In Ultra-High-Frequency(UHF)partial discharge detector system,mixer technique has anti-in-terference function suit to complexed industrial scenario,such as power transformer substations,but there is 3dB image spectrum interference in down conversion.In order to solve the interference problem,this paper proposes an improved orthogonal mixer image interference suppression method.After band-pass filtering and low noise discharge,the partial discharge signal is processed by orthogonal mixing.Then I and Q orthogonal zero if analog signals are output and converted into digital signals through anti-aliasing filtering,amplifica-tion and ADC sampling.In the digital domain,the Q-channel signal is shifted backward by 90° through a high quadruple sampling clock,and then the cached I-channel signals are combined to realize the superpo-sition of digital domain signals,completely eliminate the image frequency interference,and improve the sensitivity and detection reliability of UHF partial discharge receiver.
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