V and H Coordinates

The V and H coordinate system is used in many telephone databases to geographic location.

Jay K. Donald of AT&T created the V&H coordinate system in 1957 to simplify the calculation of distance between telephone rate centers. The system is based on Donald Elliptic Projection. It is a two-point equidistant projection for the continental United States and Canada. It uses units of the square-root of one-tenth of a mile. The system was designed allow calculations in the field using a slide-rule.

To calculate the distances between a point 1 and 2 each with V and H coordinates use this formula:

Distance in miles = square_root( ( (V1-V2)**2 + (H1-H2)**2 ) /10 )

Converting from V and H to or from Latitude and Longitude appears not to be simple.
Here are some links that have source code and commentary on the conversion process

There are also a number of products you can purchase that have functions to do the conversion.

See Also

Created by: jht2, Last modification: Sat 21 of Feb, 2009 (23:21 UTC) by kc8esj
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