Fast frequency estimation algorithm of resonant SAW sensor based on modulated FFT

For the fast and accurate frequency estimation of resonant surface acoustic wave (SAW) sensors in high dynamic environments, a fast frequency estimation algorithm for resonant SAW sensors based on modulated fast Fourier transform (FFT) is proposed. First, N-point sampling of the response signal of a single resonant SAW sensor and calculation of modulating FFT are performed to obtain the spectrum of response signal, and the two adjacent spectral lines of the maximum spectral line are used to replace the spectral lines refined by the I_Rife algorithm for estimation of frequency offset, and finally the factor of frequency offset is used to correct the maximum frequency of spectrum. Compared with the I_Rife algorithm, this algorithm does not need to judge the direction of frequency correction, so that 3N times of complex multiplications and 4(N-1) times of complex additions can be omitted, and the average root mean square error of frequency estimation is reduced by 26%. This algorithm realizes fast frequency estimation of resonant SAW sensor while improving the accuracy.