Time to first fix

Time to first fix is a measure of the time required for a GPS navigation device to acquire satellite signals and navigation data, and calculate a position solution.

Scenarios

The TTFF is commonly broken down into three more specific scenarios, as defined in the GPS equipment guide:
; Cold factory
; Warm normal
; Hot standby
Many receivers can use as many as twelve channels simultaneously, allowing quicker fixes. Many cell phones reduce the time to first fix by using assisted GPS : they acquire almanac and ephemeris data over a fast network connection from the cell-phone operator rather than over the slow radio connection from the satellites.
The TTFFs for a cold start is typically between 2 and 4 minutes, a warm start is 45 seconds, and a hot start is 22 seconds. In older hardware where satellite search is slower, a cold start may take more than the full 12.5 minutes.