Design And Implementation Of Phasemeter Test System For Space Gravitational Wave Detection

In order to derive the information about gravitational wave,the detection of space gravitational wave uses the principle of laser heterodyne interference to mea-sure the distance variation between the two test masses.The payload,which can measure the phase information,is called the phasemeter.According to the mission of the space gravitational wave detection,the main beat-note,sideband beat-notes,pilot tone and communication code are all needed to be processed simultaneously by the phasemeter,which has the complicated process and extremely high.Therefore,on the ground,the comprehensive testing of the phasemeter plays an important role in the space engineering tasks.In recent years,the research of both domestic and overseas on the phasemeter mainly focuses on the phase readout performance of the phasemeter.Meanwhile,the test signal mainly includes a single sine signal generated by an optical bench or a signal generator and the main beat-note and two sideband beat-notes signals simu-lated by a digital signal simulator designed by AEI.However,due to the limitation of the optical bench and commercial signal generators,the comprehensive testing requirements of the phasemeter cannot be satisfied.Therefore,the design of the ded-icated phasemeter test system is required.At present,only Iouri Bykov of the Albert Einstein Institute（AEI）has designed a special digital signal simulator for the phase measurement system of LISA and the importance of designing a phasemeter test sys-tem has been explained.However,the design process and principle of the digital signal simulator are not explained in detail by previous literature.In this thesis,the comprehensive testing requirements of phasemeter are researched.By analyzing the characteristics of the heterodyne interference signal,the model of heterodyne inter-ference signal is deduced and established.Meanwhile,the principle of the signal and noise generation is studied.Besides,the realization of the communication modula-tion and demodulation are researched based on testing requirements of space laser communication function based on phasemeter.Furthermore,a phasemeter test sys-tem for the space gravitational wave detection is designed to verify the effectiveness of the phasemeter.The two parts,which are signal generation and modulation and demodulation self-test of DS/SS,are included in the phasemeter test system.The part of the signal generation can simulate the signals,which has the spatial laser heterodyne interfer-ence characteristics,including the main beat-note,sideband beat-notes,communica-tion code,Doppler shift,shot noise,laser frequency noise and QPD noise.All signal and noise generation modules are independent of each other,and the types and pa-rameters of signals can be generated by a PC to satisfy the test requirements of the phasemeter.Meanwhile,the generated signal can be demodulated with the part of DS/SS modulation and demodulation self-checking to simulate and verify the func-tion realization of the inter-satellite laser communication.The thesis mainly involves the basic principle of space gravitational wave detection,the signal composition and action mechanism analysis of the laser heterodyne interference signal,the establish-ment of laser heterodyne interference signal model,the simulation of beat-notes sig-nals and white noise,the realization of DS/SS modulation and demodulation,and the phasemeter test system hardware platform design.Besides,the application of the direct digital synthesizers,hybrid congruence algorithms,Costas Loop and Delay-Locked Loop are also researched in this thesis.The overall design flow of the phasemeter test system,the core is FPGA,is proposed based on the analysis of key technology.Furthermore,the establishment and implementation process of each module are analyzed in detail.Finally,the char-acteristic of analog signals,which are generated by the phasemeter test system,are analyzed in time domain and frequency domain characteristics.The experimental results show that the voltage range is±1V,the suppression of second harmonic up to-52d Bc and the spurious free dynamic range up to-58d Bc during the frequency range of 2～20MHz The frequency-domain characteristics of the generated signal are satisfied the theoretical expectations.Meanwhile,the bit error rate of DS/SS commu-nication demodulation module under different noise levels and different modulation indices is tested.The experimental results show that it can satisfy the communication requirements of 10^-6EBR under the condition of 90d Bc Hz shot noise,when the rate of the communication code is 1Mbps and the proportion of the optical power is 1%.The overall design flow of the phasemeter test system,which the core is FPGA,is proposed based on the analysis of key technology.Furthermore,the establishment and implementation process of each modules are analyzed in detail.Finally,the char-acteristic of analog signals,which are generated by the phasemeter test system,are analyzed in time domain and frequency domain characteristics.The experimental results shows that the voltage range is±1V,the suppression of second harmonic up to-52d Bc and the spurious free dynamic range up to-58d Bc during the frequency range of 2～20MHz.The frequency-domain characteristics of the generated sig-nal are satisfied the theoretical expectations.Meanwhile,the bit error rate of DS/SS communication demodulation module under different noise levels and different mod-ulation indices is tested.The experimental results shows that it can satisfy the com-munication requirements under the condition of 90d Bc Hz shot noise,when the rate of the communication code is 1Mbps and the proportion of the optical power is 1%.