Frequency Offset Estimation Algorithm of VDES Signals Based on Cross-Correlation

In VHF data exchange system(VDES), in order to solve the wide-range frequency offset problem of VHF data exchange-satellite (VDE-SAT) downlink, a frequency offset estimation algorithm for VDES Signals based on crosscorrelation was proposed. Firstly, character sequence and different Doppler frequency offset is available for the construction of local sequence, which is used of intercorrelation analysis with received signal to get a coarse estimation. Then, the rough estimated value compensated to received signal for eliminating the phase folding caused by argument calculation of the signal autocorrelation function. Finally, the proposed method overcomes the contradiction problem between high accuracy and wide extent of frequency offset estimation. Simulation results show that the range of the proposed algorithm can reach -4000Hz~4000Hz, and its accuracy is approximate to the Cramer-Rao bound. This estimation algorithm is reasonable for used of VDES receiver.