Extremely odd route to go home

[Steve M]

After two weeks pottering around Spain and France, returning to the U.K. via Rotterdam to Hull I entered “Where to” and “Go Home” in my Zumo XT.

This gave a surprising arrival time (>24 hrs) so I checked the route. This shows a waypoint - nothing to do with anything I’ve created as far as I know - in the South Atlantic.

Took a couple of snaps of what appeared on the screen and… (second photo from Wetherby services where I retried the Route)

[Steve M]

Addendum.

It seems to have righted itself now I’m home but still wondering what happened.

[jfheath]

That location looks suspiciously like 0 degrees N and zero degrees west. ie on the Greenwich Meridian on the equator.

Which means that it doesn't know where you are. It has to have something, so it starts with 0,0. Goes hunting for satellites that should be int he vicinity at that time. Finds something. Once it has found four it can get a sort of better position. Its not very accurate because the satellites that it finds will be near the horizon where positional errors will be very high.

It then repeats the calculation using (hopefully) better information - but of course it could have found satellites that were further south - which isn't going to halp a great deal. Remember you are a lot further north than it thinks that you are.

And so it goes on. It can take quite a long time to get an accurate fix. Even longer if you keep moving while it is doing it. Really you need the Zumo to be prevented from turning off with a good view of the sky.

Or - and I haven't tried this - you could find out your current position from a Michelin map and enter the details into the Position.gpx You would need to copy it and edit it in a text editor and then copy it back.

The bottom line of the file contains this entry.

<text>Garmin International</text>
</link>
<time>2024-09-24T12:14:30Z</time></metadata>
<wpt lat="51.123456" lon="1.765432"></wpt>
</gpx>

Just alter the two coordinates. Leave everything else exactly as it is. It doesn't have to be spot on. Use those coordinates if you wish - somewhere in the middle of a field N of Salisbury.

This isn't a definitive answer, 'cos I don't know. I am guessing that putting value in Position.gpx closer to your actual location will speed up the process of getting an accurate fix when you turn it on.

Though why it would draw a route or try to navigate before it has got an accurate fix, I don't know, so I'm not entirely convinced. Tell you what - I'll set min to 0,0 see what happens !!

If anyone can guess a better answer than I'd love to read it !!

[jfheath]

No - it wasn't fooled by that !! It didn't put me on the equator. There must be another record of its value somehwere. I'd still try it though.
The real answer is just to leave it on, looking for a good signal.

[Steve M]

Thanks for the reply. It gave strange results from both Hull, after being out of satellite range for several hours, but also from Wetherby having been in the U.K. for a couple of hours - albeit in motion. It did appear to know where we were in the ferry terminal as it displayed the route out - it only went pear shaped where the M62 joined the A1(M).

I’ve since tried it and it appears to be working just fine. Hopefully that will be a one-off but I’ll monitor it as a matter of course.

[jfheath]

it only went pear shaped where the M62 joined the A1(M)

To be fair, I feel the same way when I get to that junction ! Its the only one that I know where you leave one motorway heading south to join another motorway heading east and you end up running for a mile side by side with the motorway you have just left, apparently on the wrong side of you.