| As a special airborne equipment, the flight data recorder can provide comprehensive and objective method to keep the aircraft safe and find the cause of the accident. The signal processing circuit is the key to processing and transfer data in the flight data recorder. It has a great significance to guarantee the normal work of the flight data recorder and to improve the safety level of the flight data recorder.In this paper, a method to design a simple, flexible and low-cost signal processing circuit based on ground verification application is present. Firstly, an overall scheme of the signal processing circuit is proposed, according to the design requirements, the performance, the cost and the period. And the selection of the main components in circuit is confirmed by the scheme. Secondly, hardware and software design of the system are described in detail. Hardware design which centers on the AVR microcontroller includes circuit design and PCB design of fore-acquisition circuit, channel selection circuit, signal amplifier circuit, A/D converter, serial communication circuit, ARINC429 data sending and receiving circuit, CPLD minimum system and power circuit. Software design is mainly to finish the design of SCM control software, address decoding software and PC interface. SCM control software is used to control the circuit to finish acquisition, processing and transmission of the signal. Address decoding software makes CPLD control the gating of peripheral device. PC interface is used to check data processing in PC in real time. In the end, it is necessary to debug and test the system. And problems arise in debugging and the corresponding solutions are described in detail. The test results show that the signal processing circuit can meet target requirements.The signal processing circuit designed in this paper has many advantages like low-cost, anti-interference and easy upgrade. So it can provide a good support for verifying electrical character of the flight data recorder on ground. |
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