This standard specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage of heterodyne channel processors in cable distribution systems for 5MHz~1750MHz television and sound signals. This standard applies to channel processors in cable distribution adjacent frequency systems for 5MHz~1750MHz television and sound signals GB/T 11318.4-1996 Cable distribution system equipment and components for television and sound signals Part 4: General specification for channel processors GB/T11318.4-1996 Standard download decompression password: www.bzxz.net

1 Scope
National Standard of the People's Republic of China
Equipment and components used in cabled distribution systems primarily intended for television and sound signals
Part 4: Generic specifications for channel processors
Equipments and components used in cabled distribution systems primarily intended for television and sound signalsPart 4:Generic specifications for channel processorGB/T11318.4—1996
Replaces GB/T14948.5-·1994
This standard specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage of heterodyne channel processors in cabled distribution systems for television and sound signals of 5MHz~1750MHz. This standard applies to channel processors in cabled distribution adjacent frequency systems for television and sound signals of 5MHz~～1750MHz. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were all valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T6510—1996 Cable distribution systems for television and sound signals GB/T11318.1-1996 Cable distribution systems for television and sound signals Equipment and components Part 1: General specifications GB/T11318.13-1996 Cable distribution systems for television and sound signals Equipment and components Part 13: General specifications for receiver converters
3 Definitions
This standard adopts the following definitions. Other definitions comply with the relevant provisions in GB/T6510 and GB/T11318.1. 3.1 Adjacent channel rejection The ability of a channel processor to suppress interference from the upper and lower adjacent channel television signals of its input television channel. 3.2 Frequency conversion accuracy The deviation between the output image carrier frequency of the channel processor and the nominal output image carrier frequency at the specified working ambient temperature. 3.3 Sound carrier control characteristics sound carrier control The ability of the channel processor to control the output sound carrier level when the input sound carrier level changes. 3.4 Band edge rejection Band edge rejection The ability of the channel processor to attenuate the signal level at the output image carrier frequency f2MHz under specified working conditions. 4 Requirements
4.1 General requirements
Approved by the State Administration of Technical Supervision on September 9, 1996 and implemented on May 1, 1997
GB/T 11318.4—1996
The general requirements for channel processors shall comply with the provisions of 4.1.1 of GB/T11318.1-1996. 4.2 Performance parameters
The performance parameter requirements of the channel processor are shown in Table 1. Table 1
Input channel
Output channel
Reflection loss
Input level range
Maximum output level
Working output level
Output level continuously adjustable range
Spurious output suppression
AGC characteristics
Frequency conversion accuracy
Noise figure
Carrier-to-noise ratio
Sound carrier control characteristics
Sound carrier level adjustable range||t t||Intermediate frequency image carrier frequency
Intermediate frequency sound carrier frequency
Intermediate frequency output level
Performance parameters
Any specified channel in A, I, B, N, V ​​bands
1.Any specified channel in A, I, B, N, V ​​bands≥12
50~90 or,55～85
≥125, ≥120, ≥115.≥110
≥120.≥115, ≥110,≥105
0～ -15
Output level changes by 1dB
VHF: ≤8, UHF10
VHF:≥57;UHF≥54
Audio output level changes by 1dB
?5～25
Measurement method
GB/T 11318.1 1996
4.2.2.2.5
GB/T11318.11996
4.2.2.2.2
Input level is the range specified in item 4 of this table
GB/T 11318.1 1996
4.2.2.2.4
65101996
3.47 Input 70 dBμV
Audio input level change ±10
Relative to the output image carrier frequency
RF input level is within the range specified in item 4 of Table 1, only the processing with intermediate frequency output interface is tested
Intermediate frequency input level range
Adjacent channel suppression
False image suppression
Band edge suppression
Intra-band fluctuation
Chroma/luminance delay difference
4.3 Environmental adaptability
GB/T 11318.4—1996
Table 1 (end)
Performance parameters
VHF: ≥60;UHF≥40
2 (frequency range f.+3.58MHz)
Measurement method
RF output level change
±1dB3, only the processor with intermediate frequency
input interface is tested
GB/T 11318.1--1996
4. 2. 2. 2. 1. 3. 3
IGB/T6510-1996
The environmental adaptability requirements of the processor of the channel shall comply with the provisions of 4.3 of GB/T11318.1--1996. The intermediate test item is AGC characteristics, and the qualified criterion is: when the input level change range is the range specified in item 4 of Table 1, the output level change is within ±3dB. The test items after high temperature, constant humidity, sweep frequency vibration and collision test are AGC characteristics. After low temperature test and free fall test, the performance test is carried out according to the items specified in Table 1. The test results should meet the relevant provisions of Table 1. 4.4 Reliability
The lower limit value 6 of the reliability index of the channel processor, the mean time between failures (MTBF), should not be less than 5000h. The failure criterion is the AGC characteristic. When the input level change range is within the range specified in item 4 of Table 1, the output level change exceeds ±3dB or the accompanying sound is abnormal. 4.5 Safety
The safety requirements of the channel processor shall meet the relevant provisions of 4.5 in GB/T11318.1--1996. 4.6 Electromagnetic Compatibility
The electromagnetic compatibility requirements of the channel processor shall meet the relevant provisions of 4.6 in GB/T11318.1-1996. 5 Test methods
--General requirements
The test methods for general requirements of channel processors shall be carried out in accordance with the provisions of 4.1.2 of GB/T11318.1-1996. 5.2 Performance parameters
5.2.1 Continuously adjustable range of output level
5.2.1.1 The measurement block diagram
is shown in Figure 1.
RF signal generator
Tested channel processor
Frequency-selective voltmeter
Figure 1 Equipment connection for measuring the continuously adjustable range of output level 5.2.1.2 Measurement
5.2.1.2.1 Adjust the output frequency of the RF signal generator to the nominal value of the input image frequency of the tested channel processor, and the input level of the tested channel processor to 70±2dBμV. GB/T 11318.4—1996
5.2.1.2.2 Adjust the output level of the tested channel processor when its output attenuation is the minimum, then gradually increase the attenuation, and the output level decreases continuously. When the output attenuation of the tested channel processor is the maximum, measure its output level again. The difference between the two output levels is the continuously adjustable range of the output level.
5.2.2 Parasitic output suppression
5.2.2.1 The measurement block diagram
is shown in Figure 2.
RF signal generator
5.2.2.2 Measurement
Mixer
Channel processor under test
Figure 2 Equipment connection for parasitic output suppression measurement Spectrum analyzer
5.2.2.2.1 Adjust the RF signal generators G1, G2 and G3 so that the frequency and level of the input of the channel processor under test are as follows: fi is the image carrier frequency of the input channel under test, and the level is 70dBμuV. f. is the sound carrier frequency of the input channel under test, and its level is 10dB lower than the image carrier level. f. is the color subcarrier frequency of the input channel under test, and its level is 17dB lower than the image carrier level. 5.2.2.2.2 Adjust the channel processor under test so that its image carrier output level reaches the specified working output level value, and the sound carrier output level is 15dB lower than the working output level.
5.2.2.2.3 Use a variable attenuator and spectrum analyzer to measure the parasitic output. Measure the difference between the image carrier output level and the maximum parasitic output level of the channel processor under test. The difference is expressed in decibels, which is the parasitic output suppression. The measurement is carried out within the specified frequency range. 5.2.3 AGC characteristics
5.2.3.1 The measurement block diagram
is shown in Figure 3.
Channel processor under test
RF signal generatorWww.bzxZ.net
5.2.3.2 Measurement
Figure 3 Equipment connection for AGC characteristics measurement
Frequency-selective voltmeter
5.2.3.2.1 Adjust the output frequency of the RF signal generator to the nominal value of the input image carrier frequency of the channel processor under test. The input level of the channel processor under test is 70 dBμV. 5.2.3.2.2 Adjust the channel processor under test so that its image output level reaches the specified working output level value. 5.2.3.2.3 Adjust the attenuator so that the input level of the channel processor under test is within the range specified in item 4 of Table 1. Use a frequency-selective voltmeter to measure the change in the output level of the image carrier, which is the AGC characteristic. Note: When the channel processor adopts the keying AGC mode of TV signal synchronous pulse action, the signal source should be a TV signal source. 5.2.4 Frequency conversion accuracy
5.2.4.1 Measurement block diagram
As shown in Figure 4.
5.2.4.2 Measurement
RF signal generator
GB/T11318.4—1996
Measured channel processor
Frequency counter
Constant temperature box
Figure 4 Equipment for measuring frequency conversion accuracy Connection frequency counter
5.2.4.2.1 The measured channel processor should be preheated for at least 0.5h in the indoor ambient temperature of 15℃～30℃. 5.2.4.2.2 Adjust the output frequency of the RF signal generator to the nominal value of the input image carrier frequency of the measured channel processor, and the input level of the measured channel processor is 70dBμV±2dBμV. 5.2.4.2.3 After being kept constant at the upper and lower limits of the specified working ambient temperature for 2h, measure the output image carrier frequency of the measured channel processor respectively, and take the maximum deviation between it and the nominal image carrier frequency as the frequency conversion accuracy. 5.2.5 Sound carrier control characteristics
5.2.5.1 Measurement block diagram
As shown in Figure 5.
Measured channel processor
Selector voltmeter
Mixer
Radio signal generator
Figure 5 Equipment connection for measuring sound carrier control characteristics 5.2.5.2 Measurement
5.2.5.2.1 Adjust the RF signal generators G1 and Gz so that the frequency and level of the measured channel processor input are as follows: fi is the measured input channel image carrier frequency, and the level is 70dBuV. f2 is the measured input channel sound carrier frequency, and its level is 10dB lower than the image carrier level. 5.2.5.2.2 Adjust the processor of the channel under test so that its image carrier output level reaches the specified working output level value, and the sound carrier output level is 15dB lower than the working output level, and its value is A1. 5.2.5.2.3 Adjust the variable attenuator so that its attenuation increases or decreases by 10dB, and the image and sound carrier output level A2 of the processor of the channel under test is measured. The sound carrier control characteristic is |A-Az1. 5.2.6 Adjustable range of sound carrier level
5.2.6.1 The measurement block diagram
is shown in Figure 6.
5.2.6.2 Measurement
RF signal generator
GB/T11318.4—1996
Tested channel processor
Mixer
Frequency-selective voltmeter
Figure 6 Connection of equipment for measuring adjustable range of sound carrier level 5.2.6.2.1 Adjust RF signal generators G1 and G2 so that the input frequency and level of the tested channel processor are as follows: f1 is the image carrier frequency of the tested input channel, and the level is 70dBuV. f2 is the sound carrier frequency of the tested input channel, and its level is 10 dB lower than the image carrier level. 5.2.6.2.2 Adjust the tested channel processor so that its image carrier output level reaches the specified working output level value. 5.2.6.2.3 Adjust the tested channel processor and measure its sound carrier output level when its sound carrier output attenuation is minimum and maximum respectively. The difference between the two sound carrier output levels and the image carrier working level, expressed in decibels, is the adjustable range of the sound carrier level. 5.2.7 Intermediate frequency output level
5.2.7.1 The measurement block diagram
is shown in Figure 7.
Tested channel processor
Radio signal generator
5.2.7.2 Measurement
Intermediate frequency output
Figure 7 Equipment for measuring intermediate frequency output level Connection frequency-selective voltmeter
5.2.7.2.1 Adjust the output frequency of the RF signal generator to the nominal value of the input image carrier frequency of the tested channel processor, and adjust the variable attenuator so that the input level of the tested channel processor is within the specified range of item 4 in Table 1. 5.2.7.2.2 Use the frequency-selective voltmeter to measure the intermediate frequency image carrier output level. 5.2.8 Intermediate frequency input level range
5.2.8.1 Measurement block diagram
As shown in Figure 8.
Intermediate frequency input
RF signal generator
5.2.8.2 Measurement
Tested channel processor
Frequency-selective voltmeter
Equipment connection for intermediate frequency input level range measurement5.2.8.2.1 Adjust the output frequency of the RF signal generator to 38MHz, adjust the variable attenuator to make the input level of the tested channel processor 90dBμV, and use the frequency-selective voltmeter to measure the image carrier output level value. 5.2.8.2.2 Adjust the variable attenuator to change the input level of the tested channel processor, and measure the input level range when its image carrier output level changes by ±1dB.
5.2.9 Adjacent channel suppression
5.2.9.1 Measurement block diagram
As shown in Figure 9.
5.2.9.2 Measurement
Radio signal generator
GB/T 11318.4-1996
Tested channel processor
"Mixer
Equipment connection for adjacent channel suppression measurement
Spectrum analyzer
5.2.9.2.1 Adjust the RF signal generators G1G2, G: and G4 so that the input frequency and level of the tested channel processor are as follows: f, is the image carrier frequency of the tested input channel, and the level is 70dBμV. f. is the sound carrier frequency of the tested input channel, and its level is 10dB lower than the image carrier level. f: is the carrier frequency of the tested input channel image carrier frequency fi-1.5MHz, and its level is not less than 6dB relative to the image carrier level of the tested channel.
f. is the carrier frequency of the tested input channel image carrier frequency fi+8MHz, and the level is 70dBuV. 5.2.9.2.2 Adjust the tested channel processor so that its image carrier output level reaches the specified working output Output level value, the sound carrier output level is 15dB lower than the working output level.
5.2.9.2.3 Measure the decibel difference between the image carrier output amplitude and the amplitude of the parasitic product caused by the adjacent channel signal in the measured channel, and take the worst value.
5.2.10 False image suppression
5.2.10.1 Measurement block diagram
As shown in Figure 10.
Measured channel processor
Mixer| |tt||RF signal generator
5.2.10.2 Measurement
Figure 10 Equipment connection for pseudo-image measurement
Spectrometer
5.2.10.2.1 Adjust the frequency of the RF signal generator G. to the image carrier frequency f of the input channel of the measured channel processor. The input level value of the measured channel processor is 70dBμV, recorded as A. And the output level value is recorded as B. 5.2.10.2.2 In [(f,+38) + (33 ~ 38)】MHz pseudo image frequency range, at this time the interference signal level value D at the input end of the measured channel processor.
5.2.10.2.3 Pseudo image suppression is [-A) + (BC) IdB. 5.2.11 Band edge suppression
5.2.11.1 Measurement block diagram
As shown in Figure 11.
5.2.11.2 Measurement
. Sweeper
GB/T11318.4—1996
Measured channel processor
Figure 11 Equipment connection for band edge suppression measurement
Detector
5.2.11.2.1 Do not connect the measured channel processor first, directly connect to the measurement system, preset the variable attenuator A, and A2-to a suitable value. Adjust the frequency sweeper so that the output level of A, reaches the working output level of the tested channel processor and displays a clear curve with a certain amplitude. This curve is the reference curve.
5.2.11.2.2 Connect the tested channel processor and increase the attenuation of A, so that the reference frequency in the frequency response curve coincides with the reference curve. 5.2.11.2.3 Adjust the tested channel processor so that the output level of the sound carrier is 15dB lower than the output level of the image carrier. 5.2.11.2.4 Reduce the attenuation of A2 so that the output image carrier frequency f!:5MHz in the frequency response curve coincides with the reference curve. The change in the reading of A2 is the band edge suppression value, and the minimum value is taken. 5.3 Environmental adaptability
The environmental adaptability test method of the channel processor shall be carried out in accordance with the relevant provisions of 4.3 of GB/T11318.1-1996. The test temperature group is group 1.
5.4 Reliability
The reliability test method of the channel processor shall be carried out in accordance with the relevant provisions of 4.4 of GB/T11318.1-1996. The test plan is Plan I.
5.5 Safety
The safety test method of the channel processor shall be carried out in accordance with the relevant provisions of 4.5 of GB/T11318.1-1996. 5.6 Electromagnetic compatibility
The electromagnetic compatibility test method of the channel processor shall be carried out in accordance with the relevant provisions of 4.6 of GB/T11318.1-1996. 6 Inspection rules
The inspection rules of the channel processor shall comply with the relevant provisions of Chapter 5 of GB/T11318.1-1996. The main electrical performance parameter detection items during the acceptance inspection are in-band flatness, AGC characteristics, adjacent channel suppression, parasitic output, maximum output level and adjustable range of the accompanying sound carrier. 7 Marking, packaging, transportation and storage
The marking, packaging, transportation and storage of channel processors shall comply with the relevant provisions of Chapter 6 of GB/T11318.1-1996. 356
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