Author Topic: Random GPS topics too unimportant etc etc.  (Read 1333 times)

T42

  • Tea tank
Random GPS topics too unimportant etc etc.
« on: November 06, 2016, 04:05:27 pm »
Such a thread my already exist but ICBA to look beyond the first ¾ page of the GPS section. Anyway:

Funny one with my eTrex 30x today: It usually takes a couple of minutes after starting to get the altitude right, but today it took over half an hour.  The error was over +50 metres on setting out and still +20m half an hour later. 6 or 7 satellites were well visible and accuracy was 3m.

First time I've seen anything like that.
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Kim

  • Timelord
Re: Random GPS topics too unimportant etc etc.
« Reply #1 on: November 06, 2016, 04:09:08 pm »
Barometric shenanigans, perhaps?
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Pingu

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Re: Random GPS topics too unimportant etc etc.
« Reply #2 on: November 06, 2016, 05:45:19 pm »
I've had that on a couple of occasions, but not quite as much as 50m out.

Re: Random GPS topics too unimportant etc etc.
« Reply #3 on: November 06, 2016, 06:26:29 pm »
In such a case it's best to visually check the actual sea-level when riding near the coast.

T42

  • Tea tank
Re: Random GPS topics too unimportant etc etc.
« Reply #4 on: November 07, 2016, 08:35:30 am »
Barometric shenanigans, perhaps?

Hum. I've always considered the 30x barometer a needless complication. Maybe I'd better have a gander.

I'd need a second "trip computer" screen to accommodate it, and all the other data I'd like to see en route.  Annoyingly, the GPX extensions at the beginning of the file only include the figures in the TC display and not the other possibles.  Garmin aren't likely to oblige, though.
I've dusted all those old bottles and set them up straight.

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Random GPS topics too unimportant etc etc.
« Reply #5 on: March 03, 2017, 10:51:27 am »
For turn by turn instructions, is it the .tcx file or the .gpx?
“Procrastination is the thief of time, collar him.” –Charles Dickens

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: Random GPS topics too unimportant etc etc.
« Reply #6 on: March 03, 2017, 11:24:27 am »
You'll get differing advice on that one.  For me, .tcx
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ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Random GPS topics too unimportant etc etc.
« Reply #7 on: March 03, 2017, 11:26:30 am »
That's what I thought, thanks

Route is straightforward anyhow, but just in case.
“Procrastination is the thief of time, collar him.” –Charles Dickens

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Random GPS topics too unimportant etc etc.
« Reply #8 on: March 03, 2017, 12:43:07 pm »
GPS Babel seems to have doen soemthing odd with the tcx files.  They are uploadable to the device, but I can't see any tracks, odd.

May just have to go with the gps this time.  I've definitely done this before, but can't quire remember how.
“Procrastination is the thief of time, collar him.” –Charles Dickens

frankly frankie

  • I kid you not
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Re: Random GPS topics too unimportant etc etc.
« Reply #9 on: March 03, 2017, 04:53:45 pm »
Barometric shenanigans, perhaps?
Hum. I've always considered the 30x barometer a needless complication. Maybe I'd better have a gander.

Bit late replying to this, oh well.  In a E30 or 30x, you basically have 3 options for viewing/recording elevations.
* The factory default and most commonly used mode (and best, IMHO) is Barometer mode 'Variable elevation' and Auto calibration set to 'On'.
* An alternative would be the same mode with Auto calibration set to 'off'.  Then of course you have to periodically calibrate it yourself which might be workable in very stable weather conditions but generally in British weather would be far more trouble than its worth. 
The Auto calibration may not be perfect, and can be bizarre for a while after switch-on, but I'm willing to bet it will give better results overall than any manual calibration regime.

In either of these modes the elevation you see, in any data field displayed on any page**, and the elevation that is recorded into the Tracklog, is derived from the barometer.   
**There is one exception, which is the elevation displayed on the 'Satellites' page - this is always the GPS-derived figure.

* The 3rd option is to turn the barometer off - well actually you can't, but you can set it to 'Variable pressure'.  In this mode the elevations you see, on any page, and the elevation that is recorded in the Tracklog, is GPS-derived.
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