The Study Of Programmable Telemetry Signal Acquisition And Encoding System Based On DSP And CPLD

Through the research of data-acquiring technique,a suit of programmable telemetry signal acquisition and encoding system based on DSP(Digital Signal Processing) and CPLD(Complex Programmable Logic Device) is designed. A basic PCM system is introduced in detail,then a complete technique project is brought forward according to this system's requirement. This system is constituted by four modules:analog signals acquisition module,digital signals acquisition module,CPLD control module and central DSP module.The Digital Signal Processor(DSP) is the brain of the system,and analog signals and digital signals are acquired,stored and handled by DSP,at last a standard serial PCM data is outputted.All conversion circuits and control signals that other modules require are produced by CPLD. Aanalog signals acquisition module and digital signals acquisition module are the interface between the system and the external signals. The DSP chip that the system select is TMS320VC5409,and it's high-speed operation capacity meets the system's requirements.Two on-chip peripherals in DSP,Multichannel Buffered Serial Port(McBSP) and Direct Memory Access(DMA),are introduced in detail.Because these on-chip peripherals could be set by the software,if they are made use of well,not only data output process is simplified,but also less resource from DSP CPU is taken by data acquisition process.The high integration characteristic of CPLD simplify the hardware design,reduce the system's developing period and enhance the system's reliability and security.In addition, the ISP(In System Programmable) performance make system's development more convenient. DSP+CPLD mode make this system rather programmable,and system's operation state could be changed easily. The interface between the system and the external signals could be expanded by CPLD,so the system's data acquisition capacity is enhanced.Because DSP is the core of the system,asynchronous serial signals could be acquired directly. In addition,telemetry data could be specifically handled by means of the given applied programme,as if a base is ready for the future applications. It is shown from the final debugging results that the system's encoding error meets the technical requirements and the designing scheme is feasible.Finally,some experiences on the basis of these problems involved during design are introduced,and some suggestions about improving system's performance are put forward.