تبادل
لینک هوشمند
TheHistoryofTellurometer
BrianSTURMAN, South Africa, and Alan WRIGHT, United Kingdom
Keywords: Aerodist, Hydrodist, Tellurometer.
SUMMARY
This paper covers the development of the Tellurometer family of electronic distance- measuring instruments from the original specification, through the prototype and the subsequentmodelsand systemsuptothelastinstrumentsproduced.Thejointauthorscan claimalmost60yearsofcombinedexperiencewithinthedevelopmentoftheseinstruments and will illustrate the different lines ofapplication.
AtimelinefocusontheclassicTellurometersdesignedaroundtheneedsofGeodeticSurvey showshowthemodelsfromMRA1throughtoMRA7werereplacedasimprovedelectronic technologybecameavailablewithverylittlesignificantimprovementintheaccuracyorrange of the products but with large leaps inthe readout presentation and ease of use.
TheHydrographicmodelsfollowedasimilartechnologypathbutprimedevelopmentwork wasfocussedontheproblemsarisingfrommultipatheffectsgeneratedfromtheproximityof large“flat”reflectingwatersurfacesandthebattletofindantennaethatcouldresolvethe issue.
The“commercial”instrumentsweregenerallytheresultofarequestfora“cheap”instrument thatcouldbeusedbythesmallfirmandindividualsurveyorswhowantedtousetheproducts butcouldnotaffordthe capital outlaythatwasstandardinthegovernmentalandmilitary users’ domain.
Thepapertracestheproductfromtheexcitementofdiscoveringnewmethodsforsurveying throughtheperiodofintensecompetitiontotheeventualreplacementoftheproductbyGPS systemsandalsohighlightsafewapplicationswheretheTellurometerstilloffersasolutionto a measurement need that cannot be replaced by alternative means.
HS 1 -Session 1
TheHistory of Tellurometer
BrianSturman and Alan Wright
IntegratingtheGenerations
FIGWorkingWeek 2008
Stockholm, Sweden 14-19June 2008
TheHistoryofTellurometer
BrianSTURMAN, South Africa, and Alan WRIGHT, United Kingdom
1.INTRODUCTION Tellurometer logo
BeforetheTellurometerortheGeodimeterwereinvented,surveyorshadfordecadesoreven centuriesusedbars,rods,chainsandsteeltapesformeasuringdistances,andcompassesand anglemeasuringdevicesfor determiningdirections.Triangulationwasusedforextending frombaselines.Inthe20th centuryradarwasaddedtothesedevicesforbothdistancesand directions,andtheseledto Shoran and Hiran, both of which were used for long-range surveyingbutwerenotsufficientlyaccuratefornormallandsurveying.The Tellurometer introducedtrilaterationforextendingcontrolatanacceptableaccuracy.Thisnewformof instrumentationalsoestablishedanewindustryinMicrowaveinstrumentation,laterfollowed byinfra-redmeasurementequipment.InTellumat,thecompanywhichisthemodernversion of Tellurometer Pty. Ltd., this has developed into a centre of excellence in microwave technology,thatcurrentlydevelopsdigital radios(forthecellphoneindustry),microwave communications and transponder products.
AftertheTellurometer,thenextrevolutioninsurveyingtechnologywastheuseofsatellite receivers.FirstlytheTransitSystemSatellitesandotherslikeitandsecondlyGPSSatellites andothersnowjoiningtheskieswiththem.Nextcamethelaserscanners.Herewedealonly with the Tellurometers.
2.ORIGINAL SPECIFICATION FOR THE TELLUROMETER
In 1954 Colonel H. A. Baumann, Director of the South African Department of TrigonometricalSurvey,wasfamiliarwiththeperformanceofRadarandoftheShoranand Hiransystemsbutwaslookingforasystemwithanaccuracyofbetterthan1in100,000at distancesofupto30milesandnoneoftheexistingsystemscouldprovidethis.Hisrequired systemneededtobeeasilyman-portable,workonlineofsightandhavearesolutionofafew inches.ThisrequirementwasbroughttotheattentionofFrankHewittinthe Councilfor ScientificandIndustrialResearch(CSIR)inJohannesburg.TheCSIRhadplentyofother projectsonhandanditwaswellinto1955beforetherewasanopportunitytogivethisproject to anyone to look at. The person chosen was Trevor Wadley.
3.THE PROTOTYPE (WADLEY WITH PROTOTYPE)
InaremarkablyshorttimeWadley,ashewasoftenknown,haddrawnupadesign,put togetherthe necessarycomponentsandwasmakingdistancemeasurements.Itisonrecord thatthefirst“routine”measurementwasmadeinthefieldbetweentwobeaconssome50km
HS 1 -Session 2
TheHistory of Tellurometer
BrianSturman and Alan Wright
IntegratingtheGenerations
FIGWorkingWeek 2008
Stockholm, Sweden 14-19June 2008
aparttotheNorthofJohannesburgon14th June,1955.TheresultwasexpressedinEnglish Feet!Twoslightlydifferentequipmentswereinvolved;onewascalledtheMasterandone was the Remote.
4.ELECTRONIC PRINCIPLES OF THE TELLUROMETER (MRA1 Block diagram)
(Diagramshowing a comparison of two different frequencies)
Theprincipleswereapparentlysimplebut,inpractice,wereactuallycomplex.Inthefirst Tellurometermodel,commonlyknownastheMRA1,twoslightlydifferentequipmentsare involved. One instrument is called the “Master” and the other the “Remote”.
Aninstrumentissitedateachendofthelinetobemeasuredandaradiolinkestablished betweentheinstruments.Theradiolinkiscontinuouslymaintainedduringthemeasurement process and the “housekeeping” tasks of alignment and operation using speech communications and signal strength measurement are performed on this “Carrier Wave”.
TheTellurometerisbasicallyatimemeasuringdeviceandthisisachievedbymeasuringthe phaseofafrequencywhichhasbeenmodulatedontothecarrier.Ontheearlyinstrumentsthis processgaveareadoutin nanosecondswhichthenhadtobetranslatedintodistancesby multiplying by the speedofradio waves, corrected by the refractive index ofair.
Laterinstrumentsusedfrequencieswhichgavereadoutsdirectlyinmetres,alreadycorrected foranaveragerefractiveindexandarrangedinasequencewhichgaveaseriesofdiffering “pattern lengths”. While the readout process was performed manually these pattern frequencies wereinmultiplesoftentoavoidambiguityandtoeasecomputation.Withdigital readouts,ofcourse,thisisnolongernecessaryandthepatternlengthsarechosentosuitthe processing systems.
5.PRODUCTION OF THE TELLUROMETER MRA1 (MRA1)
Theproductionwasinitiatedbyanorderreceivedfor6instrumentsfromaMr.W.H.Miller, theDirectoroftheSurveyandMappingBranchoftheDepartmentofMinesandTechnical SurveysofCanada.HevisitedCapeTowntoseetheprototypeandonthestrengthofthat visit placed an order for the first six production receivers. The name Tellurometer was selectedand theproductionfacilityof Tellurometer(PTY)Limitedwasset-upatPlumsteadin CapeTownTherewereinitialdifficultiesbecauseofgroundswing.Measuringslopedistance insteadofhorizontaldistancegavecomparisonmisunderstandings.Theseallwereovercome, theTellurometerproveditselfandtheCanadianinstrumentsweredelivered.M=Master.R=
HS 1 -Session 3
TheHistory of Tellurometer
BrianSturman and Alan Wright
IntegratingtheGenerations
FIGWorkingWeek 2008
Stockholm, Sweden 14-19June 2008
Remote.A=Ancilliaryequipment.Tellus=GreekforEarth.Meter=measure.Hence
Tellurometer MRA1.
6.TESTS AND TRIALS
(Wadleylecturing at Ridgeway Base) (MRA1 on Jungfrau Glacier)
(ArthurAllen and MRA1 on Malindi – Isiolo traverse) (Malindi – Isiolo traverse map)
In1955,1956and1957,newsofthesuccessspreadrapidlythroughouttheworldandtest measurements were made in a wide variety of countries and climates. These tests and demonstrationsweremadeintheUK,inSwitzerland,inCanada,inAfricaandinAustralasia. Duringthisperiod,theCanadiansutilisedtheinstrumentsverysuccessfullyinaircraftusinga “line-crossing”technique.ThisalsowasusedinAustralia. Newapplicationswerebeing foundeverywhere.InKenya,theUKDirectorateofColonialSurveys(DCS)hada2½-year planforatriangulationtraversefromMalinditoIsiola.UsingtheTellurometerinstruments this “2½-year” traverse was completed by trilateration in 28 days.
7.TELLUROMETER WORLD NETWORK FOR DISTRIBUTION (Mr. Fixit (Monkey) servicing an MRA2)
Thesamethreeyears(1955to1957)sawthedevelopmentofafive-brancheddistribution network under the direction of theCape Town headquarters, namely:
Tellurometer (PTY) Limited, Cape Town, South Africa. Tellurometer (UK) Limited, Staines, England. Tellurometer Canada Limited, Ottawa, Canada. Tellurometer Inc., New York, USA.
E.L. Heymanson & Co. (Pty) Limited, Melbourne, Australia.
ThroughthesefivecompaniesTellurometerInstrumentsweresuppliedtomanyoftheworld’s
NationalSurvey Departments, Armies and Universities.
8.FURTHER DEVELOPMENTS (Tellurometer Chronology)
1959sawthedevelopmentoftheMRA2and1960theMRB2orHydrodist,aninstrument designedforhydrographicapplicationswhereoneendofameasuredlinewasfixedonland andtheotherendwasonashipandalwaysmoving.ThiswasimportantfortheNaviesand harbour authorities of the world. Future developments can be streamed into three main
HS 1 -Session 4
TheHistory of Tellurometer
BrianSturman and Alan Wright
IntegratingtheGenerations
FIGWorkingWeek 2008
Stockholm, Sweden 14-19June 2008
channels,namely“landsurvey”,“dynamic/hydrographicsurvey”and“infra-reddistance measuring / engineering”.
9.TELLUROMETER LAND SURVEY DISTANCE MEASURING INSTRUMENTS (Photograph of the MRA2)
(MRA2in Canada)
TheMRA2incorporatedboththeMasterfunctionandtheRemotefunctioninoneinstrument andthepower supplyunit(PSU)wasbuiltintothemaininstrumenthousing.Sincethe acceptedpracticeofmeasuringa linewastomeasureitfrombothends,thisdualfunction abilityproducedthebenefitsofhavingtocarryonlyoneinstrumenttoeachofthepointsof measurementinsteadoftwo(MasterandRemote),noPSUsandonly halfthenumberof batteries.Powerconsumptionwaslowerandsothisalsohelpedtoreducethebatteryload. The measuring result, instead of inches or millimicro-seconds, was now metres and centimetres.
(Wadleywith MRA3)
TheTellurometerMRA3wasofmodularconstructionandusedtransistorisedcircuitry(apart fromtheklystronforgeneratingthecarrier),hadanimprovedaccuracyof+/-15mm+3ppm becauseoftheuseofa3cm (10GHz)wavelength,hadanintegralantennaprotectedbya radomeandhadtheoptionofthreedifferenttypesofreadout.Acathoderaytubeasinthe MRA1andMRA2,oradigitalreadout,oradial-readout.Allofthesegaveresultsdirectlyin metres. The more favoured readout in termsof numbers ordered was the “Dial Readout”.
(MRA101in Greenland)
In1964theMRA101wasproduced.ThiswasdirectlycompatiblewiththeMRA3butwas muchlighterin weightandalsowassolidstateexceptfortheKlystronthatgeneratedthe signaloutput.Themainpartofthecircuitrywascontainedonasingleprintedcircuitboard which made it much easier and cheaper to produce
Thiswas primarily intended for civilian use.
(InsideanMRA101 (MRA301)
Two years later, in 1966, the MRA301 was produced specifically for a U.S. Army requirement.ThisAmericanorderwasplacedwiththreeseparatecustomers–Tellurometer, Electrotape and ?Keuffel & Esser?. Each supplied one third of the instru<span style=&a
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