2019 GPS Week Rollover

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2019 rolloverSome GPS receivers may malfunction on or after 6 April 2019 due to the GPS Week Rollover.

This is a known issue caused by the way that GPS used to handle the week element of the navigation signal. GPS used a 10 bit field to encode the week number in each GPS time message. This means that a maximum of 1024 weeks could be handled. This period is called an epoch. At the end of each epoch, the receiver resets the week number to zero and starts counting again.

The current epoch started on 1 August 1999. The next GPS rollover is 6 April 2019 when the receiver will revert to week number zero and start counting up to 1023 again.

Testing your receiver is easy with a LabSat 3.

1) Download the relevant test scenario for your LabSat system by filling in the form below.

2) Cold start your GPS receiver and replay the entire scenario.

If the date shown is April 7th 2019 and correctly counting up the time then all is fine for the 2019 rollover.

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However, that’s not necessarily the end of the story. Many receiver manufacturers will set the receiver to run for the full epoch from the date of their firmware. So if your receiver manufacturer has set the epoch start date in the middle of the epoch then it will run to the middle of the next epoch. Please contact the manufacturer to enquire if they have a firmware update for the 2019 rollover. If not check on the firmware date and, with our SatGen software, create a rollover scenario with a full epoch ahead and retest.

Multiband receivers accepting modern GPS signals that use 13-bit week encoding (L2C, L5) do not have the 1024 week epoch issue.

Simulate leap second corrections

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Did you know that you can simulate leap second corrections with LabSat, including the one on 31st December 2016? RACELOGIC offer live recordings of the leap second events on 30 June 2015 and 31 December 2016 for GPS and GLONASS.

What is a leap second?

A leap second is a second which is added to Coordinated Universal Time (UTC) in order to synchronize atomic clocks with astronomical time to within 0.9 seconds. The reason we have to add a second every now and then, is that Earth's rotation around its own axis, is gradually slowing down, although very slowly. Atomic clocks however, are programmed to tick away at pretty much the same speed over millions of years. Compared to the Earth's rotation – which determines the length of a day – the atomic clocks are simply too accurate.

Since 1972, a total of 27 seconds have been added. The last leap second was added to the world's clock on December 31, 2016 23:59:60 UTC.

Why test leap second updates?

It is up to your GPS devices' firmware and algorithms to manage leap seconds correctly. To uncover any negative effects of the upcoming leap second event, leap second conformance of your device/application should be tested at every leap second event.

How to test leap second updates?

BeiDou leap secondsYou can easily simulate the leap second event on your bench using a LabSat GPS Simulator.
RACELOGIC offer live recordings and simulations of the leap second events on 30th June 2015 and 31st December 2016.

You can download the scenarios for free (several GB) or order them to be sent to you on an SD card at a price of £25 (+VAT if applicable) + shipping.


Please fill in this form to download for free or order:

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SatGen Software Trial

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What is SatGen?

SatGen complements the LabSat range of GNSS simulators, and is available in single, dual & triple constellation versions.

To enable you to experience the full power of SatGen Simulation Software, we provide a demonstration version which will allow you to try these new features.

The demonstration software is a full copy of the SatGen software but is restricted to run for only 120 seconds when creating GPS scenarios. This will allow you to trial the use of SatGen in your own test facility or laboratory.

How to get the trial?

To receive a free copy of this demo version, please complete the form on the right.

Straight after submitting the form you will receive login details which will enable you to download the software online.

Please note that the SatGen v3 Simulation Software requires a 64 bit Windows operation system and will not install on a 32 bit system.


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Free GPS NMEA Simulator software

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SatGen Suite

“Create a driving / flying scenario anywhere in the world, at any height, and at any speed, and test your device with realistic data.”

Do you want to test your GPS product or app?

If you’re looking for an easy and free way to test your GPS enabled device, you’ve come to the right place. As you know, simply going out on the road and testing your system live takes a long time, it’s limited to your geographical area, and due to the constantly moving satellite paths, you can never repeat a test twice.

However investing in a full GPS simulator is expensive. So we thought we’d produce some free software to make your GPS device testing faster and more effective.

SatGen NMEA is a very powerful, free piece of GPS Simulation software from Racelogic that allows you to create NMEA files and generate real-time NMEA serial streams.

What does SatGen NMEA Simulation Software allow you to do?

You can use the software to stream synthesised NMEA data into your target device, replacing the serial output from a GPS engine. This means you can create a driving/flying scenario anywhere in the world, at any height, and at any speed, and test your device with realistic data.

It is easy to create your own NMEA data simply by sketching out a route anywhere in the world in Google Earth, and then importing the Google Earth KML file into the SatGen software. The software will then turn your rough sketch into a fully realistic journey, filling in any gaps and smoothing out any sharp corners.


This data is saved to file and can also be output on a serial port at an update rate specified by the user.

If you want to more precisely define your own speed, route and height profile, you can use the User Commands input to write simple scripts which are translated into very accurate NMEA data.

The free software is fully functional except for a single, static advert at the bottom. It has the same front end as our full SatGen LabSat Scenario creation software.

Fill-in-handwritingThis download is a zip file which includes the SatGen NMEA program, some sample files and a manual. No installation is needed, just put the .exe file in a suitable directory and launch the application!

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SatGen NMEA Software Screenshots

LabSat3-GPS-SimulatorInterested in a full GPS Simulator at a competitive price?

Try LabSat. It’s the original GPS/GNSS simulator with record and replay functionality, meaning you can record and replay GPS / GLONASS / Galileo / BeiDou signals at the same time. For the ultimate testing system, you can also synchronise multi camera video and external data such as accelerometers. More info here >

SatGen-280SatGen software allows you to generate custom scenarios. This gives the ability to test your GPS device under almost any dynamic scenario, anywhere in the world.

More info here >