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?