Bit Design Criteria And Evaluation Methods For Study

With the development of the avionic technique, airborne equipment becomes more and more complicated. And high reliability and maintainability level of the electronic equipment is required. Improving the fault diagnosis ability and system reliability, the BIT (Built-in Test) takes an important role in the area. As BIT design is made respectively by the product manufacture, there is not a unitive, normal and general standard. There is not a unique evaluation criterion for the fault diagnosis ability of BIT too. So it is necessary to research the design rule and evaluation method of the BIT.First, the fault reasons and fault types of digital system are analyzed, the typical function circuit of the digital system is divided reasonably, and their fault models are set up respectively. The rules of the BIT design and the testing point selection are summarized. The shortages of the traditional testing method for a functional circuit are analyzed, and a refined software and hardware testing method for the important functional circuit is proposed.Then, the systematic fault validation method based on C language simulation and the hardware fault simulated testing method based on Multisim are presented, according to the specialities of BIT detection. A sampling plan based on binomial distribution is proposed, the testability of the system is evaluated, and the testability parameter design conformance is verified.Finally, the influence of the designed BIT circuits on the reliability and maintainability of the original system is analyzed.The combined software and hardware simulation testing method is successfullyverified by simulation testing results. The data of fault simulated testing is analyzed, calculated and evaluated, and the conformance of system testability design based on BIT design rule of function circuit fault modeling is verified.