Delay Test Method

Range measurement plays a critical role in many fields such as TT&C and navigation positioning. To improve accuracy of range measurement, it is necessary to accurately measure absolute transmission delay of signal in transmission and reception system. However, in all wireless RF system, distortionless transmission of signal requires system must have excellent group delay characteristics. Therefore, research on system delay characteristics has two purposes. One is to determine signal transmission delay generated by system according to system delay characteristics, so as to define electrical length of system. The other one is to learn about signal linear distortion generated by system according to delay characteristics and seek the method to reduce signal linear distortion.The thesis summarizes fundamental principles and methods of delay measurement by analyzing fundamental definitions of delay parameters. Meanwhile, current advanced and feasible test implementations are also summarized, based on further discussion and experiment of delay test technology, in combination with modern instrument devices. Among them, vector mixer calibration technology, which employs vector network analyzer to measure delay characteristics of frequency-changing system, is the only way to measure absolute delay in frequency-changing mode. It is innovatively proposed to use oscilloscope to measure BPSK modulator delay. Moreover, dual-channel vector signal analyzer is used to measure channel delay with related technology in complex digital modulation mode, which also enables measurement of delay characteristics of the system in real operational mode.Other than summarizing various measurement methods, the thesis systematically analyzes measurement uncertainty of every measurement methods, which provides reference to accuracy analysis for practical engineering application (such as ranging and positioning).The thesis develops and accurately calibrates (weighted average of multiple measurement methods) delay reference device. The method of using closed-loop measurement to verify system ranging accuracy is proposed. New means of"closed-loop measurement"and"delay transfer standard"are put forth. Measurement conditions and uncertainty for each implementation are also analyzed.