Modulation and demodulation method for improving sensitivity of terahertz passive imaging unit

Abstract

The invention discloses a modulation and demodulation method for improving sensitivity of a terahertz passive imaging unit. The modulation and demodulation method comprises a noise source modulation module, a data acquisition module in signal connection with the noise source modulation module, and a demodulation module in signal connection with the data acquisition module. The noise source modulation module comprises a switch, a noise source and a noise source modulation control circuit, wherein the noise source and the noise source modulation control circuit are in signal connection with theswitch. The noise source modulation control circuit is used for modulating the output and cut-off frequency of the noise source. The data acquisition module comprises a power detector and an analog-to-digital converter in signal connection with the power detector. And the demodulation module comprises a demodulation circuit. According to the invention, low-frequency noise introduced by devices such as the power amplifier and the like adopts a new modulation and demodulation method and a new system structure, so that an effective 1 / f noise filtering method is realized, the detection sensitivityof the passive imaging unit can be greatly improved, the noise pollution problem of an acquired image is improved, and the resolution of the image is improved.

Description

technical field [0001] The invention relates to the technical field of modulation and demodulation to reduce noise and improve detection sensitivity and imaging quality, in particular to a modulation and demodulation method for improving the sensitivity of a terahertz passive imaging unit. Background technique [0002] Terahertz (THz) imaging technology has very important application prospects in the fields of medicine, biology, industry, military and security monitoring. Terahertz radiation (1THz=10 12 Hz) refers to electromagnetic waves with a frequency between 0.1Hz and 10THz (wavelength between 3mm and 30μm), and its wave band is between millimeter waves and infrared light. Because terahertz waves are very penetrating to materials such as plastics, paper, textiles, and leather, they will not cause ionization damage to biological tissues, and they have higher imaging resolution than millimeter waves. Therefore, at this stage, terahertz imaging has become a powerful supp...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a modulation and demodulation method that improves the sensitivity of the terahertz passive imaging unit. The low-frequency noise (1 / f noise) introduced by devices such as power amplifiers, adopts a new The modulation and demodulation method and system structure realize an effective 1 / f noise filtering method, which can greatly improve the detection sensitivity of the passive imaging unit, improve the noise pollution problem of the acquired image, and improve the resolution of the image

Images