Research On Rf Signal Monitoring Based On Microwave Photonic Technology

Compared with the traditional electrical methods,the microwave photonic radio frequency signal monitoring technology has the advantages of large bandwidth,low transmission loss and no electromagnetic radiation.In order to meet the needs of the application of artificial radio-frequency interference signal monitoring in the extreme electromagnetic silence area around the fast(500m aperture spherical radio telescope)of "China sky eye",this paper studies the radio-frequency signal monitoring technology based on the microwave photonics method.The main research work is as follows:1.Theoretical analysis and optimal design of microwave photonic RF signal monitoring system.The model of RF signal monitoring system based on the external modulation microwave photonic link is established.The factors such as link gain,noise coefficient and RF amplification that affect the sensitivity of RF signal monitoring are simulated and analyzed.On this basis,the optimal design of the external modulation microwave photonic RF signal monitoring system is completed.2.Based on the optimized design,a prototype of microwave photonic RF signal monitoring system is developed.The performance of the prototype is tested and analyzed,including the RF signal monitoring performance under different antenna distance,different RF frequency and different antenna angle.At the fast station,based on the field test of the prototype for typical radio-frequency interference signals,including mobile,Unicom,telecom and other mobile signals,walkie talkie signals,satellite TV signals,etc.,the results show that the prototype can achieve the radio-frequency signal monitoring capability in the frequency range of 30 MHz ~ 5GHz,with the highest sensitivity up to-90 dbm.3.In order to further realize the miniaturization and integration of the microwave photonic RF signal monitoring prototype,the RF signal monitoring scheme based on the direct modulation microwave photonic link is studied.The influences of the slope efficiency and relative intensity noise of the direct modulated laser on the noise coefficient,the system noise bottom and the lowest detection power of the RF signal monitoring system are analyzed,which provides a technical scheme for the miniaturization and integration of the prototype.