Beat Frequency Spectrum Detection System

Abstract

A beat frequency type frequency spectrum detection system comprises a sweep frequency light source, a phase modulator, an optical fiber, a photoelectric detector, a power divider, an electric amplifier, a combiner, an electric filter, an oscilloscope and a signal source to be detected, wherein the swept frequency light source, the phase modulator, the optical filter, the optical fiber, the photoelectric detector and the electric amplifier form an annular photoelectric oscillator resonant cavity together; and when a Fourier domain mode locking condition is met, the photoelectric oscillator resonant cavity can generate a broadband-adjustable frequency sweep signal. According to the beat frequency type frequency spectrum detection system, a signal to be detected is coupled into a Fourier domain mode locking photoelectric oscillator, the signal to be detected oscillates in a loop circuit and in the photoelectric oscillator to beat frequency, and the time domain waveform of an output signalis observed through the oscilloscope after the signal is filtered by the electric filter, so that the frequency information of the signal to be detected can be obtained through the appearance time ofthe waveform observed by the oscilloscope by utilizing the characteristic that the output frequency of the Fourier domain mode locking photoelectric oscillator is related to the time.

Description

Technical field [0001] The invention relates to the technical field of microwave photonics, in particular to a beat frequency spectrum detection system. Background technique [0002] In radar and other electronic warfare systems, high-precision measurement capabilities for intercepted unknown microwave signals are crucial. Modern electronics technology can achieve high-precision frequency detection, but the frequency of the signal to be measured may be distributed in a wider frequency band, and the bandwidth of the pure electronic method is limited when measuring, and the measurement is susceptible to electromagnetic interference . [0003] The photonics method can avoid the above-mentioned drawbacks of electronics technology. In principle, microwave signal frequency detection schemes based on photonics can be roughly divided into three categories, namely, photonics-based channelization technology, frequency-to-power mapping, and frequency-to-time mapping. Channelization technol...

AI Technical Summary

Problems solved by technology

Frequency measurement based on photonics channelization technology can achieve large bandwidth, but its frequency measurement error is very large, usually greater than 1GHz, which cannot meet the application requirements of most electronic warfare systems; the method based on frequency-to-power mapping can achieve relatively more High-precision frequency detection, but this method can only detect single-frequency microwave signals, and cannot simultaneously detect multiple point-frequency signals, so its application is limited

The method based on frequency-to-time mapping can realize the detection of multi-point frequency signals, but at the same time, the frequency resolution of this method is limited by the accuracy of the optical time gate in the system, which is on the order of hundreds of MHz

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