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 Post subject: How to calculate distance between 2 GPS coordinate
PostPosted: Tue Oct 13, 2009 5:29 pm 
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Joined: Thu Sep 18, 2008 4:04 pm
Posts: 207
Location: Kuantan, Pahang
Any maths guru can help me with this? Assumig the distance is less than 10 km so the sperical issue should not be a big problem in the calculation.

Tks.


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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Tue Oct 13, 2009 8:09 pm 
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Joined: Wed Sep 17, 2008 10:53 am
Posts: 1809
Location: Penang - Nuvi 300, 205W, 2575RLM, M1200, M1000B/C, Papago N1
The easiest way to know the distance between two coordinates is to create the two way points in Mapsource and than check the route distance. Ensure you select Use Direct Route in preference.... Let technology work for you... :D

To use Maths you have to know the Latitude and find the circumference there.... than the rest is knowing the circumference of Earth (assuming the Earth is a perfectly round ball) for the Longitude and using Pythagoras to calculate the Hypotenuse of the Triangle... let me check my books to confirm... :mrgreen:

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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Tue Oct 13, 2009 10:06 pm 
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Joined: Tue Sep 23, 2008 10:48 am
Posts: 610
Location: JB
Hi,

Not sure if you want to know to derive the formula or you just want the distance.

http://www.movable-type.co.uk/scripts/latlong.html

http://www.fcc.gov/mb/audio/bickel/distance.html


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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Wed Oct 14, 2009 4:04 pm 
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Joined: Thu Sep 18, 2008 4:04 pm
Posts: 207
Location: Kuantan, Pahang
Tks for the link. I'm trying to get a simplified version for the calculations. Not that I need it to be super accurate (to keep track of SWMBO positon) :evil: . The distance of my transponder I intend to rig would be <10 km most of the time in a straight line. Anyting further and BIG BROTHER will be after my skin, I do know some that can go 40 miles running on 900Mhz but that is strictly clear line of sight. The memory available for programming is small and I have to keep its calculations as simple as possible.

Looks like I'll have to digest the data and hopefully come up with some resonable workaround. :frus:

Unfortunately, mapsource option is not in the equation otherwise. :thumbsup:

Tks. Pls keep me updated if you come across a more simple calculation. :prayer:


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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Thu Oct 15, 2009 11:47 pm 
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Joined: Tue Sep 16, 2008 11:15 pm
Posts: 64
I am no soldier. But during my scouting days in secondary school, I remember a simple way to calculate distance with a given set of coordinates. It uses Pythagorean theorem to calculate the distance(the a equals to the squareroot of b square plus c square thing).

I found this at one of the websites, http://www.movable-type.co.uk/scripts/latlong.html:

1° ≈ 111 km (110.57 eq’l — 111.70 polar)
1′ ≈ 1.85 km (= 1 nm) 0.001° ≈ 111 m
1″ ≈ 30.9 m 0.00001° ≈ 1 m

I think this is the one you are looking for.

Hope it helps.


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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Fri Oct 16, 2009 10:16 am 
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Joined: Wed Sep 17, 2008 10:53 am
Posts: 1809
Location: Penang - Nuvi 300, 205W, 2575RLM, M1200, M1000B/C, Papago N1
Bro TurboS,

The Lontitude distance at the Equator is definitely longer than near the Poles. So having a fix distance to calculate between two points is not practical...isn't it?... cheers....

Happy Depavali !!!... :mrgreen:

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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Fri Oct 16, 2009 4:42 pm 
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Regional Mapper

Joined: Thu Sep 18, 2008 4:04 pm
Posts: 207
Location: Kuantan, Pahang
Tks. Pythagorean theorem was one method I was looking at. It's calculation may be compounded by elevation, like the rest of the formulas. Anyway it is lot lot easier as I do not need to deal with trig calculations and that can zap quite a bit of memory. I know I should be able to get the uBlox receiver module to broadcast altitude too. Its quite a chip considering 160dBm 50 channel ability. Hopefully will work as good indoor too. I should be receiving it mid next week .. hopefully :prayer: . I guess, will have to test out the options given by everyone and see what is the best compromise.

Considering the very close, straight line 10 km distance, plus GPS positioning offset, I may be prepared for a big compromise. :mrgreen:


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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Sat Oct 17, 2009 2:46 pm 
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Joined: Tue Sep 16, 2008 10:15 pm
Posts: 207
Location: Puchong, SEL (Symbian MXT)
Attachment:
Distance.JPG

If your activity coverage area is small (let say 50km x 50km) and you can compromise with the distance accuracy, then the above equation can be further simplified by using fixed average latitude of the activity coverage area instead of local latitude, i.e.

D = [a – (a - c) K1] x SQRT[K2 x Long-D2 + Lat-D2]

where
K1 = sin2(Lat-F)
K2 = cos2(Lat-F)
Lat-F = fixed average latitude of coverage area

Example :
Coverage area = 50km radius from Hamilton of New Zealand
Lat-F = latitude at Hamilton
Distance ~= 10km
Error = +-70m


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Last edited by 76gpsguy on Sat Oct 17, 2009 3:14 pm, edited 1 time in total.

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 Post subject: Re: DISTANCE BETWEEN 2 GPS COORDINATES
PostPosted: Sat Oct 17, 2009 3:02 pm 
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Joined: Fri Sep 19, 2008 10:16 pm
Posts: 97
Location: Shah Alam. Garmin nuvi200W(sold), nuvi710, nuvi765 & GPSmap 60CSx, Garmin-Asus G60, Zumo550
=P~ WAW, like going back to school days.... :thumbsup: :peace:

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