A Study on Influencing Factors for the Output Signal-to-Noise Ratio of FFT Processor and Its Utilization

The influencing factors on the output signal-to-noise ratio (SNR) of FFT processor are studied and a novel method to select the optimal word length for FFT processors is proposed. Taking fixed-point FFT as example, the expressions of showing the influence of input SNR, word-length, and FFT size on the output SNR have been given. Based on the relationship between the SNR of input sequence and the one of output sequence, the minimal word-length selection criterion for FFT processors is derived. The expressions are confirmed by experiment results and the word-length selection criterion is of great importance in designing FFT processors