基于FPGA的通用PCM接收解码电路的设计

摘要

In order to accurately extract the PCM( Pulse Code Modulation) data received from a telemetry system,a common PCM receiving and decoding circuit based on FPGA is designed. The circuit can receive PCM data of dif-ferent rate by using the bit synchronizer based on phase-locked loop. Its frame synchronizer is based on three-state searching theory so that it can distinguish the data with different structure. The code converter module can convert the six patterns that is NRZ-L/M/S,BiФ-L/M/S. At last the demodulated data is sent to the computer through the USB interface for storage,display and processing. The decoding circuit can identify PCM data stream which has dif-ferent rates, different patterns and different frame synchronizing code groups. It has both single-ended and differential input interfaces,so it has strong versatility in the field of telemetry.%为了准确接收提取某遥测系统的PCM数据，设计了基于FPGA的通用PCM接收解码电路，该电路通过基于锁相环的位同步器实现不同码率的PCM数据流接收，通过三态搜索理论的帧同步器可判别不同帧结构数据，码型转换模块识别并转换NRZ-L/M/S、BiФ-L/M/S 6种码型，最后电路将解调出的数据通过USB接口传送至计算机进行存储、显示和处理。该电路可识别码型不同、码速率不同以及帧同步码组不同的PCM数据流，兼有单端和差分输入接口，在遥测领域具有很强的通用性。