GB/T 11318.1-1996 Cable distribution system equipment and components for television and sound signals Part 1: General specifications

This standard specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage of cable distribution system equipment and components for television and sound signals. This standard applies to cable distribution system equipment and components for television and sound signals (hereinafter referred to as equipment or components). GB/T 11318.1-1996 Cable distribution system equipment and components for television and sound signals Part 1: General specifications GB/T11318.1-1996 Standard download decompression password: www.bzxz.net

GB/T 11318.1~~11318.14—1996 Foreword
This series of standards is a revised version of GB11318.1~11318.6-89 (Part 1: General technical conditions; Part 2: Performance parameter requirements; Part 3: Measurement methods; Part 4: Environmental requirements and test methods; Part 5: Reliability requirements and test methods; Part 6: Inspection rules), GB/T14948.1~14948.6--94 (Part 1: Technical conditions for power supply equipment; Part 2: Technical conditions for system output ports; Part 3: Technical conditions for pilot signal generators; Part 4: Technical conditions for trunk amplifiers; Part 5: Technical conditions for channel processors; Part 6: Technical conditions for attenuators, equalizers, filters and notch filters) and SJ/T10471--94 "Technical conditions for receiver converters in cable distribution systems".
This series of standards has slight changes from the original standards in the following aspects: the frequency range is changed from 30MHz to 1GHz to 5MHz to 1750MHz; - the original GB11318 series standards are merged into the current GB/T11318.1 "General Specifications", and the new series standards GB/T11318.2~11318.14 are supplemented. GB/T 11318.1--1996 will replace GB 11318.1~11318.6--89 from the date of entry into force; GB/T 11318.2-1996 shall replace GB/T14948.3-94 from the date of its effectiveness: GB/T11318.4-1996 shall replace GB/T14948.5-94 from the date of its effectiveness; GB/T11318.8--1996 shall replace GB/T14948.4-94 from the date of its effectiveness: GB/T11318.9-1996 shall replace GB/T14948.1-94 from the date of its effectiveness; GB/T11318.11-1996 shall replace GB/T14948.6--94 from the date of its effectiveness; GB/T11318.12--1996 shall replace GB/T14948.2--94 from the date of its effectiveness; GB/T11318.13 shall be invalidated as of its effectiveness, and SJ/T10471-94 shall be invalidated. This series of standards is proposed by the Ministry of Electronics Industry of the People's Republic of China. This series of standards is under the jurisdiction of the Standardization Institute of the Ministry of Electronics Industry. Drafting units of this series of standards: Standardization Institute of the Ministry of Electronics Industry, Wuhan Radio Antenna Factory, Shanghai Electronic Instrument Standard Measurement and Testing Branch 1, Beijing Television Equipment Factory, 14th Institute of the First Academy of the Ministry of Aerospace, Sichuan Mianyang Jiang Machinery Factory, CCTV Screen Technology Company, Shanghai Jinling Co., Ltd., Shanghai Image Data Communication Company. The main drafters of this series of standards: Xi Shucun, Qi Shijian, Zhang Fang, Huang Wuming, Lv Junxiang, Gao Zongmin, Wang Bangjun, Dong Shupei, Zhou Xinmin, Chen Zhige, Zhang Wanshu, Guo Wei.
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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 1: General specifications
Equipments and components used in cabled distribution systems primarily intended for television and sound signals Part 1: Generic specifications GB/T11318.1—1996
Replaces GB11318.1~11318.6-89
This standard specifies the requirements, test methods, inspection rules, and marking, packaging, transportation and storage of equipment and components used in cabled distribution systems for television and sound signals.
This standard applies to equipment and components used in cabled distribution systems for television and sound signals (hereinafter referred to as equipment or components). 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB191-90 Packaging, storage and transportation pictorial symbols
GB2421--89 General principles for basic environmental testing procedures for electric and electronic products GB/T2422--1995 Terminology for environmental testing of electric and electronic products GB2423.1--89 Basic environmental testing procedures for electric and electronic products Test A: Low temperature test method GB2423.2-89 Basic environmental testing procedures for electric and electronic products Test B: High temperature test method GB/T2423.3-93 Basic environmental testing procedures for electric and electronic products Test Ca: Steady-state damp heat test method GB/T2423.6-1995 Environmental testing for electronic products in power plants Part 2: Test methods Test Eb and guidelines: Collision GB/T2423.8-1995 Basic environmental testing procedures for electric and electronic products Test Ed: Free fall test method GB/T2423.10-1995 Basic environmental testing procedures for electric and electronic products Test Fc: Vibration (sinusoidal) test method GB2423 .18-85 Basic environmental test procedures for electric and electronic products Test Kb: Alternating salt spray test method (sodium chloride solution) GB/T2423.23-1995 Environmental test for electric and electronic products Test Q: Sealing GB2828-87 Count sampling procedure and sampling table for batch inspection (applicable to inspection of continuous batches) GB2829-87 Count sampling procedure and sampling table for periodic inspection (applicable to inspection of production process stability) GB3187-82 Basic terms and definitions of reliability GB/T3358-93 Statistical terms
GB5465.2-85 Graphic symbols for electrical equipment GB/T6510-1996 Cable distribution systems for television and sound signals GB8898-88 Safety requirements for household and similar general-purpose electronic and related equipment powered by mains power supply Approved by the State Administration of Technical Supervision on September 9, 1996 310
Implementation on May 1, 1997
GB/T 11318.1--1996
GB/T11318.2--1996 Cable distribution system equipment and components for television and sound signals Part 2: General specification for pilot signal generators
GB/T11318.3-1996 Cable distribution system equipment and components for television and sound signals Part 3: General specification for television modulators
GB/T11318.4--1996 Cable distribution system equipment and components for television and sound signals Part 4: General specification for channel processors
Cable distribution system equipment and components for television and sound signals Part 5: General specification for channel changers GB/T 11318.5-—1996
GB/T11318.6—1996 Cable distribution system equipment and components for television and sound signals Part 6: General specification for mixers GB/T11318.7-1996 Cable distribution system equipment and components for television and sound signals Part 7: General specification for amplifiers GB/T11318.8-1996 Cable distribution system equipment and components for television and sound signals Part 8: General specification for trunk amplifiers
Cable distribution system equipment and components for television and sound signals Part 9: General specification for power supply equipment GB/T 11318.9-1996
GB/T11318.10—1996
Cable distribution system equipment and components for television and sound signals Part 10: General specification for distributors and user taps
GB/T 11318.11—1996
Equipment and components of cable distribution systems for television and sound signals Part 11: General specifications for attenuators, equalizers, filters and notches
GB/T 11318.12—1996
Equipment and components of cable distribution systems for television and sound signals Part 12: General specifications for system output ports
GB/T 11318.13—1996
Equipment and components of cable distribution systems for television and sound signals Part 13: General specifications for receiver converters
GB/T11318.14--1996 Cable distribution system equipment and components for television and sound signals Part 14: General specification for lightning arresters
GB 13836-92
Radiated interference characteristics of cable distribution system equipment and components for sound and television signals from 30MHz to 1GHz Allowable values ​​and measurement methods
GB15949-1995 Immunity characteristics of cable distribution system equipment and components for sound and television signals Limits and measurement methods 3 Definitions and symbols
This standard adopts the following definitions and symbols. Other definitions and symbols shall comply with the relevant provisions in GB/T2422, GB2828, GB2829, GB3187, GB3358. GB/T6510 and GB/T11318.2~11318.14. 3.1 Operating frequency band Unless otherwise specified, the general provisions are as follows: TV channel: center frequency f. 4MHz;
FM band: 86.9MHz～~108MHz.
3.2 Reference frequency For channel type components, it refers to the image carrier frequency of the operating channel; for broadband type components, it refers to the upper limit frequency of the operating frequency band; for FM band components, it refers to 97.5MHz.
3.3 Frequency response (in-band flatness, in-band fluctuation and out-of-band attenuation) amplitude frequency response The characteristics of the gain and attenuation of components that change with frequency. 3.3.1 In-band flatness flatness in operating band In the operating frequency band of broadband type components, the positive and negative deviations of the highest amplitude frequency response level and the lowest amplitude frequency response level relative to the average response level of the two are expressed in decibels.
GB/T 11318.1-1996
Note: For components with a certain slope, their slopes should be excluded. 3.3.2 Ripple in operating band The difference between the highest amplitude-frequency response level and the lowest amplitude-frequency response level in the operating channel of a channel-type component, expressed in decibels. 3.3.3 Attenuation out of operating band For VHF channel-type components, it refers to the difference between the level of each frequency point outside the operating channel center frequency F. ±12MHz and the level of the reference frequency point (the level of the reference curve for passive components); For UHF channel-type components, it refers to the difference between the level of each frequency point outside the operating channel center frequency f. ±20MHz and the level of the reference frequency point (the level of the reference curve for passive components); For FM band components, it refers to the difference between the level of each frequency point outside the reference frequency (97.5±30.5)MHz and the level of the reference frequency point (the level of the reference curve for passive components); The out-of-band attenuation value is expressed in positive decibels, taking the minimum value. 3.4 Spurious output rejection The difference between the rated output level of the image carrier frequency and the level of the useless signal within the specified frequency range, expressed in decibels, taking the minimum value. 3.5 Frequency accuracy The difference between the component output signal frequency and the nominal frequency at the reference temperature (20°C). 3.6 Total frequency deviation The difference between the component output signal frequency and the nominal frequency takes the maximum value at the extreme operating temperature. 3.7 Three-tone crossmodulation ratio When three signals are input to the measured component, the output signal frequency and relative level are shown in Figure 1. Due to the nonlinearity of the component, a new frequency (fi + 2MHz) is generated. The difference between its level and the f1 signal level, expressed in positive decibels, is the three-tone crossmodulation ratio.
Intermodulation ratio
fi+2MHz
Figure 1 Three-tone intermodulation ratio
3.8 Carrier to intermodulation ratio within channel frequency
Three signals are input to the channel-type component under test, and the frequency and relative level of the output signal are shown in Figure 2. Due to the nonlinearity of the component, a new frequency (v+2.07MHz) is generated. The difference between its level and the channel output level, expressed in positive decibels, is the carrier to intermodulation ratio within the channel.
GB/T 11318. 1—1996
f+2.07MHz
Note: fv: video carrier frequency; fc: color subcarrier; JA: audio carrier frequency. Figure 2 In-channel carrier intermodulation ratio
3.9 Maximum output level For channel type components, it refers to the channel output level when the carrier intermodulation ratio in the channel is 54dB; 10dB
For broadband type components, it refers to the output level when the three-tone intermodulation ratio between the highest two channels in the working frequency band is 60dB. FM components: to be determined.
3.10 Carrier to second order intermodulation ratio
carrier to second order intermodulation ratio In broadband type components, two signals are input so that their output level is the recommended working level or the nominal maximum output level (suitable for broadband amplifiers), as shown in Figure 3.
Due to the nonlinearity of the component, a new frequency (f1 + f2) is generated. The difference between its level and the maximum output level, expressed in positive decibels, is the carrier second order intermodulation ratio.
Note: is the lowest image carrier frequency, and +2 is the highest channel image carrier frequency.次欢
Figure 3 Carrier to composite second order ratio
3.11 Carrier to composite triple beat ratio (C/CTB) In broadband components, all working channel signals are input, the ratio of the image carrier output level of the channel under test to the sum of the levels of one or several clustered combined triple beat components in the channel, expressed in decibels. 3.12 Carrier to composite second order ratio In broadband components, all working channel signals are input, the ratio of the image carrier output level of the channel under test to the sum of the levels of one or several clustered combined second order components in the channel, expressed in decibels. 3.13 Composite crossmodulation In broadband components, all working channel signals are input, and one working channel is transfer modulated by the modulation components of all other working channels.
3.14 Insertion loss insertionloss
GB/T 11318.1—1996
In the transmission system, the ratio of the power absorbed by the load before a measured component is connected to the power absorbed by the load after connection, expressed in decibels. Table 3.15 Tapping loss tappingloss
The insertion loss between the input end and the branch output end of the tapper, or between the input end of the cascade unit and the system output port. 3.16 Mutual isolation The insertion loss between a certain output end (or input end) of a component and another similar output end (or input end) of the component. For example: The mutual isolation of a tapper refers to the insertion loss between a certain branch output end and another branch output end. 3.17 Return isolation The insertion loss between the main output end of a tapper (or cascade unit) and any branch output end (or system output port). 3.18 Symbols
α—-Manufacturer's risk;
User's risk;
-Total test time;
Acceptable mean time between failures;
Limiting mean time between failures;
Discrimination ratio: 0./01;
Number of samples (reliability), sample size (inspection); Co—Acceptance number;
Number of failures;
Acceleration factor,
N—Batch;
A. Acceptable judgment number;
R. -Unqualified judgment number;
AQL—Acceptable quality level;
RQL—Unqualified quality level.
4 Requirements and test methods
4.1 General requirements
4.1.1 Requirements
The appearance of the equipment and parts should be neat and tidy, and there should be no obvious dents, scratches, cracks, burrs, deformation, etc. on the surface; the surface coating should not bubble, crack or fall off; the metal parts should not be rusted or mechanically damaged. The injection material should not overflow. The operation of switches, buttons and knobs should be flexible and reliable, and the mechanical structure and parts of the whole machine should be tight and not loose. The text symbols and graphic symbols that describe the functions should be complete, correct, clear and firm, and the graphic symbols should comply with GB5465.2. 4.1.2 Test method
Inspect by visual inspection and/or hand feel. 4.2 Performance parameters
4.2.1 Performance parameter requirements
The performance parameter requirements for equipment and components shall comply with the relevant provisions in GB/T11318.2~11318.14. 4.2.2 Measurement method
This standard only specifies the general measurement methods for equipment and components. Other special measurement methods for relevant equipment and components shall comply with the relevant provisions in GB/T11318.2~11318.14. Any equivalent method that can ensure the same accuracy may also be used. When there is a dispute, the method specified in this series of standards shall prevail. 4.2.2.1 Relevant measurement regulations
4.2.2.1.1 Measurement frequency
The operating frequency specified for the equipment and components. 4.2.2.1.2 Measurement level
GB/T 11318.1--1996
4.2.2.1.2.1 For passive components, the level should be as large as possible according to the actual use of the components and the specified limits of the measuring instrument. 4.2.2.1.2.2 For active components, the nominal working level of the measured component. When measuring nonlinear distortion indicators, if the measurement is difficult, the working level can be appropriately increased.
4.2.2.1.3 Measurement regulations for the three (two) times beat ratio of carrier combinations 4.2.2.1.3.1 The measurement should be carried out on the specified channel. If not specified, the measured indicator should be the worst value measured on all working channels.
4.2.2.1.3.2 When measuring, all carriers should be placed at the nominal working level specified for the component. If the levels of each carrier are different, the relationship between the levels should be explained.
4.2.2.1.4 Combined intermodulation measurement regulations
4.2.2.1.4.1 The measurement should be carried out on the specified channel. If not specified, the measured index should be the worst value measured on all working channels.
4.2.2.1.4.2 During measurement, all carriers should be placed at the nominal working level specified for the component. If the measurement is difficult, the working level can be appropriately increased so that the combined intermodulation ratio index of the measured component is 60dB. If the levels of each carrier are different, the relationship between the levels should be stated. 4.2.2.1.5 Impedance
The impedance of the RF and video measurement system should be unbalanced 75. The interfaces of each measurement device should be well matched. 4.2.2.1.6 Termination
During measurement, all RF vacant ports except the port under test should be terminated with a 75Q load. 4.2.2.1.7 Power Supply
When measuring active components, unless otherwise specified, the power supply used by the measured components shall have a deviation within 5% of the rated value, and the power supply frequency deviation shall be within ±1 Hz.
4.2.2.1.8 Atmospheric Conditions
Unless otherwise specified, measurements shall be made under the following normal atmospheric conditions: temperature: 15℃～35℃;
Relative humidity: 45%~75%,
Atmospheric pressure: 86kPa～106kPa.
4.2.2.1.9 Measuring Instruments
When measuring, measuring instruments that can ensure measurement accuracy and have passed metrological qualification shall be used. 4.2.2.1.10 Others
Unless otherwise specified, attenuators and equalizers inserted in all active devices and components shall be set to 0dB during measurement. 4.2.2.2 Measurement
4.2.2.2.1 Loss, frequency response, gain and isolation4.2.2.2.1.1 Measurement block diagram
As shown in Figure 4.
Sweeper
GB/T 11318.1—1996
Parts under test
Detector
Note: The amplifier indicated by the dotted line depends on the measurement needs, but its distortion and frequency response at the test level must be checked, and its value should be negligible compared with the actual value of the part under test.
Figure 4 Equipment connection for loss, frequency response, gain and isolation measurement4.2.2.2.1.2 Measurement of passive components
4.2.2.2.1.2.1 Determine the reference curve
Do not connect the part under test first, directly connect the measurement system, and preset a suitable value for the variable attenuator A. Adjust the frequency sweeper and variable attenuator A so that the output signal level of A' is large enough so that the display shows a clear curve of a certain amplitude. Note the amplitude of the curve within the measurement range on the display, which is D. This curve is used as the reference curve. 4.2.2.2.1.2.2 Loss and Isolation
4.2.2.2.1.2.2.1 Insertion loss, distribution loss Connect the corresponding port of the component under test, reduce the attenuation of variable attenuator A, so that the lowest point of the frequency response curve in the specified frequency band (wideband type component) or the reference frequency (channel type component) coincides with the reference curve, then the change in the reading of variable attenuator A' is the measured loss value.
4.2.2.2.1.2.2.2 Mutual isolation, reverse isolation Connect the corresponding port of the component under test, reduce the attenuation of variable attenuator A', so that the highest point of the frequency response curve in the specified frequency band coincides with the reference curve, then the change in the reading of variable attenuator A2 is the measured isolation value. 4.2.2.2.1.2.2.3 Branch loss and deviation Connect the corresponding port of the component under test, reduce the attenuation of the variable attenuator A, so that a certain frequency in the frequency response curve within the specified frequency band coincides with the reference curve, and the change in the reading of the variable attenuator A, is the branch loss at that frequency. Measure the maximum and minimum branch losses within the specified frequency band respectively, and the difference between them and the nominal branch loss is the deviation. 4.2.2.2.1.2.3 In-band fluctuation
Connect the corresponding port of the component under test, reduce the attenuation of the variable attenuator A, so that the lowest point of the frequency response curve within the specified working channel coincides with the reference curve, and record the reading of A at this time as a1, and then adjust the attenuation of A so that the highest point in the frequency response curve within the specified working channel coincides with the reference line, and record the reading of A at this time as α2, and α2-ai is the in-band fluctuation value. 4.2.2.2.1.2.4 In-band flatness
Connect the corresponding port of the component under test, reduce the attenuation of the variable attenuator A2, so that the lowest point in the frequency response curve in the specified working frequency band coincides with the reference curve, and record the reading of A2 as 6. Then increase the attenuation of the variable attenuator A, so that the highest point in the frequency response curve in the specified working frequency band coincides with the reference line, and record the reading of A2 as c, then the in-band flatness. 2
4.2.2.2.1.2.5 Out-of-band attenuation
On the basis of 4.2.2.2.1.2.1, connect the corresponding port of the component under test, reduce the attenuation of the variable attenuator A, so that the highest point in the frequency response curve outside the specified frequency point coincides with the reference line, then the change in the reading of attenuator A is the out-of-band attenuation value. 4.2.2.2.1.3 Measurement of active components
4.2.2.2.1.3.1 Determine the reference curve
Do not connect the component to be tested first, directly connect the measurement system, and preset the variable attenuator A, to a suitable value. Adjust the sweep frequency meter so that the output level of A,316
GB/T 11318. 1--1996
reaches the normal output level of the component to be tested. Adjust A, so that the display shows a clear curve with a certain amplitude, and record the amplitude of the curve within the measurement range on the display, the value of which is D. This curve is used as the reference curve. 4.2.2.2.1.3.2 Gain
Connect the component to be tested, increase the attenuation of the variable attenuator A, so that the amplitude of the frequency response curve at the reference frequency returns to the value of D, and the change in attenuator A1 is the gain value.
4.2.2.2.1.3.3 In-band fluctuation
Based on 4.2.2.2.1.3.2, reduce the attenuation of variable attenuator A1 so that the lowest point in the frequency response curve in the specified working channel coincides with the reference curve. Note the reading of A1 at this time as a1. Then increase the attenuation of A1 so that the highest point in the frequency response curve in the specified working channel coincides with the reference line. Note the reading of attenuator A1 at this time as a2. Then a2-a is the in-band fluctuation value. 4.2.2.2.1.3.4 In-band flatness
On the basis of 4.2.2.2.1.3.2, reduce the attenuation of variable attenuator A, so that the lowest point in the frequency response curve within the specified working frequency band coincides with the reference curve, and record the reading of A at this time as b, and then increase the attenuation of A, so that the highest point in the frequency response curve within the specified working frequency band coincides with the reference line, and record the reading of A at this time as c, then 2 is the in-band flatness. 2
4.2.2.2.1.3.5 Out-of-band attenuation
On the basis of 4.2.2.2.1.3.2, reduce the attenuation of variable attenuator A2, so that the highest point in the frequency response curve outside the specified frequency point coincides with the reference line, and the change in the reading of variable attenuator A2 is the out-of-band attenuation value. 4.2.2.2.1.3.6 For the measurement of components with automatic gain control, the automatic gain control should be changed to manual control, and the above measurements should be performed at the nominal maximum gain and minimum gain respectively, and the worst value should be taken. For components that cannot be changed to manual control, their measurement methods are under consideration. 4.2.2.2.1.3.7 For the measurement of amplifiers with slope compensation, the above measurements should be performed after connecting cables or analog circuits in series. 4.2.2.2.2 Maximum output level, three-tone intermodulation ratio, and intra-channel carrier intermodulation ratio 4.2.2.2.2.1 The measurement block diagram
is shown in Figure 5.
RF signal generator
Note: The bandpass filter in the dotted box depends on the measurement needs. A
Part under test
Frequency-selective voltmeter
Figure 5 Equipment connection for measuring maximum output level, three-tone intermodulation ratio and intra-channel carrier intermodulation ratio 4.2.2.2.2.2 Measurement of broadband components
4.2.2.2.2.2.1 Adjust the output frequencies of the three signal generators so that f2 is the image carrier frequency of the highest channel of the part under test, f is 2MHz higher than J, and f1 is the image carrier frequency of the second highest channel. Set the variable attenuator A, to 5dB~10dB, and Az is slightly higher than 60dB. Adjust the output amplitudes of signal generators G, G2 and G, respectively, so that the value read by the frequency-selective voltmeter at f, is α, and the attenuation of a plus A should be equal to the nominal maximum output level of the part under test. The values ​​read at 2 and f: are both 6dB lower than a. Use a frequency-selective voltmeter to measure the component at f, ±2MHz, and reduce Az so that its reading is still the value of α. The change in the variable attenuator A2 is the three-tone intermodulation ratio. 4.2.2.2.2.2.2 Adjust the variable attenuator A1 so that the three-tone intermodulation ratio is exactly 60dB. At this time, the value read by the frequency-selective voltmeter at fi plus the attenuation of the variable attenuator A is the actual value of the maximum output level of the measured component. 317
GB/T 11318.1—1996
4.2.2.2.2.2.3 If necessary, a bandpass filter can be used to avoid overloading the frequency-selective voltmeter. At this time, the insertion loss of the filter should be included.
4.2.2.2.2.3 Measurement of channel type components
4.2.2.2.2-3.1 Adjust the output frequencies of the three signal generators so that f, is the image carrier frequency of the input channel of the measured component. It is 4.43MHz higher than f, and 6.5MHz higher than fi. Set the variable attenuator A, to 5dB～10dB, and the attenuation of Az is slightly higher than 60dB. Adjust the output amplitudes of the signal generators GI, G2 and G respectively so that the value read at f) of the frequency selection voltmeter after the J channel conversion type component is converted is a. The attenuation of a plus A should be 8dB lower than the nominal maximum output level of the measured component. The values ​​read at fJ2) and: (f:) are 17dB and 10dB lower than the nominal maximum output level respectively. Use a frequency-selective voltmeter to measure the component of +207MHz (or f+2.07MHz), and reduce the attenuation of the variable attenuator A, so that the reading on the meter is still a. The change of the variable attenuator A, plus 8dB is the carrier intermodulation ratio in the channel. 4.2.2.2.2.3.2 Adjust the variable attenuator A1 so that the carrier intermodulation ratio in the channel is just 54dB. At this time, the value read by the frequency-selective voltmeter at fi (or f\) plus the attenuation of the variable attenuator A, plus 8dB is the actual value of the maximum output level of the component under test.
4.2.2.2.2.4 Measurement of components with automatic gain control Change the automatic gain control function to manual control, and perform the above measurements at the nominal maximum gain and minimum gain respectively, and take the worst value.
For components that cannot be changed to manual control, their measurement methods are under consideration. 4.2.2.2.3 Carrier Secondary Intermodulation Ratio
4.2.2.2.3.1 Measurement block diagram
As shown in Figure 6.
RF signal generator
Note: The bandpass filter in the dotted frame depends on the measurement requirements. 1
Tested component
Figure 6 Equipment connection for carrier secondary intermodulation ratio measurement 4.2.2.2.3.2 Measurement
Frequency-selective voltmeter
4.2.2.2.3.2.1 Adjust the output frequencies of the two signal generators so that f, is the image carrier frequency of the lowest channel, and f, is the difference between the image carrier frequency of the highest channel and the image carrier frequency of the lowest channel. 4.2.2.2.3.2.2 Set the variable attenuator A1 to 5dB~10dB, and the attenuation of the variable attenuator A2 is slightly larger than the nominal value of the secondary intermodulation ratio. Adjust the output amplitude of signal generators G1 and G2 so that f1 and f2 reach the nominal maximum output level of the component under test at the output end of the component under test, which is equal to the reading α of the frequency-selective voltmeter plus the attenuation of A2. 4.2.2.2.3.2.3 Use the frequency-selective voltmeter to measure the level at the highest channel image carrier frequency (i.e., fl+f2), and reduce the attenuation of the variable attenuator A so that the reading on the meter is still the value of α. The change in the reading of the variable attenuator A2 is the carrier secondary intermodulation ratio. If a certain type of component requires the carrier secondary intermodulation ratio at the recommended operating level, the change in the reading of A above should be added to the difference between the above nominal maximum output level or the appropriate test level and the recommended operating level. The sum is the carrier secondary intermodulation ratio of this type of component. 4.2.2.2.3.2.4 If necessary, a bandpass filter can be used to prevent the frequency-selective voltmeter from overloading. In this case, the insertion loss of the filter should be taken into account.
Note: When making measurements in 4.2.2.2.2 and 4.2.2.2.3, if a spectrum analyzer is used instead of a frequency-selective voltmeter, an ultra-high frequency millivoltmeter should be used to read the maximum level value.
4.2.2.2.4 Noise figure
4.2.2.2.4.1 The measurement block diagram
is shown in Figure 7.
Noise signal generator
Note: The amplifier indicated by the dotted line depends on the measurement requirements. GB/T11318.1—1996
Parts under test
Figure 7 Equipment connections for noise figure measurement
4.2.2.2.4.2 Measurement
Frequency-selective voltmeter
4.2.2.2.4.2.1 Disconnect the noise signal generator first and connect a well-shielded terminating load to the input terminal of the part under test. 4.2.2.2.4.2.2 Use a frequency-selective voltmeter to measure the noise level of the component under test at the reference frequency. The bandwidth of the frequency-selective voltmeter should be below 1MHz, and the noise level is read as n.
4.2.2.2.4.2.3 Increase the attenuation of variable attenuator A by 3dB, remove the terminal load at the input end, connect the noise generator, and adjust its output so that the frequency-selective voltmeter returns to the original reading n. At this time, the noise index value indicated on the noise generator is the noise factor of the component.
If the impedance of the noise generator is not 75Q, it should be connected and the value should be corrected according to the provisions of its instruction manual. 4.2.2.2.4.2.4If the component under test has an automatic gain control function, it should be controlled manually and the above measurement should be performed at the maximum gain. 4.2.2.2.4.2.5 The measurement should be performed in a well-shielded shielded room. 4.2.2.2.5 Reflection loss
4.2.2.2.5.1 The measurement block diagram
is shown in Figure 8.
Scanner
4.2.2.2.5.2 Measurement
Detector
Reflection loss
Power consumption bridge
Part under test
Shielded terminal load
Figure 8 Equipment connection for reflection loss measurement
4.2.2.2.5.2.1 Do not connect the part under test first, but directly connect the measurement system. Adjust the frequency range of the sweeper to meet the measurement requirements. 4.2.2.2.5.2.2 Open the test end of the reflection loss bridge and adjust the output level of the sweeper to reach the highest working level of the port of the part under test (the passive component should be as high as possible). 4.2.2.2.5.2.3 Adjust the display so that the curve is near the full scale, and attenuate the sweep signal by 20 dB so that the curve is near the bottom scale line. 4.2.2.2.5.2.4 Restore the sweep signal to its original level, and connect the reflection loss bridge test end to the measured end of the component under test. 4.2.2.2.5.2.5 The decibel drop of the curve is the reflection loss of the measured port. 4.2.2.2.5.2.6 For components with automatic gain or manual gain control and components with inserted equalizers and attenuators, the values ​​obtained by the above measurements shall meet the technical index requirements when the gain, equalization and attenuation are in any combination of values. 4.2.2.2.6 Automatic gain control characteristics of channel-type components 4.2.2.2.6.1 The measurement block diagram
is shown in Figure 9.
4.2.2.2.6.2 Measurement
RF signal generator
GB/T 11318.1—1996
Tested Component
Frequency Selective Voltmeter
Figure 9 Connection of Equipment for Measuring Automatic Gain Control Characteristics of Channel-Type Components 4.2.2.2.6.2.1 Preset attenuator A to an appropriate value and adjust the output level of the signal generator so that the output of attenuator A is the rated input level of the tested component. Record the reading of the frequency selective voltmeter as α. 4.2.2.2.6.2.2 According to the parameter requirements of the tested component, increase and decrease the input level respectively, and read the change relative to the value a on the frequency selective voltmeter, which is the automatic gain control characteristic. 4.2.2.2.7 Frequency Accuracy, Total Frequency Deviation and Image and Sound Carrier Frequency Spacing 4.2.2.2.7.1 Measurement Block Diagram
As shown in Figures 10a and 10b.
Modulator under test
Spectrometer
Standard signal generator
Frequency counter
Equipment connection for measuring frequency accuracy, total frequency deviation and image and sound carrier frequency spacing of modulator Diagram 10a
Channel conversion components under test
Standard signal
Generator
Frequency counter
Frequency counter
Channel conversion components Frequency accuracy, total frequency deviation and Diagram 10b
Equipment connection for measuring frequency accuracy, total frequency deviation and image and sound carrier frequency spacing 4.2.2.2.7.2 Measurement
4.2.2.2.7.2.1 The components under test should be preheated for at least 0.5h in an indoor ambient temperature of 20C. 4.2.2.2.7.2.2 Measurement of modulator:
a) Adjust the output carrier frequency of the standard signal generator so that it completely coincides with the output image carrier frequency of the component under test displayed on the spectrum analyzer. The reading of the frequency counter at this time is the frequency of the signal under test. The difference between it and the nominal frequency value is the frequency accuracy. When measuring, the resolution of the spectrum analyzer should be as high as possible;
b) At the upper and lower limits of the specified working environment temperature, measure the output channel image carrier frequency of the component under test according to 4.2.2.2.7.2.2a), and the maximum deviation from the nominal image carrier frequency is the total frequency deviation; c) According to 4.2.2.2.7.2.2a), measure the output image carrier frequency and the sound carrier frequency of the component under test, and the difference between the two is the image and sound carrier frequency spacing.
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