[aprssig] Σχετ: proposal for APRStt grid loc. Σχετ: 60 Grid Square............

George Vastianos gvastianos at yahoo.gr
Sat Feb 14 16:13:17 CST 2015

Thanks for the correction! 

I had in my mind that you have to look for the first letter on the black row below and then look for the second letter on the black column on left... so i wrote "Row 1st, Col 2nd" BUT THIS IS WRONG
The correct is "Col 1st, Row 2nd" that means "Find the Column of 1st letter and then the Row of 2nd letter"
e.g.  KM = 502, NQ=536, UW=902


      Απο: Lynn W. Deffenbaugh (Mr) <ldeffenb at homeside.to>
 Προς: TAPR APRS Mailing List <aprssig at tapr.org> 
 Στάλθηκε: 11:57 μ.μ. Σάββατο, 14 Φεβρουαρίου 2015
 Θέμα: Re: [aprssig] proposal for APRStt grid loc. Σχετ: 60 Grid Square............
 Pardon my literalness, but if you say "Row 1st, Col 2nd", then for KM I'd go to row K up the right side and column M across the bottom and get 520 whereas your example says it's 502 which seems to be column K and row M?
 More than one example would make it more clear for those of us that need to see what you're talking about.
 Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32
 On 2/14/2015 7:33 AM, George Vastianos wrote:

           Hello Bob
 IMO in APRStt the conversion between grid and numbers should be very easy in a way that no calculation algorithm will be needed by the user and only a small printed table will be enough. In this way  with a small printed paper in the pocket and the low cost HT anyone could define his position in the APRS system (of course if he knows his position and if there is APRStt infrastructure in his area...)
 In the attached file (PNG picture) you can find my proposal for a simple conversion table
 the result is that you add a group of 3 number-digits for each 2 letters of the grid
 eg. KM = 502, KM17 = 50217, KM17uw = 50217902, KM17uw48 = 5021790248
 based on the fact that my proposal uses only the 0-9 digits and not the *,#,A-D this makes it compatible with the APRStt format.
 The conversion table was designed in a way that the conversion from the number to ascii will be very easy (even for 8-bit microcontrollers) and will not require usage of memory lookup tables.
 Below is a sample code (in basic style) that will convert the 3-digit number into the Grid Square letter characters (e.g. for i=502 then Chr(C1) becomes "K" and Chr(C2) becomes "M")
 'example I=536 will print "NQ"
 Dim I, X, CO1, CO2, C1, C2 As Integer
 I = 536
 If (I >= 100 And I < 340) Then
     CO1 = 10: CO2 = 65
 ElseIf (I >= 400 And I < 640) Then
     CO1 = 40: CO2 = 75
 ElseIf (I >= 700 And I < 940) Then
     CO1 = 70: CO2 = 85
 End If
 X = Int(I / 10)
 C1 = 65 + X - CO1
 If C1 < 65 Or C1 > 88 Then End 'ERROR i is outside limits
 C2 = I - X * 10 + CO2
 If C2 < 65 Or C2 > 88 Then End 'ERROR i is outside limits
 MsgBox Chr(C1) & Chr(C2) 
 In the above sample code the C1 and C2 are integers that contain the ASCII value of the 2 characters..... This proposal is not only for the satellite app but for the APRStt in general.
  P.S. The limit of 40KB in aprssig list....really sucks! i tried 3 times to send the same email until it  fits in limits. SORRY in case you received multiple times the same message (e.g. amsat-bb)
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