Study Of Weak Signal Detection And Acquisition Technology

When researching on macroscopical and microcosmic world, the weak signal detection is needed. Much internal noise exists in traditional detection instruments and the signal is covered by noise, so the useful signal can't be detected by using amplifier and filter. Because the periodicity and the correlation of signal and the randomicity of noise, the noise can be wiped off by correlation detection and chaotic oscillator.In this paper, according to the Wiener-Khinchine theorem: auto-corrlation function and the power spectrum function are two Fourier transformations. With this theory, the correlation can be realized by software. Digital LIA (Lock-in amplifier) changes correlation to the power spectrum computation.In this paper, according to the characteristic of Duffing equation: chaotic oscillator is immune against the white noise and the periodical signal whose frequency is different to the inherent frequency of chaotic oscillator. Therefore, the detected signal can be gained by detecting the intermittent chaotic periodicity of chaotic oscillator. Firstly, the detected signal is put into the chaotic oscillator array. One chaotic oscillator in the chaotic oscillator array will be in the intermittent chaotic state due to the characteristic of chaotic oscillator. Then the frequency and amplitude of detected signal can be obtained.In this paper, weak signal acquisition card based on S3C4510 of Samsung is designed whose responsibility is to control AD and USB, to complete the weak signal detection arithmetic. This acquisition card transmits data to host computer by USB which is plug-and-play and universal. Therefore, the weak signal detection equipment is digital, multiple and microcomputer-realized.