Weak signal detection device with strong anti-interference performance

Abstract

The invention discloses a weak signal detection device with strong anti-interference performance, the weak signal detection device comprises a filter circuit, a pre-amplification circuit, a lock-in amplifier, a multi-channel amplification circuit, a multi-channel AD acquisition circuit, a DSP, a CAN box and an upper computer which are electrically connected together in sequence, the filter circuitreceives signals, and the lock-in amplifier comprises a modulation module. The device disclosed by the invention is used for a direct current signal or a slow change signal with smaller amplitude; inorder to prevent adverse effects of 1 / f noise and direct current drifting (such as temperature drifting of input offset voltage of an operational amplifier) of direct current amplification, a modulator or a chopper is generally used for converting the direct current drifting into an alternating current signal, then the alternating current signal is amplified and processed, and then demodulation and low-pass filtering are carried out to obtain an amplified detected signal. The weak signal detection device designed based on the lock-in amplifier shows excellent performance in the aspect of weaksignal detection.

Description

technical field [0001] The invention belongs to the field of oil field logging, in particular to a weak signal detection device with strong anti-interference performance. Background technique [0002] In oil and gas evaluation, weak signal not only means that the amplitude of the signal is small, but also mainly refers to the signal submerged by noise. For various weak signals to be measured, such as weak light, weak magnetism, micro pressure, micro vibration, micro temperature difference, etc., they are generally converted into micro current or low voltage by corresponding sensors, and then amplified by amplifiers to achieve Indicates the size being measured. However, because the measured signal is weak, the background noise of the sensor, the inherent noise of the amplifier circuit and the measuring instrument, and the external interference noise are often much larger than the amplitude of the useful signal. The process of amplifying the measured signal also amplifies the...

AI Technical Summary

Problems solved by technology

However, because the measured signal is weak, the background noise of the sensor, the inherent noise of the amplifier circuit and the measuring instrument, and the external interference noise are often much larger than the amplitude of the useful signal. The process of amplifying the measured signal also amplifies the noise , and will inevitably add some additional noise, such as the internal inherent noise of the amplifier and external interference noise, so the weak signal cannot be detected only by amplification

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