h1. GNSS Research

Research into Global Navigation Satellite Systems (GNSS) and related technologies.
Example GNSS: GPS, GLONASS, Galileo, BeiDou.  

h2. Assisted GNSS (A-GNSS)

Also known as Assisted GPS (A-GPS). Greatly improves the Time To First Fix (TTFF) by downloading almanac and ephemeris data via mobile broadband or WiFi, instead of waiting for the slow download via the GNSS signal.

h3. SUPL

SUPL (Secure User Plane Location) is the most common protocol used to retrieve almanac data.
There are no free software SUPL servers that we know off. Android uses Google's servers (@supl.google.com@) by default. Most carriers also default to @supl.google.com@ on their APN. GrapheneOS runs a proxy at @supl.grapheneos.org@.

h3. PSDS

PSDS (Predicted Satellite Data Service).