Research On Microwave Photonic Mixing And Phase Coding Based On External Modulator

The microwave photonic mixing is the key signal processing technology of radar communication.The frequency of microwave signal generated by microwave photonic mixing has the advantages of large bandwidth and tunability,which is widely used in modern communication radar.In pulse radar,the phase coding signal generated by microwave photonic has the characteristics of large time-bandwidth product,which could effectively meets the requirements of high resolution and high precision.At present,people have carried out a lot of research on microwave photonic devices and achieved many results.However,with the development of multi-functional radar,microwave photonic signal processor is required to meet multiple functions such as mixing and phase coding and so on.Therefore,this paper will focus on microwave photonic mixing technology and the phase coding technology,the contents are as follows :Firstly,the research background of this paper is introduced.Meanwhile,the research status,the significance of microwave phase coding signal and photonic mixing are also expounded.Besides,the existing microwave photonic mixing and phase coding generation methods are analyzed.What's more,the commonly external modulator devices,sideband modulation methods and key performance indicators of the system are introduced.In addition,the theoretical analysis and formula derivation of the related devices are carried out.Secondly,in the aspect of using optical method to generate microwave mixer.In order to generate stable,high-frequency signal and reduce the frequency requirements of the system,a photonic mixing with phase-shifting based on DPol-MZM without using optical filter is proposed and simulated.By controlling the amplitude of the RF signal and DC bias of the modulator,the up / down mixing microwave signal with 360 degree phase can be generated.The scheme does not use any electrical and optical filters,and uses the polarization controller instead of the optical filter to remove the spurious sideband,which produces a wide range of tunable microwave signal.Thirdly,in order to improve the flexibility of transmitters and receivers in modern communication systems,a scheme which could realize dual-channel simultaneous output up/down mixing with phase shift based on DPMZM is proposed and simulated.The upper DPMZM is used to realize CS-DSB modulation,while the lower DPMZM is used to realize CS-SSB modulation and be injected into PM to realize signal phase shift.Then,the sideband signal output by the upper DPMZM is coupled with the lower DPMZM after the effect of FBG.Eventually,the output signal enters the PD.In this scheme,the system outputs two microwave signals that can be up-converted and down-converted at the same time,and the generated dual-band microwave signal has high conversion efficiency and spurious-free dynamic range,and the signal has a fixed frequency interval,and the frequency can be flexibly adjusted in a large range,so that modern communication radars can work in multiple frequency bands.Finally,combining technology of photonic mixing and phase coding,the phase coding signal generation method without optical filter and the phase coding microwave signal method with dual output are proposed.The simulation software is used to verify the feasibility of the two schemes.The phase coding signals are used to finish Hilbert transforming,the phase information of the initial coding signal can be completely recovered.The pseudo-random code with rate of 1G / bits and duration time of 128 ns is used to verify the pulse compression performance.The compression ratio of the generated pulse signal is close to the theoretical value,which proves that the generated phase coded signal has good pulse compression performance.The frequency of the generated signal can be continuously adjusted from 1-59 GHz,which has a wide range of application prospects in the future radar wave radar.