The Design And Implementation Of WLAN Terminal Radio Frequency Automatic Test System

Automatic test system is capable of realizing measurement automation, fault diagnosis, data processing, storage, transmission, and display or output in an appropriate manner. It integrates the computer technology, virtual instrument technology, information technology and database management technologies together to form a powerful platform for the modern complex electronic equipments testing and maintenance. In modern society, the status of testing technology is constantly upgrading and testing technical level also reflects a country's productivity level. In order to improve testing speed and testing accuracy, eliminating the human factor influence, the testing areas are in the promotion of the use of automatic test systems as a means of testing which has become increasingly evident to be the mainstream.Described in this article, the WLAN terminal RF automatic test system is mainly used by national Radio Frequency Spectrum Monitoring and Testing. Center for the Type Approval testing, which is aimed at ensuring all devices communicate with each other successfully within the network and promising equipments of different systems in the same bands work properly. For WLAN products testing, it is necessary to inspect whether the equipment is able to complete the function of the need to achieve, to meet the performance requirements, to comply with the 802.11 standards to ensure products can be a reliable, stable and secure operation. As a large number of wireless LAN terminals urgently needed to be certified, long-time continuous RF test is essencial.This system is based on GPIB bus and virtual instrument technology, on the 802.11 standard which is able to automatically test the RF terminal and generate the report. It adopts multi-system design, according to the type and working frequency of the devices under test to choose different test subsystems execute test. These subsystems will adopt a consistent design style in order to maintain the overall unity.The system comprises testing program sets, PC machine, GPIB bus and testing instruments. By means of operating the PC, the automatic test software controls testing instruments in the appropriate test environment in the implementation of the test items, saveing the results, completing the test results processing and displaying, test report generation and so on. At the same time, it can be combined with the background database, completly and timely save the basic information of the device under testing, testing project information, the testing results corresponding to the test items, testing instruments'basic parameters and information and so on. In the Software design process, we make full use of the virtual instrument technology, platform and modular design of programs to achieve system scalability, portability, reusability.This paper firstly introduces the development of WLAN technology, to clarify the practical significance of this paper. Then it introduced the current mainstream standard, which leads to the system involved in the WLAN terminal type approval test items and test methods, test items described in detail and the definition and purpose of the test, manual testing process. After that, it introduced the development of automatic test systems and virtual instrument technology, followed by software and hardware separately described in detail for the automatic test system design. Hardware components included hardware selection and interconnection, as well as GPIB bus, etc. In software design and development part, based on the of analysis of items in the software requirements, the general framework and database design is given, and gives concrete realization method of the main modules under this program Finally, some examples of system operation is demonstrated and a large number of testing results is showed comparing with manual testing, which fully proves the system's stability and superiority. In the last part, a brief description of the basic concepts of uncertainty and the method of evaluation processes is issued. Accordingly, mathematical models and mathematical approach for the uncertainty of RF conduction calculation in use of the automatic test system is given to Calculate and report the uncertainty of this system. Finally, according to the report of the analysis, we propose effective recommendations to reduce the uncertainty of this system.