A test method for transponder third-order intermodulation based on vector network analyzer

Abstract

The invention relates to a high-efficiency and high-precision testing method for third-order intermodulation of a repeater based on a vector network, which comprises the steps of (1) performing calibration parameter setting for the vector network, and completing measurement channel calibration in a mode of Swept IMD Converters; (2) connecting a radio frequency testing cable, and building a complete satellite-ground testing circuit; and (3) setting relevant testing parameters in the built calibration environment, turning on double-tone radio frequency excitation power, testing third-order intermodulation characteristics of the repeater, and drawing a test result curve. The method provided by the invention can significantly improve the test convenience, the test efficiency, the test precision and the test automation degree of dual-carrier third-order intermodulation of a communication satellite repeater system, and can greatly reduce the test cost particularly for a large-scale multichannel repeater.

Description

technical field [0001] The invention belongs to the field of satellite testing, and relates to a testing method for a communication satellite transponder subsystem, which is particularly suitable for power amplifiers and satellite transponders with a large number of channels, and can greatly improve testing efficiency under the premise of ensuring measurement accuracy. Background technique [0002] The transponder subsystem is an important part of the communication satellite, and the performance of its radio frequency channel directly affects the signal quality of the satellite communication service. In the process of satellite communication, when two carrier signals of different frequencies enter the transponder system at the same time, due to the nonlinearity of the input and output characteristics, in addition to the amplified useful signal of the input carrier, there will be other frequency signals in the output signal. intermodulation products. On the one hand, the int...

AI Technical Summary

Problems solved by technology

This method has certain limitations in actual engineering testing:

[0005] (1) The test system consists of two signal sources, a power meter, a spectrum analyzer, a switch matrix and a test computer. It requires a 22U test cabinet to integrate all the test equipment, which is large in size and power consumption. The cost is high, and there are many radio frequency connections between the devices. The two signal sources and the spectrum analyzer are independent of each other and require an external common time base, so the system is complex to build;

[0006] (2) During the test, it is necessary to manually level the output power of the two independent signal sources based on the single-carrier saturation reference and the reading value of the uplink monitoring power meter, and after the test link makes the transponder work at the required operating point, the power adjustment process Complicated and lengthy, manual leveling cannot achieve high accuracy, and there is a risk of over-motivation

In the third-order intermodulation test of large-scale multi-channel transponders, this method will seriously affect the test efficiency;

[0008] (4) In the test system, due to the large number of test equipment and the complexity of the RF connection link, the two excitation signal sources synthesize the signal through the combiner inside the switch matrix, so the RF signal passes through multi-level passive equipment and multiple connection end faces, Causes a large mismatch error in the entire system

This test method only uses a power meter to monitor the uplink input power, and does not analyze and process the mismatch error of the test system

In addition, this method uses a spectrum analyzer to measure the power of downlink intermodulation products, which has a large uncertainty and a large error in the test results;

[0009] (5) In the remote test, every step of the control of the test equipment, the reading of the measurement data, and the calculation of the test results need to be completed by specially compiling the host computer software. The software execution process has complex loop nesting, timing relationships and It is difficult to design and debug, and the robustness of the test system is not strong

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