美国陆军数字阵列雷达的材料.ppt

October 11, 2007,U.S. Army . Program Executive Office, Intelligence, Electronic Warfare leading in cooling requirements For a particular technology, overall system DC conversion efficiency and I2R distribution loss also to be considered to assess its advantage; trade-off should be noted,Comparison of Technology for S-Band PA,,,Super heterodyne receiver architecture/concept - Theory was developed for CW RF - Doppler or information detection achieved by frequency domain filtering But, most modern Radar are pulsed Radar Use multiple pulses Increase transmission power Require very high SFDR Require super oscillators… Limited Performance: Doppler-range ambiguity,Conventional Radar:,“There has been no significant change in Doppler Radar front-end architecture/concept since World-War II. The only difference in modern radar is the digital electronics for signal processing.”,,,,,,,,LNA,RF in,LO,LF,A/D,IF,Skolnik,The Philosophy of Radar Design,DARPA Funded Seeding Efforts at Army Research Lab:Investigate the MicroDoppler signature Theoretical modeling and simulationMicroDoppler detection Noise analysisStudy the experimental feasibility of interferoceiverFiber recirculation loop experimentTechnology survey,RF-Photonic Interferoceiver For MicroDoppler Radar,,RF - Photonic Correlation Receiver for Channelizer Concept,True time domain self correlation produced by the fiber recirculation loop,,,filter,,Fourier Transform,Self-correlation data in,,,,,,,Laser,Modulator,,1x2,,,,φ,,,λ,RFin,,,,,,,,,,,,,,,,,,t1,EDFA,Optical Amplifier,Coupler,,,,,t2,L1,L2,fiber,Interference combiner +sq law detector,,A/D,,,,,∆l,Astrophysicists are able to retrieve their signal 36dB below noise level! (Joe Taylor),,,,,,,,,Photonic Pulse Doppler Radar / Experimental,Laser,Laser,Modulator,Modulator,,,WDM,,,,,,,φ,,,,,RFLO,,,λ1,λ2,RF in,Receive antenna,,,,,,,,,,,,,,,,,,Doppler out,System Design:,Pulse Doppler Radar:,,t,Tpulse,,Optical Amplifier/absorber,Coupler,WDM,,Let’s Transition This Technology,So that the future RF Radar systems can:Use single transmit / receive pulseDon’t worry about SFDRDon’t worry about speed and bandwidth of A/DUltra wide band and frequency agileChannelizing with extreme large number of channels (large bandwidth, high resolution)1 Hz resolution micro Doppler detectionPrecise range and Doppler for long distance high speed targetDetect small signal from the noise floor,,BACKUP,RF-Photonic Interferoceiver,One pulse can determine Doppler Beating,Both loops have the same length L,n is the number of circulations,,Interfering Amplitudes,Intensity Variation,RF-Photonic Correlation Receiver For Channelizer,Self-Correlation in time domain,Time domain correlation spectrum analyzer: But A/D sampling a CW signal.,,,,,t,Again, not a true time domain correlation!,,,,True Correlation Receivers,True Time Domain Correlation,Self-Correlator,,,,,,,,,,,,,,,,,,,,,,,,,,Received RF,Reference RF,,Optical Fiber RecirculationLoop,,t,,,t,,,,,Received RF,,Optical Fiber RecirculationLoop: L1,Optical Fiber RecirculationLoop: L2,,,Transfer,Transfer,,,ω,ω,,,,,,,True Correlation Receiver,The Power of Time Domain True Correlation ReceiverAstrophysicists are able to be able to retrieve their signal 36dB below noise level! (Joe Taylor),,t,,ω,,,,ωo,Received signal f(ωt),Reference (LO),,,,f(ωot),For CW RF:,,,Time domain,Frequency domain,,,Doppler,Cannot get info with short pulse,,We need to do correlation for pulse RF!,