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随着科学技术的发展,检测淹没在噪声中微弱的周期信号已日益迫切了。通常的高 Q 值选频方法,当其被测信号的信噪比低于6dB(即4:1时),就很难实现。相关理论指出,噪声是随机的,而被测的微弱周期信号是相关的,如进行 N 次同相迭加积累后,可以使被测信号的信噪比有 N~(1/2)倍的提高。本文介绍的选频放大器指标如下:(1)输入信号分400Hz、800Hz、1kHz、2kHz四档,每档可调频率范围不小于其标值的±5%;
With the development of science and technology, it is increasingly urgent to detect periodic signals submerged in the noises. The usual high-Q frequency selection method, when the measured signal SNR is less than 6dB (ie, 4: 1), it is difficult to achieve. Relevant theories point out that the noise is random, and the weak periodic signal under test is correlated. For example, N times (1/2) times the signal-to-noise ratio of the signal under test can be improved . This article describes the frequency selective amplifier indicators are as follows: (1) the input signal points 400Hz, 800Hz, 1kHz, 2kHz fourth gear, adjustable frequency range of each file is not less than ± 5% of its value;