A Fitting Method of RF Channel Group Delay Characteristics for High Precision Navigation

The group delay and amplitude characteristics of the receiver signal channel are mainly determined by the Radio Frequency front-end, whose amplitude and phase characteristics can be approximated to a nonlinear phase band-pass filter. Among them, group delay has a great influence on high-precision navigation and positioning system. In the high-precision navigation receiver, in order to better evaluate the influence of group delay characteristics on the receiver, it is necessary to accurately measure the group delay characteristics of the receiver and fit it with high-precision. Based on the group delay characteristics of the receiver channel measured by the vector network analyzer, this paper proposes a fitting method which combines the piecewise fitting and the Fourier decomposition. Through the experimental simulation, it can be concluded that this method has the advantages of high precision and small computation compared with the polynomial fitting method based on the least square method (LSM) and approximate fitting method of group delay Fourier decomposition.