Precise method for group delay measurement of frequency-translating devices based on software defined radio technology

Precise measurement for group delay of Frequency-Translating Devices (FTD) is always a difficult problem in measurement field. Modulation method almost becomes the exclusive choice to measure the group delay especially for the group delay of FTD that can't accept other local oscillator. To resolve the problem of precise measurement of the group delay of FTD, a new double-frequency phase difference method come from the definition of group delay has been put forward based on software defined radio technology (SDR). This method is especially suitable for the precise measurement of FTD that can't accept other local oscillator. The formula of the new method is deduced in detail in this paper. This paper concentrates on the design and the measurement methods of an experimental system. Simulation result shows that the accuracy of this method is better than that of traditional modulation method by 1 order magnitude.