MPH Sure Shot - 12 OPERATIONAL RECOMMENDATIONS; 12.1 Theory of Operation; 12.2 Laser System Usage Considerations

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12 OPERA TIONALRECOMMEND ATIONS
Laserunitsoperatingtodeterminespeedandrangingarecommonlyusedbylawenforcementtoday.
Thebasicpremiseofhowtheyworkisbasedonknowingthespeedoflightthroughtheatmosphereand
averyhighspeedcounter.
12.1 THEORYOFOPERATION
Whenyouaimthelaseratatargetandpullthetrigger,thelasersendsoutpulsesoflighttowardthe
targetwhilesimultaneouslystartingahighprecisiontimer.Whenthelightpulseshitthetargetthey
tendtoreflectbacktowardthelaserunit.Thesereflectedenergypulsesarecaptured
bythelaser’s
opticsandthetimervalueisread.
Knowingthetimefromshootingthepulsestocapturingtheirreflectionsgivesusthetotaltimeofflight
forthelightpulses.Sincethespeedoflightthroughtheatmosphereisknown,wecancalculatethe
totaldistancetraveledby
thelightpulses.Dividingthatdistanceinhalfwillprovidethedistancefrom
thelasertothetarget.Becausethespeedoflightissomuchfasterthanthespeedthetargetcouldbe
moving,thechangeindistanceduetothetarget’smovementisnegligible.
Bynowtakingsuccessiverange
readingsforthesametargetandnotingthetimeelapsedbetween
readings,wecanimplementadetailedalgorithmtocalculatethespeedofthetarget.
Oncewehavethespeedand/orrangecalculate d, we candisplaythatonthescreenandintheHUDfor
youtosee.
Becausethe
laserusesverynarrowlightpulsestodetectdistanceandspeeds,itismuchmoresuitable
tousewhenidentifyingspecifictargetsthanarethebroaderbeamradarunits.Adrawbacktousing
laser,however,isthattheusermustbestationaryandholdingthelaserstillandaimeddirectlyat
the
target.Radarsystemsallowthetargetstopassthroughtheirmicrowavebeamandtheycalculatethe
speedsofthetargetswithinthebeam.Becausetheaimingoftheradarismuchlessconstrained,this
lendsitselftoidentifyingtargetswhilenotstationarysuchasinmovingpolicevehicles.
12.2 CONSIDERATIONSFORUSINGALASERDETECTIONSYSTEM
Whilethelasersystemisindeedaverypowerfulme asurementinstrument,certainconsider ations
shouldbetakenintoaccountwhenusingittomeasuretargets.
WhenaimingthereticleintheHUDatapotentialtarget,youmustnottrytomovethelaserwhilefiring.
Tryingtofollowthetargetwith
thelasercandelaygettingresults.TheSureShot™hasalgorithmsin
placethathelptoalleviatethatissue,butitisbesttojustholdthelaseraimedatatargetasstillas
possible.
Whentryingtomeasureapotentialtargetyoushouldalsotrytoaimat
themostreflectivepartofthe
vehicle–preferablythefro ntorrearofthetargetdependingonwhichsideisfacingthelaserwhen
shooting.Higherreflectivesurfacesmaximizethereflectedlightenergybacktothelaseropticsfor
measurement.Headlights,reflectivelicenseplatesandfrontgrillesareexcellentreflector
surfaces.
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