Assisted GPS and Bundling

Assisted GPS and Bundling

In order for a GNSS receiver to provide a navigation solution, it must have satellite orbits data so that it can accurately determine the expected location of each visible GPS satellite. If the receiver does not have this data, or if the data it has is too old, it must collect the data from the satellite after its signal has been acquired.

Typical TTFF of 30+ Seconds

Even under the best circumstances, where initial position and time are known, the broadcast ephemeris download process can take up to 30 seconds, which in turn can mean a Time To First Fix (TTFF) of 30+ seconds. In typical real world environments, where the receiver does not have a clear view of the sky, TTFF can be even longer.

Telit TTFF of 2-15 Seconds

The goal of Assisted GPS (AGPS) feature is to provide the GNSS device with the Ephemeris data required to perform a faster time to navigation. The ephemeris data (often called Ephemeris Predictions, Extended Ephemeris or EE) are stored in a server and are downloaded through different means, such as a cellular internet connection. In this way, the GNSS device is able to provide a navigation fix in just a few seconds compared to cold/warm start conditions that could range from 30 seconds to several minutes, depending on the signal environment.

Telit Ephemeris Prediction

Telit provides Ephemeris Prediction support for all Telit GNSS modules through Telit’s AGPS Servers.

Telit Cellular modules are able to download, store and manage the AGPS files that can be used to improve Telit’s GNSS module TTFF performance.

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