Rolling out SDX Release 17.1

Freshly out from our coding lab, here’s the latest update to Skydel SDX.

GNSS Signals Simulation with Multipath

Release 17.1 adds a fine level of control on signal multipath. Multipath is a term that refers to the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. In the field of GNSS, this most commonly happens when satellites’ signals are reflected and diffracted before reaching the receiver, for example by hitting objects such as buildings, trees, vehicles or the ground. These signals are often named echoes.

Example of the signal reaching the GNSS receiver through multipath echoes

In urban environments, multipath echoes are a common occurrence. Their effects are non-trivial, as they can compromise the accuracy of the positioning, resulting in errors that can reach tens of meters. To add to the problem, the effects of multipath echoes are notoriously difficult to test “in the real world” with live sky signals: for example, naturally occurring signal echoes cannot be isolated to create a successful test scenario.

Furthermore, in some instances, multipath signals can be the only ones available in a scenario called Non Line-of-Sight (NLOS). In this case, the direct, Line-of-Sight (LOS) signal from the GNSS satellite is blocked and only multipath signals are reaching the receiver.

NLOS scenario: the direct line-of-sight signal is blocked and only multipath echoes reach the receiver

SDX 17.1 introduces a powerful multipath simulation option, enabling our users to create less-than-ideal signal propagation conditions for their GNSS testing. Multipath echoes can be added and fined-tuned for each satellite, per signal. Control is possible via 4 fundamental attributes: pseudorange offset, power loss, Doppler shift and carrier phase offset.

User Interface for Multipath

It’s now convenient to create simplified test conditions otherwise impossible to achieve with the live sky. As always, these new options are fully controllable through the SDX API, and can be modified on-the-fly while the simulation is running.

CNAV Message Modification & Corruption

Release 17.1 also adds L2C navigation message modification. Besides the usual conditions such as start & stop time and PRN number, you can specify the message type, and the message content to match.

User Interface for CNAV Message Modification

Since the CNAV message is 300 bits long and not subdivided in words like the NAV message, managing the modifications as a per-bit fashion would be tedious. The interface solves this by letting you add modifications for portions of the message – and lets you add as many as you need.

Armed State

Software-defined radios (SDR) can take a few seconds to initialize when starting the simulation. In order to improve software synchronization performance, we’ve added an armed state. Upon clicking the arm button (or issuing the command through the API), the armed state prepares all hardware. When the start command is later received, the delay to emit the GNSS signals is minimal.

The new arm button in the dashboard

There’s a few more things packed in this update: see the release notes for the full list. As always, existing licensees benefit from an immediate upgrade.

We’re not stopping here. Among the next items on SDX’s development agenda is the release of advanced jamming capabilities through an innovative integration with the GNSS simulator.