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TCP-group 1994


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Re: smashing down callsigns into 32 bits




On 94 Dec 02 at 16:49, Fred Goldstein wrote:

 FG> The original poster's fallacy, of course, was in forgetting 
 FG> how to determine permutations.  The proper value of a field 
 FG> AA9AAA is 26^5 * 10, noting of course other formats too so 
 FG> more likley 27^5 and when you add non-US signs like C21 and 
 FG> 4N7 it gets a bit bigger... fred k1io

The rule imposed by international treaty is that amateur callsigns are always
exactly 6 characters in the form:

          Xx9aAA

          where:  X is alphabetic, numeric, or space;
                  x is alphabetic or numeric;
                  9 is numeric;
                  a is alphabetic;
                  A is alphabetic or space.

There are certain additional restrictions: the 2nd character cannot be numeric
if the 1st character is numeric or a space, and the 1st and 5th characters
cannot both be space.  As far as I know, the only callsign that does not
conform to this rule is JY1, used by the king of Jordan.

There are three cases:

1. The 1st character is alphabetic.

   26 x 36 x 10 x 26 x 27 x 27  =  177,409,440

2. The 1st character is numeric.

   10 x 26 x 10 x 26 x 27 x 27  =   49,280,400

3. The 1st character is space.

    1 x 26 x 10 x 26 x 26 x 27  =    4,745,520

                                  ------------

   Total worldwide callsigns:      231,435,360

Since 24 bits can only represent 16,777,216 permutations, and we need to
represent just under 14 times more values, this is obviously impossible.
 
-- Mike
 





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