Abstract: To solve low accuracy of parameter estimation and high complexity of algorithms in frequency hopping signal under low signal-to-noise ratio (SNR) and complex electromagnetic environment, a new algorithm combined short-time Fourier transform (STFT) with smoothed pseudo Winger-Ville distribution (SPWVD) is proposed. Firstly, the received signals are converted to time-frequency domain by using STFT, and then adaptive noise reduction is used in time-frequency domain. Secondly, the accurate frequency is estimated by adaptive clustering algorithm. Thirdly, the time-frequency information of the signals is extracted and all kinds of interference are eliminated. After the network is sorted, the rough estimation range of the hopping time can be calculated. Finally, SPWVD algorithm and a truncation threshold are used to deal with the rough estimation range, and then a precise frequency estimation is obtained. Simulations show that the parameter estimation of the algorithm has high accuracy and low complexity under the condition of hybrid networking and low SNR. The parameter estimation problem of existing frequency switching time in actual frequency hoppingcommunication system has been effectively solved.

Key words: hybrid networking, frequency hopping, blind parameter estimation, short-time Fourier transform, smoothed pseudo Winger-Ville distribution