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用双通道相位计测量两信号间的相位关系是一种最常用的方法。由于受噪声影响,信号幅度及相位会产生抖动,造成相位差测量误差。本文探讨检波器前、检波器本身以及检波器后的三种噪声对四探头式超高频相位计的误差、灵敏度及动态范围的影响。分析检波器前的噪声对测量结果的影响时,假定不存在其本身及其后的两种噪声。在双通道相位计(见图2)检波装置输入端上,信号与噪声相互作用而产生的电压可表示如下:
Measuring the phase relationship between two signals using the two-channel phase meter is one of the most commonly used methods. Due to noise, the signal amplitude and phase will produce jitter, resulting in phase error measurement. In this paper, the effects of three kinds of noise before the detector, the detector itself and the detector on the error, sensitivity and dynamic range of the four-probe UHF phase meter are discussed. When analyzing the influence of pre-detector noise on the measurement results, it is assumed that there are no two kinds of noise itself and thereafter. The voltage generated by the interaction of the signal and the noise at the input of the detector of the dual-channel phase meter (see Figure 2) can be expressed as follows: