Dual-phase lock-in amplifier based on dsp and labview
A technology of lock-in amplifiers and operational amplifiers, applied in amplifiers, parametric amplifiers, amplifier types, etc., can solve the problem of weak sinusoidal signal detection effect is not good enough, and achieve the effect of friendly interface, fast data operation and processing, and low cost
Active Publication Date: 2017-11-17
HARBIN INST OF TECH
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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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[0040] combine figure 1 Illustrate this embodiment, the digital dual-phase lock-in amplifier based on DSP and LabVIEW described in this embodiment, described lock-in amplifier comprises signal conditioning module, DSP module and LabVIEW software module;
[0041] The signal conditioning module includes a preamplifier circuit, a low-pass filter circuit and a bias and protection circuit. The measured signal is amplified by the preamplifier circuit and then input to the low-pass filter circuit, and the measured signal filtered by the low-pass filter circuit is input to the Bias and protection circuit, the signal to be tested after DC biasing by the bias and protection circuit is input to the DSP module;
[0042] The pre-amplification circuit is used to amplify the weak signal that is annihilated by noise, so that it can reach the range suitable for detection. The low-pass filter circuit eliminates part of the high-frequency noise to reduce the amount of subsequent data processing....
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A digital dual-phase lock-in amplifier based on DSP and LabVIEW belongs to the field of weak signal detection. In order to solve the problem that the detection effect of the existing low-end dual-phase lock-in amplifiers is not good enough for the weak sinusoidal signal of known frequency that is annihilated by noise. It includes: the signal conditioning module amplifies, low-pass filters and DC biases the measured signal and then inputs it to the DSP module; the DSP module is used to sample the conditioned measured signal to obtain the measured signal sequence; generate and be measured The sine reference signal sequence and the cosine reference signal sequence with the same frequency as the measured signal are multiplied with the measured signal sequence respectively, and the results of the two multiplication operations are sent; the LabVIEW software module is used to receive the results of the two multiplication operations, and Perform low-pass filtering on it to obtain a stable DC constant, calculate the amplitude and phase of the measured signal according to the DC constant, and display the amplitude, phase and waveform of the measured signal. Used to detect weak signals drowned out by noise.
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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IPC IPC(8): H03F7/00H03L7/00
Inventor 齐超黄奕毅张文生张渤晗
Owner HARBIN INST OF TECH