Abstract: Group delay is one of the key performance specification in frequency converter link. Group delay calibration method of satellite RF test system’s frequency converter link is studied in this paper. Satellite RF test system is the important part of Satellite Ground Test Equipment. Its group delay of frequency converter link has important significance for the test of Satellite Ranging and the quality of signal transmission. From the definition of group delay, this paper discussed the test theory and method of group delay and presented the modulation method based on software defined radio technology to measure the group delay. This method is suitable for the precise measurement of frequency converter link that can’t accept other local oscillator. The formula of the modulation method is deduced in detail and the calibrating device is founded in this paper. The result of experiment demonstrate that the modulation method has more precision to measure the group delay.

Key words: Group-delay, Frequency converter link, ⁺Software defined radio technology, Modulation method