Telemetry For The Design Of The Thermal Recorder

Wireless telemetry is a significant test technique by which characteristics of the aerocraft can be described exactly and the safety of the aerocraft also can be ensured .In this paper, the method of wireless telemetry is presented. Considering of the multi-channel signals acquisition, a project of the PCM signal wireless acquirement system is put forward. In this system, a PCM demodulation board is designed. It can decode the PCM code strings which contain the information of the multi-channel signals. A print Board is also designed to receive signals after demodulation on heat-sensitive papers. CPLD is used in the project to digitize the system and reduce the design cost of terminals. Approved by experiments, the project can not only demodulate and print PCM signals but also cut down the volume of the system and achieve the reconfiguration. In chapter 2 and chapter 3, the whole project of the telemetry system and the terminal is brought forward and a brief introduction of my task in this system is also given. In chapter 4, the design method and circuit of the PCM demodulation board are provided ,then the consult of waveform emulation on the software flat of MAXPLUS II is followed. It is proved that the scheme is feasible. It is absolutely necessary to demodulate the time-coordinated signal for a real-time system. The format of the time-coordinated signal and the demodulation circuit are given in chapter 5. In chapter 6,the design project of the telemetry signals record on heat-sensitive papers is introduced including the mechanical structure of heat-sensitive head,the D/A switch of signals,the drive of step-motors. Part of this section is realized on CPLD with the programming language of VHDL. Some programs are offered and interpreted. In the end, the consult of waveform emulation is provided.