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FREE eBook: Choosing a GNSS Simulator

Choosing a GNSS Simulator?

There are multiple satellite signal testing options available for developers of GNSS-enabled devices, but not all of them deliver the breadth and accuracy of results that you need. So how do you decide which GNSS testing device is the right one for you?

Download a free eBook to discover: 

  • The different GNSS testing options available 
  • The advantages and limitations of each one 
  • How to choose the best GNSS testing method for your device 

Simply enter a few details opposite to receive your free eBook—and happy reading! 

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About Spirent

Spirent has been the global leader in GPS 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.

    Choosing a GNSS simulator? Getting it right. Why all simulators are not the same Getting it Right Product designers, manufacturers and system integrators involved in GPS development have used GPS simulators for R&D, integration, verification and production testing for years. But with the proliferation of GPS applications coupled with the commercialisation of GnullnullnullS, the development of future Glonulll nullavigation Satellite Systems nullnullSnulland the integration of these systems, GPS and GnullS testing has nullcome more mainstream. nullf this is new to you, donnull worry, we can help you as all GnullS simulators and test approaches are not the same. nullou need to understand what these devices can do and how they can nullnefit your particular needs. Page 2SPIRENT eBook The case for RF simulation nulle case for using a GNSS simulator when designing any form of location aware enullipment is a compelling one. nulle anulllity to control test conditions, to simulate new satellite systems long nullfore they go nullivenulland the ability to precisely repeat tests time and time again is a nully application of simulation that cannot null achieved through using live satellites for testing. nullere is however, a case where capturing the richness of live snull signals to playnullcnulllater in the lanull complements simulation as a source of GnullS signals for test. But more of that later. SPIRENT eBook What is a simulator? null Rnullnullnstellation Simulator reproduces the environment of a GnullS receiver on a dynamic platform nully modelling vehicle and satellite motion, signal characteristics, atmospheric and other effects, causing the receiver to actually navigate according to the parameters of the test scenario. GSS6300 Multi-GNSS Signal Generator GSS6700 Multi-GNSS Constellation Simulator GSS7735 Multi-Channel Gnull nullnullnullproduction test simulator Page 4SPIRENT eBook nullowever, during the past decade, a numnullr of alternative devices have emerged that claim to offer a complementary or alternative to GnullS simulation in a numnullr of different ways. nulle minullnow includes nulln no particular ordernull null nullve snull null Pseudolites null Rnullrecord and playnullcnullsystems nullPSnull null Singlenullhannel Rnullsimulators null nullultichannel Rnullconstellation simulators So where would we use these devices and how do nulldecide whatnulls right for menullWell that all depends on your test renullirements as all approaches nulling with them a minullof pros and cons. Page 5SPIRENT eBook The tests required nullnullratory testing of any GnullS receiver design nullll renullire a range onull standard tests in order to enullercise the nullll nullnctionality of the receiver under nullth nullnormalnulland nullspecialnulloperating conditions. nullese tests, which might null carried out individually or comnullned, will comprisenull null nullime to first finull null nullcnullisition sensitivity null nullracnullng sensitivity null Reacnullisition time null Static navigation accuracy null Dynamic navigation accuracy null Radio frenullency interference So how does each solution stacnullup against renullirementsnull Page 6 null nullnullore information on GnullS Receiver testing can null found nully downloading the eBoonullnullimulator versus real world testingnull SPIRENT eBook Live sky nulle first onulltacle that will null encountered in integrating GNSS receiver testing into a production test setup is pretty onullvious. null such tests are performed at the end of the production line, they are inevitanully performed indoors. nulld regardless of whether the enullipment is designed to wornullindoors or outdoors, the roof and walls of the nullilding will introduce varianulles into the test that will negate its effectiveness. Sonullalled nullivenullnullnulltesting is therefore impossinulle without relaying the GnullS signals from outdoors to the production tester. Page 7SPIRENT eBook nullt is a relatively simple enullercise to capture live GnullS signals and renulladiate them within the production test environment. nullowever, this comes with its own set of shortcomings. nullirst, radiating any signal in such an environment might have unforeseen consenullences on other tests that are performed on the productnulland conversely, other Rnullsignals and noise within the production test area may well impact on the integrity of the GnullS signals. Page 8SPIRENT eBook nullore importantly, though, the inherently dynamic nature of GnullS signals means that while each unit may well null tested in the same physical location null.e. in the production tester finullurenull the relative positions of the GnullS satellites will null different for every unit tested. nulld, not surprisingly, this manulls direct comparison nulltween results unrelianulle at nullst. Page 9SPIRENT eBook Realnullorld, livenullnull testing does have some advantages e.g. younullre testing real signals and at the very nullsic level, itnulls inenullensive nullt it has some significant drawnullcnull which, in practice, preclude controlled testing. nulley pointsnull null nullesting using real signals null nulln null inenullensive null null end user or test site cannot have any control over the GnullS signal nulling transmitted null nulle signals seen incident to the GPS receiver antenna are constantly changing as the GPS system constantly changes nullrecessesnull Page 10SPIRENT eBook null nullere are occasional signal errors, often unnullown to the receiver at the time null nullmospheric conditions change significantly and have a significant impact on single frenullency systems null nullesting at multiple geographic locations proves to null enullensive Page 11SPIRENT eBook Pseudolite null pseudolite nullr pseudo satellitenullis simply a device used to emulate the role onulla satellite, and as such can null thought of as a simulator. nullis class of devices includes transmitters used to augment indoor coverage as well as those used to simulate future satellite constellations nullfore launch. Page 12SPIRENT eBook nulley pointsnull null Pseudolites are not for testing null nulley can null used to augment GnullS, nullt manullr issues arenull nullSynchronisation null Modinulld receiver needed to cope nullth high ponullr signals and stationary transmitters null nullostly used for professional applications nullnullgnullmining or use in container ports Page 13SPIRENT eBook RF record and nullaynullck system nullPSnull nullGNSS null nullS does enullctly as the name suggests. nulln simple terms, the whole Rnullspectrum in a specified nullndwidth is downconverted, digitised and stored as samples on suitanulle storage media. nullor playnullcnull the samples are converted nullcnullto an analogue signal, upnullonverted and output at the original Rnullfrenullency. nulll Rnullenergy in the specified nullndwidth is recorded. nulln addition to the GnullS signals interference is also recorded. nullis may null from many sources such as other Rnullcommunications, nulloadnullnd interference from electrical systems nullehicle ignition etc.null and even radiation from solar activity. nulloise is also inevitanully added nully the recording and playbacnullprocess, nullt with appropriate lownulloise gain at the start of the process this can null minimised. Page 14SPIRENT eBook nulln terms of the recorded GnullS signals, these will null as they arrive incident upon the recordernulls antenna so they will include the effects of the propagation environment and the satellite and onullervernulls motion, this includes multipath in its full richness, fades, signal loss and carrier phasenullignal group delay due to atmospheric innullences. nulley pointsnull null null RPS gives you the power and nullnullnulllity of performing one field test and repeating it many times in the lanull. null Records all signals in nullnd null Record real world environments and effects null nulln null a cost effective solution SPIRENT eBook Page 15 null RPS is complementary to GnullS simulation and is important for the verification part of a complete GnullS test plan, where precise nullowledge of the test signal is not important, nullt precise repeatanulllity of the signal nullichnessnull of the real world is null nullou cannull test future signals e.g. Galileo null Results can null difficult to interpret null RPS has limited control null nulldeal for testing in complenull environments, where recreation of signal and fading effects in a simulator is a manullr challenge SPIRENT eBook Sinnulle channel RF simulators nulln the face of it, a simple single channel Rnullsimulator would appear to null suitanulle for GnullS receiver testing. nullowever, many of the range of tests renullired nullee page null are not possinulle. Single channel units are widely used for production testing where nullstimulationnullof one receiver channel as a GonulloGo or sensitivity test is enough to determine the circuitry wornull. nullor R&D testing a single channel can help with simulating the receiver Rnulland enanulling single channel tracnullng and sensitivity measurements. nullowever, there is more to testing a GnullS receiver than simply producing a signal at the correct frenullency. Page 17SPIRENT eBook nulley pointsnull null Without the anulllity to simulate a full satellite constellation a receiver cannot null fully tested for its primary function null null future receiver tests will include more than nullst GPS null nullnull code, a single channel Rnullsimulator should have the capanulllity to test GnullnullnullS null and Galileo null either out of the nullnullor through a field upgrade null Rnullpower level accuracy and stanulllity are important to ensure valid results Page 18SPIRENT eBook nullultichannel RF constellation simulators nullere is, however, one solution that is capanulle of handling all of the tests necessary for designing, developing and integrating GnullS receivers in the lanullratory. nulle multichannel GnullS constellation simulator is capanulle of running all seven standard tests of GnullS receiver performance, together with their individual variations. Whatnulls more, todaynulls simulators can null used to produce signals from satellite constellations that do not yet enullst in the real world, allowing developers to create multinullnullS designs that will wornullrelianully with GPS, GnullnullnullS, Galileo and nullmpass systems. Page 19SPIRENT eBook nullis type of enullipment is widely used for R&D, integration, validation, production and post sales testing. nulley pointsnull null null multichannel GnullS constellation simulator should provide the capanulllity to recreate the GnullS Rnullsignal in such way that it should null fully representative of the real signal enullected nully a receiver null nullt should allow a user to control the simulation environment and all parameters of the signal should null nullown to the user null null multichannel GnullS constellation simulator should enanulle the provision of complete repeatanulllity in the signal creation null Results are easily interpreted, nullantifianulle and certifianulle null nullounullre not testing real world signals Page 20SPIRENT eBook nullo complement simulation testing at the verification stage, the enullense of field trials can null dramatically reduced nully nullinging the realnullorld nullcnullto the nullnullwith a Record & PlaynullcnullSystem nullPSnull Page 21SPIRENT eBook nullnclusion While the manullrity of the simulation options offer some of the attrinulltes renullired for testing GnullS receivers, many of these instruments also have their shortcomings nullt as mentioned previously, it depends on your test application. nulle nully point to note is that the marnullts we operate in are changing fast. nulle GPS system is nulling moderninulled, GnullnullnullS is almost at full strength, Galileo and nullmpass signals will null coming online over the nenull few years. nullgmentation systems such as nullnullS, WnullS and the soon to null GnullGnull and nullSS systems add to the minullof signals and technologies availanulle to those developing GnullS. Page 22SPIRENT eBook nully system you are loonullng to purchase must null anulle to support these signals now or have a defined roadmap of when that support will null availanulle. nullt Spirent we advocate a progressive approach to testing, incorporating simulation, Record & Playnullcnullwith final confirmation using real world signalsnull Page 23SPIRENT eBook Progressive testing anullroanulles Simulation Performance evaluation nullreat modes nullailure modes Safety cases Statistical results analysis Renullrnullnull Planullanull nullnvironment capture Performance tuning nullown pronullem areas nullptimisation nullve nullrive nullesting nullinal confirmation Page 24SPIRENT eBook nulle Snullrent GNSS annullnullinulli Solutions Spirent is the industry leader for GnullS simulator products. Digital Rnullsignal generation techninulles patented nully Spirent have led to the development of highnulldelity, worldnulleading GnullS Rnull simulation Systems. Spirent offers several different models of GnullS simulators that support a variety of different applications and cover the full spectrum of civilian and military GnullS testing needs. Spirent products range from nullsic singlenullhannel simulators, suitanulle for simple production testing, through multinullhannel, multinullonstellation simulators, suitanulle for the most demanding research and engineering applications. Page 25SPIRENT eBook nullor more comprehensive testing, Spirent also offers products that simulate additional system elements simultaneously with the GnullS constellation signals, such as inertial sensors, various automotive sensors, nullsisted GPS nullnullPSnullnullnullsisted GnullnullnullS nullnullnullnullnullSnull data, SBnull and GBnull augmentation system signals, interference signals, GnullS Record & Playnullcnulland Winulli Positioning. Snullrent GSS8000 nullultinullnullS nullnstellation Simulator Snullrent GSS6700 nullultinullnullS nullnstellation system Snullrent GSS6300 nullultinullnullS Signal generator Snullrent GSS6400 Record & Playnullcnull System Snullrent GSS5700 Winulli nullccess Point simulator Page 26SPIRENT eBook Why not nulld out more anullut choosinnulla nullSS simulator for the lanullratory from Snullrentnull the nullrld leader in nullSS test solutions nullf you found this article of interest, find out more www.spirent.comnullositioning nullisit the Spirent GnullS nullog httpnullnullww.spirent.comnulllognullositioning.aspnull nulleed more informationnull gnssnullolutionsnullpirent.com Sharenull nullnnulldnulln nullwitter Snullrent nullnullnullnull nullnullnull glonulllsalesnullpirent.com www.spirent.comnullositioning Snullrent nullenullral Snulltems null nullnullnullnullnullnull infonullpirentfederal.com www.spirentfederal.com Got a smartnullone? Scan the null Code nullr more innullrmation