电光与控制
電光與控製
전광여공제
ELECTRONICS OPTICS & CONTROL
2014年
2期
80-84
,共5页
GPS接收机%载波跟踪环%鉴相器%鉴频器%CORDIC
GPS接收機%載波跟蹤環%鑒相器%鑒頻器%CORDIC
GPS접수궤%재파근종배%감상기%감빈기%CORDIC
GPS receiver%carrier tracking loop%phase discriminator%frequency discriminator%CORDIC
目前GPS接收机载波跟踪环路往往采用易于硬件实现，但精度不高、跟踪速度慢的鉴别器。针对该现状，在现有CORDIC算法基础上加以改进，并在FPGA上完成了二象限反正切鉴相器和四象限反正切鉴频器的设计。在原有CORDIC算法上加入象限转换和相位转换功能，使反正切计算范围扩大至-180°～180°；通过增加鉴频器门限设定，消除了导航电文翻转带来的误差。该设计方案使载波跟踪鉴别器共用一个反正切模块，减少了硬件资源。最终仿真结果表明：改进后的鉴别器提高了鉴相与鉴频的精度，加快了稳定跟踪的速度。
目前GPS接收機載波跟蹤環路往往採用易于硬件實現，但精度不高、跟蹤速度慢的鑒彆器。針對該現狀，在現有CORDIC算法基礎上加以改進，併在FPGA上完成瞭二象限反正切鑒相器和四象限反正切鑒頻器的設計。在原有CORDIC算法上加入象限轉換和相位轉換功能，使反正切計算範圍擴大至-180°～180°；通過增加鑒頻器門限設定，消除瞭導航電文翻轉帶來的誤差。該設計方案使載波跟蹤鑒彆器共用一箇反正切模塊，減少瞭硬件資源。最終倣真結果錶明：改進後的鑒彆器提高瞭鑒相與鑒頻的精度，加快瞭穩定跟蹤的速度。
목전GPS접수궤재파근종배로왕왕채용역우경건실현，단정도불고、근종속도만적감별기。침대해현상，재현유CORDIC산법기출상가이개진，병재FPGA상완성료이상한반정절감상기화사상한반정절감빈기적설계。재원유CORDIC산법상가입상한전환화상위전환공능，사반정절계산범위확대지-180°～180°；통과증가감빈기문한설정，소제료도항전문번전대래적오차。해설계방안사재파근종감별기공용일개반정절모괴，감소료경건자원。최종방진결과표명：개진후적감별기제고료감상여감빈적정도，가쾌료은정근종적속도。
Discriminators in carrier tracking loop of GPS receiver are often good at hardware design,but poor at accuracy and tracking speed .Aiming at this actuality,we made an improvement based on the existing CORDIC ( coordinate rotation digital computer ) algorithm,and achieved the design of a two-quadrant arctangent phase discriminator and a four-quadrant arctangent frequency discriminator in FPGA .The functions of quadrant conversion and phase conversion were added to the original CORDIC algorithm,thus the arctangent calculation range was expanded to-180°~180°.The error caused by navigation message inversion was eliminated by adding threshold setting to discriminators .Because it made the phase discriminator and the frequency discriminator share the same arctangent module,so it was able to reduce hardware resources .The simulation results indicated that the improved discriminators can achieve better accuracy of discriminating phase and frequency,and can also accelerate the stable tracking speed .
