A single-board NMR spectrometer based on a software defined radio architecture

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1、IOPPUBLISHINGMEASUREMENTSCIENCEANDTECHNOLOGYMeas.Sci.Technol.22(2011)015902(8pp)doi:10.1088/0957-0233/22/1/015902Asingle-boardNMRspectrometerbasedonasoftwaredefinedradioarchitectureWeinanTangandWeiminWangInstituteofQuantumElectronics,SchoolofElectronicEngineeringandComputerScience,Peking

2、University,Beijing,PeoplesRepublicofChinaE-mail:wmwang@ele.pku.edu.cnReceived4September2010,infinalform29October2010Published13December2010Onlineatstacks.iop.org/MST/22/015902AbstractAsingle-boardsoftwaredefinedradio(SDR)spectrometerfornuclearmagneticresonance(NMR)ispresented.TheSDR-based

3、architecture,realizedbycombiningasinglefieldprogrammablegatearray(FPGA)andadigitalsignalprocessor(DSP)withperipheralradiofrequency(RF)front-endcircuits,makesthespectrometercompactandreconfigurable.TheDSP,workingasapulseprogrammer,communicateswithapersonalcomputerviaaUSBinterfaceandcontrol

4、stheFPGAthroughaparallelport.TheFPGAaccomplishesdigitalprocessingtaskssuchasanumericallycontrolledoscillator(NCO),digitaldownconverter(DDC)andgradientwaveformgenerator.TheNCO,withagilecontrolofphase,frequencyandamplitude,ispartofadirectdigitalsynthesizerthatisusedtogenerateanRFpulse.The

5、DDCperformsquadraturedemodulation,multistagelow-passfilteringandgainadjustmenttoproduceabandpasssignal(receiverbandwidthfrom3.9kHzto10MHz).Thegradientwaveformgeneratoriscapableofoutputtingshapedgradientpulsewaveformsandsupportseddy-currentcompensation.ThespectrometerdirectlyacquiresanNMR

6、signalupto30MHzinthecaseofbasebandsamplingandissuitableforlow-field(<0.7T)application.DuetothefeaturedSDRarchitecture,thisprototypehasflexibleadd-onabilityandisexpectedtobesuitableforportableNMRsystems.Keywords:nuclearmagneticresonance,spectrometer,softwaredefinedradio(Somefiguresinthisarti

7、cleareincolouronlyintheelectronicversion)1.Introductiondigitalsignalprocessingchipsareusedinbuildingthereceiver[12].Recently,withthedevelopmentandapplicationofportableForconstructingaportableNMRspectrometer,someschemesmentionedaboveseemcomplexandbulky(manynuclearmagneticresonan