Rosetta "seeking satellites" near Brize Norton

[Joe M]

Today (23rd September) I flew South West from Enstone, with my Samsung tablet running SkyDemon/Pilot Aware helpfully showing me traffic until I got to Charlbury when I got the dreaded "seeking satellites". My phone (using location services) continued operating SkyDemon normally.

I am raising this topic because the last time I flew the same thing happened in the same place. On 22nd August I flew from Enstone to Brimpton, near Newbury. I go seeking satellites around Charlbury going South. Having set up again when I left Brimpton I then got seeking satellites around Wantage as I returned to Enstone.

Any ideas gratefully received.

G-GRPA
404C04

[steveu]

I can only suggest GPS jamming. As the phone may have access to lots of constellations, it may service or dodge the jamming...

Not sure what constellations the mouse can see...

[Joe M]

If it had been a one off I would suspect jamming, but to have this on 3 occasions on 2 days a month apart in a well frequented piece of airspace made me wonder if there could be a problem specific to my Rosetta?

[Joe M]

Having consulted with my syndicate partner I can give a fuller description of the problem.

12 months ago we began to have a regular problem when flying from Enstone to Shobdon. The Rosetta would lose gps as we passed Malvern going West. Service could not be re-established until on the ground at Shobdon. As we took off service would disappear again once we were a few hundred feet up. This happened repeatedly. I updated software, shared log files, and Keith very helpfully looked at some ground station data that confirmed it was happening, but we never got to the bottom of why.

Yesterday (26th September) we had exactly the same problem on our first return to Shobdon this year - "seeking satellites" from Malvern to Shobdon, and the same on the return leg.

On my original post I described having the same experience between Charlbury and Wantage on 3 occasions this month, having not had any problems before when regularly visiting this area.

If it is interference, why is it only affecting us? Memory or software corruption?

Any advice gratefully received.

Regards, Joe

[steveu]

It could also be when the antenna warms up or the Pi itself.

Where is the antenna? Internal to the Rosetta or external?

Have you considered moving the GPS connector to a different USB port?

Can we assume that GPS lock is lost because the Rosetta sees fewer and fewer satellites, or does the coverage just drop full stop?

[Joe M]

Thank you Steve, good questions.

Warming up: I hadn't considered that, but the outages we have had don't appear to relate to duration of power up or air temperature, but are very geographically specific and repeatable.

The gps antenna (mouse) is mounted just inside the windscreen with a clear view of the sky.

I'll have a look at a different port next time I'm at the hangar.

All appears to be normally functioning, then reverts to "seeking satellites".

[Admin]

by any chance, does this coincide with usage of the radio on a particular frequency ?
I recall some users having radio interference from the radio due to a harmonic close to the GPS frequency

[Joe M]

I don’t think a common frequency applies, but that is something I can try out - thanks.

[Admin]

Hi Joe
What version of software is your rosetta running ?

Thx
Lee

[Joe M]

Our software is version 20220805.

My colleague flew on 6th October from Enstone to Shobdon, and the problem recurred exactly as before.
Outbound all worked well until a few miles before Shobdon, then "seeking satellites".
When returning all worked well on the ground, but shortly after take-off failed again in the same way. Various attempts were tried (restart the Rosetta, re-log on with tablet, log-on with phone) without success.

I have downloaded the track files for that day if they are of any diagnostic use.

I am very puzzled that we seem to have such a tremendously consistent problem in a specific geography, that presumably other people don't have.

Edit - just realised that there is something odd about software version. When we started having problems I updated the software, so it should be a later version than 20220805! Not sure how that happened, I will update to 20241006 tomorrow and try again.

[steveu]

I have downloaded the track files for that day if they are of any diagnostic use.

They will be if you want to have a look yourself.

Navigate to:

https://playback.pilotaware.com/playback

and upload a file where you saw the problem. I'd suggest you avoid making the file public unless you want to.

Now, with the uploaded file processed, drag the white ball along the timeline. You should see the track you recorded in the PAW, along with the number of satellites you were seeing plus any recorded traffic.