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

A precise measurement for the group delay of Frequency-Translating Devices (FTD) is always a difficult problem in measurement field. It almost has no choice but the modulation method for measuring group delay especially the group delay of FTD which can´t accept the other local oscillator. To resolve the problem that a precise measurement method for group delay of FTD, a new double-frequency phase difference method has been put forward based on software defined radio technology (SDR). This method is especially suitable for measuring group delay of FTD which can´t accept the other local oscillator. The formula of the new method is deduced in detail in this paper. This paper concentrates on two aspects of the practice system: the design and the measurement method. The simulation shows the accuracy of this method is better than the traditional modulation method by 1 order magnitude.