中频数字化直接序列扩频接收机的实现

Implement of IF Digital Direct Sequence Spread Spectrum Receiver

给出了统一信道直接序列扩频通信系统的中频数字化接收机的实现方案。采用该方案所实现的直接序列扩频通信系统的载波与伪随机码的捕获分别采用了FFT辅助捕获技术,载波的跟踪采用了数字CPAFC环路牵引,数字COST-AS环路精确跟踪技术,伪码跟踪采用的是数字DLL环路实现。系统中I通道采用可编程GOLD扩频,Q通道采用截断m序列直扩,并置截断m序列与GOLD码具有相同速率、倍周期的关系,以简化系统伪码的同步电路设计。最后,讨论了该系统应用于扩频测距时,测量数据的"置中值"处理方法。

A realization scheme on IF digital receiver of unified channel spread spectrum communication system is introduced. The FFT estimation algorithm is used for carrier and pseudo - random code captures, the CPAFC loop and the COSTAS loop are used for its tracking,GOLD code tracking uses digital DLL loop. These technologies can effectively be used to reduce the Doppler shift to impact on this system performance. When GOLD code synchronization, the same rate and cycle times of GOLD code and truncated m sequence are used for guiding truncated m sequence synchronization rapidly. Finally, a constant resolution and data link method of ＂Median Values＂ is discussed.