Calling Tiompan

close
gjrk G
gjrk May 30, 2009 18:58:39

Bit of a layman's maths crisis. I wonder if you can help, George?

I'm writing something up at the moment and was going to use an example of three sites lining up across the countryside. Obviously, there's quite a good chance that three points can coincide fortuitously, particularly if there's a lot of them around. I'm not claiming that it's deliberate, just that it's there.

I've identified a number of lines by using the utility at:

http://www.iol.ie/~geniet/eng/azimuth.htm

and each site's coordinates. I established the azimuths and distances between each point and then solved the triangle to find the distance between the respective lines.

With the following, for example:

(a) N51.64614, W-9.06488
(b) N51.64749, W-9.00848
(c) N51.64805, W-8.98150

I calculated a line 'ac', length 5.749km where 'b' is 5.72m from 'ac' (+17.55m to -6.12m for 5m GPS error).

Does this add up, or have I gone wrong anywhere?

Thanks in advance,

Gordon.

T tiompan
tiompan May 30, 2009 23:42:42
Replying to gjrk

gjrk wrote:
Bit of a layman's maths crisis. I wonder if you can help, George?

I'm writing something up at the moment and was going to use an example of three sites lining up across the countryside. Obviously, there's quite a good chance that three points can coincide fortuitously, particularly if there's a lot of them around. I'm not claiming that it's deliberate, just that it's there.

I've identified a number of lines by using the utility at:

http://www.iol.ie/~geniet/eng/azimuth.htm

and each site's coordinates. I established the azimuths and distances between each point and then solved the triangle to find the distance between the respective lines.

With the following, for example:

(a) N51.64614, W-9.06488
(b) N51.64749, W-9.00848
(c) N51.64805, W-8.98150

I calculated a line 'ac', length 5.749km where 'b' is 5.72m from 'ac' (+17.55m to -6.12m for 5m GPS error).

Does this add up, or have I gone wrong anywhere?

Thanks in advance,

Gordon.

Hi Gordon , a quick calc and it looks like the maximum "error " is 26 metres over the 5.7 Km distance , there are no rules so it's up to you as to how "straight " you consider that is . The gps error might be greater so it could actually be slightly better or worse . What are the sites and are they intervisible ? Not far off E-W too .