LF: Distance calculator (off topic)

["Walter Blanchard" <blanch@pncl.co.uk>]

At 07:32 04/01/03 G0MRF wrote:

> Hello
> Group.    Happy New Year. 
>
> Does anyone know of, or have, any windows software that can calculate
> distances based on the UK National Grid Reference system? 
> (e.g.  TQ147951 ) 
>
> I have one for the Maidenhead system (if anyone would like it just ask)
> but not for calculating distance between two NGR's. 
>
> Many Thanks 
>
> 73 
>
> David 


I wrote a little program 15 yrs ago to do this, available free to anyone
who wants it.
Also converts  NGR to/from lat/lon at about the 10m level.
Will not pass this reflector as an attachment. Sent one to David
direct.

NGR distances are easy to do in a spreadsheet . Unlike  Maidenhead
and Lat/Lon  
NG is a true rectilinear grid so if you know how to translate NGR's
given as e.g. TQ 169483  into actual Eastings and Northings in terms
of metres
all you have to do is a root sum of squares equation.  Done this way
distances will be correct but bearings will be in terms of Grid North -
about
2 degs different  from True North in Central England. My program
corrects for this
and gives bearings as degs True. 

If you really want to go to town get onto Ordnance Survey's  GPS
website -
www.gps.gov.uk ,
get a password and log in and you can get, free, a 
massive 10 Mb program that converts everything to everything at
millimetre 
accuracy (GridInquest). Or it lets you do conversions on-line.

Walter G3JKV.
 

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