一种改进的CPFSK信号频率估计方法

针对突发信号解调中多普勒频偏大的问题，提出了一种改进的连续相位移频键控信号(CPFSK)频率估计方法。首先接收信号平方运算使信号的调制指数加倍，再通过一次离散傅里叶变换(DFT)，用搜索信号平方谱谱峰的方法实现突发信号频率估计。仿真实验表明，在低信噪比条件下，该算法的频率估计精度比经典的相位差频率估计算法提高了20%；该算法与广泛用于高动态突发信号的频率插值估计算法相比，同道干扰信道下信干比改善可达4 dB，DFT长度缩短约1/3。

An improved carrier frequency estimation method for CPFSK signals

To solve the problem of large Doppler frequency shift in high dynamic burst signal demodulation,an improved frequency estimation method is proposed for continuous phase frequency shift keying(CPFSK) signals. The received signal is first processed using square operation so as to make the modulation index of the signal twiced. Then the spectrum peak is searched using the square spectrum of CPFSK signal to estimate the carrier frequency after one discrete Fourier transform(DFT) operation. Simulation results show that,accuracy of frequency estimation is improved 20% when compared with that of the differenced phase algorithm in low signal-to-noise ratio(SNR) condition. When compared with the interpolated fast Fourier transform algorithm widely used in high dynamic burst signal,the proposed method gains an improvement of 4 dB in signal-to-interference ratio(SIR) with one third shorter DFT points in co-channel interference(CCI) condition.