GPS Satellite Count
Edit on GitHubReading the satellite count as a diagnostic: what the numbers mean, how many is enough, and the fix that follows a low count.
GPS Satellite Count
The satellite count is the fastest GPS diagnostic you have. It tells you more than “fix or no fix”: it tells you why.
Reading the number
The OLED GPS line shows the count of satellites used by the current fix (in view vs used is a separate question; see GPS Fix Quality).
| Count | Meaning |
|---|---|
| 0 | No satellites seen: antenna, power or wiring problem |
| 1 - 3 | Signal reaching the module but no fix possible |
| 4 - 6 | Marginal fix: geometry poor, position wanders |
| 7 - 10 | Normal open-sky tracking |
| 11+ | Excellent sky view, best accuracy |
The diagnosis ladder
| Symptom | Check |
|---|---|
| Count stays 0 indoors | Expected; go outside (see GPS Testing Indoors) |
| Count 0 outdoors | Antenna blocked (see GPS Sky View), module unpowered, or UART wiring |
| Count climbs but never fixes | Sky view poor, or the module lost its almanac |
| Count drops after a fix | Antenna moving into shadow, or interference |
The climb test
The classic field diagnostic: walk 20 m uphill or away from the obstacle. If the count climbs with elevation, the problem was sky view. If it stays at zero, the problem is electrical.
Related pages
- GPS Fix Quality for the quality fields
- GPS Sky View for the antenna side
- GPS Troubleshooting for the fault list