A Switching Equipment With Self-examination & Self-protection For Horizons

The horizon as one of the most important airborne equipments is used to reflect the airplane's pose. This paper mainly discusses the design of the switching equipment used in the new test system for the horizon BDP-4.The switching equipment as the key component of the test system is used to control the whole measuring procedure. The switching equipment uses single-chip microcomputer and CPLD to design the control module. The measuring module uses the array of relays and current sensors to control the measurement of several voltages, currents and resistances. And the switching module switches several AC and DC power supplies and signals of the horizon system. The switching equipment can be remote controlled by the host computer with the RS232 interface. Its array of relays has the self-examining and self-protecting function, which improves the testing reliability and safety.The paper firstly discusses the whole function, the design scheme and the internal structure of the switching equipment based on the horizon BDP-4 principle and the whole test system scheme. Then, the hardware design of all modules, as well as the operation flow of the system and the software design are discussed in detail. Finally, the way to design the PCB boards and EMC consideration are presented. And the reliability of the software and hardware is also given.The new horizon BDP-4 test system using the switching equipment as key component with the characteristics of high measuring precision, automation and intelligent level has been used in aeronautic service factories.