Time to First Fix (TTFF)

Definition

Time to First Fix (TTFF) describes the time and process required for a GPS device to acquire enough usable satellite signals and data to provide accurate navigation.

A GPS must have three sets of data before it can provide accurate position: GPS satellite signals, almanac data, and ephemeris data.

If a GPS is new, has been turned off for a long period of time or has been transported for a long distance since it was turned on, it will take longer to acquire these data sets and get a "Time to First Fix" (TTFF).

GPS manufacturers use various techniques to speed up TTFF, including downloading and storing almanac and ephemeris data with via wireless network connections (faster than acquiring via satellite).

A "cold" start refers to a situation in which the GPS must acquire all data in order to start navigation and may take up to 12 minutes.

A "warm" start means the GPS has most of the data it needs in memory, and will start quickly - a minute or less.

Also Known As: TTFF

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