基于调制FFT的谐振式SAW传感器快速频率估计算法

针对高动态环境下的谐振式声表面波（Surface Acoustic Wave，SAW）传感器快速精确频率估计，提出一种基于调制快速傅里叶变换（Fast Fourier Transform，FFT）的谐振式SAW传感器快速频率估计算法。对单次谐振式SAW传感器回波信号进行N点取样后进行调制FFT计算，获得回波信号频谱，然后利用最大谱线的两相邻谱线取代I_Rife算法频谱细化后的谱线对频率偏移因子进行估计，最后使用频率偏移因子对最大频谱频率进行修正。该算法较I_Rife算法不需要判断频率修正方向，减少了3N次复数乘法和4（N-1）次复数加法运算，频率估计均方根误差的平均值减小了26%。该算法在提高精度的同时，实现了对谐振式SAW传感器的快速频率估计。

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.