根据高精度靶场测角要求, 设计了一套以IRIG-B码终端为时间基准, 基于数字信号处理器(DSP)和现场可编程门阵列(FPGA)的CCD曝光中心测量系统。首先给出了CCD曝光中心的测量原理及硬件组成, 利用共源的两台IRIG-B码终端控制发光二极管和CCD探测器, 通过调整B码终端输出信号时延控制发光二极管, 得到了1 Hz脉冲前后沿和曝光脉冲前后沿对齐的2个关键时刻。针对人工图像判读精度低的问题, 提出了利用图像重心的提取算法和改进的Krisch边缘算法, 自动计算得到CCD曝光中心, 其精度优于17 μs。在外场对多套光电经纬仪CCD曝光中心进行了测量, 并将测量结果应用到外场校飞数据处理中, 结果表明, 在飞机过航捷时光电经纬仪的测角误差平均减少了55%。该系统稳定、可靠, 在靶场测量中有着广泛的应用前景。

According to the demands of a photoelectric theodolite for angle measurement accuracy, a CCD exposure center measurement system by taking the IRIG-B code terminal as time reference was designed based on a Digital Signal Processor(DSP) and a Field Programmable Gate Array(FPGA). The measuring principle and hardware components of the CCD exposure center were given. Then two sets of IRIG-B terminals with a total source code were used to control a light emitting diode and a CCD detector. By adjusting the B code terminal output signal time delay to control the light-emitting diode, two key moments along with the front and back edges for 1 Hz pulses and the exposure pulses were obtained, respectively. Aiming at the low accuracy of artificial image interpretation, an image edge extraction algorithm based on the image centre and an improved Krisch algorithm were proposed, and the CCD exposure center with a precision better than 17 μs was automatically calculated. Finally, several sets of CCD exposure centers for photoelectric theodolites were measured in the field, and the measurement results were applied to the outfield calibration flight data processing. Obtained results show that the angle measuring error of photoelectric theodolite is reduced by 55% on average in the Czech Airlines time, and the system is stable, reliable and has a wider application prospect.