Integrating Long-Range Laser Ranging With Velocimetry and Communication for LiDAR via Hybrid Modulation

In this paper, a Light Detection and Ranging (LiDAR) system based on a hybrid modulation technique is proposed, which integrates ranging, velocimetry, and communication functions. First, the system performs pulse width modulation (PWM) on the baseband signal. This PWM-modulated signal controls the on-off keying (OOK) modulation of the high-frequency sinusoidal signal. Then, the OOK-modulated signal is used to perform pulse-based intensity modulation on a continuous-wave laser, which is then transmitted toward the target. Thus, the system incorporates a hybrid modulation scheme combining PWM, OOK, and intensity modulation. Experimental results demonstrate that the time interval of the pulsed signal enables coarse positioning of distant targets, while phase difference measurements of the high-frequency sinusoid within each pulse ensure ranging precision better than 9 mm. The Doppler frequency shift induced by target motion is utilized to measure dynamic target velocity, achieving a precision better than 7.98 mm/s. Accurate demodulation of the baseband signal is achieved through pulse-width extraction from the echo signal. Furthermore, multi-dimensional point cloud images of various targets are successfully realized. This work provides a viable technical approach for developing multi-functional-integrated LiDAR systems.