SDR101HamRadioUniversity2021RiaJairam,N2RJyoutube.com/RiaJairamn2rj.com
AboutN2RJLicensed1997-TrinidadandTobago
Licensed2001-BrooklynNYUSA
Occupation:ITsystemsengineeringteamlead
Hamradiohasnurturedmygiftoftechnicalcuriosityandhasenabledmetolearntechandengineering.MyhamradioElmerswereTonyLee-Mack,9Y4AL(teacher),andSteveMendelsohn,W2ML.
Igotinvolvedinhamradioinschool,throughtheinfluenceofateacher.
IamproudtohelpandservetheamateurradiocommunityasadirectorofARRLanddistrictchairforYLRL.
Noteonradios
• IamaFlexradiouser,butthatdoesnotmeanthatthesetechniquescannotbeappliedtootherradios.Iwillbemostlytalkingaboutmyexperiences,andshowinghowIoperateontheFlexRadioplatform
• Thistalkisnotspecificallyendorsednorsponsoredbyanyradiomanufacturer
Myradiostory
• I’veenjoyedDXingeversinceIwasachild-SWLing,listeningtodifferentcountries,culturesbutmostimportantlyenjoying“radioforradio’ssake”
• Ihavelearnedsomuch• Aboutmystation• Aboutpropagation• Abouttheworld
OtherthingsI’vedone/do
• Emcomm/ARES• Primarilyinanurbanenvironment
• Homebrew/kits• Drones/sUAS• Contesting• Ragchews
WhatisanSDR?
• AnSDRreplacessomeorallofthecomponentsofananalogradiowithsoftware
• SpecificallyRFcomponents• Detector• Modulator
• DirectSamplingtakestheRFoutoftheairandconvertsittodigitalbits
• “Baseband”SDRstakeRFdownconvertedtobaseband• I/Qsignals
Today’sSDRlandscapeSoftwaredefinedradiosarethenewkidon
theblockbutinrealitythey’vebeenaroundforawhilenow.
Whatisdifferentisadoption.WefindthemainstreamradiomanufacturersadoptingDirectSamplingSDRtechnology,andthe“boutique”onesgoingmainstream.
Thetippingpointhasbeenreached.SDRismainstream.
WhatcananSDRofferyou?1.Visibility-SEEthespectrum2.Performance-thebestperformingradiostodayaretypicallySDRs.
3.Integration-everythingcantalktoeverything4.Remoteoperation-SDRsenableyoutobethere,evenwhenyouarenot.
VisibilitySeethespectrum
VisibilityThisoneisstraightforward.SDRstypically
havesophisticatedbandscopes.Theycanshowyouwhatishappeningwellbeyondwhatyoucanhear.
VisibilitywithdecodingSDRscanalsofeedentirebandsand
multiplebandstodecodepopularmodes.
TodaywecandecodeMorsecodeanddigitalmodes.
VisibilitywithoverlaysSomeSDRsoffertheabilitytooverlay
informationonthepanadapterdisplay.ThiscanbefedfromaDXtelnetclusterorotherinformationsource.
ThiscanenablepointandclickorpointandtapDXing
ApracticalapplicationforDXing
VisibilityforEmcomm
• Scoutoutclearspots• Seewhoisinterfering• FiltersincludingTNF
PerformanceWhenyouplacesignalsintheanalog
domain,theyareaffectedadverselybyenvironmentalfactorsinourelectricallynoisyworld.
Whensignalsareinthedigitaldomain,theyareisolatedfromtheseenvironmentalfactors.
ThereforeyouwillfindthatthingslikenoiseflooranddynamicrangearesubstantiallybetteronanSDR
Additionally,withdirectsamplingSDRsyouwillfindthatlessrelianceonanalogmixersmeanslessphasenoise.
PerformanceRobSherwood,NC0Bhasbeendoingtests
ofreceivers(andnowtransmitters)foralongtime.Hisrankingsaregenerallyconsideredtobethemetricthatthecommunitylooksfortheirreceiverstobemeasuredby.YoucanseethatagoodnumberofthetopperformersareSDRs.Butaswithanything,therearecaveats.
Inparticular,receiversaremeasuredfortheirabilitytopickoutweakersignalsinterspersedbetweensmallerones.However,anythingabove80-90dB3rdorderdynamicrangeismoreofanumbersgame
Performance-ARRLLabtests
ARRLlabalsotestsSDRs,withgenerallyhighperformanceaswell.
ARRLhasdevelopedthemetriccalled“RMDR”or"ReciprocalMixingDynamicRange"whichalsomeasurestheabilitytohearweaksignalsamongadjacentstrongones.
Caveat-dynamicrangeAnSDRcansufferfromoverloadpretty
quickly.ThisiswhythetopperformersgenerallyhaveanalogfiltersbeforetheADC.
Clippingintheanalogworldisn’tasnearlyasbadasinthedigitalworld.Onceyoureachthetopindigital,youareatthetop.Thereisnowiggleroom.
SometraditionalradiomanufacturershavetheSDRafteratraditionalfront-endtomitigatethis.
IntegrationTheconnectedshack
Integrationandtheconnectedshack
Todaytheaveragehamstationisnotjustaradioandapaperlogbook.Today’shamshackiscenteredaroundtheradioANDthecomputer.Notjustfordigitalmodesbutforlogging,contestingandautomation.
Alotofthiscanbe“blamed”ontheriseofWSJT,butalsothingsweretrendinginthatdirectionanyway.
SoftwaresuchasN1MM+,DXLogandothersarebestusedwithaconnectiontotheradio.Softwaredefinedradioimplementationstendtoberichinconnections.
WhyIntegrationmatters
• Concentrateonthemission• Onceyougetonesoftwareapplicationworkingyoucaneasilygetothersworking
• Winlinkersalreadyknowthis,butit’snotintuitiveunlessyougetintoit!
• I’llbegivingthefulltreatmenttosystemintegrationatQSOTodayhamradioexpoinMarch2021
Integration-lesswiring
BetterIntegrationalsomeanslesswiring.Thiscanincreasereliabilityandoffergreatercapabilitytointegrate,evenovertheInternet.
Manyradiostoday,SDRandnonSDRcomewithUSBconnectionsthatcarrymanysignalsononebus.
EthernetportsManySDRradiostoday,especially
computercontrolledonescomewithanethernetport.Thiscanenablelesscableclutterandremoteoperation.
RemoteoperationWhenyourworldisyourshack
Nohumanbeingcanbeeverywhereatonce
• Mylifedoesnotrevolveamonghamradio.Ihavefamilyandothercommitments.
• However,IstillmanagetoworkrareonesandfillupmylogbookwithDX,andputprettyplaquesonthewall.Howcanthisbe?
RemoteoperationforEmcomm
• Goodlocationforradio,badforoperators• Radioonmountaintop,operatorsincity
• Solution:Remoteoperation• Shareradioswithyourcrew• OperateNCSeasilywithapowerfulstation• TheinternetbecomesyourSTL(Broadcastersknow!)
RemoteoperationRemoteoperationofyourownstationisa
powerfultooltokeepontheairevenwhenyouareawayfromhome.
Severalsolutionstothisexist-someturnkey,somenotsoturnkey
Whentheradioissoftwaredefineditisaloteasier,astheseradiosarebasedondataratherthananalogsignals,sotheycanbesentanywhere
Moretoolsofthetrade
WSPRforpropagationanalysis(learnwhenbandopensandclosesatyourlocation)
FT8forcrude(buteffective)propagationanalysis
Whatcanyougetfor$1?
Nothing!
ButyoucangetafunctionalSDRreceiverfor$21
SoftrockisthegrandaddyofcheapSDR
NeedsaPCsoundcardbutitworksratherwell.
CanbeusedforCWskimmerandmonitoringoftheband
CommercialsolutionsThesearebasedonRTL-SDR
Areyougettingout?Seehowwellyougetoutwithinternet
connectedSDRs.
SendafewCQsandthengotoreversebeacon.netandseehowyouarebeingheard,andwhere.
Thisisagoodwaytoseehowyourstationcomparestoyourpeers…
Whose(signal)isbigger?
Aneatlittletoolcantellyou.
www.reversebeacon.net/analysis
Chooseaspotter,andthenentercallsigns.Plotthemonagraph.
YouTube.com/RiaJairam
Questions?
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