Research On Generation Of Pulse Compression Signal And De-chirping Technique Based On Microwave Photonics

Pulse compression technology can improve radar detection range and range resolution,dechirping can transform the target distance information into frequency information and reduce the sampling rate,the two technologies are important for radar detection.In recent years,the increasing complexity of the electronic countermeasures environment requires the radar system to realize higher demands and more comprehensive functions,the radar system is gradually developing towards the direction of large bandwidth,tunable,integrated,multifunction,multi-band and distributed,etc.However,the electronic radar system is limited by the electronic bottleneck,it is difficult to meet the increasing demand.Microwave photonics,which combines microwave and photon,has injected new power into radar technology.Due to its advantages of high frequency band,large bandwidth,low power consumption,small size and immunity from electromagnetic interference,it is gradually playing a key role in the next generation radar system.However,the tuning range of microwave photonic radar is still small,the number of bands and signal types are relatively single,and the demand for local vibration frequency is high.Based on the above problems,this paper studies the microwave photonic radar system and proposes two pulse compression generation schemes,one which can generate multi-function signals and the other which can generate multi-band signals.Finally,a photon de-chirping scheme is proposed.The specific research contents are as follows:1.A multi-function pulse compression signal with frequency quadrupling generation scheme based on dual parallel orthogonal keying modulator(DPQPSK)and polarization modulator(POLM)cascade is proposed and simulated.The scheme can generate a variety of pulse compression signals such as LFM signal,two-phase coded signal and P4 coded signal.The frequency quadrupling reduces the requirement of the system.The simulation generates the LFM signal with the starting frequency of 12 GHz and the bandwidth of 10 GHz,the twophase coded signal and the P4 coded signal with the central frequency of 12 GHz.2.A multi-band LFM signal generation scheme based on Dual-Polarization Modulator(DPolMZM)and Sagnac ring is proposed and simulated.The scheme can adjust the power of rf signal and the use of filter according to the different demand,thus producing the double chirped signal and single chirped signal of three or six bands,which can be flexibly applied to the multi-band system.Double chirped signals can eliminate the range-doppler coupling effect.The simulation results show that the 3-band dual-chirped LFM signals from 2GHz to 10 GHz,the 6-band dual-chirped LFM signals from 2ghz to 22 ghz and the 6-band dualchirped LFM signals from 3ghz to 33 ghz are generated.3.A photon de-chirping scheme based on dpol-mzm and Mach-zehnder Modulator(MZM)was proposed and simulated.The scheme can adjust the center frequency of the detection signal by changing the frequency of the loaded rf signal so as to reduce the demand for the sampling rate of baseband LFM signal waveform generator.The scheme realizes the dechirping reception,reduces the sampling rate of the post-processing,and can detect the distance and speed of the object.By simulation,the up chirp LFM signals from 8GHz to 8.5GHz are generated,and the down chirp LFM signals from 6GHz to 5.5GHz are generated,and the detection of the 90 m target object is realized.To verify the tunability,the up chirp from 13 GHz to 14 GHz and the down chirp from 9GHz to 10 GHz were generated,and the detection of 960 m and 840 m target objects is realized.The system can be tuned flexibly and the detection results are accurate.