In order to collect useful signal without distortion for ultra-high frequency detection

this paper proposed a signal conditioning and collecting system using the mixing principle to realize frequency-shift of UHF partial discharge in power transformer by virtue of ARM microprocessor.Customer software was coded based onμC/OS-Ⅱoperation system to process and calculate the signal Various phase distributions and statistical operator were extracted.The results show that the signal conditioning unit based on the mixing principle can reach a very good down-changing function of time-domain signal with UHF narrow band

and it can supply a variety of exact and credible characteristic parameters for partial discharge pattern recongnition.