Research On General Calibration Technology For Automitic Test Equipment

Automatic test equipment is used to detect whether the function and performance of the weapons systems are eligible. Furthermore, periodical calibration is the most important method to assure the validity and effectiveness of the automatic test equipment. With the types and quantity of automatic test equipment are being more and more, the need of general calibration will be much more increasingly, Therefore this thesis focuses on researching on general calibration technology for automatic test equipment.First, this thesis introduces the status of research and development in the general calibration technology for automatic test equipment. Then this thesis analyses the calibration instrument's functional requirement and technical target, By implementing of the design principle of "automated, regulated, generalized", a main scheme that adopts the integrated calibration philosophy is brought forward. The scheme adopts module design philosophy, which reduces the bulk of the system, and improves the reliability and maintainability of the system. According to the calibration instrument's functional requirement, the system is composed of voltage test unit, frequency test unit, waveform generator unit, current source unit and DC voltage generator unit. In the hardware design part , this thesis adopts many key techniques, including sigma-delta A/D converting technology, improved direct digital frequency synthesis (DDFS) technology, and multi-cycle synchronism measurement technology. The application system software using Lab Windows/CVI as the software development platform adopts an automatic calibration software frame based on ODBC technology and database technology. It has achieved the calibration software is relatively independent with the hardware circuit, the operating system and the calibration process, the application of which makes the system greatly improved in terms of flexibility, maintainability and expandability.The test errors of all function modules are theoretically analyzed and simulated on the computer and this thesis proposes to make a scheme correct for the test results, which has been proved reliable and stable during the debugging process. At present, a prototype of the calibration instrument has been accomplished and the experimental results show that the technical performance has met all the design requirements.