Dual-phase lock-in amplifier based on DSP (Digital Signal Processor) and LabVIEW

Abstract

The invention discloses a digital dual-phase lock-in amplifier based on a DSP (Digital Signal Processor) and LabVIEW, belongs to the field of weak signal detection, and aims to solve the problem of poor detection effect on weak sinusoidal signals of known frequencies submerged in noises in existing medium and low-level dual-phase lock-in amplifiers. The digital dual-phase lock-in amplifier comprises a signal conditioning module, a DSP module and a LabVIEW software module, wherein the signal conditioning module is used for inputting tested signals into the DSP module after amplification, low-pass filtering and direct-current biasing; the DSP module is used for sampling the conditioned tested signal to obtain a tested signal sequence, generating a sinusoidal reference signal sequence and a cosine reference signal sequence having the same frequency as the tested signals, multiplying the sinusoidal reference signal sequence and the cosine reference signal sequence with the tested signal sequence respectively, and transmitting results of two multiplying operations; and the LabVIEW software module is used for receiving the results of the two multiplying operations, performing the low-pass filtering on the results to obtain stable direct-current constants, solving amplitudes and phases of the tested signals according to the direct-current constants, and displaying the amplitudes, phases and waveforms of the tested signals. The digital dual-phase lock-in amplifier is used for detecting the weak signals submerged in the noises.

Description

technical field [0001] The invention belongs to the field of weak signal detection, in particular to a dual-phase lock-in amplifier based on DSP and LabVIEW. Background technique [0002] The lock-in amplifier is based on coherent detection technology, using the frequency of the reference signal to correlate with the frequency of the signal to be measured, and not correlated with the frequency of the noise, and then extracting useful signals from a strong noise background. The most effective means of weak signals. At present, lock-in amplifiers are widely used in weak voltage and current signal detection, pollution gas detection, trace substance concentration detection (such as: chlorophyll, bacteria, etc.), medical detection, optical signal detection, light source scattering characteristic measurement and other research. [0003] The traditional lock-in amplifier is completely implemented by analog components. The analog lock-in amplifier technology has been developing, bu...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the detection effect of the existing low-end dual-phase lock-in amplifier is not good enough to the weak sinusoidal signal of known frequency annihilated by noise. The present invention provides a digital dual-phase lock-in amplifier based on DSP and LabVIEW. lock-in amplifier

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