Time delay measuring system and method for analog mixer and low-pass filter

Abstract

The invention discloses a time delay measuring system and method for an analog mixer and a low-pass filter. The time delay measuring method comprises the steps that the analog mixer and the low-pass filter are used for high carrier frequency narrow bandwidth signals, based on a phase unwrapping method and three parameter sinusoidal approximation method and with a high-resolution oscilloscope, downconversion time delay of the analog mixer and the low-pass filter is measured; frequency reducing is carried out on high carrier frequency narrow bandwidth FM signals through the analog mixer and thelow-pass filters , the high carrier frequency is reduced to a lower level, so that the FM signals can be collected by using a lower sampling rate; and by changing the frequency of the modulated signals or the carrier frequency, FM signals of different narrow bandwidths or different carrier frequencies are obtained, through demodulation and calculation, the time delay of the analog mixer and the low-pass filter at different frequency points or different carrier frequencies are obtained and compensated, and thus the measurement accuracy is improved. The time delay measuring system and method have the advantages of simple measuring process and wide frequency range.

Description

technical field [0001] The invention belongs to the field of vibration and test measurement, and more specifically relates to a method for improving the precision of laser interferometry. Background technique [0002] In recent years, heterodyne laser interferometers have been widely used in vibration sensor calibration. The performance of vibration calibration mainly depends on the accuracy and real-time performance of vibration measurement, as well as the acquisition and demodulation of heterodyne interference signals. Laser interference signals are usually collected using the Nyquist sampling method, which requires equipment with high sampling rate and large memory, which increases the cost of measurement. However, using analog mixers and low-pass filter analog devices to down-sample laser interference signals will cause The introduction of time delay reduces the measurement accuracy. By measuring the time delay of the analog mixer and low-pass filter, the delay correcti...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the shortcomings of low measurement accuracy due to the time delay of analog devices introduced by the current heterodyne laser vibrometer method, the implementation example of the present invention provides an analog mixer and low-pass filter time delay measurement system, including:

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