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General Category => General Discussion => Topic started by: targabill on January 20, 2009, 06:41:39 AM

Title: ? on trip odometer vs. mapsource
Post by: targabill on January 20, 2009, 06:41:39 AM
I went snowshoeing last Sunday on the AT in Vt. and decided to track the trail, 2 questions.

I reset the trip odometer and started the tracks. I went out 2.01 miles according to the trip odometer. Stopped the track and saved it. When I loaded it into map source it said I went 2.9 miles. Why is this different? There was a little elevation gain but not much. 

And, the day before I snowshoed up a hill behind my house, Pretty steep for 1/4 mile.. But my dog was pretty cold so my friends went on and I ran back down to put her in the house and back up... OK I started at about 1000' elevation, went up to 1750'... went back down to where I started and back up. But when I profile it, it shown me starting at 1000, but when I came back down to the same spot the elevation only went down to 1440 or so.. How can this be so far OFF... And at the end it says I finished at about 1500 ' .
I use the 60csx but I don't have a TOPO for Vermont. thanks, Bill
 
Title: Re: ? on trip odometer vs. mapsource
Post by: -Oz- on January 20, 2009, 08:01:30 AM
For the elevation: did the weather change while you were out there?  The 60csx uses a barometer for elevation.  I would recommend calibrating it.  The easiest way is just to wait till you have a great signal then tell the GPS to calibrate using the GPS elevation. It'll correct itself from there.

What was your vertical ascent reading?

For the odometer; I'm not sure whats up with that.  I've never compared my track in mapsource to the one from the GPS.  It is possible that mapsource actually calculates the travels along the route and the trip odometer is just horizontal.  But for 750' elevation that wouldn't have changed that much.

Is this a saved track log or the active/track log from the sd card?
Title: Re: ? on trip odometer vs. mapsource
Post by: LeeT on February 11, 2009, 02:46:19 PM
I've had this same problem on weekly hikes for the past year.  Trip Odometer has always shown longer hikes than the profile from the MapSource  regardless of whether I use TOPO US 08 or the New Mexico topo downloaded from this site.  Have tried other map programs, MapTech, with same result.  I'm using a GPSmap 60Cx and wonder if there is a way to calibrate the trip odometer.
Thanks, Lee
Title: Re: ? on trip odometer vs. mapsource
Post by: -Oz- on February 11, 2009, 05:50:17 PM
has anyone seen if the trip odometer says a mile when driving on the interstate between mile markers?
Title: Re: ? on trip odometer vs. mapsource
Post by: LeeT on February 15, 2009, 06:18:09 AM
Thanks for the suggestion.   Miles on 60cx agree with road mile markers and when I transfer track to map, miles agree with those two. But when hiking trails the 60cx and map miles do not agree.  Next step, so to speak, is walk between two mile markers to see what happens. 
Lee
Title: Re: ? on trip odometer vs. mapsource
Post by: LeeT on February 15, 2009, 02:24:59 PM
Thanks,
Will change the gps' settings for next Thursday's hike.
 Lee
Title: Re: ? on trip odometer vs. mapsource
Post by: smith on March 02, 2009, 07:39:14 AM
has anyone seen if the trip odometer says a mile when driving on the interstate between mile markers?
I had the pleasure of driving my family 4000+ miles to Disney World and back a few weeks ago.  Made me feel like Clark Griswald.  While checking mileage the trip meters would read roughly 350 on the truck odometer and around 355 on both my nuvi205W and rino530.  I never compared the mile markers to GPS.  I'd guess that my difference is due to the larger than stock tires on my truck causing error on the odometer.  The MPH showed a little under on the dash as well.
Title: Re: ? on trip odometer vs. mapsource
Post by: maps4gps on March 02, 2009, 09:06:38 AM
Tire size will definitely make a difference on the odometer/speedometer.  Full tread new tires versus worn tread near replacement also makes a small difference as the unit works off the number of revolutions of the shaft.  The unit can be adjusted with replacement gears, but few bother to do so.  Just watch your speed as you are going faster than indicated on the speedometer.
Title: Re: ? on trip odometer vs. mapsource
Post by: LeeT on March 05, 2009, 06:27:06 PM
Following the suggestion.  I adjusted  "record method" to "auto" and "most often" and saved track on the data card.   For the last two weekly hikes the map distance and trip odometer are within 3% - Quite satisfactory.  
Thanks
Lee