Real-time laser range finding system for moving target based on all-phase fourier transfrorm spectrum analysis

The traditional laser range finder cannot meet the need of real-time, high-resolution measurement because of its low anti-jamming capability and time-consuming measurement. Owing to this, multi-channel transmitting and receiving system for phase-shift laser range finder based on parallel digital signal processor (DSP) was designed. Multi-frequency modulation laser can be transmitted and received at the same time, whish improves the measurement speed and avoids the wrong data fusion because of target moving. A new frequency correction method was proposed according to the amplitude spectrum acquired by all-phase FFT, amplitude spectrum is expanded into Taylor series and the correction value of frequency is calculated by relation of spectral lines. Monte-Carlo simulation results proved that the new frequency correction method had higher resolution and better stability than Rife method and centro-baric method. In experiments, the sampling frequency of AD converter is 937.5 kHz, the all-phase FFT transform point number is 1024, the phase difference resolution better than 0.003° and the frequency resolution better than 0.033 Hz are obtained. Experiments proved that the system can meet the need of high-accuracy, real-time distance measurement of moving target.