Supporting Mobile Applications with Real-Time Visualisation of GPS Availability

A current investigation topic already mentioned in Defining Uncertainties in Can You See Me Now? is to visualise the current state of GPS availability in real-time for scenario planning for certain types of mobile applications and as aid for analysis of location logs. Supporting Mobile Applications with Real-Time Visualisation of GPS Availability by Anthony Steed introduces a tool called satview which visualises the current likely availability of GPS coverage. The tool takes a 3D model of the local environment, and the satellites positions. In real-time, the tool shows where on the ground plane one would likely be able to get a position fix from three or more satellites.

GPS units usually report position estimates and the satellites in view (azimuth, elevation and signal strength) using the NMEA 0183 communications standard. Anthony uses a graphical shadow algorithm on a 3D model for any one satellite (acting as the light source).

The development of satview was motivated by two scenarios

• Predicting and showing current black spots to GPS users and therefor prevent frustration caused by inaccuracy or availability.
• Planning data collectiong sessions that need GPS. Satview is used to plan which regions are more favorable at what time to collect logs of pollution levels.

A reference I should get my eyes on is:
Galileo Performance: GPS Interoperability and Discriminators for Urban and Indoor Environments. GPS World June 2003