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Application Note: Testing GNSS Systems for Automotive Applications

Testing GNSS Systems for Automotive Applications

Bridges, tunnels, multi-storey car parks—the automotive environment continues to present significant challenges to GNSS systems, at a time when drivers expect consistent performance from their GNSS-enabled devices.

Download the Application Note to discover how Spirent RF simulators accurately reproduce all relevant aspects of this complex environment to support the comprehensive testing and optimisation of GNSS receivers. Topics include:

  • The specific challenges of the automotive environment for GNSS and INS systems
  • How Spirent simulators model the automotive environment’s various effects
  • The benefits of simulation for designers and integrators of GNSS receivers

Simply enter a few details opposite to receive the Application Note—and happy reading!

About Spirent

Spirent has been the global leader in GNSS testing for near 30 years. Spirent delivers navigation and positioning test equipment and services to governmental agencies, major manufacturers, integrators, test facilities and space agencies worldwide.

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    Testing GNSS Automotive and Telematic applications For System Integrity APPLICATION NOTE Spirent Communications PLC Paignton, Devon, TQ4 7QR, England nullenull nulltpnullnullnullnullpirentnullomnullositioning Telnull null4 nullnull nullnullnull Fanull null4 nullnull nullnullnull Copyrignull nullnullnull Spirentnull nulll Rignulls Reservednull nulll onulltnull company names andnullr nulland names andnullr product names renullrred to in tnulls document, in particular, tnull name nullpirentnulland its logo device, are eitnullr registered trademarnull or trademarnull onull Spirent plc and its sunullidiaries, pending registration in accordance nulltnullrelevant national lanullnullnulll otnullr registered trademarnull or trademarnull are tnull property onulltnullir respective onullersnull Tnull innullrmation contained in tnulls document is sunullect to cnullnge nulltnullut notice and does not represent a commitment on tnull part onullSpirentnull Tnull innullrmation in tnulls document is nulllieved to null accurate and relianullenull null ever, Spirent assumes no responsinulllity or lianulllity nullr any errors or inaccuracies tnullt may appear in tnull documentnull Page 2SPIRENT Application Note Contents nulludience 4 Introduction 4 Tnull nullutomotive nullSS Environment null nullSS system errors null Receiver errors null Integrated nullSS nullInull navigation systems null Inull errors 7 Simulating tnull nullutomotive nullSS Environment null Reproducing tnull enullnullcts null Enullernal nullnullcuration null Roadside nulluildings and cuttings null nullridges null Tunnels and covered car parnull null nullatural surrounding terrain null nulldnullcent and passing venullcles, nullgnullay enullipment null nullnnullenullcle onullcuration null nullultipatnull null Finulled nullnullnullet nullultipatnull null nullertical Plane nullultipatnull null Signal Loss null Radio Frenullency Internullrence null nullSS nullInull null Simnullnull null Reproducing real drive tests null nullEnull nullnull messages null nullEnull Conversion nulltility null Conclusions null Renullrenced Documents null Page 3SPIRENT Application Note Audience Tnulls nullpplication nullote is nullr designers, developers, integrators and testers onull nullSS receivers or systems, nullo need to ensure tnullir products nullll pernullrm in tnull automotive environmentnull Spirent recommends you nullve a nullsic understanding onullsatellite navigation principles and anullreness onullRF simulation as a test metnulld is desiranullenull Introduction Tnullre is a steady gronullnullin tnull use onull nullSS navigation systems in all areas onulltnull automotive marnulltplacenullnull variety onullnullSS receivers, commonly renullrred to as nullat nullavnull systems, are nonullnullund in venullcles used nullr private and recreational purposes, as nullell as commercial and punullic transportnullIn some cases, tnullse systems rely solely on standalone nullSS operation, in otnullr cases tnully are coupled nulltnullan Inertial nullavigation System nullnullnull Tnull increasing use onullnullSS nullings an increasing reliance on tnull tecnullologynull Individuals, nullsinesses and organisations are all relying on tnull tecnullology nullr anytnullng nullom personal pleasure and sanullty to commercial advantagenull nullitnulltnulls in mind, it is important nullr designers, manunullcturers and consumers onulltnullse products to understand nullat to enullect nullom nullSS systems, nullicnull renullires an understanding onulltnull limitations and pronullems onullnullat can onullen null a nullagile, prone to error, and easily disanulled tecnullologynull Tnulls application note discusses some onulltnull main sources onullerror nulltnullspecinull to tnull automotive environment, and more generally applicanulle to nullSS systemsnullComplementary to tnulls, it demonstrates nullnullSpirentnulls range onull nullSS Test Solutions enanulle tnull simulation onulltnullse conditions in a controlled and repeatanulle nully, allonullng a nullSS receiver andnullr nullS nullInull system to null properly tested nullr use in automotive applicationsnull Page 4SPIRENT Application Note The Automotive GNSS Environment null nullSS receiver nullrnull nullst nullen it nulls a clear, unnullnterrupted vienullonulltnull ornullting satellites transmitting tnull ranging and navigation signalsnullIn tnull automotive environment tnulls is onullen not tnull case and ranging measurements to tnull satellites are anullnullctednullnull nulladio rangingnull is tnull nullsis onullsatellite navigation, any degradation onulltnull ranging measurement nullll cause degradation in tnull Position, nullelocity, Time nullnullnullsolution calculated nully tnull receivernull nullarious environmental nullctors contrinullte to a receiver not nulling anulle to receive tnull necessary signals, generally renullrred to as onullcurationnull Tnull main causes are as nulllonull Enullernal onullcuration can null denulled as everytnullng outside tnull connulles onulltnull nullst venullcle tnullt nullocnull tnull Lnull signal, preventing it reacnullng tnull receivernulls antennanullTnull automotive environment presents onullcuration in a numnullr onullnullysnull Some are descrinulld as nullllonullnull nulloadside nullildings null nully structure tnullt is adnullcent to tnull roadnully tnullt stands in tnull nully onulltnull receivernulls direct vienullonulltnull satellitesnull nullridges null nullnulltruction onulltnull snull occurs progressively as a venullcle passes under a nullidgenullTnull duration onulltnull signal nullocnullge depends on tnull pnullsical cnullracteristics onulltnull nullidge comnullned nulltnulltnull speed onulltnull venullclenull Tunnels null nulle can consider tunnels as an enullension onulla nullidgenullnullonullever, complete onullcuration occurs nullr a period onulltime, and cnullnges in venullcle direction can also occur nullile tnull venullcle is in a curved tunnelnull nullnderground and multinulltorenullcar parnull null nullnullct a receiver in a similar nully to tunnelsnullDisorientation is onullen a primary concern, particularly upon enullt nullom tnull car parnull nullen a nullicnullnavigational decision is renullirednull Cuttings null nullany roads are placed in cuttings, nullicnullreduce tnull visinulllity onulllonull elevation satellitesnull Natural terrain nullillsnullmountainsnullvallenullnull trees and vegetationnull null null nulltnulltnull anullve enullnullcts, onullcuration is determined nully tnull cnullracteristics onull tnull terrainnullnullills, mountains and valleys nullocnullsignals as a nullnction onulltnullir nullignull or deptnull Trees and vegetation attenuate and nullocnullsignals according to tnull type, density and nullter content onulltnull nullliage and structure onulltnull trunnullnullancnullsnull Adnullcent and passing vehicles null nullery dependant on tnull relative speed onulltnull venullclesnullTnull onullcuration may null momentary, or last longer nullor enullmple a nullgnullsided venullcle passing at a speed tnullt is only slignullly nullster tnulln tnull receivernulls nullst venullclenull nullighnullnullenullipment nulltreet lightingnull signsnullgantriesnull null Issues nulltnullperiodic signal onullcuration, causing complenullsignal disturnullnce enullnullctsnull Page nullSPIRENT Application Note nullSS system errors nullpart nullom tnull enullnullcts onulltnull local automotive environment errors also enullst due to tnull nullSS system, nullatellite constellation and controlnullonitoring systemsnull Tnullse are nullyond tnull nullcus onulltnulls application note, nullicnullconcentrates tnull automotive environmentnullnullonullever, tnully snulluld not null ignorednullFor more innullrmation on nullSS system errors, and nullnullto simulate tnullm, donullload tnull Enulloonullnull Common nullSS Errors null Receiver errors nullotnullr source onullerrors can null attrinullted to tnull receiver itselnullnull nullodern receivers nullve multiple digital receiver cnullnnels, and nulltnullsilicon cnullp integration densities increasing, more parallel processing is possinulle, leading to snullrter time to nullst null pernullrmancenull nullonullever, nulltnullincreased processing comes increased noise, nullenulldesigns are still susceptinulle to classical error sources sucnullas Lnull noise, PLLnullLL tnullrmal noise, oscillator pnullse noise and nullC aliasingnull Renullrence null states tnullt an average modern receiver snulluld contrinullte less tnulln nullnullm rms error in nullas and less tnulln nullnullm in noisenull Integrated nullSS nullInull navigation systems Tnull use onullnullSS nullInull in automotive navigation systems is increasing, largely due to operational pernullrmance issues caused nully some onulltnull errors descrinulld anullvenullTnullse errors cannot null completely eliminated, even nulltnullan optimised standalone nullSS receivernull In many systems, primary navigation is nullsed on signals nullom enullsting onnullenullcle sensors nulldometers, nullS nulleel sensors, gyronulls and so onnullnulltnullnullSS position, velocity and time innullrmation providing a renullrence or nullcalinullation nullctornull tnullt regularly corrects tnull diverging errors innullrent in tnull Inull systemnull null classic automotive environment pronullem is tnullt onulla curved road tunnelnull nullSS receivers can nullcome connullsed nullen tnully emerge nullom a tunnel nullading in a dinullnullrent direction to tnullt travelled upon entering tnull tunnelnullnullitnullan Inull coupled into tnull navigation system, innullrmation nullom tnull nulleel sensors or gyroscope, corrects tnull nullading cnullnge in tnull anullence onulltnull nullSS innullrmationnullnullavigation tnullougnullut tnull tunnel and nullyond is maintained, nulltnullut nullving to rely solely on tnull nullSS system nullicnullcould null trying to correct itselnullnullom tnull connullsed state nullst descrinulldnullTnulls advantage is also true in otnullr environments, nullr enullmple underground car parnullnull Page nullSPIRENT Application Note INS errors nulltnullugnulla comnullned nullSS nullInull navigation system solves many onulltnull pronullems tnullt innullnullt standalone nullSS, tnully are still sunullect to errors tnullt can corrupt tnull navigation solutionnull Tnulls is particularly true in commercial automotive applications, nullicnulluse cnullaper, less accurate devices instead onull tnull enullensive, nullgnullaccuracy sensors used in tnull aviation sectornullIn some cases, nulleel sensors are tnull sole metnulld onullcalculating venullcle nullading rate, as nullD gyros are pronullnulltively enullensivenullSee Renullrence nullnull Common enullmples onullerrors includenull null nulleel slips nullpulses nullom nulleel sensors are sent to tnull navigation system at a particular ratenullernullevolutionnullInulla nulleel looses contact nulltnulltnull road and spins, tnull rate onullpulses increases, and is no longer matcnulld to tnull pnullsical distance travellednullIntroducing an errornull null Snulldding nullnullen a snulld occurs, tnull nulleel slonull donull, or stops completely, leading to reduced or no pulsesnull null nulleadnulland error nullnullctive nulleel speed sensors employ nullallnullnullnullct transducers, Tnullt nullve a minimum speed nulllonullnullicnull no motion is detected nulltnull sonullalled nulldeadnullandnull nulln tnull order onullnullto nullnullnull, Tnull dead nullnd can present real pronullems in urnulln areas, nullere tnull venullcle is progressing very slonully in tranullc congestion and tnull navigation systemnulls nulldead recnullningnull algoritnulls are not anulle to cope nulltnulltnull conditionnull null Stucnullgnulloscope nullnullyros are mecnullnical devices and prone to nullilure or impernullctionsnullnullyronullompasses output tnull dinullnullrence nulltnulleen tnull nulled gyro nullading and tnull pnullsical venullcle direction, inullnullnullever tnull gyro nullcomes stucnull nullue to a nullilure onulltnull gimnulll nullr enullmplenulltnull signals nulld to tnull navigation system nullll null in errornull Page null SPIRENT Application Note Simulating the Automotive GNSS Environment In tnulls section nulle loonullat nullnulla nullSS RF Constellation Satellite Simulator enanulles tnull simulation onulltnull conditions nulle nullve discussed in a controlled and repeatanulle nullynullTnulls allonull testing onulla nullSS receiver andnullr nullSS nullInull system nullr use in automotive applicationsnull null RF Constellation Simulator reproduces tnull environment onulla nullSS receiver on a dynamic platnullrm nully modelling tnull venullcle and satellite motion, signal cnullracteristics, atmospnullric and otnullr enullnullcts causing tnull receiver to actually navigate according to tnull parameters onulltnull test scenarionull Inullnulle consider tnull errors nullgnullignulled in tnull previous section, tnullre is no need to simulate receiver errors as tnull receiver is included in tnull test and nullll contrinullte its onull real errorsnullIn all cases, nulle consider simulation onulla Land nullenullcle nulltnullone nullS antenna receiving nullS LnullCnull code signals using Spirentnulls nullSnullnull nullultinullnullS Constellation Simulator System nullnullnullnnel LnullCnullcode nullSnullnullS simulator nulltnullSimnullnull sonullnullrenull For more innullrmation on Simnullnull sonullnullre, see renullrences nulland null nullr tnull nullSnullnull see renullrence null Reproducing tnull enullnullcts nully its very nature, simulation is a representation onulltnull real nullrldnull Simulation cannot reproduce tnull nullll ricnulless onullreal nullrld conditionsnull null common misconception is tnull need to enullctly replicate real nullrld conditions nullr a nullSS test to null validnullnullonullever, application onullrepresentative enullnullcts via simulation is proven nullver some null years onulltestingnullto enullercise receivers and adenullately identinull tnullir limitations allonullng nullr design centring and optimisationnullnullore importantly, it gives complete repeatanulllity, control and enullct nullonulledge nulldonull to nullt level nullonulltnull signal stimulating tnull receivernullTnulls is not possinulle in tnull real nullrldnullnullitnulltnulls in mind, nulle snulluld loonullupon simulator testing as representing tnull real nullrld, ratnullr tnulln replicating itnull Spirent simulators include statistical models enanulling simulation onullricnullr multipatnullenvironments, nullt consideration onulltnullse is outside tnull scope onulltnulls documentnull Figure nullsnullnull tnull concept onullsimulation, using a nullSnullnull , LnullCnull code nullultinullnullS simulatornull Figure null RF Simulation Concept Page nullSPIRENT Application Note Enullernal Onullcuration In tnulls section nulle consider simulation onull pnullsical onullects enullernal to tnull venullcle tnullt onullcure tnull nullSS signalsnull nulloadside nulluildings and cuttings Simulation onullonullcuration due to roadside nullildings is possinulle using tnull nullertical Planes nullature onullSpirentnulls Simnullnull nullr nullindonullnullsonullnullrenullnullertical Planes allonull you to denulle a series onullvertical, rectangular onulltructions or planes to tnull lenull and rignull onulltnull venullcle, relative to tnull direction onulltravelnull nullou denulle tnull distance, nullignull and nulldtnullnullenulled as durationnull Signals nullll null onullcured inulltnull planes occur in tnull Lnull patnullnulltnulleen tnull satellites and tnull venullcle antennanull nullery nullgnullplanes at a snullrt distance nullom tnull venullcle nullll onullcure more signals tnulln lonullnullignull planes at an increased distance nullom tnull venullclenull nullertical Planes are a good nully onullsimulating nullildings in an urnulln canyon environmentnullnullou can increase tnull complenullty onulltnull onullcuration nully adding more planes nulltnulldinullnullring proportionsnull Inulltnull simulation is run at a dinullnullrent time andnullr date, dinullnullrent onullcuration nullll null seen, as tnull satellite geometry nullll nullve cnullngednullnulliven tnulls, you can nullild up a series onulltests tnullt give a complete nullpicturenull onulltnull onullcuration resulting nullom your set onullvertical planes over a nullnullour period nullnullcnullenullates to one complete ornullt nullr all satellitesnull Figure nullsnullnull an illustration onullnullertical Planes positioned to tnull rignull onulltnull venullcle nullenullnullide planes omitted nullr claritynull Simnullnull automatically considers tnull venullcle and satellite motion nullen determining nullicnullsignals are onullcured nully tnull planes nullnd not present on tnull simulator RF outputnull Cuttings can null simulated in a similar nully to roadside nullildingsnullnullsing nullertical Planes, you can replicate tnull onullcuration onulllonull elevation satellites nully specinulling a continuous plane eitnullr side onulltnull venullcle at a nullignull and distance tnullt causes tnull same masnullng angle as tnull cuttingnull Figure nullsnullnull nullnulltnull planes can null denulled at lenullnullignull distance nulland nullignull y to provide tnull same masnullng enullnullct as tnull cutting pronullenullTnull green snullded area indicates no onullcurationnullTnull unnullnullded area represents onullcurationnull Figure null nullertical Planes Concept Page nullSPIRENT Application Note nullridges Simnullnull can pernullrm a representative simulation onulla nullidge, nully simply turning onullnull, and tnulln on, all satellite signals nullr a certain period onulltimenullTnull onullcuration enullnullct onulltnull nullidge is determined nully tnull lengtnullonulltime tnull satellites are snulltcnulld onullnullnullIt is possinulle to snulltcnullonullnullsatellites in realnullime, using tnull ponuller control nullndonullin Simnullnull , in a prenullrdered nulle onullcommands, or even using a remote command, inulltnulls metnulld is nulling used to control tnull simulatornull Tunnels and covered car parnull In mucnulltnull same nully as nullidges, tunnels and car parnull are simulated nully snulltcnullng onullnullall satellites, nullt nullr a longer periodnull During tnull onullnulltime, tnull venullcle may cnullnge nullading, nullr enullmple, representing a curved tunnel, or a car driving around in an underground car parnull Figure null Enullmple onullnullnullcuration Due to a Cutting Page nullSPIRENT Application Note Figure 4null nullmninullirectional Terrain nullnullcuration Natural surrounding terrain Simnullnullnulls Terrain nullnullcuration nullature allonull you to apply omninullirectional terrain onullcuration nulltnulla pronulle modelled according to data sets you can modinullnullTnull terrain properties nullve nullinimum nulleignull and nullanullmum nulleignull nullldsnullTnull current onulltacle nullignull is pseudonullandomly selected nulltnulleen tnullse limits eacnulltime an onulltacle nulldtnullperiod is completednull Tnull terrain properties also nullve nulltnull nullinimum nullidtnulland nullanullmum nullidtnull nulllds to nullrtnullr improve tnull realism onulltnull enullnullctsnullTnull onulltacle nulldtnullmaps directly to distance travelled nully tnull simulated venullcle and its period is dictated nully venullcle speednull Tnull essential scnullme onulltnulls nullature is tnullt nullen a specinulld tranullctory is enullecuted at dinullnullrent speeds, tnull onullcuration pattern is repeated at an appropriately dinullnullrent rate, simulating a venullcle moving tnullougnull tnull same terrain nullt at a dinullnullrent speednull Tnull terrain onullcuration is omninullirectional, so is at tnull same distance nullom tnull venullcle in all nullrinullontal directionsnullIt is analogous to a circle, nullere tnull venullcle is at tnull centre, and tnull terrain is around tnull circumnullrencenull Regardless onullspeed or tranullctory, tnull venullcle remains at tnull centre onulltnull nullterrain circlenull Figure 4 illustrates tnulls principle and snullnull tnull terrain denullition in detail nullr one onulltacle nulldtnullperiodnull Page nullSPIRENT Application Note Adnullcent and passing vehiclesnull highnullnullenullipmentnull Tnullse are enullnullcts tnullt are simulated using nullertical Planesnullnullile tnull enullct enullnullct onull an adnullcent venullcle approacnullng, passing and receding, or passing street lignullsnullign gantries is not modelled precisely, a representative enullnullct is appliednull null already stated, enullct replication is not necessary in order to nullenullercisenull tnull receiver appropriately, and determine its limitationsnull For a passing venullcle sucnullas a nullgnullsided goods venullcle, you simply set up a vertical plane nulltnulla suitanulle nullignull and distance onullnulletnullEnullally, nullr nullgnullay enullipment, you set up a vertical plane nulltnulltnull appropriate cnullracteristics representing tnull onullectnulls pnullsical nullrmnull Onnullehicle onullcuration So nullr nulle nullve considered pnullsical onulltructions enullsting enullernally to tnull nullst venullcle, tnullt are cnullnging as a nullnction onull venullcle motionnull nullnnullenullcle onullcuration is, in almost all cases nulled and does not vary nulltnullvenullcle motionnullnullitnulltnulls in mind, tnull nullst nully onullsimulating sucnullenullnullcts is nully using Simnullnullnulls nulltenna Pattern nullaturesnull Tnull simulator considers tnull receivernulls antenna as tnull point at nullicnull signals are modellednullnulll pseudoranges, ponuller, signals types, delays, motion and otnullr enullnullcts are renullrenced to tnulls pointnull Tnull electrical properties onulltnull antenna are most onullviously and appropriately denulled nully its antenna pattern, nullt in tnulls case so too are tnull nulled pnullsical onullcuration properties onulltnull immediate environment surrounding tnull antenna linull tnull venullcle nulldynull Tnull orientation onulltnull antenna pattern is alnullys nulled nulltnullrespect to tnull orientation onulltnull venullcle, nullst as tnull nullSS receivernulls antenna is nulled to tnull venullclenull Tnull nulltenna Pattern Editor allonull you to denulle tnull signal ponuller level attenuation and pnullse delay nullr elevations onullnullnullto nullnullnullr tnull nullll nullnulldegrees onullanullmutnull around tnull antennanullTnull resolution can null as nulle as nulldegree nullnulldegree, allonullng you to model tnull onullcuration created nully tnull venullclenulls nulldynullrnullnulloors, door pillars, roonulletcnull and to specinull areas nullere tnull antenna nulls a vienullonulltnull snull nullindonull, nullndscreen, sun roonullnullnullttenuation due to nullndonulltinting or denullisternulleater elements can also null nullctored innull Figure nullsnullnull tnull nulltenna nullain Pattern Editor nulltnulla simple representation onull masnullng tnullt mignull null enullerienced nully an innullar dasnulloard mounted nullSS receivernull Page nullSPIRENT Application Note Tnull nulltenna Pattern Editornullallonull you to denulle tnull signal ponuller level attenuation and pnullse delay nullr elevations onullnullnullto nullnullnullr tnull nullll nullnulldegrees onullanullmutnull around tnull antennanullTnull resolution can null as nulle as nulldegree nullnulldegree, allonullng you to model tnull onullcuration created nully tnull venullclenulls nulldynullrnullnulloors, door pillars, roonulletcnull and to specinull areas nullere tnull antenna nulls a vienullonulltnull snull nullindonull, nullndscreen, sun roonullnullnullttenuation due to nullndonulltinting or denullisternulleater elements can also null nullctored innull Figure nullsnullnull tnull nulltenna nullain Pattern Editor nulltnulla simple representation onull masnullng tnullt mignull null enullerienced nully an innullar dasnulloard mounted nullSS receivernull nullonullload tnull Spirent nullpplication nullote nullnulleeping nullour enulle on the snull null nullr more innullrmation on modelling your nullSS nulltennanull nullultipath Simulation onullmultipatnullenullnullcts is possinulle in a numnullr onullnullys using Simnullnullnull Some advanced tecnullinulles enanulle complenullmultipatnullto null creatednull Simnullnull allonull you to create tnull nullllonullng types onullmultipatnull nullFinulled onullnullet multipatnull nullnullround renullction multipatnull nullDoppler onullnullet multipatnull nullRenullction Pattern multipatnull null ertical Plane multipatnull nullPolynomial multipatnull nullLegendre multipatnull nullSinusoidal multipatnull nullLand monullle multipatnull nulle nullll nullienull consider tnull onulltnullse types nullrenull nullinulled Onullnullet nullultipath and vvnull nullur nullpplication nullote nullSimulating nullultipathnull loonull in more detail at simulating multipatnulltypesnull Figure null nulltenna Pattern Editor Page nullSPIRENT Application Note nullinulled Onullnullet nullultipath Tnulls is tnull simplest metnulld onullsimulating a multipatnullsignalnull For a given satellite, it allonull you to denulle an enullct copy onulltnull Lnull signal nullom tnullt satellitenullIt allonull you to specinull nulltnulla range onullnullet in metres and attenuation in dnullnulltnullrespect to tnull Lnullnull Tnull simulator nullll tnulln, using a separate nullrdnullre cnullnnel, create tnulls signalnull Tnull range onullnullet is alnullys positive, representing tnull multipatnullsignal nullving travelled a longer patnullto tnull receiver tnulln tnull LnullnullTnull level can only null enullal or lonuller ponuller compared to tnull Lnull, representing renullction loss enullerienced nully tnull multipatnullsignalnull nullsing nullser nullctions, you can denulle a Finulled nullnullnullet nullultipatnullsnulleitnullr in real time using tnull nullI or remote control, or prior to tnull scenario runnullnullser nullctions is a nulle onull prenullcripted commands enullecuted at set times in tnull scenarionull null receiver nulltnullut multipatnullmitigation trying to tracnullnulltnull signals nullll not null anulle to determine nullicnull one is tnull real signal, and nullll generate a range measurement errornull ou can tnulln determine tnull receivernulls multipatnull pernullrmance nully nullnullr enullmple nulllonullering tnull ponuller onulltnull multipatnulluntil tnull correlator nullr tnullt cnullnnel stops trying to tracnulltnull unnullnted signalnull nullor more innullrmation on simulating multipatnull donullload tnull Spirent Application Notenull nullertical Plane nullultipath nulle nullve already seen nullnullSimnullnullnulls nullertical Planes nullature is usenulll nullr simulating tnull enullnullcts nulle nullve discussed, along nulltnulltnull associated multipatnull capanulllitynull ertical Plane nullultipatnulladds to tnull onullcuration capanulllities nully allonullng tnull geometric modelling onullsatellite signal renullctions nullom tnull surnullces onulltnull planes, tnullt represent nullildings in an urnulln environmentnullFor prenulletermined multipatnull signals, Simnullnull calculates nulletnullr a renullction is possinulle nullsed on tnull relative geometry onulltnull selected satellites, venullcle and renullcting surnullcesnullDepending on tnulls geometry, tnull receivernulls antenna may nullseenull nullst tnull Lnull signal, Lnull and multipatnull nullst tnull multipatnullor no signals at allnullnullitnullmore complenullplanes and venullcle motion, more complenullmultipatnull nullll resultnullTnull nully point is tnullt all signals are calculated and tnullrenullre nullantinulldnull Tnull comnullnation onullsignals, nullnullever complenull nullll null repeated enullctly run anuller runnullFigure nullsnullnull an enullmple onullnullertical Plane nullultipatnull Figure null nullertical Plane nullultipatnull Page nullSPIRENT Application Note Figure 7nullSignal nullttenuation and nullsociated Pattern Signal Loss Tnull sensitivity onulltnull nullSS receiver nullll determine nullnullnullell it can tracnullsatellite signalsnullnullery sensitive receivers nullll null anulle to tracnullattenuated signals nulltter tnulln ones nulltnullpoor sensitivitynull nullenerally, tnullre are tnull parameters onullconcernnullnullcnullisition Sensitivity and Tracnullng Sensitivitynull null Acnullisition Sensitivitnull is tnull ponuller level at nullicnulltnull receiver can recognise tnull signal as a nullSS signal nulltnulln tnull noise nullTnullt is recognise tnull codenull null Tracnullng Sensitivitnull is tnull ponuller level at nullicnulltnull receiver is anulle to tracnull tnull signal and determine tnull satellites anullmutnulland elevationnullIn practice, tnulls is usually a lonuller level tnulln tnull nullcnullisition Sensitivitynull Simnullnull allonull you to control tnull ponuller level onulltnull simulated signal to a nullgnull degree onullresolution and over a nullde dynamic rangenullPonuller control can null carried out eitnullr in realnullime nullile tnull scenario is running, or using a prenullcripted set onullcommandsnullRealnullime control can null applied using tnull Simnullnull nullI or remote commands nullnulltnull simulator is nulling controlled nully a remote systemnull It is possinulle to control tnull ponuller independently on individual satellites, or on all satellitesnullLevel can null displayed as anullolute ponuller, or relative to a renullrencenullTnull resolution onullponuller control nullor tnull nullSnullnull simulatornullis very nulle, nulling nullnulldnullover tnull range nullnull dnull nullnulldnull nullnulldnull Tnulls nulle control allonull you to accurately test a receivernulls acnullisition sensitivity and tracnullng sensitivity as nullell as otnullr nullndamental parameters sucnullas TTFF in cold, nullrm and nullt start conditionsnull For nullrtnullr reading on tnull sunullect onull nullndamental receiver pernullrmance cnullracterisation, see our nullpplication nullote nullnullundamental GNSS nulleceiver Characteristicsnull nulle nullve already seen nullnulltnull nulltenna Pattern nullature can null used to simulate onullcuration and signal attenuation due to tnull venullclenullIt is also usenulll nullr simulating signal attenuation due to enullernal onullectsnullnullecause Simnullnull allonull denullition onullup to nullur dinullnullrent antenna patterns, it is possinulle to tanull tnull nullseline pattern tnullt includes tnull onnullenullcle onulltruction, and add enullra attenuation at certain elevations and anullmutnull to simulate, nullr enullmple nullgnullsided motornully sound nullrriers onulltnull type nullund adnullcent to primary routes tnullougnullurnulln areasnull nullou can instruct Simnullnull to snulltcnull to tnull modinulld pattern and snulltcnullnullcnull to tnull nullseline pattern at discrete times in tnull scenarionull Figure 7 snullnull tnull concept onullsignal attenuation caused nully motornully sound nullrriers and nullnulltnull nullrriers are represented nully an antenna patternnull Page nullSPIRENT Application Note nulldio nullrenullencnullInternullrence Spirentnulls nullSnullnull and nullSnullnull and nullS7nullnullseries onullsimulators nullve an RF nullammernull input port tnullt allonull you to innullct an enullernal RF signal into tnull main nullSS signal patnullin a controlled nully using a directional coupler inside tnull simulatornull Depending on tnull cnullracteristics onulltnull internullrence signal, you nullll null anulle to stop tnull receiver nullom navigating correctlynull null nulle nullve seen in section null a relatively small internullring signal nullll stop a commercial nullSS receiver nullom nullrnullngnull null signal innullcted nullom a tnullrdnullarty signal generator nulluld not null conullrent nulltnull tnull simulatornulls nullSS signalnull nullonullever, an Internullrence Simulation System option nullnullS77null nullis availanulle nullr nullSnullnull and nullSnullnull series simulatorsnull Tnulls allonull specinull signal generators to null controlled nully Simnullnull in eitnullr a conullrent or nonnullonullrent nully, nulltnulla variety onullsignal modulation types, and nulltnullmodelled ponuller, nullicnullsimulates tnull relative distance enullnullcts onulltnull internullrence source nulltnull respect to tnull simulated nullSS positionnull For more innullrmation regarding tnull nullS77null internullrence simulation option, see renullrence 4null Figure nullsnullnull tnull concept onullinnullcting an internullrence signal into tnull simulatornull Figure null Internullrence Signal Innullction Concept Page nullSPIRENT Application Note GNSS nullINS Spirent Simulators tnullt are controlled nully Simnullnull nullve an optional capanulllity called Simnullnullnull Tnulls option provides tnull anulllity to simulate signals tnullt nulluld normally come nullom deadnullecnullning venullcle sensorsnull SimAnullO comprises onullsonullnullre nullatures in Simnullnull and Digital and nullalogue Inullcards nullted to tnull Simnullnull nullst PCnullSignal and data canulle sets are also providednull SimAnullO nulls tnull anulllity to generate simulated signals nullr tnull nullllonullng parametersnull null nullehicle nulleading nullte nullTnulls nullpolar analogue voltage output can null used to simulate tnull output onulla Rate nullyronull Tnull voltage onulltnull signal is proportional to tnull angular rate at nullicnulltnull venullcle nullading is cnullngingnull null nullehicle Anullolute nulleading nullTnulls nullpolar analogue voltage output can null used to simulate tnull output onulla gyro or compassnullTnull voltage onulltnull signal enullates to tnull venullcle nulladingnull null Turntanulle Control nullnull an alternative to emulating sensor outputs, and nulltnull suitanulle sanullty precautions tanulln, nullilt in sensors may null stimulated on a rate tanullenullSimnullnullnullsupports tnulls application nulltnulla suite onullcalinullation procedures to aid in tnull determination onulltnull appropriate scale nullctors and DC onullnulletsnull nullalogue voltage signals representing turntanulle speed and positions are also providednull null nullehicle Speed and nullirection nullSeven digital outputs are allocated to tnull simulation onullvenullcle speed, nullur onullnullicnull can null directly mapped to represent independent nulleel speed sensorsnull null nulligital Speed Pulses nullSeven digital outputs are allocated to tnull simulation onullvenullcle speed, nullur onullnullicnullcan null directly mapped to represent independent nulleel speed sensorsnullTanulle nullsnullnull tnull mapping onulltnull seven outputsnull Tnull signals presented are snullare nullves nullnull duty cyclenullnullere tnull nullenullency is proportional to tnull venullcle speed and a usernullpecinulld scaling nullctornullnull separate, independent scale nullctor can null specinulld nullr eacnullonulltnull seven signals tnullugnulltnull nullur nulleel sensor outputs nulluld normally use a common scale nullctornull nullutput Signal null nullenullcle Centre speednull null Front nulleel nulldometer nullpeed calculated as average onulltnull nullnullont nulleelsnull null Rear nulleel nulldometer nullpeed calculated as average onulltnull nullrear nulleelsnull 4 Front lenull nulleel speed null Front rignull nulleel speed null Rear lenull nulleel speed 7 Rear rignull nulleel speed Tanulle null Speed Sensor nullutput nulllocation Page nullSPIRENT Application Note Simnullnullnullis capanulle onullsimulating various nulleventsnull nullicnullcause a disturnullnce or error on tnull signalsnull null nulleel Speed Events nullnullou may simulate nullero nulleel speed, sucnullas during a snulld nullere one or more nulleels locnullupnullFaster or slonuller nulleel speed, sucnullas occurs during a nulleel slip or partial snulldnullnullgoritnullic errors, simulating randomised and systematic errors denulled nully a nullrmulanull null Gnulloscope Events nullnullou may simulate a stucnullgyro, randomised gyro noise and giro nullas in sympatnull nulltnulla temperature ramp or nulled valuenull null CANnullus nullessages nullSimnullnullnullcan generate Cnull messages consistent nulltnull modelled sensor nullnullviournullSpirent can modinull tnullse to your renullirementsnull Figure nullgives an overall scnullmatic snullnullng tnull principle onullSimnullnullnulls operation in connullnction nulltnulltnull standard Simnullnull null RF Simulator systemnull nulleproducing real drive tests nulle nullve seen nullnullponullernulll a simulator can null in allonullng you to denulle representative tests to simulate many dinullnullrent conditionsnullnullonullever, a standard Simnullnull application allonull you to tanull data nullom real nullld tests and convert it into a motion nulle, used to simulate tnull venullcle motion tranullctorynull itnullut leaving tnull lanullyou can reproduce an identical nullurneynull Tnulls is a very usenulll nullature tnullt can dramatically reduce tnull cost, eliminate tnull unnullepeatanulllity and save tnull time associated nulltnullreal drive testsnullIt also allonull reproduction onullsignal onullcuration tnullougnulluse onullappropriate datanull NnullA nullnull messages nullost nullSS receivers output data in tnull nullEnull nullrmat nullr position, velocity, Snull, satellite visinulllity etcnullTnulls data is used nully tnull receivernulls control sonullnullre, nullr enullmple, to provide a navigation solution to a displaynullFor more innullrmation, see tnull nullational nullarine Electronics nullsociation nullenullitenull nullnullnullmeanullrg Figure null Simnullnullnullnullperational nullervienull Page nullSPIRENT Application Note NnullA Conversion nulltilitnull nullEnull conversion is pernullrmed using a tool nulltnulln tnull Simnullnull application called SimPRnullESS nullee renullrence null Tnull SimPRnullESS application is a compiled nullTLnull standalone application tnullt uses a nullll encrypted componentnulluntime installation onullnullTLnullnullnull sucnullit manulls availanulle a very ponullernulll set onulldata analysis and visualisation nullnctions nullee onullcnullrge to Simnullnull usersnull SimPRnullESS itselnullsnulluld null seen as a sonullnullre toolnullnullnullicnulluses a standardised user internullce nullr accessing any numnullr onullSimPRnullESS tools nullicnullnullll null made availanulle in tnull nullturenullTnull nullEnull to motion utility converts your receiver log nulle containing nullEnull nullnull messages into a motion nulle nullnullmtnullnullr replay in Simnullnullnull Tnull motion nulle contains motion commands at nullnullms intervalsnull Tnull utility also uses satellite Cnull data nullom tnull nullEnull nullnullmessages to replicate tnull satellite ponuller levels as seen at tnull receivernulls antennanullnullou can replicate a real drive test, nullere tnull receiver is sunullected to onullcuration, nullicnullnullll null renullcted in tnull nullnullmessage onulltnull logged data, nullnd can tnullrenullre null replicated nully tnull simulatornull nullitnulltnulls capanulllity, you can replicate any onullcuration present on tnull real route nulltnullut using Simnullnullnulls nullaturesnull Tnull limitation onulltnulls approacnullis tnullt tnull simulated tranullctory nullll not necessarily null enullctly tnull same as tnull receiver position nullen tnull nullEnull data nulls recorded, tnulls is nullcause it is nullsed on nullEnull data recorded nullom a real receiver sunullected to all tnull environmental conditions and signal errors already descrinulldnullnullnullcourse, manual manipulation onulltnull nullEnull data to remove onullvious gaps or errors is alnullys possinulle nullnd Spirent recommends tnulls approacnullnullnullonullever, Simnullnull nullll nullitnullully convert tnull data it is given, regardless onullits original accuracynull Tnull nully principle nullre is tnull simulation can null repeated time and againnull nullile tnull data may not represent tnull pnullsical route precisely, tnull repeatanulllity is precisenullIn some cases, nullving inaccurate nullt repeatanulle tranullctory data is actually nullnenullialnullnullany innullar nullSS systems employ map matcnullng algoritnulls and snapnullonulload nullatures, you can test tnull ronullstness onulltnullse nullatures using impernullct tranullctory data and sunullenullent attempts at improving tnull algoritnulls can null renullested using tnull same datanull For more innullrmation on nullnullto reduce drive test times, donullload tnull Spirent nullpplication nullote nulleduce Real nullorld Drive Test Timesnull Page nullSPIRENT Application Note Conclusions Tnulls nullpplication nullote nulls enulllored some onulltnull main pronullems enullerienced nully nullSS receivers operating in tnull automotive environmentnullIt nulls snullnull nullnullproper product testing during design, development, integration and production pnullses is onullparamount importance to prove its suitanulllity nullr tnull intended applicationnullTnulls nullpplication nullote nulls nullgnullignulled tnull nullys in nullicnullan RF Simulator can readily null used to pernullrm representative tests addressing eacnullonulltnullse pronullemsnullnully using a simulator you can reproduce tnull enullnullcts enullctly eitnullr onenullynullne, in any comnullnation or all togetnullr nulltnullanullolute control onulltnull simulation parametersnullTnull approacnulls descrinulld nullll manullmise test enullnullctiveness and ensure manullmum nullness nullr purpose onulltnull developed product nullile minimising your development cyclesnull nullenullrenced nullocuments nullnless otnullrnullse stated, renullrence to tnull latest issue onulleacnulldocument is innullrrednull null Dnullnullnullnullnull Simnullnull Sonullnullre nullser nullanual null nullnullnull Simnullnull nullr nullindonull Product Specinullation null nullnullnull nullSnullnull nullultinullnullS Constellation Simulator System Product Specinullation 4null nullnullnull nullS77null Internullrence Simulation System Product Specinullation null nullnullnull SimnullnullnullProduct Specinullation null nullDnullnullnullnull Simnullnullnulldata snullet 7null Dnullnullnull Testing nullSS System Errors nullpirent nullpplication nullotenull null Dnullnull4 Simulating nullultipatnull nullpirent nullpplication nullotenull null Dnullnullnull Fundamental nullSS receiver cnullracterisation nullpirent nullpplication nullotenull nullnull Turn Turn Turn, nulleelnullpeed deadnull recnullning nullr venullcle navigationnull nullnullnullay, nullS nullorld nullct nullnullnull nullnull nulllonulll Positioning SystemnullTnullory and nullpplications nullradnullrd nullnullParnullnson, nullames null Spilnullr nullnull nullnull nullnderstanding nullS nullprinciples null applications nullnullnullplan, Cnullnullegartynull nullnull nullulneranulllity assessment onulltnull transportation innullastructure replying on tnull nulllonulll Positioning System nullnullonull null nullolpe, nullSC, nullug nulltnull nullnullnull Page 2nullSPIRENT Application Note GlossarnullonullTerms nullmanac nullppronullmate satellite ornullt innullrmation Cnull nullus Controller nullea nulletnullrnullnullus Epnullmeris Detailed satellite ornulltal positional data nullS nulllonulll Positioning System nullSS nulllonulll nullavigation Satellite System nullI Sonullnullre nullrapnullcal nullser Internullce Inull Inertial nullavigation System InullS Innullenullcle nullavigation System LnullS Line onullsignull nullavigation Data nullnulls data message nulloadcast nully nullS satellites Pseudorange Satellite to receiver distance as measured nully radio ranging Pnull Position nullelocity nullTime Scenario null prenullenulled test running on Simnullnull sonullnullre Snull Signal to nulloise ratio, as measured at nullsenullnd nully a receiver TTFF Time To First Finull Page 2nullSPIRENT Application Note CONTACT null Spirent Communications null4 nullnull nullnullnull glonulllsalesnullpirentnullom nullnullnullpirentnullomnullositioning Spirent nullederal Snulltems null 7null nullnullnullnull innullnullpirentnullderalnullom nullnullnullpirentnullderalnullom nullnullnot share this documentnull Got a smartphonenull If you have a smartphone download a QR Code reader and then point your phone camera at the QR Code to read the graphic. DnullnullnullISSnull nullnull Facenullonull LinnulldIn Tnulltter Tecnullorati nulloogle nullunull Digg Delicious Reddit Stumnulleupon RevnullnullnullSept nullnull nulle are adding nenullcontent to our nullenullite on a regular nullsisnull nullonullarnullthis linnull nullnullnullpirentnullomnullositioning nullisit the Spirent GNSS nullognullthere are currentlnullover null posts nullth 2 to 3 nenullposts added each nulleenull Catch up on nullatnulls nenullnull nullnullnullpirentnullomnulllognullositioningnullspnull Need more innullrmationnull gnssnullolutionsnullpirentnullom