Design of Digital Measurement System for Sensor Signal Distortion Based on Undersampling Theory

Based on the single chip microcomputer (MSP432P401R) as the core, automatic gain control (AGC) circuit, signal conditioning circuit, LCD display module, frequency measurement circuit, wireless transmission module and other circuits as peripheral modules constitute the overall system scheme. In the processing part of analog to digital converter (ADC) signal acquisition, the principle of undersampling in signal acquisition is adopted. Through theoretical analysis, the effective high-order harmonic components are extracted in the case of spectrum aliasing, so that the complete high-frequency signal waveform can be obtained at lower sampling frequency, and then the fundamental and high-order harmonic components in the signal are analyzed to obtain the total harmonic distortion (THD). Based on reliable hardware design and software algorithm, the function of distortion measurement is realized, which has the advantages of high precision, fast response and high integration.