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Axiom Pro internal GPS loss of lock
12-22-19, 12:33 AM (This post was last modified: 12-22-19 09:38 PM by Tom - Raymarine - Moderator.)
Post: #1
Axiom Pro internal GPS loss of lock
As I mentioned in this thread I had suspicions that this problem was caused by loss of GPS data. It was not.

However, I have experience on a few occasions what appears to be loss of GPS lock.

A couple of days ago I experienced one of these and the only reason I knew because my autopilot gave a track error.

I stopped immediately and looked at the satellite display. It showed all satellites in orange (there were at least 20 showing).

The GPS locked again in perhaps 30 seconds. Most of the satellites on the screen except the very fringe turned green. The fringe ones took perhaps another minute.
It was a clear sky. I was in open water with no boats around, with perhaps 8knots of wind. The HDOP usually sits at 0.7.
It was as if the MFD had lost communication with the GPS. I don't think the GPS had to reacquire, though it could have.

The signal strength for each satellite when functioning on the satellite display varies from .42 to .21 (on the fringe).

Is this signal level reasonable?
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12-22-19, 09:45 PM
Post: #2
RE: Axiom Pro internal GPS loss of lock
Hello BernieK,

From your description, what I would guess is happening is that your system is intermittently acquiring a Differential fix from the Japanese MSAS service. As described at, this is known to cause a drop in fix quality or loss-of-fix in Australia and NZ and probably some other parts of the world not currently covered by local Differential services. Differential defaults to On for most users around the world this gives better fix accuracy, but not here.

If you disable Differential mode in the Settings tab of the GPS menu, I think your fix accuracy and reliability will improve markedly. If not, please come back to me with a bit of video of what's happening in your Satellites page.


Raymarine since 1999.
Interests: Diagnosis of problems in sonar/fishfinders, NMEA2000, ethernet comms, autopilots, thermal cameras
Location: Sydney, Australia.

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