Home PageFacebookRSS News Feed
PocketGPS
Web
Read the current newsletter! Weekly
Newsletter
SatNav,GPS,Navigation
Pocket GPS World - SatNavs | GPS | Speed Cameras: Forums

Pocket GPS World :: View topic - Unit over-reading mileage
 Forum FAQForum FAQ   SearchSearch   UsergroupsUsergroups   ProfileProfile   Log in for private messagesLog in for private messages   Log inLog in 

Unit over-reading mileage

 
Post new topic   Reply to topic    Pocket GPS World Forum Index -> Satmap Active 10
View previous topic :: View next topic  
Author Message
reklawpete
Occasional Visitor


Joined: May 06, 2008
Posts: 40

PostPosted: Thu Sep 12, 2013 10:31 pm    Post subject: Unit over-reading mileage Reply with quote

On a recent walk we stopped for coffee and my Active 10 read 4.05 miles. Another walker with the same GPS and 2 others with Garmins all read about the same 3.3 miles. Why is mine over-reading? I zeroed it before starting the walk.
Back to top
View user's profile Send private message
LostMike
Frequent Visitor


Joined: Jan 17, 2008
Posts: 369
Location: Monmouthshire

PostPosted: Fri Sep 13, 2013 2:15 pm    Post subject: Reply with quote

Hi reklawpete.

I do not know why your GPS read more than the others on this one occasion. What I find more odd it that three other GPS devices all read the same.

Almost every week a group of people I walk with compare the different distances that their GPS devices record for the distance walked. They are hardly ever the same. And interestingly I get the impression that they look to me (with my A10) as having the more reliable distance record..

Also, when I finish my walk the track show a certain length for the walk but when I save the file, Satmap rounds up the oddities and it always gives a shorter distance - not much but shorter all the same.

Reasons for differences, apart from a faulty unit can be many-fold.

The device may not have got a good fix when the track was started. I never start tracking until the device reports a good fix.

Different people have different walking styles and walk different routes some wander from side to side looking at things some walk a straighter route.

Where the GPS device is carried and the cover of trees etc can effect the signals reaching the device. This impacts on the accuracy and the fix.

I'm sure I could come up with more but I think I will leave it there for now. You might like to check on future walks and see if any trend appears. If you appear to be getting consistently high distance readings, or if your location does not seem to be accurate on a regular basis then it might be worth contacting SatMap.

Did that help?
_________________
LostMike
Satmap A10. Platform 21
Software version 1.5.9193
Satsync 1.525
Back to top
View user's profile Send private message
reklawpete
Occasional Visitor


Joined: May 06, 2008
Posts: 40

PostPosted: Fri Sep 13, 2013 5:15 pm    Post subject: Reply with quote

Thanks LostMike for your thoughts. As soon as a had a fix I zeroed the unit and zeroed it again as we started the walk. Our path was single file in many places so not much chance of walkers wandering.

As this is not the first occasion when the mileage seemed odd I have decided to have it serviced to see if that solves the problem.
Back to top
View user's profile Send private message
LostMike
Frequent Visitor


Joined: Jan 17, 2008
Posts: 369
Location: Monmouthshire

PostPosted: Fri Sep 13, 2013 6:32 pm    Post subject: Reply with quote

Seems a reasonable course of action.

Do let SatMap know of your concerns when you send it back.

And do let us know if it helps.

Good luck.
_________________
LostMike
Satmap A10. Platform 21
Software version 1.5.9193
Satsync 1.525
Back to top
View user's profile Send private message
GPSwalker
Occasional Visitor


Joined: Nov 29, 2009
Posts: 27
Location: Yorkshire

PostPosted: Sun Sep 15, 2013 12:38 pm    Post subject: Reply with quote

I have found that my A10 usually over-measures walk distances by 5-8%, thus a 10 mile walk reads nearer 11 miles. Other walkers with different GPSs on the same trail tend to do the same, so our mileages are similar.

It does improve things if you turn off and back on the device during a lunch or coffee stop, because I have noticed that small distances are still added when you are going nowhere.

Perhaps a software addition could allow for a 5% (and other percentage)error by user optional calibration, i.e., a devise's distance measurements could be reduced by say 5% to compensate for the typical over-measurement.

I often check my new walk distances using the premium Xpedition map and its measuring tool. This always gives a lower mileage than my GPS, usually in the range 5+%. Can anyone tell me if a GPS actually measures distance covered during up and down hills, which is going to be more than a straight line 'as the crow flies' as measured on a map?
Back to top
View user's profile Send private message
JimmyTheHand
Frequent Visitor


Joined: Apr 16, 2005
Posts: 386

PostPosted: Tue Sep 17, 2013 10:39 pm    Post subject: Reply with quote

GPSwalker wrote:
I have found that my A10 usually over-measures walk distances by 5-8%, thus a 10 mile walk reads nearer 11 miles. Other walkers with different GPSs on the same trail tend to do the same, so our mileages are similar.


I have found it reads wrong - even on fairly flat ground. I am a suspicious it might be a rounding issue in its calculations because when I have imported track into PC I get a different measurement (at least that is what I recall as haven't done it for a while)
_________________
J.
Back to top
View user's profile Send private message
davidor
Regular Visitor


Joined: Nov 14, 2008
Posts: 117

PostPosted: Sat Sep 21, 2013 11:09 am    Post subject: distance Reply with quote

I've always been a bit wary of the distance recorded as I noted how much distance it records when just sitting on a table. My Garmin doesn't log any distance if it is not acutually moving.

The same goes for speed - the A10 shows a significant variation in speed when walking at a steady pace. Walk at 3mph say at it will show the moving speed as anything between 1.5 and 8 mph. Again, my Garmin shows a steady speed. My A10 has recently been "tuned" in a Satmap service as well.

As for height...
Back to top
View user's profile Send private message
dales
Frequent Visitor


Joined: May 04, 2008
Posts: 744
Location: Knaresborough, North Yorkshire.

PostPosted: Sat Sep 21, 2013 3:32 pm    Post subject: Reply with quote

Hi reklawpete,

0.7 miles in 3.3 miles is a pretty large discrepancy. If you plotted your track on the PC, you'd probably see it caused by a "spike" in the track, veering way off to one side and back again. You can get these errors in areas of difficult reception eg woodland cover or high ravines. I would treat it as a one-off for now.

Personally I wouldn't send the unit back, unless the fault is persistent.

As has been said, you can get small discrepancies a) because people measure the map in straight lines, whereas the path weaves and so do walkers; b) because the fix is not 100% precise, you do get "wander" of the fix during your rest break; c) because some people carry their device with the aerial facing the stars and the satellites, whereas others stick it in their pocket, shielding reception somewhat and reducing accuracy. Saving the track to computer reduces the number of trackpoints significantly, and so does serve to smooth out the recorded path and reduce tracking error.

Dales.
_________________
nuvi 2599LMT-D, oregon 700, basecamp, memory-map.
Back to top
View user's profile Send private message
Cullin
Occasional Visitor


Joined: Oct 10, 2010
Posts: 9
Location: Nottingham

PostPosted: Wed Oct 09, 2013 8:59 pm    Post subject: Reply with quote

I was wondering if you were getting poor geometry, so your position was not being shown at the correct location, hence adding this distance to your mileage.
Back to top
View user's profile Send private message







Posted: Today    Post subject: Pocket GPS Advertising

Back to top
Display posts from previous:   
Post new topic   Reply to topic    Pocket GPS World Forum Index -> Satmap Active 10 All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

Powered by phpBB 2.0.11 © 2001 phpBB Group
phpBB port v2.1 based on Tom Nitzschner's phpbb2.0.6 upgraded to phpBB 2.0.4 standalone was developed and tested by:
ArtificialIntel, ChatServ, mikem,
sixonetonoffun and Paul Laudanski (aka Zhen-Xjell).

Version 2.1 by Nuke Cops 2003 http://www.nukecops.com

Make a Donation



CamerAlert Database

Click here for the PocketGPSWorld.com Speed Camera Database

Download Speed Camera Database
20.081 (03 Aug 22)



WORLDWIDE SPEED CAMERA SPOTTERS WANTED!

Click here to submit camera positions to the PocketGPSWorld.com Speed Camera Database


12mth Subscriber memberships awarded every week for verified new camera reports!

Submit Speed Camera Locations Now


CamerAlert Apps



iOS QR Code






Android QR Code







Terms & Privacy


GPS Shopping