Symbol Synchronization Algorithm Based on Delay Multiplication for Non-cooperative Communication Signals

In order to monitor non-cooperative communication signals, a symbol synchronization algorithm for non-cooperative signals is proposed based on delay multiplication. We estimate a rough value of the symbol rate by estimating the bandwidth of non-cooperative signals. Determining the delay time with the rough symbol rate, we obtain the Fourier component of the symbol rate by delay multiplication. Then we estimate the symbol rate accurately by spectral line detection and extract the symbol synchronization clock by filtering and shaping. The proposed algorithm can be calculated quickly by FFT and is robust, which is useful in monitoring of non-cooperative signals. Simulation results show that the algorithm can estimate symbol rate and extract symbol synchronization clock accurately when the SNR is greater than -4.5 dB. Experiment results of cooperative signal show that the algorithm can estimate the symbol rate with high accuracy and obtain the symbol synchronization clock accurately. Experiment results of non-cooperative signals show that the algorithm is also effective for non-cooperative signals.