Here3 Inconsistent (LOW) Sat Number

ArduCopter Copter 4.2
1

Hi!

One of our drones is showing a weird discrepancy between the number of satellites for each Here3 receiver (sometimes 8 satellites while the other gets 16!). We’ve been using a dual Here3 setup since 2020 and I don’t recall any similar episode.

Setup:

  • Cube Orange+
  • Kore Carrier Board
  • Dual Here3 (simetrically placed)

Important Considerations:

  • There are other drones, same model, that aren’t showing this issue
  • We swapped CAN ports and the issue was still in the same receiver
  • Antena interference is unlikely because of the simetric placement and lso because this issue is not happening in other drones.
  • The difference sometimes gets smaller, but there is a difference almost all the time.
    *Parameters are correct
    *The receivers are in the same FW and version.
  • The “bad” GPS is indeed showing much worse GPA values, but the latitude and longitude reported through the flight, from both “bad” and “good” receivers, are perfectly matched.

Screenshots

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**Link to LOGS"
https://drive.google.com/drive/folders/1FiAfmymgP33VA6Ahzo6ZShRFOAEZacTv

We’ll change the receiver, but in the meantime I’d like to dig deeper on this matter.

Questions

  • What could cause such an obstruction?
  • Could a small interference on the Here3 cable (the cable, not the receiver itself) cause that?
2

Just a few checks:
Is one GPS mast vibrating more that the other?
Do both units have a good solid 5.0 volts?
Tried one on each CAN bus instead of both on the same CAN bus?

Try:

GPS_GNSS_MODE,65
GPS_GNSS_MODE2,65

to leave out some constellations to see if they cope better.

1 Like
3

Hi!

Yes, we swapped the CAN port and the issue stays with the same receiver.

We tried with GNSS MODE 65 as well. Same result.

4

Satellite count is highly unlikely to change just by changing the CAN port or wiring. Either you are experiencing interference or the antenna is possibly defective. If you are confident the problem lies just with this particular unit, contact CubePilot or your supplier for a possible replacement.

1 Like
5

Yes. Only in this particular unit. We’ll replace the GPS, installing the new one in the same port, same wiring, etc. I’ll update this post with the results.