本文基于數字信號處理中信號經過多次疊加平均后，信號中的隨機噪聲將被消除的原理，設計了一種針對周期性信號的隨機噪聲消除電路。該電路主要由鎖相倍頻、周期延時及放大電路組成。本文對該電路的原理進行分析，并通過實驗對包含有較大隨機干擾的周期性信號進行處理，得到了消除各種隨機干擾的檢測信號。該電路目前已成功用于EAS系統中的隨機干擾信號的消除。

　　Abstract:

　　Based on the theory that the random noise of digital signal will be eliminated after multiple stacking average， this article designed a random noise elimination circuit aiming at periodic signals. The circuit was mainly consisted of phase-locked frequency circuit， cycle delay circuit and amplifying circuit. This paper analyzed the theory of the circuit， processed periodic signal that contained a large random interruptions in the experiment， and got detection signal which could eliminate all kinds of random interruptions. The circuit has been successfully used in EAS system to eliminate the random interruptions signal.