This standard specifies the electrical performance measurement method of tropospheric scatter communication equipment. This standard is used for the electrical performance measurement of various tropospheric scatter communication equipment. As shown in Figure 1, the tropospheric scatter communication equipment referred to in this standard includes the equipment between the auxiliary multiplexer and the auxiliary tap to the antenna feeder interface. For special requirements and measurement methods not specified in this standard, they may be specified separately in the product technical conditions. SJ 20042-1992 Measurement method of tropospheric scatter communication equipment SJ20042-1992 Standard download decompression password: www.bzxz.net
This standard specifies the electrical performance measurement method of tropospheric scatter communication equipment. This standard is used for the electrical performance measurement of various tropospheric scatter communication equipment. As shown in Figure 1, the tropospheric scatter communication equipment referred to in this standard includes the equipment between the auxiliary multiplexer and the auxiliary tap to the antenna feeder interface. For special requirements and measurement methods not specified in this standard, they may be specified separately in the product technical conditions.

GJB 367.2-1987 General technical conditions and environmental test conditions for military communication equipment

Military Standard of the Electronic Industry of the People's Republic of China FL5820
.SJ20042—92
Measurement Method for Troposphering Scattering Communication Equipment
Mothods of Measurement for Tropsphering Scattering Communication Equipment1992-02-01 Issued
China Electronics Industry Corporation
Implementation on 1992-05-01
Military Standard of the Electronic Industry of the People's Republic of China Troposphering Scattering Communication Equipment
Mothods of Measurement for Tropsphering Scattering Communication Equipment1 Subject Content and Scope of Application
This standard specifies the electrical performance measurement method for troposphering scattering communication equipment. SJ20042-92
This standard is used for the electrical performance measurement of various troposphering scattering communication equipment. As shown in Figure 1, the tropospheric scattering communication equipment referred to in this standard includes equipment between the auxiliary multiplexer and the auxiliary demultiplexer and the antenna feeder interface. For special requirements and measurement methods not specified in this standard, they may be specified separately in the product technical conditions. 2 Reference standards
GJB367.2--87 General technical conditions and environmental test conditions for military communication equipment. 3 Standard test conditions
The measurement should be carried out under standard conditions. After the equipment under test is adjusted under standard test conditions, except for the adjustments that must be made as required, its working state should be kept unchanged during the entire measurement cycle. The measuring instruments and meters used must comply with the corresponding technical conditions.
3.1 Standard power supply conditions
3.1.1 AC power supply conditions
Unless otherwise specified, usually during the entire measurement period, the AC power waveform should be roughly a sine wave. The deviation between the instantaneous value of any part of the power waveform curve and the instantaneous value of its fundamental wave does not exceed 5% of the fundamental wave amplitude, then the AC power is considered to be basically a sine wave. The voltage and frequency shall not deviate from the standard values ​​by more than the following values: Fixed equipment
Voltage: rated value ±10%;
Frequency: rated value ±5%.
Mobile equipment
Voltage: rated value +10%
-15%;
Frequency: rated value ±5%.
The internal resistance of the power supply should be low enough so that its influence on the equipment under test can be ignored. 3.1.2 DC power supply conditions
The voltage and ripple voltage shall not exceed the following values: Fixed equipment
Voltage: rated value ±10%;
China Electronics Industry Corporation Issued on February 1, 1992 and implemented on May 1, 1992
Bit error meter
(transmitting)
Bit error meter
(receiving)
Multiplexer||tt ||Splitter
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Modulator
Synthesizer
High screw head
High forehead
Receiver
Commercial power
Amplifier
Transmitter
Attenuator
Figure 1 Connection block diagram of tropospheric scatter communication equipment system Ripple voltage: less than 2%.
Mobile equipment
Voltage: rated value +15%
-10%;
Ripple voltage: less than 2%.
Vehicle coupler
Splitter
Precision variable
Attenuator
Unless otherwise specified, during the entire measurement period, the internal resistance of the power supply should be so small that its influence on the equipment under test can be ignored. 3.2 Standard atmospheric conditions
3.2.1 Normal test atmospheric conditions
Usually, the test should be carried out under the following ambient temperature, relative humidity and air pressure conditions (see GJB367.2): temperature: +15~+35℃,
relative temperature: 45%~75%;
air pressure: 86~106kPa.
The measurement results should indicate the temperature, relative humidity and air pressure of the on-site measurement scene. If the measured parameter value changes with temperature, humidity and air pressure, and their changing rules are unknown, the standard arbitration conditions in Article 3.2.3 should be adopted.
3.2.2 Standard reference conditions
If the measured parameter value changes with temperature and/or air pressure, and their changing rules are known, the parameter value should be measured according to the conditions specified in Article 3.2.1. If necessary, the measurement results can be corrected by calculation to the values ​​under the following standard reference atmospheric conditions2
Temperature: +20℃;
Air pressure: 101.3kPa.
SJ20042-92
Note: There is no requirement for relative humidity because it is usually impossible to correct by calculation. 3.2.3 Standard arbitration conditions
If the measured parameter value changes with temperature, humidity and air pressure, and the changing pattern is unknown, the supply and demand parties shall negotiate and select one of the following combined conditions for measurement: Temperature
+20±1℃
+23±1℃
+25±1℃
+27±1℃
Relative humidity
63%~67%
48%~52%
48%~52%
63%~67%
86~106kPa
86~106kPa
86~106kPa
86~106kPa
With the consent of the supply and demand parties, measurement may not be carried out under the above conditions. However, at this point, appropriate limits for the parameters should also be agreed upon. The actual temperature, relative humidity and pressure values ​​during the measurement period should be given in the measurement results. 4 Radio Frequency Measurements in Troposcatter Communication Equipment
This chapter describes the measurement methods for the radio frequency range of the transmitting and receiving equipment in troposcatter communication equipment. 4.1 Carrier Frequency
4.1.1 Definitions and General Considerations
In troposcatter communication equipment, the output of the device under test usually has more than one carrier frequency. The carrier frequency is the frequency in the RF signal spectrum that is modulated by the information signal. The following direct measurement method can be used for measurement, which is applicable to unmodulated RF carriers.
The carrier frequency can be measured at the RF output of the transmitter or after transmission through some subsystem. In this case, different measurement values ​​will be obtained due to the error of the local oscillator frequency. The frequency of the local oscillator can also be measured by the method described here. 4.1.2 Measurement Methods
The general equipment configuration for measuring the unmodulated RF carrier frequency is shown in Figure 2. Before making the measurement, both the device under test and the measuring equipment should be thermally stabilized. Then, the digital frequency meter is read at intervals of a certain length, such as one second, which will be determined by the gate time selection of the instrument used. Generally, the recorder shown in Figure 2 can be used to record the values ​​of the digital frequency meter, and 100 counts are sufficient.
Equipment under test
Bandpass filter
(Set as required)
Attenuator or
Amplifier
Frequency converter
(Set as required)
Frequency meter
Figure 2 Block diagram for measuring the frequency of an unmodulated RF carrier Recorder
(Set as required)
In a multi-carrier system, each carrier should be measured separately, and the other carriers should either be removed or filtered out with appropriate filters.
4.1.3 Result Expression
When the direct measurement method is used to measure the unmodulated RF carrier, the reading of the digital frequency meter can be recorded manually or automatically3
SJ20042--92
as a function of time. The gate time of the selected digital frequency meter should be given. 4.2 Measurement Method of Main Technical Indicators of Transmitter 4.2.1 Transmitter Output Power Measurement
4.2.1.1 Definition and General Instructions
Transmitter output power is defined as: the power supplied by the transmitter to the corresponding standard load impedance under rated working conditions. The transmitter output power should be measured in two states: modulation with pseudo-random sequence test code (the code length is preferably 215-1) and no modulation (pure carrier). The power measured on the standard load when modulated is taken as the actual output power of the transmitter. During measurement, the nominal intermediate frequency excitation level is input, the transmitter is adjusted to the rated working state, the measurement point is selected on the interface end face between the transmitter and the feeder, and the terminal is connected to the rated standard load. 4.2.1.2 Measurement method
The transmitter output power measurement is divided into two methods: direct measurement method and indirect measurement method. 4.2.1.2.1 Direct measurement method of transmitter output power As shown in Figure 3, a high power meter is used to directly measure the output power of the final amplifier, that is, the transmitter output power. If the power exceeds the maximum range of the power meter, the indirect measurement method should be used. Error meter
(transmitter)
transmitter
Figure 3 Block diagram of direct measurement of transmitter output power 4.2.1.2.2 Indirect measurement method of transmitter output power As shown in Figure 4, according to the degree of directional coupler and the reading of the low power meter, the output power of the high power amplifier can be measured by the calibration curve obtained by the direct measurement method. BERT
(transmitter)
Multiplexer
Modulator
High power
Synthesizer
Filter
High power
Amplifier
Transmitter
Coupler
Figure 4 Block diagram of indirect measurement of transmitter output power 4.2.1.3 Result presentation
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The measurement results should be presented in tabular form. See Table 1 for an example. Table 1
Direct measurement of output power
Output power
4.2.2 Measurement of output level of modulator, up-converter and frequency synthesizer 4.2.2.1 Definition and general description
Indirect measurement of output power
The modulator output level is the nominal intermediate frequency excitation level input to the up-converter: the frequency synthesizer output level (or power) is the nominal RF mixing level input to the up-converter, and the transmitter end preamplifier input power is the up-converter output power. When measuring, the equipment is adjusted to the rated working state, and the measurement point is selected on the interface end face of the two. Impedance matching should be considered when measuring.
4.2.2.2 Measurement method
As shown in Figure 5, when the system equipment reaches thermal stability, the modulator output level is measured directly at point A of the modulator output terminal using an ultra-high frequency transistor millivoltmeter.
Bit Error Tester
(Transmitter)
Multiplexer
Modulator
Synthesizer
Power Meter
Figure 5 Block diagram of modulator, up-converter, and frequency synthesizer output level (or power) measurement Use a power meter to measure the frequency synthesizer output power directly at point B of the frequency synthesizer output terminal. Measure the up-converter output power directly at point C of the up-converter output terminal. 4.2.2.3 Result Representation
Represent in a table corresponding to each measurement result. See Table 2 for examples. Table 2
Frequency synthesizer
Output frequency
Frequency synthesizer
Output power
4.2.3 Measurement of transmitter spurious and harmonic interference output Modulator
Output frequency
Modulator
Output level
Up converter
Output power
4.2.3.1 Definition and general description
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The spurious and harmonic interference output of a transmitter is defined as: all other useless signal outputs except the useful signal. The spurious and harmonic interference output of the transmitter is measured at the transmitter output port. During the measurement, the transmitter operates at the rated state.
4.2.3.2 Measurement method
The measurement of the spurious and harmonic interference output of the transmitter can be carried out as shown in Figure 6. Rate
Synthesizer
Bit error meter
(transmitter)
Multiplexer
Spectrum analysis
only or measurement
Receiver
Modulator
High power
Variable attenuator
Coupler
Transmitter
High power
Amplifier
Filter
Figure 6 Transmitter spurious and harmonic interference output measurement block diagram 4.2.3.3 Result representation
Use a copy of the spectrum graph displayed by the spectrum analyzer to represent it. It is best to use a spectrum analyzer with a microcomputer printing device to draw a copy of the spectrum graph.
4.2.4 Transmitter output voltage standing wave ratio measurement (cold test) 4.2.4.1 Definition and general description
The transmitter output voltage standing wave ratio is defined as: the ratio of the output impedance (Z) on the end surface of the transmitter final amplifier output and the feeder connection end to the transmission line characteristic impedance (Z). VSWR
4.2.4.2 Measurement method
The transmitter final amplifier output voltage standing wave ratio measurement method usually adopts the measurement line measurement method and the sweep frequency meter and X-Y recorder measurement method.
4.2.4.3 Measurement steps
Measurement line measurement
Transmitter
(Final amplifier)
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Measurement line
Amplifier
Isolator
Signal source
Figure 7 Measurement of voltage standing wave ratio at transmitter output terminal-Measurement line measurement (cold test) block diagram Measurement steps: Connect the equipment as shown in Figure 7. During measurement, the RF signal source is modulated with a 1000Hz square wave (inner). Measure at the rated transmitter operating frequency and the useful band edge frequency (attenuation of 1.5dB frequency point). Usually, the in-band standing wave ratio is smaller than the standing wave ratio at the passband edge. If the standing wave ratio (scanning) of a certain frequency point in the band is larger than the passband edge, the standing wave ratio of this frequency point should be recorded. The measurement should be performed on the end face of the transmitter feeder interface. The results show that: "From ×× frequency to ×× frequency range (within the working frequency band), the voltage standing wave ratio VSWR2 Measurement method
The measurement of transmitter spurious and harmonic interference output can be carried out as shown in Figure 6. Rate
Synthesizer
Bit error meter
(transmitter)
Multiplexer
Spectrum analysis
Only or measurement
Receiver
Modulator
High power
Variable attenuator
Coupler
Transmitter
High power
Amplifier
Filter
Figure 6 Block diagram of transmitter spurious and harmonic interference output measurement 4.2.3.3 Result presentation
Use a replica of the spectrum graph displayed by the spectrum analyzer to present it. It is best to use a spectrum analyzer with a microcomputer printing device to draw a replica of the spectrum graph.
4.2.4 Transmitter output voltage standing wave ratio measurement (cold test) 4.2.4.1 Definition and general description
The transmitter output voltage standing wave ratio is defined as: the ratio of the output impedance (Z) on the end surface of the transmitter final amplifier output and the feeder connection end to the transmission line characteristic impedance (Z). VSWR
4.2.4.2 Measurement method
The transmitter final amplifier output voltage standing wave ratio measurement method usually adopts the measurement line measurement method and the sweep frequency meter and X-Y recorder measurement method.
4.2.4.3 Measurement steps
Measurement line measurement
Transmitter
(Final amplifier)
SJ20042—92
Measurement line
Amplifier
Isolator
Signal source
Figure 7 Measurement of voltage standing wave ratio at transmitter output terminal-Measurement line measurement (cold test) block diagram Measurement steps: Connect the equipment as shown in Figure 7. During measurement, the RF signal source is modulated with a 1000Hz square wave (inner). Measure at the rated transmitter operating frequency and the useful band edge frequency (attenuation of 1.5dB frequency point). Usually, the in-band standing wave ratio is smaller than the standing wave ratio at the passband edge. If the standing wave ratio (scanning) of a certain frequency point in the band is larger than the passband edge, the standing wave ratio of this frequency point should be recorded. The measurement should be performed on the end face of the transmitter feeder interface. The results show that: "From ×× frequency to ×× frequency range (within the working frequency band), the voltage standing wave ratio VSWR2 Measurement method
The measurement of transmitter spurious and harmonic interference output can be carried out as shown in Figure 6. Rate
Synthesizer
Bit error meter
(transmitter)
Multiplexer
Spectrum analysis
Only or measurement
Receiver
Modulator
High power
Variable attenuator
Coupler
Transmitter
High power
Amplifier
Filter
Figure 6 Block diagram of transmitter spurious and harmonic interference output measurement 4.2.3.3 Result presentation
Use a replica of the spectrum graph displayed by the spectrum analyzer to present it. It is best to use a spectrum analyzer with a microcomputer printing device to draw a replica of the spectrum graph.
4.2.4 Transmitter output voltage standing wave ratio measurement (cold test) 4.2.4.1 Definition and general description
The transmitter output voltage standing wave ratio is defined as: the ratio of the output impedance (Z) on the end surface of the transmitter final amplifier output and the feeder connection end to the transmission line characteristic impedance (Z). VSWR
4.2.4.2 Measurement method
The transmitter final amplifier output voltage standing wave ratio measurement method usually adopts the measurement line measurement method and the sweep frequency meter and X-Y recorder measurement method.
4.2.4.3 Measurement steps
Measurement line measurement
Transmitter
(Final amplifier)
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Measurement line
AmplifierwwW.bzxz.Net
Isolator
Signal source
Figure 7 Measurement of voltage standing wave ratio at transmitter output terminal-Measurement line measurement (cold test) block diagram Measurement steps: Connect the equipment as shown in Figure 7. During measurement, the RF signal source is modulated with a 1000Hz square wave (inner). Measure at the rated transmitter operating frequency and the useful band edge frequency (attenuation of 1.5dB frequency point). Usually, the in-band standing wave ratio is smaller than the standing wave ratio at the passband edge. If the standing wave ratio (scanning) of a certain frequency point in the band is larger than the passband edge, the standing wave ratio of this frequency point should be recorded. The measurement should be performed on the end face of the transmitter feeder interface. The results show that: "From ×× frequency to ×× frequency range (within the working frequency band), the voltage standing wave ratio VSWR
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