Go Back   ADVrider > Riding > Mapping & Navigation
User Name
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Thread Tools Search this Thread Rating: Thread Rating: 2 votes, 5.00 average. Display Modes
Old 08-02-2005, 04:44 AM   #1
Dartmouth, Massacusetts
Joined: Aug 2004
Location: Dartmouth, MA
Oddometer: 1,578
how does a GPS measure distance?

over a long trip, how does a gps measure distance? point to point and then adding it all up or as the crow flies?
Roy B
Dartmouth, MA
2007 BMW K1200R Sport abs,2007 DL650 V Strom abs
2004 Honda VFR abs,2001 Moto Guzzi Rosso Mandello
1971 Honda Trail CT90
RoyB is offline   Reply With Quote
Old 08-02-2005, 04:48 AM   #2
H.I.D. Positive
Kaumajet's Avatar
Joined: Jun 2003
Location: Ottawa
Oddometer: 10,137
Assuming you have an auto-routing GPS, or one that will navigate roadways - if you're in Automobile mode, the GPS will calculate the distance along a route determined by your criteria (shortest route, fastest route, avoid this or that). The distance it comes up with will be the actual distance along the roadway.

In marine or other modes, depending on the GPS, the distance wil be straight line, without slope correction.
"I understand the dilemma. Correct spelling takes time that could be spent licking the windows on the short bus." mac62

"There is just something special about a stripper with a tail" ilmostro
Kaumajet is offline   Reply With Quote
Old 08-02-2005, 06:46 AM   #3
Jabba's Avatar
Joined: Nov 2002
Location: Just east of the Pine Beatle- Evergreen, CO
Oddometer: 12,559
Huh- I was gonna go with "triangulation, knucklehead".
"Everybody loves cunnilingus!" Chacifer

"The road to paradise is paradise" Jacques Yves Cousteau
Jabba is offline   Reply With Quote
Old 08-02-2005, 08:05 AM   #4
Gnarly Adventurer
Joined: Oct 2004
Oddometer: 350
A GPS will take a position every second (or 5 seconds for some older units) and then calculate the distance between the two measurements. For the trip odometer of the GPS it will simply add those distances up to compute the total miles (or kilometers) traveled.

The distance includes changes in altitude as well if you have enough satellites (3D Navigation).

If your GPS does have track logs (typically for back tracking a route) those will not match the odometer (in most cases) since they "smoothen" out the number of points and will come up with a more straightline approach. This will result in slightly smaller distance numbers. Found this when comparing a longer trip with lots of twisty roads and comparing the total of the GPS odometer with the individual track logs (differed by about 3% - still better than the bike odometer).

'09 R1200GSA
'09 F800GS
'05 KLR650
reinerka is offline   Reply With Quote
Old 08-02-2005, 10:50 AM   #5
Finding My Way..
Infracaninophile's Avatar
Joined: Sep 2001
Location: New England, USA
Oddometer: 7,521

Edit: Now that I think about it, it must be Trig, not geometry. Math is hard.


Infracaninophile screwed with this post 08-02-2005 at 03:15 PM
Infracaninophile is offline   Reply With Quote
Old 08-02-2005, 11:34 AM   #6
Road Captain
FatChance's Avatar
Joined: Jun 2003
Location: Durango, Colorado, USA
Oddometer: 10,590
Math is hard.
Pain in the Butte Ranch
Durango, Colorado

- Calculated risk or forbidden fruit?
FatChance is offline   Reply With Quote
Old 08-02-2005, 04:26 PM   #7
jktpa's Avatar
Joined: Jun 2002
Location: Orlando/Blairsville
Oddometer: 791
By Fucking Magic
Low Tech-Hi Fun
jktpa is offline   Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

Times are GMT -7.   It's 02:56 PM.

Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2015