Design Research On Frequency Measuring Project Of EPIRB Tester

EPIEB is one of the essential distress position alerting equipments used in COSPAS/SARSAT System, it has been widely used in sailing vessel due to the ability to alarm shipwreck quickly and effectively at present. As the testing equipment, EPIRB tester is responsible for the important work to assess the performance of EPIRB.Firstly, the frequency detecting indexes of the beacon are introduced. Secondly, direct frequency measuring method, multi-periods pulse synchronization frequency measuring method, vernier method, analog interpolation frequency measuring method and continuous frequency measuring method are compared and analyzed. In comparison, the method based on the phase coincidence points between two periodic signals is better. By using the equivalent phase cycle to control the phase coincidence points identificating gate and adding reference frequencies, the phase coincidence frequency measuring method is improved. The accuracy is improved because two different measurements happen in one time. The BP neural network is built to analog the improved frequency measuring system and estimate parameters to simplify the selection of frequency sources.Simulation results show that the improved phase coincidence points frequency measuring method can reduce signal counting errors and weaken the impact of the integer multiple relationship between the reference signal and measured signal.In the end, the research work is summarized, the advantages and further research directions are analyzed.