小型舰艇高精度辅助定位无线电探测系统

摘要

针对海面小型舰船GPS定位信号易受干扰和安全性差的问题,设计了一套VHF无线电辅助定位测向系统.系统采用5元均匀线性阵列接收舰船的脉冲应答信号,利用FPGA硬件处理模块快速实现基于多重信号分类(MUSIC)算法的超分辨测向测距,其中特征向量分解(EVD)模块采用Jacobi快速迭代算法,达到ms级响应速度;校准模块采用仅需移位加法运算的坐标旋转数字计算机(CORDIC),不仅节约了硬件计算资源,还减少了阵列误差对测向结果的影响,有效提高了系统测向精度.通过与浮动目标建立了基于时分多址(TDMA)的通信机制,能够以软件方式自适应改变工作频段和工作时间,大大增强了抗干扰能力强.测试结果表明:系统测距偏差在15 m以内,在阵列正前方±40°夹角内时测向偏差能够保持在3°以内,能够快速有效的获知目标方位距离信息,为小型舰船在复杂干扰环境下的高精度定位提供了一种有效辅助测量手段.%Due to GPS signals to be the poor safety and vulnerability under interference when applied to mini oceanic ship,a VHF radio auxiliary positioning system is designed.In this system,a 5-element linear array is adopted to receive impulse response signal from ship-mounted transponder.FPGA hardware processor implements MUSIC-based direction of arrival(DOA)estimation algorithm.Interval eigenvector decomposition(EVD)module of the processor adopts Jacobi iterative core,which can reduce response time to ms level.Calibration module is realized by coordinate rotation digital computer(CORDIC),which not only saves computation resources but also improves estimation precision.By applying time division multiplexing(TDMA)communication protocol,system software can adjust working frequency and time slot adaptively,which greatly improves anti-jamming effect.The final test results show that,when included angle between azimuth and array normal is less than 40°,distance measurement deviation is within 15 m,and maximum DOA estimation error is within 3°.Therefore,this rapid and precise DOA estimation method provides an effective azimuth measurement approach under complex electromagnetic environment.