4

Assisted GNSS

GNSS receivers need accurate satellite position data from at least 4 satellites to produce a fix.

Accurate satellite data, ephemeris data, is valid for several hours based on the active constellations.

After that time, a receiver must download new ephemeris data.

Ephemeris download can take from dozens of seconds to several minutes, hours or can fail to download.

Assisted-GNSS is a mechanism to provide ephemeris assistance from external source; this reduces considerably

the time to get fix especially in critical environments when the ephemeris download time could be very long.

Teseo-LIV4F supports one type of Assisted GNSS: real time assisted GNSS.

4.1

Real-time assisted GNSS

Real-time assisted GNSS (RT-AGNSS) solution is a server based assisted GNSS. It requires a network

connection to download assistance data from the server.

RT-AGNSS works downloading by an assistance server the real time ephemeris data. Server access is allowed

thanks to internal keyword provided by Teseo-LIV4F to the host processor and the acquired real-time data have to

be provided to Teseo-LIV4F.

Proprietary NMEA commands are supported on Teseo-LIV4F to acquire the credential access to the external

server and to inject the data to Teseo-LIV4F.

STMicroelectronics partner provides available server solution access on Teseo-LIV4F solution.

Real-time A-GNSS allows continuous real-time satellite position determination.

Teseo-LIV4F

Assisted GNSS

DS13957 - Rev 6

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