Frequency agility signal phase coherent accumulation method

The invention provides a frequency agility signal phase coherent accumulation method. Firstly distance FFT is performed on pulse pressure data, and the possible range of velocity and the velocity accuracy required to be compensated are set; then the echo is compensated and distance IFFT is performed; non-coherent accumulation of multiple pulses is performed and the maximum value is taken as an evaluation criterion of the current velocity value, the velocity corresponding to the velocity evaluation criterion maximum value is taken as the estimated target velocity and the echo is compensated by using the velocity, and finally distance IFFT is performed so as to complete envelope correction; and a distance unit of which the energy of the first frequency point is greater than the threshold value after envelope correction is selected, then the phase of the distance unit of the corresponding position of each subsequent frequency point is compensated into the same phase of the first frequency point, and finally the