failures (MTBF)
(1)Frequency range
(2)Resolution
(3)Frequency accuracy
(4)Frequency synchronization
2Input level
(1)Input range
(2)Zero level accuracy
GB 9039—
Continued Table 1
Reference to 0 dB(dBm):±0. 1 dB
10 kHz~18. 6 MHz≥4B dB
≥65dB
≥30dB
5o0o h
refer to dB(dBm),±2 d
10 kHz~10 MHz,±0. 1 dB
10 kHz~~18. G MHz+ = 0. 2 dB10 kHz--18. 6 MHz240 dB
refer to;±0. 3 d
10 kHz~10 MHz:±0. 2 dB
10 kH2~-18. 6 MHz, ±0. 3 dB10 kHz--10. 0 MHz40 dH
10 kHa--18. 6 MHz35 dB
1 000 h
Table 210 kHz~18. 6 MHz frequency-selective level meter Main technical indicators Level
10 kHz~1&- 6 MHz
100 Hz or 10 Hz
±2×10-5±1 word
10 kHz~18- 6 MHz
After calibration
When locked: ±1×10-5±300 Hz
Continuous: ±3×10-4Hz±30kHz
10 kHz~-18- B MHz
250 Hz
After calibration
When locked: =1×10:5±450 Hz
when continuous, 3X1-dHz3z
level meter synchronizes the oscillator or camera!
Level meter Synchronous oscillator Oscillator
Level meter Synchronous oscillator or oscillator
Synchronous level meter
Synchronous level meter
Based on α dB(dBm), each step of 10
Based on 0 dB(dBm), each step of 10
dB-110 ~+10 dB (or - 100
+20 dBm)
Under reference conditions:
Based on 100 kHz0 dR(dBm):
0~40℃:±0. 2 dB
dB --.110 ~ +10 dB (or-- 100~+20 dBm)
Under reference conditions;
Based on 100 kHz0 dB(dBm):
±0.15 dB
0~40C± 0. 25 dB
Synchronous level meter
Based on, 1 step -
110~+10B
Under reference conditions:
Based on 100 kHzx0 d: ± 0. 2
U~40:±0. 3 dB
(3) Attenuator accuracy
70-+10 dB
80~—110 dB
(4) Frequency response
Based on 100 kHz, 0 dB
(5) Level display resolution
3 Frequency selectivity
Band attenuation
Abs0. 5 dB
Bandwidth Ab=3dB
Stopband attenuation b≥50 rB
b=60 dB
Effective noise bandwidth
Intrinsic distortion attenuation
When sensitivity is improved
Secondary, three-ohm distortion
5Intermediate frequency attenuation
6Image attenuation
fa+2,
fm+2
? Input impedance
(1)Nominal value
(2)Reflection reduction
8Local spurious (including combined interference) bandwidth
Width:1- 74 kHz
Mean Time Between Unexpected Failures (MTBF)
GB 9039—88
Continued Table 2
Based on 100 kHz, referenced to dB
(dBm)±.1dB
Each 10 dB step: ± 0.1 dB (can be accumulated)
10 kHe10 MHz:±0.1 dB
10 kHz~18. 6 MHz+±d. 2 dB
With narrowband function
and can meet the requirements of measuring pilot
±500Hz
1- 74 kHz
±2kHz
1. 74 kHz
≥60 dB
≥34 dB
≤—120 B
At 100 kHz, referenced to 0 dB
At 100 kHz, referenced to 0 dB: ±
(dBm), ±0.15 dB
Every 10 steps: ±0.2 dB (accumulative
10kHz~10MH±0.3dB
10 kHz--18.6 MHz±0.4dB
With pull function
±500Hz
1.74 kHz
±2 kHz
1-74 kHz
≥65 dB
-120 dB
Every 10 steps: ±0. d(capable of x
10 kHz~J0 MHz:+0.4 dB
10 kHz~18. 6 MHzt±0. 5 dB
With difficult band function
±500 Hz
zl. 74 kHz
±4 kHz
1-74 kHz
260 dB
260 dB
≥26 dB
≤—120 dB
1.3 The environmental conditions of this transmission tester shall comply with the provisions of GB6587.1—86 General Program for Environmental Test of Electronic Measuring Instruments Group 1. 1.4 The power supply frequency and voltage of this transmission tester shall comply with the provisions of GB6587.8--86 Power Supply Frequency and Voltage Test of Electronic Measuring Instruments:
GB 9039-88
1.5 The basic safety conditions of this transmission tester shall comply with the provisions of Class II safety instruments in GB6587.7-86 Basic safety test for electronic measuring instruments.
2 Test methods
2.1 Test method for level oscillator
See Appendix A.
2.2 Test method for selected level meter
See Appendix B.
2.3 Basic safety test
Follow the test method specified in Class I safety instruments in GB6587.7-86 Basic safety test for electronic measuring instruments. 2.4 Temperature test
Perform according to the provisions of Group 1 of GB6587.2-86 Temperature test for electronic measuring instruments. 2.5 Humidity test
Perform according to the provisions of Group 1 of GB6587.3-86 Visibility test for electronic measuring instruments. 2.6 Vibration test
Perform according to the provisions of GB6587.4-86 Electronic measuring instrument vibration test "Group I". 2.7 Impact test
Perform according to the provisions of GB6587.5-86 Electronic measuring instrument impact test "Group I". 2.8 Transportation test
Perform according to the second level circulation conditions of GB6587.6-86% Electronic measuring instrument transportation test". 2.9 Power supply frequency and voltage test
Perform according to the provisions of GB6587.8-86 Electronic measuring instrument power supply frequency and voltage test. 2.10 Reliability test
Perform according to SJ1889-81 "Reliability test plan for electrical measuring instruments". 3 Inspection rules
Perform according to the provisions of GB6593-86% Electronic measuring instrument quality inspection rules. The working characteristics given in this standard are all main performance characteristics. In GB6598-86, the tests for which method standards have not been formulated (see Table 1 of the standard) can be temporarily suspended. 4 Marking, packaging, transportation, storage
4.1 Marking
4.1.1 The instrument should have the following markings: the name and model of the instrument, the factory number, the name and trademark of the manufacturer. 4.1.2 The packaging box of the instrument should indicate: the name, model and quantity of the instrument, the name and trademark of the manufacturer, the storage and transportation operation mark (such as "upward", "avoid mixing", "handle with care" and "no rolling", etc. The marking graphics should comply with the provisions of GB191-85 "Packaging Storage and Transportation Pictorial Marking"), the year and month of packing, etc.
4.1.3 The nameplate or certificate of conformity, instruction manual and packaging of each product should use the "Manufacturing Instrument License" mark. 4.2 Packaging
The packaging box of the instrument should be appropriately packaged according to the specified storage and transportation conditions to ensure that the instrument is not damaged during storage and transportation.
4.3 Transportation
After the instrument is packed for transportation, it can be transported by common means of transportation, but rain, snow and mechanical collision should be avoided. The transportation environment conditions should meet the standards GB 1798.2-84
9039—88
4.4.1 The instrument should not be stored close to the ground, walls and roof in the warehouse. The warehouse should be kept dry, ventilated and free of corrosive gases such as acid and alkali. Strong vibration and impact and strong electromagnetic field should be avoided. 4.4.2 The storage period in the packaging box shall not exceed six months. A1 General
GB 9039—88
Appendix A
10 kHz~18.6 MHz level oscillator test method A1.1 The test conditions and requirements of the test methods specified in this standard shall comply with the relevant provisions of the product standards or product technical conditions. A1.2 The test instrument must be measured and accompanied by correction data. A1.3 The instrument and the oscillator to be tested shall be preheated as specified in the technical conditions and powered by a regulated voltage, and the voltage stability accuracy shall be less than 1%.
A1.4 The impedance between the test instrument and the oscillator to be tested shall be matched. A2 Test method
A2.1 Zero level accuracy
The test block diagram is shown in Figure A1.
Tested level detector
Corrected level meter
The tested level oscillator outputs a 100 kHz, 0 dB signal and is tested with a calibrated level meter. The actual measured value is the zero level accuracyA2-20dB frequency response
The test block diagram is shown in Figure 42.
Tested level detector
Corrected level meter
The 100kHz, 0dB signal output by the tested level oscillator is sent to the calibrated level meter. Adjust the fine adjustment knob of the measured level oscillator to make the level meter after correction indicate zero, and then send the test frequency (selectable from 10kHz to 18.6MHz), which should include the lowest working frequency 10kHz and the highest working frequency 18.6MHz. Measure the difference between the level value of each corresponding frequency and the 100kHz0dB point, which is the 0dB rated response of the level oscillator.
A2.3 Output attenuator error
Test block diagram is shown in Figure A3.
Measured level oscillator
After correction
Selected level meter
Extension paper
GB 9039-88
. The level oscillator outputs 100kHz, 0dB signal, and the attenuator is set to 70dB after correction. At this time, the level expander has an indication, and the expander reading is adjusted to zero. Then the level oscillator outputs -10dB, -20dB, -30dB, -40dB, -50dB, -6UdB, -70dB in sequence, and the value of the attenuator after correction is changed to 60dB, 50dB, 40dB, 30dB, 20dB, 10dB accordingly. At this time, the value indicated by the expander is the attenuation error.
b. According to the above method, change the frequency to 10kl1z, 18.6MHz and measure again. A2.4 Secondary and third degree distortion attenuation measurement
The test block diagram is shown in Figure A4.
Measured level loss meter
Spectrum only or
Frequency-selective level meter
Select the frequency from 10kHz to 18.6MHz as needed, but it must include 10kHz, 1MHz, 18.6MHz, output 0dB and send it to the spectrum analyzer. Directly read the second and third times. If there is no spectrum analyzer, high-pass filter and selection meter can also be used. If the inherent distortion of the level meter is 20dB higher than the distortion index of the measured level oscillator, high-pass filter can be used for direct testing. A2.5 Reflection attenuation
Test block diagram is shown in Figure A5.
First, balance the reflection bridge according to the use of the reflection bridge, then measure the open-circuit attenuation of the reflection bridge, connect the X end of the reflection bridge to the output end of the measured level oscillator, and subtract the open-circuit attenuation value under the same frequency from the measured attenuation value of 10kHz~18.6MHz to get the reflection attenuation value. During the test, the signal source and the measured level oscillator should be placed at different frequency values. The output of the measured level oscillator is 0dB or less than 0dB. Standard resistance
Signal rating
Reflection correction
Off-level compensation
Change the attenuator switch from -70 to -10dB, and then test with the above method. A2.6 Parasitic attenuation (including carrier leakage)
Test block diagram is shown in Figure A6.
Level meter
GB9039-88
Off-level compensation
Spectrum analyzer or
Selection of topic
The oscillator under test can select a frequency between 10kHz and 18.6MHz as the main wave, and the level is 0dB. Directly look at the spectrum analyzer or use the selection table to test the levels of various parasitic signals on both sides of the main wave. The levels of parasitic signals at ±50Hz and ±100Hz from the main wave must be tested.
Appendix B
10kHz~18.6MHz frequency-selective level attenuation test method B1 General
B1.1 The test conditions and requirements of the test methods specified in this standard shall comply with the relevant provisions of the product standards or product technical conditions. B1.2 The test instrument must be measured and accompanied by image data. B1.3 The test instrument and the tested frequency-selective level meter must be preheated and powered by a regulated voltage, and the level stability accuracy should be better than 1%. B1.4 The test instrument and the tested frequency-selective level meter should be impedance matched. B2 Test method
B2.1 Zero voltage accuracy
See Figure B1 for the test block diagram.
Signal micro after correction
Frequency-selective level meter under test
The tested level meter should first self-calibrate, and then set the corrected signal source to 100kHz. Adjust the output level of the calibrated signal source so that the level meter under test indicates 0dB. At this time, the data indicated by the signal source is the zero level accuracy, but take its negative value. If the measured data is +0.01dB, the actual zero level accuracy is -0.01 dB. B2.2 Frequency response
Test method Figure B2.
Corrected signal
Sensitive frequency measurement level meter
The level meter under test is first self-calibrated, and then the calibrated signal source is increased to 100kHz. Adjust the signal source so that the level meter under test indicates 0dB, and change the signal source frequency to test point by point. The test frequency should include the lowest and highest operating frequencies of the level meter under test. Strict test rate
bSignal source indication value
A-—b response
B2.3 Attenuator accuracy
GB 9039-88
The test block diagram is shown in Figure 133.
The attenuator under test is directly compared with the attenuator after correction. The test method is the same as that of the oscillator attenuator. When the level meter under test indicates 70dB, the attenuator attenuation is actually zero.
B2.4 Selectivity test
The test block diagram is shown in Figure B4.
After correction, attenuator
Signal
Frequency meter
Attenuator
【On the meter】
Sub-selected frequency level meter
Tested selected level meter
Expander
The frequency knob or button of the tested level meter is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, and then adjust the level knob to indicate dB
c, increase and decrease the frequency of the signal source, so that the indication of the tested level meter drops to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested. The sum of the two d
AF is the bandwidth.
Measure the broadband and narrowband once according to the above method. e
f.Measure the attenuation value of J.±2kHz, f.±4kHa. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram is shown in Figure B5.
GB 9039—88
Test center frequency f=√fsmi·saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The reflection attenuation value measured minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. The range from 10 kHz to 18.6 MHz should be tested. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.The reflection attenuation value is the value measured at 6MHz minus the open-circuit attenuation value at the same frequency. During the test, the signal source and the level oscillator to be tested should be placed at different frequencies. The output of the level oscillator to be tested is 0dB or less than 0dB. Standard resistance
Signal rating
Reflection correction
Remote attenuator
Change the attenuator switch from -70 to -10dB, and then test with the above method. A2.6 Parasitic attenuation (including carrier leakage)
Test block diagram is shown in Figure A6.
Level meter
GB9039-88
Reflection correction
Spectrum analyzer or
Selection resistor
The oscillator to be tested can select a frequency between 10kHz and 18.6MHz as the main wave, and the level is 0dB. Directly look at the spectrum analyzer or use the meter to test the levels of various parasitic signals on both sides of the main wave. The levels of parasitic signals at ±50Hz and ±100Hz from the main wave must be tested.
Appendix B
10kHz~18.6MHz frequency-selective level attenuation test method B1 General
B1.1 The test conditions and requirements of the test methods specified in this standard shall comply with the relevant provisions of the product standards or product technical conditions. B1.2 The test instrument must be measured and accompanied by image data. B1.3 The test instrument and the tested frequency-selective level meter must be preheated and powered by a regulated voltage, and the level stability accuracy should be better than 1%. B1.4 The test instrument and the tested frequency-selective level meter should be impedance matched. B2 Test method
B2.1 Zero voltage accuracy
See Figure B1 for the test block diagram.
Signal after correction
Frequency-selective level meter under test
The level meter under test is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the output level of the calibrated signal source so that the level meter under test indicates 0dB. At this time, the data indicated by the signal source is the zero-level accuracy, but its negative value is taken. If the measured data is +0.01dB, the actual zero-level accuracy is -0.01 dB. B2.2 Frequency response
Test method Figure B2.
Signal after correction
Frequency-selective level meter under test
The level meter under test is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the signal source so that the level meter under test indicates 0dB, and change the signal source frequency to test point by point. The test frequency should include the lowest and highest operating frequencies of the level meter under test. Strict test rate
bSignal source indication value
A-—b response
B2.3 Attenuator accuracy
GB 9039-88
The test block diagram is shown in Figure 133.
The attenuator under test is directly compared with the attenuator after correction. The test method is the same as that of the oscillator attenuator. When the level meter under test indicates 70dB, the attenuator attenuation is actually zero.
B2.4 Selectivity test
The test block diagram is shown in Figure B4.
After correction, attenuator
Signal
Frequency meter
Attenuator
【On the meter】
Sub-selected frequency level meter
Tested selected level meter
Expander
The frequency knob or button of the tested level meter is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, and then adjust the level knob to indicate dB
c, increase and decrease the frequency of the signal source, so that the indication of the tested level meter drops to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested. The sum of the two d
AF is the bandwidth.
Measure the broadband and narrowband once according to the above method. e
f.Measure the attenuation value of J.±2kHz, f.±4kHa. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram is shown in Figure B5.
GB 9039—88
Test center frequency f=√fsmi·saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The reflection attenuation value measured minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. The range from 10 kHz to 18.6 MHz should be tested. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.The reflection attenuation value is the value measured at 6MHz minus the open-circuit attenuation value at the same frequency. During the test, the signal source and the level oscillator to be tested should be placed at different frequencies. The output of the level oscillator to be tested is 0dB or less than 0dB. Standard resistance
Signal rating
Reflection correction
Remote attenuator
Change the attenuator switch from -70 to -10dB, and then test with the above method. A2.6 Parasitic attenuation (including carrier leakage)
Test block diagram is shown in Figure A6.
Level meter
GB9039-88
Reflection correction
Spectrum analyzer or
Selection resistor
The oscillator to be tested can select a frequency between 10kHz and 18.6MHz as the main wave, and the level is 0dB. Directly look at the spectrum analyzer or use the meter to test the levels of various parasitic signals on both sides of the main wave. The levels of parasitic signals at ±50Hz and ±100Hz from the main wave must be tested.
Appendix B
10kHz~18.6MHz frequency-selective level attenuation test method B1 General
B1.1 The test conditions and requirements of the test methods specified in this standard shall comply with the relevant provisions of the product standards or product technical conditions. B1.2 The test instrument must be measured and accompanied by image data. B1.3 The test instrument and the tested frequency-selective level meter must be preheated and powered by a regulated voltage, and the level stability accuracy should be better than 1%. B1.4 The test instrument and the tested frequency-selective level meter should be impedance matched. B2 Test method
B2.1 Zero voltage accuracy
See Figure B1 for the test block diagram.
Signal after correction
Frequency-selective level meter under test
The level meter under test is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the output level of the calibrated signal source so that the level meter under test indicates 0dB. At this time, the data indicated by the signal source is the zero-level accuracy, but its negative value is taken. If the measured data is +0.01dB, the actual zero-level accuracy is -0.01 dB. B2.2 Frequency response
Test method Figure B2.
Signal after correction
Frequency-selective level meter under test
The level meter under test is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the signal source so that the level meter under test indicates 0dB, and change the signal source frequency to test point by point. The test frequency should include the lowest and highest operating frequencies of the level meter under test. Strict test rate
bSignal source indication value
A-—b response
B2.3 Attenuator accuracy
GB 9039-88
The test block diagram is shown in Figure 133.
The attenuator under test is directly compared with the attenuator after correction. The test method is the same as that of the oscillator attenuator. When the level meter under test indicates 70dB, the attenuator attenuation is actually zero.
B2.4 Selectivity test
The test block diagram is shown in Figure B4.
After correction, attenuator
Signal
Frequency meter
Attenuator
【On the meter】
Sub-selected frequency level meter
Tested selected level meter
Expander
The frequency knob or button of the tested level meter is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, and then adjust the level knob to indicate dB
c, increase and decrease the frequency of the signal source, so that the indication of the tested level meter drops to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested. The sum of the two d
AF is the bandwidth.
Measure the broadband and narrowband once according to the above method. e
f.Measure the attenuation value of J.±2kHz, f.±4kHa. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram is shown in Figure B5.
GB 9039—88
Test center frequency f=√fsmi·saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The reflection attenuation value measured minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. The range from 10 kHz to 18.6 MHz should be tested. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.6MHz frequency-selective level attenuation test method B1 General
B1.1 The test conditions and requirements of the test method specified in this standard shall comply with the relevant provisions of the product standard or product technical conditions. B1.2 The test instrument must be measured and accompanied by image data. B1.3 The test instrument and the tested frequency-selective level meter must be preheated and powered by a regulated voltage, and the level stability accuracy should be better than 1%. B1.4 The test instrument and the tested frequency-selective level meter should be impedance matched. B2 Test method
B2.1 Zero level accuracy
The test block diagram is shown in Figure B1.
Corrected signal micro
Tested frequency-selective level meter
The tested level meter is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the output level of the calibrated signal source so that the indication of the tested level meter is 0dB. At this time, the data indicated by the signal source is the zero level accuracy, but its negative value is taken. If the measured data is +0.01dB, the actual zero level accuracy is -0.01 dB. B2.2 Frequency response
Test method Figure B2.
Corrected signal
Sensitive test frequency level meter
The level meter to be tested is first self-calibrated, and then the calibrated signal source is increased to 100kHz. Adjust the signal source so that the level meter to be tested indicates 0dB, and change the signal source frequency to test point by point. The test frequency should include the lowest and highest operating frequencies of the level meter to be tested. Strict test frequency
bSignal source indicates value
A--b response
B2.3 Attenuator accuracy
GB 9039-88
Test block diagram See Figure 133.
The attenuator under test is directly compared with the corrected attenuator. The test method is the same as that of the oscillator attenuator. When the scale of the level meter under test indicates 70dB, the attenuator is actually attenuated to zero.
B2.4 Selectivity Test
The test block diagram is shown in Figure B4.
Corrected Attenuator
Signal Alcohol
Frequency Meter
Attenuator
[On the meter]
Sub-selective Level Meter
Selected Level Meter under Test
Expander
The frequency knob or button of the level meter under test is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, then adjust the level knob to make it indicate dB, increase and decrease the signal source frequency, and make the level meter indication drop to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested, and the sum of the two d
AF is the bandwidth.
Wideband and narrowband are measured once according to the above method. e
f. Measure the attenuation value of J. ±2kHz, f. ±4kHz. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram See Figure B5.
GB 9039—88
Test center epilepsy frequency f=√fsmi· saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open-circuited. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The measured reflection attenuation value minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. Test from 10 kHz to 18.6 MHz. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.6MHz frequency-selective level attenuation test method B1 General
B1.1 The test conditions and requirements of the test method specified in this standard shall comply with the relevant provisions of the product standard or product technical conditions. B1.2 The test instrument must be measured and accompanied by image data. B1.3 The test instrument and the tested frequency-selective level meter must be preheated and powered by a regulated voltage, and the level stability accuracy should be better than 1%. B1.4 The test instrument and the tested frequency-selective level meter should be impedance matched. B2 Test method
B2.1 Zero level accuracy
The test block diagram is shown in Figure B1.
Corrected signal micro
Tested frequency-selective level meter
The tested level meter is first self-calibrated, and then the calibrated signal source is set to 100kHz. Adjust the output level of the calibrated signal source so that the indication of the tested level meter is 0dB. At this time, the data indicated by the signal source is the zero level accuracy, but its negative value is taken. If the measured data is +0.01dB, the actual zero level accuracy is -0.01 dB. B2.2 Frequency response
Test method Figure B2.
Corrected signal
Sensitive test frequency level meter
The level meter to be tested is first self-calibrated, and then the calibrated signal source is increased to 100kHz. Adjust the signal source so that the level meter to be tested indicates 0dB, and change the signal source frequency to test point by point. The test frequency should include the lowest and highest operating frequencies of the level meter to be tested. Strict test frequency
bSignal source indicates value
A--b response
B2.3 Attenuator accuracy
GB 9039-88
Test block diagram See Figure 133.
The attenuator under test is directly compared with the corrected attenuator. The test method is the same as that of the oscillator attenuator. When the scale of the level meter under test indicates 70dB, the attenuator is actually attenuated to zero.
B2.4 Selectivity Test
The test block diagram is shown in Figure B4.
Corrected Attenuator
Signal Alcohol
Frequency Meter
Attenuator
[On the meter]
Sub-selective Level Meter
Selected Level Meter under Test
Expander
The frequency knob or button of the level meter under test is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, then adjust the level knob to make it indicate dB, increase and decrease the signal source frequency, and make the level meter indication drop to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested, and the sum of the two d
AF is the bandwidth.
Wideband and narrowband are measured once according to the above method. e
f. Measure the attenuation value of J. ±2kHz, f. ±4kHz. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram See Figure B5.
GB 9039—88
Test center epilepsy frequency f=√fsmi· saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open-circuited. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The measured reflection attenuation value minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. Test from 10 kHz to 18.6 MHz. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.4 Selectivity Test
Test block diagram is shown in Figure B4.
Corrected attenuator
Signal source
Frequency meter
Attenuator
【On the meter】
Sub-selected frequency level meter
Tested selected level meter
Expander
The frequency knob or button of the tested level meter is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, and then adjust the level knob to make it indicate dB
c, increase and decrease the frequency of the signal source, so that the indication of the tested level meter drops to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested. The sum of the two d
AF is the bandwidth.
Measure the broadband and narrowband once according to the above method. e
f.Measure the attenuation value of J.±2kHz, f.±4kHa. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram is shown in Figure B5.
GB 9039—88
Test center frequency f=√fsmi·saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The reflection attenuation value measured minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. The range from 10 kHz to 18.6 MHz should be tested. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88
Sensitive measurement of the frequency selection level in
After the measured level meter is calibrated, it is connected to the test system. The signal source outputs the intermediate frequency of the measured level meter respectively, and the level is αdB. b,
Increase the sensitivity of the measured level meter, so that the meter head has a certain indication and fine-tune the signal source frequency to make the level meter indicate the maximum. c.
The frequency indicated by the measured level meter should avoid the intermediate frequency input by the signal source to the measured level meter. d.
B2.8 Image frequency
The test block diagram is shown in Figure B8.
The measured level meter is connected to the test system after self-calibration, Figure B8
Sensitive frequency measurement meter
The signal source sends the frequency f, 0dB, the measured level meter receives the signal and fine-tunes the measured level meter frequency to make the meter head indicate the maximum. The signal source outputs f.+2f1f+2fzf.+2f, 0dB, which improves the sensitivity of the measured level meter, so that the meter head has an indication, and fine-tunes the level meter frequency to make the meter head indicate the maximum. The level value measured by the measured level meter is the image attenuation value (take the absolute value). Test frequency
Mirror attenuation b
B2.9 Local noise and combined interference
fai2fo
fa1 2f
Tm+2fm
After the level meter under test is self-calibrated, put the attenuator in the highest sensitivity position and fine-tune the frequency in the entire frequency band. The white starting point is the combination a
interference, and the self-starting level should be less than ~120dB. b. After the level meter under test is self-calibrated, connect a characteristic impedance to the input terminal, and then put the attenuator of the level meter under test in the highest sensitivity position. At this time, the value shown on the level meter under test is the local noise value, which should be less than -120 dB in the entire frequency band. Additional remarks:
This standard is issued by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. This standard was drafted by the Beijing Instrument Research Institute of the Ministry of Posts and Telecommunications. The main drafter of this standard is Gu Pengxu.4 Selectivity Test
Test block diagram is shown in Figure B4.
Corrected attenuator
Signal source
Frequency meter
Attenuator
【On the meter】
Sub-selected frequency level meter
Tested selected level meter
Expander
The frequency knob or button of the tested level meter is placed at 100kHz. a.
The output frequency of the signal source is also 100kHz. Fine-tune the signal source frequency to make the level meter indicate the maximum, and then adjust the level knob to make it indicate dB
c, increase and decrease the frequency of the signal source, so that the indication of the tested level meter drops to 3dB. At this time, the geometric average of the two frequencies (Fa, Fa) is determined as the test center frequency. . Based on f, increase and decrease the frequency of the signal source. When the level drops by 0.5dB and 3dB, the change frequency Af is tested. The sum of the two d
AF is the bandwidth. wwW.bzxz.Net
Measure the broadband and narrowband once according to the above method. e
f.Measure the attenuation value of J.±2kHz, f.±4kHa. Attenuation value
Frequency meter indication
Passband
Affm-fi
B2.5 Reflection attenuation
Test block diagram is shown in Figure B5.
GB 9039—88
Test center frequency f=√fsmi·saz
First, balance and calibrate the reflection bridge, and then test. Measure the reflection attenuation when the reflection bridge is open. h.
c. Connect the frequency-selective level meter to be tested (the test lead should be very short, and it is best to connect the reflection bridge directly to the level meter to be tested I.), and test the reflection attenuation value. The reflection attenuation value measured minus the reflection attenuation when the circuit is open is the reflection attenuation of the level meter to be tested. The range from 10 kHz to 18.6 MHz should be tested. d.
Change the attenuation position and retest the liquid resistance according to steps (3) and (4).
Signal source
B2.6 Intrinsic distortion
Test block diagram is shown in Figure B6
Signal source
Reflection bridge
Sub-selected level meter
Low-pass filter
The measured level meter is connected to the test system after self-calibration. The signal source is set to F and 0dB. The signal passes through the low-pass filter (the cut-off frequency is higher than f) and is sent to the measured level meter. At this time, the measured level meter is also adjusted to the frequency. First adjust the signal source frequency so that the measured level meter indicates the maximum, and then adjust the signal source output so that the measured level meter indicates 0 dB.
The knob or button of the level meter is placed at 2 or 3f. At this time, the sensitivity of the measured level meter is increased to 51dB. The measured data is the inherent distortion (take the absolute value).
The attenuation of the second and third harmonics of the signal input to the measured level meter after the low-pass filter should be at least 20 dB greater than the inherent distortion specified by the measured level meter.
B2. The test block diagram of the output frequency attenuation is shown in Figure B7.
Signal source
GB 9039-88||tt|
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