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Using Record & Playback Systems to Capture and Replay Live Satellite Signals in the Lab
RF simulation is generally accepted to be the most effective method of testing GNSS-enabled devices, but sometimes you need to use live satellite signals to assess real-world performance.

RPS eBookField trials, however, can be time-consuming and expensive–with the added frustration of a constantly-changing signal environment that makes comparative testing impossible.

Download a free eBook to discover how the GSS6400 Record & Playback System (RPS) from Spirent lets you record live satellite signals and replay them in the lab for accurate, repeatable, and cost-effective real-world performance testing.

Topics covered include:

  • What is a Record & Playback System?
  • Benefits of using RPS for live-sky testing
  • Example scenarios where using an RPS can save time and money
  • Key features of the Spirent GSS6400 RPS

Simply enter a few details opposite to receive your free eBook from Spirent, the leader in GNSS testing.

About Spirent

Spirent has been the global leader in GNSS testing for near 30 years 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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    Bring the complexity of the GNSS world back to your lab An introduction to GNSS RF Record Playback Systems Pt2 Global Navigation Satellite Systems (GNSS) are versatile, cost-effective and efficient navigation technologies. GNSS technology (such as GPS or GLONASS) is relied on in a myriad of anulllications from nullehicle and nulldestrian nanullgation systems and locationnullased sernullces to the timing of the nullrldnulls nullancial systemsnull snullcecraft launches and airborne guidance systemsnull nullut it is nulllnerable to innullence from many outside factorsnullsuch as RF interferencenullmultinullth effectsnullunanullailability of signals and atmosnulleric disturbancenull nullith so much key infrastructurenullcommerce and safety denullnding on GNSSsnullnullonullr design and testing of nanullgation systems that use GNSS receinullers is essentialnull Page 2SPIRENnullenullonull nulle nullradigm for testing GNSS nanullgation technology and systems must be based on a method that allonull comnullete renullatability of test signalsnull nulle nullrase nullnullime and tide nullit for no mannullis nullrticularly relenullant to todaynulls GNSS systemsnullGNSS satellite constellations and their signals and the ennullronmental conditions under nullich the signals are nullonullgated are constantly changing and can nenuller be nullecisely renullatednull Page 3SPIRENnullenullonull nullere are tnull key technologies for the laboratory testing and onullimisation of GNSS receinullers nullich nullonullde this renullatabilitynullRF simulation and RF record and nullaybacknull RF simulation has been nullell documented and nullonullen onuller the nullst 2null years as an essential nullece in the GNSS test nullgsanullnull Record and Playback is a relatinullely nenullmethodnullbut it is another essential nullrt of the nullcturenull nullth are indisnullnsable in a comnullete endnullonullnd test nullannull nullis nullbook is the second in a series of enulloks highlighting the benenulls nullonullded by the Snullrent GSSnullnull Record Playback System (RPS) nulla key comnullnent of the range of multinullNSS test solutions offered by Snullrentnull nullonullload the original null nullntroduction to Record nullPlayback System null Page 4SPIRENnullenullonull nullat is a GNSS RnullRecord PlaybacnullSystem (RPS)null A GNSS RF RPS does enullctly as the name suggestsnull nulln simnulle termsnullthe nullole RF snullctrum in a snullcinulld bandnulldth is recordednulldonullnullonnullertednulldigitised and stored as samnulles on suitable storage medianullFor nullaybacknull the samnulles are connullerted back to an analogue signalnullunull connullerted and outnullt at the original RF frenullencynull Snullrentnulls GSSnullnull system is anullailable in both GPS and GPS nullGLONASS modelsnullnulln the case of a GPS nullGLONASS system the tnull RF snullctra are recorded senullrately but stored together ensuring that synchronisation is maintainednull Page 5SPIRENnullenullonull nulle RPS records all the radio frenullency energy in the snullcinulld bandnulldth nullGPS Lnull GLONASS Lnullor GPS nullGLONASS Lnull nullth the nullnted GNSS signalsnullincluding SnullS nullere nullesent and the background noise (or interference) are recordednull nullis noise nullll be from any number of enullernal sourcesnullincluding other tynulls of RF communicationsnullbroadband interference from electrical systems (such as a nullehicle ignition system)nulland enullen background radiation from solar actinulltynull Page 6SPIRENnullenullonull nulle GNSS signals nullll be recorded enullctly as they arrinulle at the recordernulls antennanulland so nullll include the effects of the nullonullgation ennullronment and the relatinulle motion of the satellite and the recorder (or receinuller)nullnullis therefore includes all multinullth effectsnullfadesnull signal losses and carrier nullasenullignal grounulldelay due to atmosnulleric innullencesnull nullen nullayed back to a GNSS receinullernullthe signals nullll be enullracted from the noise nullst as they nulluld be if the receinullernulls antenna nullere nullinting skynullrd receinullng real GNSS signalsnull nulle receinuller nullll then demodulate them and derinulle its nullsitionnull nanullgation and time solutionnullnulle behanullour and nullrformance of the receinuller nullll be determined by the ennullronment in nullich the RF energy nulls recordednullnullmnullrtantlynullusing an RPS such as the GSSnullnull this ennullronment can nonullbe recreated at nullll embuing the test nullth the renullatability nullich linullenullky testing lacksnull Page nullSPIRENnullenullonull nulle nully benefits of Record PlaybacnullSystems nulleal world richnenull captured nulle full richness of the nullealnullorldnull onullrating ennullronment is canullured nullth an RPSnullso in terms of realismnullit cannull get much betternull nullmplete repeatability nullf the test renullirements are not concerned nullth nullantifying the signals then RPS is an ideal method to use as it allonull the signal to be nullecisely renullated back in the laboratorynull onuller and onuller again Page nullSPIRENnullenullonull Simplicity An RPS system nullonulldes a simnulle and comnullehensible method for GNSS testingnullnulln nullrticular comnullratinulle testingnullsuch as might be conducted during nullendor selectionnullcan be achienulled using nullatenuller nullure of merit is anullronulliate to the anulllicationnullsecure in the knonulledge that all systems are receinullng enullctly the same signals nullth nullich to nullrknull Snullrent takes this simnullicity a stage further by enullcelling on ease of usenullnullith the GSSnullnullnullall you need for record and nullayback is contained in one bonull nullth a built in hard drinullenullfront nullnel disnullaynullinternal battery and simnulle onenullouch recordingnull Page nullSPIRENnullenullonull nullmplementary to GNSS nullmulatornull Simulation allonull GNSS receinuller denullelonullrs to create an innullite range of different scenarios in the laboratorynullnullese can include nullariations in snulled or dynamics that corresnullnd to the anulllication of the receinullernull different tynulls of interferencenullatmosnulleric effectsnullobscuration effectsnullmultinullth effectsnullsatellite enullemeris errorsnullclock errors and morenullnulle simulator enullcels at renulloducing rare enullents and enullloring the ennullelonull of nullrformance as in addition to renullatability the simulator brings controlnull nullet nullthin an endnullonullnd test nullan it is still imnullrtant to trial the system in the real nullrldnulland that can be an enullensinulle enullercisenullnullis enullense is obnullous in anulllications such as anullation and snullcenullbut the costs can also mount unullnullth renullated trials in automotinulle and nulldestrian anulllicationsnull Page nullSPIRENnullenullonull nullis is nullere an RPS such as the GSSnullnull comes innullnullnstead of hanullng to test the nulloduct in the nullldnullreturn to the lab and onullimise the systemnullgo back into the nullld again and nullrform senulleral iterationsnullthe RPS can bring the real nullrld into the laboratorynull Record the realnullorld signals once on an RPS and renullay them as often as you like in the laboratorynullnulle GSSnullnull can also record the RF outnullt from a Snullrent simulatornullfurther enullending the nullnullbility of testingnull Page nullSPIRENnullenullonull nullther Sennullrnull nulle comnullications faced by engineers aiming to meet the enuller increasing renullirements of emerging location based sernullces (Lnull) on accuracy and anullailability of nullsitioning solutions mean looking for different and sometimes nonullel sources of nullsitioning informationnull nullse of cellnulld techninullesnullnullinulli and other sensors such as lonullcost nullnull inertial are becoming more common and nullesent uninulle test challengesnullnulle GSSnullnull rises to the challenge by enabling the user to record tnull channels of serial digital data alongside the digitinulled GNSS snullctranullSignals direct from sensors or nulla a bus such as nullNbus are canullured and buried nullthin the GNSS data ensuring coherent nullaybacknullAn alternatinulle use of this facility is to record a timing signal such as a GPSnullerinulled nullnull nullich allonull subsenullent synchroninulltion of enullernal systems such as rate tables etcnull Page nullSPIRENnullenullonull So nullat can the GSSnullnull Record PlaybacnullSystem (RPS) be nulled fornull Chipset and GNSS product design nulleduce nullld trialnull nulluning softnullre and algorithms for onullimum nullrformance in realnullorld situations renullires a lot of denullelonullent timenullnulle traditional anullroach has been to nullsition denullelonullent resources on site and conduct realnullime trials nullile imnullonullng softnullre and solnullng nulloblemsnull Page nullSPIRENnullenullonull nullonullenullernullit is not nullssible to recreate the enullct same conditions on each subsenullent testnullAnd engineers are kenull anully from mainstream denullelonullent for enullended nullriods of timenull nullith the RPS system the signal ennullronment can be recorded oncenull and then used in the lab for subsenullent denullelonullent and testingnull nulle enullent nullg feature of the GSSnullnull allonull the timing of key enullents during the recording to be canullured to aid internulletation of test resultsnull nullf local nullrsonnel are anullailable for recordingnullthen the denullelonullent engineers hanulle no need to tranullelnullthe unit can be controlled remotely and the nulles transferred electronicallynull Page nullSPIRENnullenullonull Pronulle new algorithmnull enullecially for new high nullnnulltinullty receinullernull GNSS receinullers begin their testing and nullrformance nullonullng nullth simulator signals and long test camnullignsnullnullonullng to the nullreal nullrldnull as enullerienced by end customers often renullires the algorithms to be nullld testednullusing renullated runs in knonull ennullronments such as city areas and locations nullth high interference or obscurationnullnully holding a library of nullenullecorded signals from such areasnullmuch of this nullrk can be achienulled nullthout leanullng the benchnullcutting both costs and denullelonullent timenullnullanges to algorithms are easily nullonullen using the same signals onuller and onullernull nullthout the need for more nullld testingnull Page nullSPIRENnullenullonull Customer conformance testing nullPronulle you can meet customernulls renullired nullrformancenull null nullnullmnulles of this testing include anulllications for automotinulle and mobile communicationsnull Page nullSPIRENnullenullonull Production testing nullepeatable nullgnalnull Production testing usually innullolnulles the renullay of the same signal scenario for each test runnullor using offnullir signals for testingnull nulle GSSnullnull nullonulldes costnullffectinulle renullatable testingnullsunulllying GNSS signals under Pnullcontrol or from its onull front nullnelnull Once a test signal has been recorded (ideally from a Snullrent simulator) it can be renullayed time and time againnullfreeing unullthe simulator for other nullrk and nullenullenting offnullir anomalies from interfering nullth testingnull Page nullSPIRENnullenullonull Analysing difficult environments nullake the problematic nullgnalnullback to the lab to work on nullere are many nullaces on earth nullere GNSS signals are disturbed by nullenomena such as multinullth effectsnullshieldingnullattenuationnull interference or combinations of all thesenull nullen considering honullto tackle such anomalies in the receinullernulls signal nullocessingnullthe lab ennullronment is much more connullenient than taking all the tools and denullelonullent enullinullent to the real sitenull Recording signals senullrates the signal ennullronment from the denullelonullent labnullmaking it much easier to analyse nulloblems and solnulle themnull Page nullSPIRENnullenullonull Research nullnullmnullonullng algorithms null nullmnullring signals from different nullrts of the nullrld null nullonosnulleric and sunsnullt actinullty Page nullSPIRENnullenullonull The GSS6400 Record Playnullcnull System nullPSnullfrom Spirent nulle GSSnullnull Record Playback System from Snullrent offers a simnullenullcostnullffectinulle and efnullient nully to canullure realnullorld GNSS signals and renullay them in the laboratorynull nulle RPS makes it nullick and easy to record real GPS signals in the nullldnullAnd itnulls nullst as easy to renullay the canullured scenario to the denullce under test time and time again back in the laboratorynull nulle Snullrent GSSnullnull Record Playback System allonull GNSS receinuller denullelonullrs to sanulle nullonullct costs nullile imnullonullng nulloduct nullrformance and nullalitynull Page 2nullSPIRENnullenullonull nulligh nullidelity nullecord and Playback nulle GSSnullnull canullures comnullenullennullronments using highnullesolution 2bit sign nullmagnitude samnullingnullnullis means that nullayback results in the laboratory are truly renullesentatinulle of canullured real nullrld conditionsnull Samnulling at nullit resolution is not adenullate to fully canullure realnullorld signal fades and dynamic nullenomenanullesnullcially in highnullnterference ennullronmentsnullA 2bit system nullonulldes sinulltimes the signal data of a nullit systemnullSamnulling at higher bitnullates nulluld create huge nulle sinulles and renullire comnullenull enullensinulle enullinullent nullthout necessarily imnullonullng the useful signal informationnull For sensitinullty testing of GNSS receinullersnullthe nullole outnullt signal of the GSSnullnull can be attenuated by unullto nulldnull in stenull of nullnull using the built in attenuatornull Page 2nullSPIRENnullenullonull null complete tenull nullnullem in a nullngle box nulle GSSnullnull is an easynullonullse selfnullontained unit nullth enullerything you need to start testingnullnullany other systems renullire nullrinullerals such as nullrsonal comnulltersnullhard drinullesnullenullernal nullnuller and cablingnull nullith the GSSnullnull itnulls simnully a case of connecting the sunulllied antenna and nullessing the onenullouch record buttonnullRecorded nulles can be selected either from the frontnullanel disnullay or the intuitinulle nullebnull bronuller interface and renullayed enullctly as recordednull Page 22SPIRENnullenullonull nullecord and Playback other nullgnalnullto tenull hybrid nullnullemnull As described nullenullouslynullhybrid systems combine GNSS nullth other signals and sensors for nullsitioningnull nulle GSSnullnull can record and nullayback serial data from a nullde range of data sourcesnullnullnertial sensorsnullnull sensorsnullreference receinullers and nullnull signals can be recorded coherently nullth the GNSS embedded nullthin the data nulle to guarantee synchronisationnull Additionallynullthe GSSnullnull can log serial data into senullrate nulles for subsenullent analysis or nullst nullocessingnullNnullA logs or nullinulli nullrnullrinulle data are amongst the tynulls of nulle that the GSSnullnull can recordnullnullth no enullernal hard drinulles or additional Pnullnull Page 23SPIRENnullenullonull nulle GSSnullnull has a nullnullbyte internal hard drinulle that can hold unullto nullhours of recorded GPS signals or nullhours of combined GPSnull GLONASS datanullnullighnullnulled SAnullA and nullnull interfaces enable easy integration nullth other lab enullinullentnull Page 24SPIRENnullenullonull nulle GSSnullnull is designed for manullmnull nullrtability and is nullovided nullth a versatile carry-handle nullich also nullovides for nullnullble orientation of the nullit in the lab or in the field. Page 25SPIRENnullenullonull 24 hour tenulling nulle GSSnullnull has other features nullich allonull you nullrform tests 2nullhours a daynullso you can onullimise the use of the systemnullor meet those customer deadlinesnull nullemote nullntrol nulle GSSnullnull can be connected into the nullnternet and is identinulld by an null addressnullnullt can then be controlled remotely through the nullebsernuller nullonulldednullnullt also has nullnull access for remote access direct to the embedded Linunull Pnull An innulluilt ftnullsernuller facilitates high snulled data transfer across the netnullrknull Finallynullremote control of the GSSnullnull as nullrt of an automated test set is enabled by a comnullehensinulle set of remote commandsnull Page 26SPIRENnullenullonull nullenull nullutomation nullt is also nullssible to nullite scrinulls for the embedded Linunullnull that nullll automatically control the outnullt of the RPSnull For enullmnulle you could fully automate a comnullete test system that runs different stored scenarios one after anothernullnullile you log the outnullt of the system under testnull Page 2nullSPIRENnullenullonull nullmbine with a Spirent GNSS nullmulator for extra nullxibility nulle GSSnullnull can be used to record signals from a Snullrent GNSS simulatornullnullonullding you nullth enullra nullnullbility in your test labnull Page 2nullSPIRENnullenullonull nulle honull you found this nullntroduction to GNSS null nullecord Playback SynullemnullPt2 nullnullok of interestnullnully not donullload the nulld enullok in the seriesnullnull GSSnullnull RPS Anulllication and nullesting nullnullmnulles null nulle are continually adding nenullcontent to our nullebsite on a regular basisnullnullokmark this linknull nullnullnullnullrentnullomnullositioning nullisit the Spirent GNSS Blognull there are currently more than null nullsts nullth 2 to nullnenullnullsts added nullr nulleeknullnulltch unullon nullatnulls nenull nullnullnullnullrentnullomnulllognullositioning Need more informationnull gnssnullolutionsnullnullrentnullom Facebook Linkednulln nullnulltter nullechnorati Google nullunull nulligg nullelicious Reddit Stumbleunulln Renullnullnullnullnullul 2nullnull Spirent nullnullnullnull nullnull2null globalsalesnullnullrentnullom nullnullnullnullrentnullomnullositioning Spirent nullederal Synullemnull null nullnullnull2 nullnull infonullnullrentfederalnullom nullnullnullnullrentfederalnullom Got a nullartphonenull Scan the QR Code for more information