非相干扩频接收机伪码跟踪环设计及FPGA实现

伪码跟踪环的设计是实现非相干扩频接收机的关键环节。为了实现非相干扩频接收机的伪码跟踪,设计了能量归一化的延迟锁定跟踪环,给出了环路的实现结构及环路参数的计算方法。分析了非相干扩频的特点,指出环路设计的关键点,在此基础上阐述了码环鉴别器、环路滤波器、超前滞后码发生器的设计及实现方法,并给出一套具体的实现参数。Modelsim仿真结果及FPGA实测数据表明所设计的环路能对伪码进行精确跟踪。

Design and FPGA realization of code tracking loop in noncoherent spectrum spread receiver

The design of code tracking loop is a key sector of the realization of noncoherent spectrum spread receiver.In order to realize the code tracking in noncoherent spectrum spread receiver,an energy-normalization digital delay-locked loop was designed,the structure of the loop and the calculating procedure of loop parameters were introduced.The characteristic of noncoherent spectrum spread was analyzed first,and then the key point of the loop design was pointed out.Based on this,the design and realization methods of code loop discriminator,loop filter,early and lag code generator were expatiated.A set of specific loop parameters were introduced as well.Modelsim simulation results and FPGA actual measured data prove the precise code tracking ability of the design.