53 lines
2.2 KiB
Plaintext
53 lines
2.2 KiB
Plaintext
From: Dave Esan <moscom!de@cs.rochester.edu>
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Subject: Re: Coordinate Tape Info Request
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Organization: Moscom Corp., E. Rochester, NY
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This followup to an article bounced back here. I'll try again.
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In article <telecom-v09i0445m03@vector.dallas.tx.us> you write:
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>Well, it is my understanding that the units in the V&H master database
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>are miles. This allows the milage based costing of the phone company
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>services to be calculated using the simple distance formula:
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>sqrt( (x1- x2)^2 + (y1 - y2)^2 )
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>although the phone companies really use the following formula:
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>sqrt( ( (v1 - v2)^2 + (h1 -h2)^2 )/10 ).
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V and H coordinates are points on a grid spread over North America. Being
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points they will be dimensionless. One can calculate the distance between
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any two points using the V and the H coordinates and simple geometry -
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eg the distance is sqrt( (x1- x2)^2 + (y1 - y2)^2 ), as noted above. But
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this will be wrong. The Earth is round, and this distance will not be correct.
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There is a distance method given in FCC #10, page 13. Basically it is
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as follows:
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1. Calculate the difference in V coordinates, and H coordinates.
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2. Divide each by three.
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3. Square the numbers and add them.
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4. If the sum of the square is > 1777 go to step #2. (Forgive me for using
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a goto statement.)
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5. If the sum of the square is < 1777 multiply it by a fudge factor based on
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the number of divisions done.
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6. Take the square root of the product, and round up.
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Of course, if it is zoned city you have to worry if the distance is < 40
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miles, in which case you have to recalculate using the zones coordinates
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rather than the master coordinates. Unless of course, this distance is
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greater than 40 miles, in which case you use the regular calculation.
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The distance between coordinates is supposed to be about 180 yards. (Maybe
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173 yards = 1/10 mile?). The point (0,0) is someplace in the Atlantic.
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Unlike ATT which calculates that cost of a call to Puerto Rico based on
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3 costing bands, Sprint calculates the mileage using a fake coordinate that
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has a negative H component.
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--> David Esan rochester!moscom!de
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------------------------------
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Downloaded From P-80 Systems 304-744-2253
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