dPMR接收机定时估计算法及FPGA实现
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摘要
符号定时同步的准确度对数字通信系统解调性能有极大影响,dPMR通信系统要求接收机的符号同步具有快速捕获和良好跟踪性能的特点。针对该要求,提出一种定时估计算法。该算法结合前导码定时算法和数字平方滤波算法的优点,首先捕捉突发信息的前导码,使用前导码定时算法实现高精度快速定时估计,之后以384个符号为间隔,使用数字平方滤波算法实现定时估计的跟踪校正。同时提出一种结构简单的FPGA实现方案,相对于经典的同步波形匹配滤波定时算法,不仅提升了接收机的解调性能且节约了硬件资源。
The accuracy of symbol timing synchronization has a great impact on the demodulation performance of digital communication systems. The dPMR communication system requires the symbol synchronization of the receiver to have fast acquisition and good tracking performance. A timing estimation algorithm is proposed for this requirement. The algorithm combines the advantages of preamble timing algorithm and digital square filtering algorithm. Firstly, when the preamble of the burst information is captured, the preamble timing algorithm is used to implement high-precision fast timing estimation. Then, a digital square filtering algorithm is used to implement tracking correction for timing estimation at intervals of 384 symbols. At the same time, a simple FPGA implementation scheme is proposed. Compared with the classical matching filter timing algorithm based on synchronous waveform, it not only improves the demodulation performance of the receiver but also saves hardware resources.
The accuracy of symbol timing synchronization has a great impact on the demodulation performance of digital communication systems. The dPMR communication system requires the symbol synchronization of the receiver to have fast acquisition and good tracking performance. A timing estimation algorithm is proposed for this requirement. The algorithm combines the advantages of preamble timing algorithm and digital square filtering algorithm. Firstly, when the preamble of the burst information is captured, the preamble timing algorithm is used to implement high-precision fast timing estimation. Then, a digital square filtering algorithm is used to implement tracking correction for timing estimation at intervals of 384 symbols. At the same time, a simple FPGA implementation scheme is proposed. Compared with the classical matching filter timing algorithm based on synchronous waveform, it not only improves the demodulation performance of the receiver but also saves hardware resources.
引文
[1]ETSI TS 102 658 V2.5.1(2015-07).Digital Private Mobile Radio(dPMR)using FDMA with a channel spacing of6,25 kHz[S].Sophia Antipolis Cedex:ETSI,2008.
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[5]陈曦.基于匹配滤波的dPMR标准码元同步器设计与实现[J].电声技术,2013,37(11):56-58.
[6]游顺.DMR终端符号同步实现技术[D].成都:电子科技大学,2012.
[7]LI X,GUO W.Efficient differential coherent accumulation algorithm for weak GPS signal bit synchronization[J].IEEECommunications Letters,2013,17(5):936-939.
[8]王申卓,胡春林,胡广垠,等.基于CORDIC改进算法的NCO设计[J].电子技术应用,2017,43(3):43-47.
[2]HUANG Y,FAN K,HUANG C.A fully digital noncoherent and coherent GMSK receiver architecture with joint symbol timing error and frequency offset estimation[J].IEEE Transactions on Vehicular Technology,2000,49(3):863-874.
[3]沈文丽,张屹,赵民建,等.基于数据辅助的CPFSK信号的定时估计[J].浙江大学学报(工学版),2007(12):2026-2030.
[4]OERDER M,MEYR H.Digital filter and square timing recovery[J].IEEE Transactions on Communications,1988,36(5):605-612.
[5]陈曦.基于匹配滤波的dPMR标准码元同步器设计与实现[J].电声技术,2013,37(11):56-58.
[6]游顺.DMR终端符号同步实现技术[D].成都:电子科技大学,2012.
[7]LI X,GUO W.Efficient differential coherent accumulation algorithm for weak GPS signal bit synchronization[J].IEEECommunications Letters,2013,17(5):936-939.
[8]王申卓,胡春林,胡广垠,等.基于CORDIC改进算法的NCO设计[J].电子技术应用,2017,43(3):43-47.