Cold starts can take half a minute. Assisted GNSS cuts that to seconds — here’s how it works and why trackers love it.

The cold-start problem

When a GNSS module powers on with no idea of the time, its position or the satellite orbits, it must download that data from the satellites themselves — a process that takes 28 seconds or more in the worst case. For a battery-powered tracker that wakes up to send one position report, that is most of its active time.

How assisted GNSS helps

A-GNSS (Assisted GNSS) delivers the same assistance data — satellite ephemeris, almanac, approximate time and position — over the cellular network instead of waiting for the satellites to broadcast it. The module starts with most of the answer already in hand, so the time-to-first-fix collapses from ~30 seconds to 1–2 seconds.

Why this matters for battery life

Faster fixes mean the radio and processor spend far less time awake per report. Combined with a low backup current and fast reacquisition, A-GNSS is one of the biggest contributors to long battery life in tracking devices — arguably as important as the raw tracking current.

“A-GNSS doesn’t improve accuracy — it improves the two things trackers care about more: speed and battery life.”

What to look for in a module

  • Native support for a free-of-charge A-GNSS service (no per-device fees)
  • Predictable cold-start and warm-start TTFF figures
  • Fast reacquisition after sleep, not just fast cold start

All of our modules support free A-GNSS for minimal start-up times in the field. Browse the modules and check the TTFF figures in each datasheet.

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