全相位FFT（apFFT）时移相位差法多频测试程序，内置5种不同的频率，可以得到很精确的幅值、频率、相位估计，仿真时精度很高。-All phase FFT (apFFT) method when multi-frequency phase-shift test procedures, built-in 5 different frequencies, can be very precise amplitude, frequency, phase estimation, the simulatio