[OSM-talk] mapping while hiking

Steve Hill steve at nexusuk.org
Sat Apr 26 08:27:56 BST 2008


Charles Basenga Kiyanda wrote:

> This is slightly off-topic, but does anyone have a trick to deal with 
> the gps when tagging while hiking trails? I carry a garmin etrex legend 
> Cx (unfortunately not the H version) and I find that it has to be 
> "looking" directly up and flat to get best reception. Especially around 
> here with often good tree cover and canyons.

I've got an old style eTrex Venture.  Generally when walking, skiing, 
etc. I clip it to a shoulder strap of my rucksack and it is ok most of 
the time.  Dense tree cover does harm the accuracy (noticable if you 
compare tracks over several walks of the same path).  I think Garmin 
receivers probably do a bit of dead-reconning even when they can see the 
satellites when they aren't in a good constellation because the 
direction you walk a route in seems to affect where the inaccuracies lie 
(i.e. if you walk along a right-hand bend under tree cover it will often 
estimate your position too far to the left, but if you walk around a 
left-hand bend it'll probably show you too far to the right).

The best advice I can offer is to make sure it has "seen" as many 
satellites as possible (i.e. shown them as black bars) before getting 
into a poor reception ares - the receivers seem to be able to hold onto 
reception from satellites they have previously locked onto much better 
than locking on to new satellites when under tree cover.

You might also think about putting the receiver in the top-pocket of a 
rucksack or something, which might give it a better view of the sky. 
But this obviously means you can't look at it without stopping and 
taking it out of the rucksack.


> something that 
> would look like an arm-band mounted pouch that I could strap to one of 
> my forearm, since they stay pretty level constantly during the hike.

When walking, I put my eTrex in an official Garmin eTrex case - looks 
like a cellphone case, with a clip on the back, etc.  That can be 
clipped to the rucksack straps, but I guess you could put a band around 
your arm and clip it to that instead.

On the odd occasion I take a GPS when I go windsurfing, I put it in an 
Aquapac, which has an arm-strap (the Aquapac I use is actually designed 
for VHF radios, but it (just) fits the eTrex).  This might not be what 
you want though - it does make it quite difficult to push the buttons on 
the receiver.

> I've tried 
> every possible permutation of having the gps stick out of one of my 
> pockets on pants(trousers)/coat/etc to no avail.

I think putting a GPS in your pocket is a bit of a no-no - the only time 
I've got a reasonable signal with the GPS in a pocket is when putting it 
in the wrist-pocket on my ski jacket.


-- 

  - Steve
    xmpp:steve at nexusuk.org   sip:steve at nexusuk.org   http://www.nexusuk.org/

      Servatis a periculum, servatis a maleficum - Whisper, Evanescence





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