The Study Of High Precision Microwave Photonic Frequency Measurement

Microwave technology is widely used in civilian,commercial and defense fields.As one of the basic applications,microwave measurement is widely used in various fields such as traffic and automotive control,electronic warfare and radar.Generally,the performance of microwave measurement ultimately determines the characteristics of microwave technology and systems.Traditional electrical microwave measurements have many advantages including high resolution and high flexibility.However,micro-wave measurements of broadband and high-speed signals are required in many appli-cations,which may not be realized by electronic devices due to speed and bandwidth limitations.Moreover,electronic equipment usually contains high-speed devices and has a large volume and weight.These drawbacks not only increase the cost of measure-ment but also lose the flexibility of the system,leading to the limitation of its practical application.Using photonic technology to process microwave signals has attracted greatly at-tention due to its inherent high time bandwidth product,small system size,light weight,and resistance to electromagnetic interference EMI).A better solution to the bottle-necks caused by the inherent shortcomings of traditional electrical processing is given.With the rise and rapid development of microwave photonics,more and more research-ers are studying the method of microwave photonics frequency measurement.This new method overcomes the limitations of traditional electrical methods and can meet the requirements of wide bandwidth and high precision microwave frequency measurement.This paper introduces the research significance and basic theory of microwave photonics and frequency measurement,and summarizes the research progress and cur-rent status of mainstream microwave photonics frequency measurement technology at home and abroad.At the same time,it analyzes and compares the proposed schemes.The thesis also elaborates and analyzes the principles and usage methods of some key devices used in the frequency measurement system link,and introduces the concept of stimulated Brillouin scattering and the conditions that need to be met for its occurrence.This paper proposes a high-precision frequency measurement system based on power ratio-frequency mapping.The stimulated Brillouin effect is used to amplify/attenuate two adjacent frequency components.At the same time,the power of the two frequency components is changed by changing the unknown signal to establish the power.Ratio function,where the power comparison function is established on different frequency bands.Therefore,its channelized frequency band provides a higher slope to achieve higher frequency measurement accuracy.This solution has the advantages of wide frequency measurement range,high measurement accuracy,and simple structure.Finally,a frequency measurement experiment was performed to obtain a measurement error within 8 MHz,and the frequency measurement range reached more than 23 GHz.This paper proposes a wide-range,high-precision multi-frequency microwave fre-quency measurement method based on phase-frequency mapping,and conducts theo-retical analysis.By setting the frequency interval of the two pump signals to 2is the frequency shift amount of the optical fiber),the Brillouin gain-loss spectrum phase compensation technology is implemented.At the same time,the correspondence between the Brillouin phase shift and the frequency is established,and the frequency is monotonously mapped onto the Brillouin phase shift curve.The inverse function of the curve is used to measure the frequency of the unknown signal.After theoretical analysis and verification,the measurement range of the system is extended from 2to 4,and the frequency measurement accuracy is 4 MHz.In addition,the effects of pump light wavelength and power changes on the performance of the frequency measurement system are also discussed.