Garmin GPS - Difference between Odometer and Track

Author

Difference between Odometer and Track

2006-10-08, 10:33 pm

Is there a reason why the Odometer and Track length would be different?
I have Garmin 60CSx and was careful to clear the Odometer and the
Tracks before starting out, but at the end the track was longer by
about 15-20 percent. The route was up and down steep hills, in case
that makes a difference. I was thinking maybe the hills added length,
but I would think both the track and the odometer were getting their
data from the same source. Reception was no problem, up to 7
satellites were always on.

Duracell Bunny

2006-10-09, 4:33 am

Al wrote:
> Is there a reason why the Odometer and Track length would be different?
> I have Garmin 60CSx and was careful to clear the Odometer and the
> Tracks before starting out, but at the end the track was longer by
> about 15-20 percent. The route was up and down steep hills, in case
> that makes a difference. I was thinking maybe the hills added length,
> but I would think both the track and the odometer were getting their
> data from the same source. Reception was no problem, up to 7
> satellites were always on.
>
If you check the archives, this problem has been reported by a number of us.
Yes, it would appear to be a bug, especially in heavy undergrowth areas. The
unit does not report losing signal, but it would appear to lose the plot
somewhat under these conditions

--
Karen

If you can't be a good example, then you'll just have to be a horrible warning.'
Catherine Aird

bcd

2006-10-09, 3:33 pm

I'm not surprised that there's a difference. A good odometer algorithm uses
every measurement. Track length is almost certainly based on whatever
measurement spacing is used to form tracks.

What DOES surprise me is that the track algorithm yields a result that is
larger than the odometer algorithm, ASSUMING there aren't a lot of outages
causing loss of data to the odometer calculation.

If your car odometer is reasonably accurate, do a little open country, dry
road, driving and see which one is closer.

On 10/9/06 12:10 AM, in article
4529f591$0$1446$5a62
ac22@per-qv1-newsreader-01.iinet.net.au, "Duracell
Bunny" <karen_oz@hotmail.com> wrote:

> Al wrote:
> If you check the archives, this problem has been reported by a number of us.
> Yes, it would appear to be a bug, especially in heavy undergrowth areas. The
> unit does not report losing signal, but it would appear to lose the plot
> somewhat under these conditions

Bill Cotton

2006-10-09, 10:33 pm

"Al" <allanrb@gmail.com> wrote in message
news:1160356593.702228.136380@c28g2000cwb.googlegroups.com...
> Is there a reason why the Odometer and Track length would be different?
> I have Garmin 60CSx and was careful to clear the Odometer and the
> Tracks before starting out, but at the end the track was longer by
> about 15-20 percent. The route was up and down steep hills, in case
> that makes a difference. I was thinking maybe the hills added length,
> but I would think both the track and the odometer were getting their
> data from the same source. Reception was no problem, up to 7
> satellites were always on.
Were the tracks unbroken? Today I did my October century number one. ( I am
committed to ride two centuries each month this year, I have 20 to date.
http://www.billcotton.com/my_training.htm ) The tracks has four segments,
the mileage are: 13.2, 10.3, 28.2 and 51.6.
The first three breaks are from lost of satellite view. The last I turn the
gps off for lunch break, I happen to look at the odometer and it was reading
5.5 mph. My Flight Deck was reading 12 mph.
My understanding is that the gps is program to hold the last reading for a
short time when satellite view is lost. When the satellite view returns the
gps add miles according to where it is on a straight line. The track doesn't
have this feature.
However, The latest version of Mapsource, (go to help, and click on Check
for Software updates, it you don't have it), has a Track Join tool. I use it
on traces from today's ride.
Today's ride; the Odometer reads 103.6
The track package above has a total of 103.3
The joined track has total miles of 104.

--
www.billcotton.com

2006-10-10, 10:33 am

One of those "it's so obvious, why didn't I think of that" moments.
Thank you. I usually drive about 40 miles to the Appalachian trail to
hike, so it will be easy to stop at a mileage marker, set both the
odometer and track to zero, and drive 20-30 miles and see what the
readings are. Will report Sat. eve.

bcd wrote:[color=darkred
]
> I'm not surprised that there's a difference. A good odometer algorithm uses
> every measurement. Track length is almost certainly based on whatever
> measurement spacing is used to form tracks.
>
> What DOES surprise me is that the track algorithm yields a result that is
> larger than the odometer algorithm, ASSUMING there aren't a lot of outages
> causing loss of data to the odometer calculation.
>
> If your car odometer is reasonably accurate, do a little open country, dry
> road, driving and see which one is closer.
>
>
> On 10/9/06 12:10 AM, in article
> 4529f591$0$1446$5a62
ac22@per-qv1-newsreader-01.iinet.net.au, "Duracell
> Bunny" <karen_oz@hotmail.com> wrote:
>

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