Author Topic: Edge 200 shows "off course"  (Read 2558 times)

Edge 200 shows "off course"
« on: 06 October, 2014, 11:20:15 am »
I've recently learned (thanks to members of this forum) to use my Edge 200 to follow a course I've loaded in .tcx format.  I've noticed that the device will show I'm off course (and in which direction), especially if I'm in hilly or "obscure" terrain.  However, when I download the actual recorded journey at the end, the route I've followed turns out to be exactly as I loaded it, give or take a hedge inspection, or two.  A friend has suggested that the device may actually be trying to "navigate".  Has anyone an idea what's actually going on?

Thanks

Peter

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Edge 200 shows "off course"
« Reply #1 on: 07 October, 2014, 09:58:10 am »
No idea.  If it were a map-capable model I'd suggest it had the setting 'Lock on road' turned on - but it isn't, and for the same reason it can't be trying to 'navigate'.
It's normal for the accuracy to drop off when in difficult terrain, and normal for it to display a message if the sky view is reduced to 3 sats or fewer for several seconds consecutively.  But that message (on my different model) is something like "Lost satellite reception", and in the Tracklog that translates to a short break in the Track (though most software turns the break into a straight line connecting the two track ends, so often it's not obvious at all).
when you're dead you're done, so let the good times roll

Re: Edge 200 shows "off course"
« Reply #2 on: 07 October, 2014, 10:22:05 am »
Still a puzzle, then, but thanks, anyway.  I think the bits where it went off course (kilometres at a stretch) were mostly in the "difficult" terrain - there's a lot of it in The Peak!  I take a routesheet with me anyway and am not really relying on the device to keep me on course, though it does that well enough on main-ish roads.

Peter

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Edge 200 shows "off course"
« Reply #3 on: 07 October, 2014, 10:44:56 am »
That doesn't sound right to me.  OK it might struggle in Winnats Pass or in one of the deeper dales, but not otherwise.
Dense woodland is usually the worst situation, and even then at cycling speeds the GPS usually gets enough gaps in the canopy to cope.  At walking speed it often doesn't.
when you're dead you're done, so let the good times roll

Re: Edge 200 shows "off course"
« Reply #4 on: 07 October, 2014, 10:52:59 am »
We were in Cannock Chase for a while, with some but not complete tree-cover.  Obviously I'll have to ride faster!

Re: Edge 200 shows "off course"
« Reply #5 on: 07 October, 2014, 02:06:57 pm »
Could be Garmin keeping us in our place in its bid for world domination.  Or a cunning ruse to make you buy another machine!

mcshroom

  • Mushroom
Re: Edge 200 shows "off course"
« Reply #6 on: 07 October, 2014, 03:17:54 pm »
How are you planning these courses? If the mapping's slightly off then it may be a case of riding along the right road, but as far as the Garmin is concerned you are riding 10m to the left of the track, or similar.
Climbs like a sprinter, sprints like a climber!

Re: Edge 200 shows "off course"
« Reply #7 on: 07 October, 2014, 03:49:45 pm »
I'm putting in a .tcx track or .gpx, either via bike-hike or from the organiser's track.  I'm aware that occasionally the mapping has you going down the pavement 3 feet to the left andso on but I get really big variations, so it's obviously a biit more involved!

frankly frankie

  • I kid you not
    • Fuchsiaphile
Re: Edge 200 shows "off course"
« Reply #8 on: 07 October, 2014, 05:31:32 pm »
An organiser's Track can often be a recorded tracklog, which may itself go for a wander every so often, instead of staying close to the road.  It's not a good way to produce a Track intended for distribution (drawing it afresh in a Planner is much better) but it is very common.

My Edge 800 occasionally alerts me to being off course like that, despite riding along a fairly straight section of road without tree cover. A few seconds later it'll announce "course found". Not sure why either.

As a cyclist (and speaking for myself as a fairly bulky one, who likes to ride very forward, looming over the bars) you have to bear in mind that almost half the sky is unavailable to the GPS right from the get-go, blocked by your body.  The signals are after all incredibly weak - of the order of 50W transmitters, and over 20,000km away.
Now the GPS spec is, I think, that given a completely clear hemisphere of sky view, the absolute minimum number of sats above the horizon (at our sort of latitudes) is 6.  A Garmin will lose itself when the number it sees drops to (I think) 3 (for a few consecutive seconds).  Even though in theory, once a position has been established using 4+ sats, 3 or even 2 should be enough to maintain a useful approximation.
So even with a clear sky view (which itself is fairly unusual), a GPS with a large human in close proximity can be on the limit.

However, that minimum of 6 is quite an uncommon and short-duration event and most of the time it's 8 or 9, and can go up to 12.  That's with the 'set' of 24 satellites.  Actually there are a few spares knocking around up there as well, and some of them are turned on, so there's actually over 30 to go at.  That's not counting the GLONASS sats, which the latest Garmins can also access, or Galileo if it ever gets off the ground and in the right orbit (the last 2 to go up didn't!)
when you're dead you're done, so let the good times roll

Re: Edge 200 shows "off course"
« Reply #9 on: 13 October, 2014, 04:58:29 pm »
I also started using an Edge 200 to navigate recently and have experienced this too. Under tree overhang often gives an off course alert but also quickly alerts me I'm back on course!

Another example is roundabouts! Even if I am going straight on the slight bend getting round will alert me to being off course and as above quickly tells me I'm back on course.

Basically I have just got used to these curve balls and instinct soon kicks in to tell you when an alert is real or just bollocks.

Great bit of kit and fits the bill for my needs. Simple track, if it goes left so do you. That could be a left turn or simply a left bend in the road.
Battery lasts forever although I carry a PNY stick and normally re-charge on Audax events. Once forgot it on a 300 and it lasted fine.
Probably best of all the screen orientates with a direction change so track is always facing foward. No more wondering which way up the map should be!

What I did was ride a few circuits I know really well and deliberately went off course and learn to read the clues the Edge 200 is giving you to get back on course. Like the dotted line and arrows. It's actually all you will ever need in most situations in my opinion.

Verdict, Simple but Brilliant


Re: Edge 200 shows "off course"
« Reply #10 on: 13 October, 2014, 06:23:07 pm »
That's pretty much my opinion, Andy, though I did start my original correspondence (on another thread) because of concerns over battery life (I'm slower than you!).  What's a PNY stick?

peter

Re: Edge 200 shows "off course"
« Reply #11 on: 13 October, 2014, 08:01:12 pm »
Hi Peter,

PNY stick is a power pack that I carry to recharge Garmin.
Looks like a lipstick and weighs just a bit more.
Very convenient to carry.
Cost about £12 on Amazon.

Andy

Re: Edge 200 shows "off course"
« Reply #12 on: 13 October, 2014, 08:04:35 pm »
Thanks, Andy.  Is it this sort of thing?  http://www.amazon.co.uk/External-Portable-Charger--Ultra-Compact-Lipstick-Red/dp/B00MBWO6ZU/ref=sr_1_23?ie=UTF8&qid=1413227394&sr=8-23&keywords=pny+charger

I'm guessing you just connect with the cable that comes with the Garmin?  Does it come with its own "USB to USB" cable for charging via a computer or a mains plug-in transformer?  I am not really well up on this stuff...

Peter

Re: Edge 200 shows "off course"
« Reply #13 on: 14 October, 2014, 08:45:01 am »
hi Peter,

That IS the sort of thing and looks like the clip would allow charging while moving, but I am no expert I just learned from others mostly...

This is one I use: http://www.amazon.co.uk/PNY-PowerPack-Lithium-Ion-Battery-Output/dp/B00DMUND1I/ref=sr_1_1?ie=UTF8&qid=1413272247&sr=8-1&keywords=PNY+PowerPack+Fancy+2600+Rechargeable+Portable+Battery (useful video included)

Yes, it comes with a USB cable to charge its input socket from a pc.

To charge the Garmin you use the Garmins own USB cable and connect to the PNY output USB.

I use mine at controls on Audax events to give my Garmin a 20 minute charge but others have little pouches on their bikes and can charge on the go.

Also see riders with more expensive power packs that have 2 USB output ports and greater storage for charging multiple devices.

Hope this helps

Andy

Re: Edge 200 shows "off course"
« Reply #14 on: 14 October, 2014, 10:44:36 am »
Yes, that's very useful, thanks, Andy

Peter