In June 2018, ESA ran an internal competition for its young graduate and national trainees to develop an app capable of making positioning fixes using only Galileo satellites. As part of this competition an augmented reality app was created, with which users can ‘see’ the satellites their smartphone is using as they hold it up to the sky.
The positioning calculations and assistance data functions for the app were developed by Paolo Crosta of ESA’s Radio Navigation Systems and Technology section, with telecom engineer Tim Watterton contributing the main structure of the app, together with how it looks and its UI.
Tim Watterton explaines, that the satellites are overlaid in real time on the camera view in their predicted positions in the sky, based on ‘ephemeris’ information, assistance data that describes the current satellite orbits with high precision. “When a signal is being received, the satellite is shown in green, overlaying the predicted position. The satellite shown in red is one of the two placed in elongated orbits, but these satellites are expected to be used soon in the operational constellation. Satellites coloured orange are transmitting, but the signal is not detected, which may be due to obstruction by terrain or buildings.”
Panning the phone around to position the crosshair over a green coloured satellite adds additional information about it, such as its signal status, ‘pseudo-range’ (the uncorrected distance the signal has travelled to reach the receiver) plus the satellite’s manufacturer, launch date among other items.
The reference app is currently being tested with the goal to make it publicly available on the Android Play Store. The competitors Apps are also being tested and will also be published after the competition has ended.
Currently, similar apps are available for smartphones like the GPS Satellites Viewer for tracking GPS satellite, but to the current status they don't offer an augmented reality function.
At present, there are 22 Galileo satellites in orbit, with four more satellites set for launch on 25 July.