Method and system for real-time calibration of FMCW linearity in terahertz imaging

Abstract

The invention discloses a method and system for real-time calibration of frequency modulation continuous wave linearity in terahertz imaging. The method comprises: mixing an echo signal reflected by a measured target with a terahertz signal to obtain a baseband signal; dividing the baseband signal into Carry out calibration calculations for two channels; one of them filters out coupling signals through band-pass filtering to obtain baseband signals carrying target information, and the other channel is used as real-time calibration data to calibrate each pulse in real time during calibration calculations; and filter out random signals before calibration calculations. Phase noise and converting acquired data to complex data. The invention can calibrate each pulse in real time, ensures the time consistency of the calibration data and the target echo data, realizes the real-time calibration, and filters out the coupling signal at the same time, thereby ensuring the system sensitivity. It has a good effect in the terahertz imaging measurement where the random phase noise is large and the measurement accuracy is high.

Description

technical field [0001] The invention belongs to the technical field of terahertz imaging, and in particular relates to a real-time calibration method and system for frequency modulation continuous wave linearity in terahertz imaging. Background technique [0002] Terahertz imaging technology has the advantages of high spatial resolution, strong anti-interference ability, and harmless to the human body. It is widely used in security inspection and anti-terrorism, medical diagnosis, atmospheric and environmental detection and other fields. Among terahertz imaging systems, terahertz FMCW radar has attracted extensive attention due to its ultra-high imaging resolution. Ideally, the frequency modulation slope of the signal in the radar system is a constant, the frequency of the transmitted signal changes linearly, and the range resolution of the radar is only related to the bandwidth of the transmitted signal. However, in actual situations, the FM slope of the sending and receiv...

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Problems solved by technology

[0008] Aiming at the deficiencies in the prior art and solving the problem of how to measure the calibration body and the measured object in real time at the same time in the prior art to obtain system linearity and compensate while ensuring the system sensitivity, the present invention provides a continuous frequency modulation in terahertz imaging The wave linearity real-time calibration method and its system can calibrate each pulse in real time, ensuring the time consistency of the calibration data and the target echo data, effectively realizing the real-time calibration, and filtering the coupling signal at the same time, ensuring the system sensitivity

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