Research Of High-speed Signal Transmission System Based On Microwave Photon Muti-Path Synthesis

Microwave photon multi-path synthesis is an important signal processing method in optical communication.With the development of national defense and civil science and technology,satellite communication technology based on microwave photon field has become a research direction in satellite communication field.The multi-array receiving system of phased array radar combined with the multi-path synthesis technology of optical beam-forming network can realize large bandwidth and high power signal reception and improve the receiving and transmitting efficiency of satellite communication.Therefore,it is of great significance and value to study the multi-path synthesis technology based on microwave photons.In this paper,the multi-path synthesis technology based on microwave photonics is deeply studied.The following work is done for the application of the optical control beamforming network used in the phased array radar reception system:(1)The influence of channel amplitude distortion and phase distortion on broadband signal is simulated by establishing FIR-filter-weight-coefficient-random-disturbance model,and the design principle of channel equalization filter is analyzed theoretically.According to the distortion model,the corresponding FIR amplitude-equalization filter and FIR phase-equalization filter are established to equalize the channel with only amplitude distortion and the channel with only phase distortion;The simulation results show that the amplitude equalization filter improves the EVM of 1 GBaud distortion signal by 8%and the phase equalization filter improves the distortion signal by 15.72%.(2)A FIR amplitude-phase equalization filter is designed to improve the single-path transmission performance in multi-path synthetic networks by using frequency domain Fourier transform method.The influence of channel amplitude-phase distortion on broadband signal is simulated on OptiSystem and MATLAB platforms,and then the amplitude-phase equalization filter is designed to equalize the signal,which verifies the good performance of the amplitude-phase equalization filter.This method is verified by experiments:using vector network analyzer to measure the S21 data of transmission path,the amplitude-phase equalization filter is established by this test data,and the time-domain equalizer tap coefficient of Fourier inverse transform is intercepted.In order to further improve the signal quality,a FIR equalizer and adaptive equalizer are proposed.The final experimental results show that the equalization algorithm can improve the demodulation EVM of 100 MBaud signal by 4.9%and optimize the demodulation EVM of 1 GBaud signal by 4%.(3)Analysis and compensation of delay difference in multi-channel synthetic link.Firstly,the delay model is established according to the system,and the influence of delay difference between two paths on broadband signal synthesis is simulated and analyzed on the MATLAB platform,including the influence on the flatness in the frequency domain and the efficiency of signal synthesis.The simulation results show that 90%synthesis efficiency can be obtained when the delay difference between the two paths is less than 20 ps for the broadband signal at 7 GHz frequency.Therefore,the minimum step of optical switch is set at 20 ps,and the synthesis of 90%power under 20 delay error is verified in the experiment.Then the phase in frequency is tested and calculated by vector network analyzer to control the delay difference between the two channels within 5 ps by replacing the delay line.The synthesis power increases by 5.9 dB,the synthesis efficiency reaches 99%,and the EVM of the received signal is improved by 4%.