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

Atmospheric Errors (Settings : Global)

This panel enables you to review and edit the ionospheric delay values for any IGPs. The map view can be navigated (pan and zoom) much like the Map panel of the simulation. The edit button brings up an IGP editor used to assign the points values or increase their current value by a set amount. Since the number of points in the grid is fairly large, the user interface works with a selection of points, allowing you to add or remove the current selection in order to quickly work your way around the whole map.

Modifications to the ionospheric delays with the grid editor

Atmospheric errors are available to all SDX licensees with the 19.1 upgrade.

Ionospheric Masks (Settings : SBAS)

Editing the SBAS masks by provider (in this case, WAAS)

SDX users with the SBAS option can use this new interface to assign the true/false value for each point of the different SBAS bands, per service provider. It reuses most of the paradigm of the aforementioned atmospheric error pane.

Ionospheric GIVE Indicators (Settings : SBAS)

SBAS GIVEI grid editor

Using a similar map interface as the two previous panels, the GIVEI (GIVE Indicators) panel enables you to provide the GIVE Indicator values for each IGP that is configured in the mask, per service provider.

The grids created or modified with these new options can all be saved and imported back into future SDX scenarios.

New GNSS Satellite Antenna Patterns

Also new in SDX 19.1 is the possibility to add user-defined antenna patterns to GNSS satellites. These new antenna pattern options shows SDX’s flexibility by allowing any user-defined antenna pattern to be applied to any satellites in any GNSS constellation.

This can prove especially useful for scientists and engineers working with space vehicles, due to their unusual orientation when we compare them to surface vehicles. High-Earth-orbiting spacecraft benefit from the side lobes of GNSS satellites to improve navigation performance. In fact, when tracking the signal from side lobes, the number of visible satellites is drastically increased, and the precision can improve from the kilometer to the meter level.

HEO spacecraft benefit from the side and even rear lobes of the GNSS emitting antennas

In addition, the new antenna patterns can be a potent tool in the context of research projects that experiment with user-defined GNSS SV Antennas.

SV antenna patterns in SDX

SDX now allows you to create, define, and manage antenna patterns for GNSS satellites using an interface very similar to the one we introduced for vehicles in SDX 18.10. As with that release, the various patterns are organized into antenna models that can be named, managed, exported, and reimported back into other simulation scenarios.

General UI Improvements

Rounding out the changes for this release, we present two user interface improvements. The first change is the addition of a “path” interface in the Settings menu.

Improvements to the Settings menu

Since the number of settings has grown since the initial SDX releases, this small UI widget helps in locating the current panel in the settings hierarchy, enabling you to jump back a few steps when in the lower settings level, saving a few clicks.

Moreover, it’s now possible to collapse the subtabs panel at the bottom of the screen in order to get a bit more real estate when working in the settings, map, or automate panel.

The subtabs can now be collapsed in SDX

2019 Has Only Just Begun

There it is for the first, but not last, SDX release of 2019. We are at this moment working on new signals and capabilities for our GNSS simulator. Expect great things for the remainder of the year!