Signal-to-noise ratio enhancement in compact intensity-modulated FMCW laser range sensor using synchronized dual-laser sources

The compact intensity-modulated frequency modulated continuous wave (FMCW) laser range sensor has a low signal-to-noise ratio(SNR) because the transmitting power is limited by heat dissipation conditions, and the detection performance is reduced in degraded visual environments. To increase the transmitting power and keep the heat low, the SNR enhancement technique using synchronized dual-laser sources is proposed. This paper established a mathematical model of the echo signal of the dual-laser sources, made a comparative analysis of the single and dual-channel laser beat signal. Aimed at the problem of unsynchronization of the two modulated signals caused by the drive circuit, a phase synchronization algorithm based on sampling feedback was proposed and verified by simulation. Finally, a synchronized dual-channel laser ranging system was built in the laboratory for experiments. Compared with a single-channel laser, the synchronized dual-channel laser transmitting power is doubled, and the echo signal SNR can be increased by 2.2dB. The experimental results indicate that the proposed SNR enhancement technique can effectively solve the problem of low SNR in compact intensity-modulated FMCW laser range sensor.