GPS Analysis from First Airborne ET Flight
Overview
I wanted to share some very interesting GPS data collected during the first flight of an Extended Telemetry UserDefind message set carrying GPS stats.
The results challenge some of my established beliefs about GPS performance relating to lock time. Some more epxeriments will shed more light on this.
The results have provided new insight and evidence into an ongoing mystery about why my tracker almost always has a 1-hour blackout period on initial launch before transmissions are received.
Major Takeaway Summary
Summary
- The GPS appears to have a huge problem with getting locks while rising
- Compared to, say, staying at ground level, or floating at altitude
- Not seemingly correlated with ground speed
- There is approximately a 1 hour period of time from launch in my area (NYC area) to first transmission, seemingly due to GPS inability to get a lock
- The number of Chinese GPS satellites visible in flight rises significantly during flight