New range-Doppler decoupling method for FMCW ladar

FMCW(frequency modulation continues wave) ladar could detect moving target. It often uses 2-dimension FFT method to decouple range and doppler frequency. When detecting high speed target, different chirp period spectrum peaks are not in the same range bin, and using 2-dimension FFT method would acquire a fuzzy speed. In the new decoupling method, one fitting line was acquired from serial period-s spectrum peaks at first, and an estimated speed was achieved. Then a Doppler compensation signal based on the estimated speed was given and plus with the original IF signal. It makes the spectrum peaks of serial periods compensated IF signal are in the same range bin. By using 2-dimension FFT method on compensated IF signal, a compensated speed was achieved. And the target speed could be the sum of compensated speed and estimated speed. Simulation results indicate that the new range-Doppler decoupling method could effectively extend no fuzzy velocity of FMCW ladar, and achieve high precision of target range and velocity at the same time.