A Device for Generating and Measuring Multiple Distorted Signals

To address the issue of signal distortion caused by nonlinear components in circuits, a device capable of generating and measuring multiple types of distorted signals was designed and implemented. The hardware structure of the device consisted of signal generation, signal selection, MCU control, local display and interaction, wireless transmission, and other auxiliary circuits. In the software, a MCU timer was used to control the ADC for signal voltage acquisition, and a DMA channel was enabled to improve data transfer speed. A DSP library was deployed to perform a fast Fourier transform (FFT) on the signal, after which the total harmonic distortion (THD) value was calculated by measuring the amplitudes of the first five harmonics. Test results indicated that for an input signal with a peak-to-peak voltage ranging from 20 mV to 3 V and a fundamental frequency between 1 kHz and 100 kHz, the device could control the output of five types of signals: top distortion, bottom distortion, bidirectional distortion, crossover distortion, and no obvious distortion through local interaction and mobile app. The mean absolute error in THD measurement for all five signal types, across various distortion levels, was found to be less than 0.008. The device has a fast response speed, supports human-machine interaction, data storage and traceability, providing a visual teaching tool for understanding the signal distortion mechanism and THD measurement, and offering a technical reference for the development of novel signal processing devices.