GNSS (Global Navigation Satellite System)
Definition
The family of satellite-based positioning systems including US GPS, Russian GLONASS, European Galileo, and Chinese BeiDou. Mobile chipsets typically support multiple constellations simultaneously. A GNSS fix records latitude, longitude, altitude, timestamp, and an accuracy estimate in metres.
- Constellations
- GPS (US), GLONASS (Russia), Galileo (EU), BeiDou (China)
- Chipset behaviour
- Most modern devices support multiple constellations
- Fix data
- Latitude, longitude, altitude, timestamp, accuracy estimate
- Forensic source
- Mobile device location logs and app data
Common questions
Why do modern phones use multiple GNSS constellations instead of just GPS?+
Combining signals from several constellations improves fix accuracy and speed, especially in urban canyons or indoors where satellites from a single system may be obstructed, giving investigators a more reliable position fix to work with.
How does the accuracy estimate in a GNSS fix affect its forensic weight?+
The reported accuracy figure, often in metres, indicates the device's own confidence in the fix; a large accuracy radius means the true position could be substantially further from the recorded coordinates, which matters when placing a device near a specific scene.
Can GNSS location data be spoofed or manipulated?+
Yes, GNSS signals can be spoofed with specialised equipment or a device's reported location can be altered through developer settings or third-party apps, so examiners cross-reference GNSS fixes against Wi-Fi, cell tower and app-specific location data where possible.
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