Opening the new year with SDX 19.1

Here at Skydel we’re always working on providing the best GNSS simulator for our clients. To that end, we’re starting off the new year with SDX 19.1, the eighteenth major revision of our GNSS Simulator. This newest GNSS simulator version adds Galileo AltBOC support, atmospheric errors, SBAS improvements, and GNSS satellite antenna patterns.

Galileo AltBOC

SDX now supports Galileo AltBOC as a new GNSS signal type. Current SDX users licensed with the Galileo E5 signal will be able to generate 8 Phase Shift Keying (8-PSK) constant envelope AltBOC after upgrading to SDX 19.1.

Galileo ALTBoc signal generated in SDX

The signal can be generated by selecting both Galileo E5a and E5b in the output - signal selection panel.

Atmospheric Delays and Improvements to SBAS

We’ve added a new error type to all SDX users in release 19.1: atmospheric delays. Moreover, these errors can be compensated with SBAS for those SDX licensees with the SBAS option installed. The SBAS message now broadcasts ionospheric error corrections.

To introduce these new features, let’s briefly review the theory behind ionospheric delays and SBAS. When a signal is broadcast from a GNSS satellite to the surface, a delay is introduced following how the signal propagates in the atmosphere. One of SBAS’ aims is to provide corrections to mitigate these delays (also called errors) in order to achieve a better positioning accuracy. SBAS accomplishes this by creating a virtual grid of points wrapped around the globe. Ground-based SBAS reference stations, located at known positions, compute corrections values for each point, which are in turn sent to, and broadcast by, the SBAS constellation. A GNSS receiver with SBAS enabled can then use the correction data relevant to its current position to compute a more accurate positioning solution. These points are called Ionospheric Grid Points (IGPs) and are organized into bands (numbered 0 to 10).

We’ve added three new interfaces to help create, manage, and use these error values in your simulation scenarios.

Creating and managing ionospheric errors in a simulation scenario

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SDX 18.10 is available now

Today we’re announcing SDX release 18.10, a new version of our GNSS simulator that features improvements to receiver antenna management and a new advanced jammer type.

Antenna model sequence during simulation

Starting with this SDX update is an upgraded paradigm for managing receiver antennas: SDX now supports the management of multiple vehicle antennas within a single scenario. Antennas can now be defined, named, and exported as antenna files that can be re-imported back into other scenarios. This handy feature will speed up antenna reuse and multi-scenario workflows for users managing numerous antenna models in GNSS simulation scenarios.

The new antenna model UI maintains the previous SDX paradigm whereby antenna patterns can be defined for gain and phase offsets.

Moreover, SDX now provides a simple and powerful sequencer for switching from one antenna pattern to another at specific times during a scenario.

The antenna sequencer is simple to use and will be useful for those who need to toggle antennas at various points in the simulation to replicate a real-world scenario.

As we do for every new feature added, the SDX API is updated—and documented—to reflect these latest changes, and these new features can be used in the programming of your automated scenarios.

Also added: IQ File as a jammer type

In addition, with release 18.10, you can now add IQ File playback as a jammer type in SDX. This feature, combined with the IQ File generation capability already available in SDX, opens a new range of possibilities, limited only by your imagination.

Selecting and playing back a IQ file as a jammer type in SDX 18.10

Users who already have the advanced jamming option installed and are eligible for this SDX upgrade can benefit from this new feature immediately by upgrading to SDX release 18.10.

Wrapping up

So far in 2018, SDX has seen the support of anechoic chambers, the support for multiple GPUs, the addition of SBAS support among many other new features in the summer release, and now SDX release 18.10 brings a new way to manage and sequence vehicle antennas.

That’s hardly the end of it: new custom simulation solutions based on SDX are coming soon, along with new features and GNSS constellation support. This is only the beginning!

SDX Release 18.7

Once again, our summer SDX update is a big leap forward. Is it becoming a tradition? We’ll know next year for sure, but until then, let’s unpack the details of SDX 18.7.

Introducing SBAS and satellite errors

SDX implements support for satellite-based augmentation systems (SBAS), enabling the replication of an augmented GPS constellation using an SBAS such as WAAS, EGNOS, MSAS, GAGAN, and SDCM.

A SDX simulation scenario with the SBAS constellation

Within SDX, SBAS can be activated for a given simulation as an additional constellation via the Output panel.

In the new SBAS settings panel, you can configure the augmentation system as you would with other constellations, with fine control over its message content, multipath signals, and more.

In SDX, configure SBAS like you would do with other constellations

Developed along with SBAS, and available for all SDX licensees, we have added new settings that permit you to simulate various GNSS satellites error sources.

Pseudorange errors

Discrepancies in PRN pseudoranges can occur, and could be caused for example by a recurring error in a satellite’s on-board clock. SDX 18.7 enables simulation developers to create randomized errors using Gauss-Markov First Order processes, or an error pattern using sine waves.

The new pseudorange errors in SDX 18.7

As always, we like to implement new features in an innovative and thoughtful way: pseudorange errors are plotted on a graph to provide a quick visualization of the error in function of the time.

In addition, a pseudorange offset can also be set in this new panel.

Ephemeris (orbital) errors

In a perfect world, orbital parameters would match perfectly the satellites’ orbits. But in reality, there is always a variation. So now with SDX 18.7, you can specify orbits’ offsets using the RIC (radial, in-track, cross-track) frame:

Orbital errors can now be specified for a satellite in SDX 18.7

These two new error types can be automatically corrected by SDX’s SBAS module, if activated (i.e., if you selected SBAS in the output panel, and opted to correct errors). In this case, pseudorange errors will be corrected during simulation by SBAS fast corrections (FCs), while SBAS long term corrections (LTCs) will rectify ephemeris errors.

Otherwise, these new errors options can be used—uncorrected—as a step closer towards simulating real-world conditions for a wide variety of scenarios.

Multiple GPUs are now supported

Unless you are new to SDX GNSS simulation, you know that SDX uses GPUs to pack a lot of power in a very cost-effective package. The architecture behind our GNSS simulator delivers unique scalability, especially in terms of signal generation. Starting with this release, we take this vision further by enabling multiple GPU cards to be used in SDX configurations.

More GPUs adds a lot of power while retaining a small simulator form factor

SDX can now drive multiple Nvidia GPUs concurrently, making for a GNSS simulator with an impressive size-to-power ratio. For example, adding a second GPU does not add to the form factor of our popular USRP-based hardware configuration, while adding a lot of power under the hood.

While having two GPUs enables computation that can unleash capabilities for the most demanding scenarios, SDX can now drive up to four Nvidia GPUs concurrently for multi-antenna simulators.

Adding GPUs enables the simulation of even more signals making possible the following example scenarios:

  • Multipath - generate a high volume of echos
  • Simulation of GEO orbits for all constellations, on multiple bands, with even more visible satellites at all time
  • Even larger multi-constellation scenarios, featuring multiple vehicles
  • Highly complex spoofing mitigation and testing setups
  • Complete anechoic chamber simulation

New Software-Defined Radio (SDR) Supported: DekTec DTA-2115B

With this release of SDX, we’re also adding a new SDR option for building a SDX hardware configuration: the single-output DTA-2115B is a PCIe card radio that combines interesting RF capabilities with a reduced form factor.

SDX now supports a new SDR: the DekTec DTA 2115B

Capable of 72 MHz of bandwidth, it is more than enough for generating RF for the wider GNSS signals, while its PCI Express interface makes it a very interesting option for racked or desktop PC-based simulators.

The DTA-2115B supports synchronization using 1PPS or 10MHz; multiple SDR cards can be used to create multi-output configurations for those requiring a small-scale, large-capabilities GNSS simulator.

A 4U systems with 4 SDR (top), and a very compact single-output 2U racked simulator (bottom)

We’ve updated the SDX turnkey configurations page to include a configuration based on the DTA-2115B. Moreover, more details about the DTA-2115B SDR can be found on our supported SDR page.

There’s more! Additional improvements and new features in SDX 18.7

This version of SDX brings many additional features available for all licensed users eligible to upgrade:

Almanac data importation: it’s now possible to import YUMA and SEM files in addition to RINEX for GPS satellites.

Geo satellites: make any GPS, Galileo, or BeiDou satellite geostationary by simply providing a longitude and SDX will do the rest. This can be handy for specific testing purposes.
Hop! Make it geo.

Message modification for Galileo: change or corrupt the Galileo navigation message

Logging improvements: log simulated downlink data for all signals in hex format

New library for downlink data: use the provided Python scripts to parse the simulated downlink data for easy manipulation or to output it in a more human-readable format.

It goes without saying that all of SDX 18.7 changes and upgrades are 100% reflected in the SDX API, ensuring that you can use the new features in your automated scenarios.


SBAS, satellites errors, multiple GPUs, new SDR and more: all in all, this is another substantial version of SDX, and it’s available now.

Do you want to learn more about SDX and these new features? A great opportunity to do so is meeting us at ION GNSS+ in Miami, at the end of September. Come by our booth to see a demo of the latest improvements to our GNSS Simulator, and take a moment to have a chat with us! We’re always eager to learn about your GNSS projects. Also, we MIGHT have a few more things to showcase at the show, but that’s a secret for now…

Announcing Partnership with GMV and Tecnobit

We’re excited to announce a partnership with GMV and Tecnobit to work on enhancing SDX to support the upcoming evolution of Europe’s Galileo GNSS! Read the full press release below:

GMV and Tecnobit partners with Skydel

GMV and Tecnobit to tailor Skydel SDX GNSS simulator for Europe

Montreal and Lisbon, 18 July 2018 - GMV, Tecnobit and Skydel today announced that they are working to adapt Skydel’s Global Navigation Satellite System (GNSS) simulation solution to support the latest developments of the Galileo GNSS, synchronizing with the European efforts to bring a modern, highly-accurate and secure positioning system to the market. GMV, Tecnobit, and Skydel aim to provide corporations, universities, and research labs with a reliable, advanced simulation system that closely follows the latest Galileo capabilities.

“Together with our partners at Tecnobit, and taking advantage of SDX’s unique software-defined architecture, we are currently working to add Public Regulated Service (PRS) support to Skydel SDX”, says Manuel Toledo, Head of GNSS Advanced User Segment Solutions Division at GMV. PRS provides position and timing data for sensitive applications that require the highest level of service continuity.

Skydel and GMV are also joining efforts on developing SDX’s capabilities for signal authentication with Galileo Commercial Service (CS) and Open Service (OS). The goal of such authentication is to increase the safety level of signals and to avert their falsification or fraud and is currently a unique feature that only the Galileo constellation can provide.

Skydel and GMV are also collaborating on projects that aim at providing signal simulation solutions for Galileo’s second generation (G2G). Galileo’s second-generation satellites are scheduled to be launched in 2025 and beyond.

“With Galileo’s Full Operational Capabilities approaching soon, we must focus on the system’s upcoming G2G services.”, said Pierre-Marie Le Véel, business development director at Skydel. “Skydel’s top priority for the European market is to provide simulation tools for the design of these next-generation GNSS devices.”

The partnership among the three companies truly unites the unique strengths of each organization. While GMV brings its expert knowledge of both the European market and the Galileo system and Tecnobit brings its expertise as developer of cryptographic systems, Skydel adds its versatile and extensible GNSS simulator, resulting in a solid technical and commercial synergy for establishing an improved GNSS service offering for Europe.

About Skydel
Founded in 2014, Skydel offers GNSS test solutions to scientists and engineers who develop navigation systems. Skydel’s flagship product is SDX, a multi-constellation, multi-frequency, software-defined GNSS simulator. Skydel continually improves and deploys SDX for worldwide clients in the military, aeronautics, and automotive, as well as industrial and academic research sectors, through a network of resellers and partners.

About GMV
GMV is a privately-owned technology business group founded in 1984 and trading on a worldwide scale in the following sectors: Aerospace, Defense and Security, Cybersecurity, Intelligent Transportation Systems, Automotive, Telecommunications and IT for public administration and large corporations. Currently, GMV is the world’s first independent supplier of satellite control centres for commercial telecommunications satellite operators and a European leader in satellite navigation systems (inc. EGNOS and Galileo).

About Tecnobit
Tecnobit is a Spanish Aerospace & Defence company with deep knowledge & background in Crypto Systems. Tecnobit became involved in Galileo PRS activities several years ago and has since developed the Galileo PRS Security Module for the Spanish PRS Receiver in partnership with GMV.

GPS week rollover — are you ready?

In the GPS L1 C/A navigation message, the week number is contained in a 10-bit binary number. This limits the maximum week number to a total of 1024, effectively making 1023 the maximum week after it loops back to 0. Hence, the event named “week rollover” occurs every 19.7 years. Modernized signals solve, or reduce significantly the occurrence of week rollover by using more bits, but many receivers rely solely on the original L1C/A signal to determine the current time.

The first ever GPS week started on January 6, 1980. The weeks counter already rolled over on August 21, 1999, and is scheduled to reach its limit again on April 6, 2019, roughly 10 months from now.

A week rollover is a great example of a difficult, if not impossible, event to test without a GNSS simulator. Testing with the live sky, in this case, is definitely not applicable. Waiting for the event to occur with fingers crossed is not a great idea either.

So, what are the implications?

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