串口数据丢帧引起的雷达测试故障原因分析

为解决某雷达高度表试验过程中发生的动作高度测试异常故障，采用故障树分析法对雷达高度表和测试设备进行故障排查。经检测发现，测试设备上位机的串口通信卡接收下位机的数据中有几十帧数据帧出现CRC校验位错误，被应用程序丢弃。原因是下位机发出的数据信号存在一定程度的畸变，上位机串口通信卡的串口控制器芯片OX16PCI694适应性不足导致数据读取出错。而应用程序在健壮性设计上也存在缺陷，以数据帧数来计算时间及雷达动作高度，但丢弃数据帧时未作相应处理。采用兼容性好的串口控制器芯片16C554重新设计通信卡，在上位机与下位机通信协议中增加数据的帧序号。经试验验证故障定位正确，解决措施有效。

Analysis of radar test failure as a result of serial data frame loss

According to the test data of a highly abnormal action occurs in the process of radar altimetertest, used fault tree analysis method for troubleshooting of radar altimeter and test equipment. There were dozens of frame data error when the serial port communication card of the host computer to receive the data of the lower machine each test. After testing found that the data signal from the lower machine had certain distortion,the adaptability of the serial controller chip OX16PCI694 used in the serial communication card of the host computer was insufficient. Lead to the received data frame CRC check digit mistakes, then the application discarded the data frame for receiving frame error. Defects exist in robust design of the application, which dependented on data frames as reference time, but discarded data frame without the relevant treatment. Increased the fault tolerance design of the host computer software, Increased frame number in protocol data from the lower machine. Communication card was designed perfect by using the serial controller chip 16C554 with good compatibility. After the hardware and software design improvements, the problem is resolved in the test.