GPS FORUM

Hi All,

Well I have finally plumped for an Off-Road GPS for my walks and last week
bought a Garmin Vista HCx and a copy of Memory-Map for the laptop. Anyway
I think the kit is great and at the weekend went for a short walk around
Chirk and Offas Dyke to test it all out before I go off to Scotland for a
week this coming weekend. Well now the reason for the post.....!!!

The Odometer reading for the walk I did is showing 5.02 miles but the
Track Log that was created is showing 6.47 miles..!! Now I know that
everything was reset before I started so why the difference?

Any feedback most appreciated. And if there is an obvious reason why then
I apologise in advance :)

--
Rgds, Mick.

Mick wrote:
Noticed that too.

GPS always shows less distance than Memory Map.

If you plot a new route over your track does it show the lower distance
as well?

--
Mike
Some pictures of the Scottish highlands here http://www.prog99.com

Do you take big steps?

Mick wrote in message
news:memo.20070821185656.5616A@mick.zen.co.uk...

Mick wrote in message
news:memo.20070821185656.5616A@mick.zen.co.uk...

Did you walk in a straight line? Perhaps you did walk 6.47 miles, but ended
up 5.02 miles from where you started off.

Marcus

Mick wrote in message
news:memo.20070821185656.5616A@mick.zen.co.uk...

Its a bug in the Vista HCx, if you walk below a certain speed it will not
record your distance. Search the Groundspeak forum for more info.

http://forums.groundspeak.com/GC/index.php?s9b7620072b3fb6c4d53da3dd69046f4&showforum=11

Micks observation is correct. Its not only a problem for the Vista HCx
but also for the 60CSx. Take a look at the time recording for the track:
time stopped and time moved. But normally in this case I observe that
the track length is less than the trip length. Perhaps you can put your
track onto a map and look if there are no anomalies in the registration
(track point a distance away of the path you walked).
A comparison to podometers isnt very helpful because podometers work
with the number of steps you have taken and a mean value of the step
length. If you walk on difficult ground and your step length varies
much, the result isnt very accurate.
Pete Rissler schreef:
http://forums.groundspeak.com/GC/index.php?s9b7620072b3fb6c4d53da3dd69046f4&showforum=11

Mick wrote:

Did you clear the track and also immediately reset the odometer? And
did you save the track at the same moment (within a few seconds or so)
of the time you saw the 5.02 reading?

Try it again clearing the track and zeroing the odometer just as you
start. When you get the ending place, note the distance on the odometer
and then turn the GPS off and back on. The off/on cycle will start a
new track segment on the *.gpx file track log. So when you look at the
*.gpx file that segment should show the same distance you saw on the
odometer.

Whenever the GPS is on it is calculating fixes, like about one per
second or so. Each fix is in a different place, even when the GPS has
not moved physically. The distance from one fix point to another is
steadily accumulated by the odometer and if that goes on long enough it
skews the numbers.

Clear you odometer and leave it laying somewhere for a while, youll be
surprised how much distance can be accumulated.

When I want accurate starting and ending times and distances, I look at
the *.gpx files on the memory card. Those will not accumulate all the
track points when you are stationary, it uses a speed threshold or
something to stop and start on saving track points. Looking at that I
can see when movement starts and stops and I can also get the distance,
speed, and average speed info from it by looking at the track properties
in MapSource or GPS Utility.

By copying and pasting portions of the track data into a second
MapSource window, I can isolate parts of a track to analyze portions of
a track or to break one long track into several shorter tracks. And I
can edit out track points, join tracks, and do similar things.

Turn the Log Track to Data Card thing on if it is not on already. The
saved tracks are useless for post travel analysis because then do not
contain the time data. And they are limited to 400 track points
(selected by the software) regardless of the length of the track or the
number of points collected.

Jack

From my experiments there is a problem with the odometer in the Vista HCx.

When deliberately walking very slow, below 3kmh, and going on a defined
track the odometer displayed .4Km. On returning over the same track, walking
fast, the distance indicated was 1.2 Km. The tracks recorded showed the
approximately same distance in both cases, 1.2Km.

Mick wrote in message
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