地质雷达信号采样定时控制

Timing Control of Geological Radar Signals Sampling

针对地质雷达信号数据采集过程中,采样时刻的定时精度与定时范围难于兼顾的实际,基于斜波发生器原理,用高分辨率数模转换器生成基准比较电压,实现高精度可编程定时电路。可编程计数范围为16bit,实际最小定时单位达8ps,折合采样频率高达50GHz。使用该定时器的地质雷达,采样时刻抖动小于1ps;室内条件下用2GHz天线在3m范围内探测移动金属板,测量误差为1%;野外环境下用100MHz天线对湖底6 2m内的不同目标进行勘探,测量误差在5%～8%范围内,实现地质雷达对地下目标体的高精度定位。

It is difficult to give attention to both timing accuracy and timing range of sampling time in the present geological radar signals data acquisition. Using a digital-to-analog converter with high resolution to bring reference comparison voltage, the high accuracy programmable timer based on the principle of ramp generators described in this paper has been developed. This timer programmable count range is 16 bits, timing precision is 8 ps, and equivalent sampling rate is up to 50 GHz. Sampling time dithering of the geological radar with this timer is lower than 1 ps. In indoor case, exploration accuracy was 1% when we used 2 GHz antenna to detect a moving metallic board within 3 m. In field case, exploration accuracy was 5%-8 % when we used 100 MHz antenna to detect a few different objects located below a lake surface within 6.2 m. So locating accurately subterranean objects by geological radar has been realized.