【摘要】 特高频(Ultra-High-Frequency, UHF)局部放电接收机中，混频技术具备较强的抗干扰性，适用于变电站等复杂的工业应用场景，但在下变频时存在3dB镜像频谱干扰。为了解决干扰问题，文中设计了一种改进的正交混频镜像干扰抑制方法，局部放电信号经带通滤波、低噪放后，采用正交混频处理办法，输出I、Q两路正交零中频模拟信号，经抗混叠滤波、放大、ADC采样转换成数字信号，在数字域内通过高四倍采样时钟实现Q路信号向后移相90°,再将缓存的I路信号进行合并，实现数字域信号叠加，完全消除镜像频率干扰，提高UHF局部放电接收机灵敏度与检测可靠性。更多还原

【Abstract】 In Ultra-High-Frequency(UHF) partial discharge detector system, mixer technique has anti-interference 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, amplification 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 superposition of digital domain signals, completely eliminate the image frequency interference, and improve the sensitivity and detection reliability of UHF partial discharge receiver.更多还原