Most distortion measuring instruments use fundamental wave suppression method. Its basic principle is to measure the total voltage U of the measured signal (including the fundamental wave) first, and then remove its fundamental wave component from the measured signal through the fundamental wave suppression circuit to obtain the total voltage Ux of each harmonic. Compare the two readings to obtain the nonlinear coefficient (Ux/U). This measurement method is called fundamental wave suppression method. The distortion tester constructed by this principle can directly read the nonlinear distortion coefficient (or distortion).
Beijing Million Electronic Science and Technology Center is a large-scale instrument manufacturer and seller. Its business fields mainly include: gas detectors, metal detectors, environmental protection equipment, medical care, laboratory instruments, chemical instruments and equipment, agricultural instruments, electromechanical equipment, fire safety equipment, power communication equipment, etc., covering almost all industries. The company's product distortion measuring instrument is a new generation of intelligent instrument with multiple functions such as fully automatic measurement of signal voltage, frequency and signal distortion, and it is also a fully digital, fully automatic and multifunctional intelligent instrument in the field of signal distortion measurement in China. GPIB interface can be added to the instrument according to the needs of users.
Distortion measuring instrument is an electronic instrument for measuring nonlinear distortion coefficient.
Uses In audio and high-frequency equipment or systems, due to the nonlinear volt-ampere characteristics of nonlinear sources (diodes, transistors, electron tubes) and the nonlinear effect of ferromagnetic devices, frequency components (harmonics and synthetic frequencies) that are not in the input signal are added to the output signal, resulting in the distortion of the output waveform, which is called nonlinear distortion. In communication systems, it is often necessary to measure the degree of nonlinear distortion in order to take measures to ensure communication quality.
Distortion measuring instruments can be divided into:
① General distortion measuring instrument. The frequency range is 20Hz~20kHz, the measuring range is 0. 1% ~ 100%, and the measuring accuracy is 10%.
② Precision deformation measuring instrument. The frequency range is 2 Hz ~ 200 kHz, the measuring range is 0.0 1% ~ 100%, and the measuring accuracy is 5%. Because the oscilloscope tube is used as a balance indicator, the waveform of harmonics can be observed.
③ Automatic deformation measuring instrument. Adopt automatic balance and digital display structure. The frequency range is1Hz ~110 khz, the measuring range is 0.003% ~ 100%, and the measuring accuracy is 2%. It can also measure frequency, voltage and level.
④ Intermodulation distortion measuring instrument. Electronic instrument for measuring nonlinear distortion based on two-tone method. Because in the electro-acoustic system, the input signal is not a single audio, when there is nonlinear distortion in the system, there are various combined frequencies in the waveform of the output signal besides harmonic components. The measurement frequency of dual-tone method can be arbitrarily combined between the high-end frequency of 3, 5, 7, 10, 15, 20kHz and the low-end frequency of 40, 50, 70, 100, 200, 300Hz. The measuring range is 0. 1% ~ 100%, and the measuring accuracy is 10%.