消除距离模糊的扩展伪随机码调制激光测距技术

Unambiguous Laser Ranging Technology Based on Extended PseudoRandom Modulation

单光子测距中采用高重复频率激光源可提高回波信噪比,同时会带来距离模糊问题。为消除距离模糊,基于调制测距和时间相关光子计数理论设计了一种测距技术,分步计算得到脉冲飞行时间所包含的不模糊时间和激光发射周期的倍数,进而得到距离。该技术具有运算量小和测距效率高等优点。基于m序列得到"1"所占比例可变的扩展伪随机序列,用来模拟噪声,并作为激光发射调制信号。测距仿真中比较了3种扩展伪随机序列的调制测距能力,结果表明:"1"所占比例为7/8的扩展伪随机序列兼顾了随机性和抗噪声能力,得到了优于全"1"序列和m序列的调制测距效果。

In single photon ranging, increasing repeating frequency can improve the echo signal-to-noise ratio and result in ambiguous distance. To avoid ambiguous distance, an arithmetic based on modulation ranging and time-correlated photon counting theory is proposed, by which the unambiguous time and multiple of laser emitting periods are calculated, and then the unambiguous distance is obtained. This technology needs less computation and is more effective. Extended pseudo-random sequences with variable proportion of＂1＂are derived from msequence, and they act as noise model and modulation signal. In simulation, ranging results with three different sequences are compared and it shows the pseudo-random sequences with proportion of＂1＂as 7/8 are random and noise resistant, of which the ranging result is better than that of all＂1＂sequence and m-sequence.