[aprssig] APRStt 4 digit grid squares...justification

Robert Bruninga bruninga at usna.edu
Mon Feb 16 07:38:32 CST 2015


> would preclude Maritime Mobile, or Hawaii-----

Standard spelling is also supported. Anyone can spell out the full 6 digit
version if they want so the entire earth is still covered.

> Another Kludge, needs a table and Only good to 1 degree...

This is only for this satellite app, and -all- satellite operators use the
four character Maidenhead grids.  And most operators do not change from
continent to continent nor change grids during operation so they can easly
remember theirs.

And -no-one- needs to decode it, since it is converted directly to APRS at
the satellite for downlink.  SO all one has to do is a one-time lookup of
their gird (for FM19, FM=18 and so my DTMF code (which I will pre-program
into a DTMF memory)  is 1819)

Then making a DTMF contact is as easy as pressing ONE BUTTON.  (replay DTMF
memory #1)

THe problem will be getting people to honor the ALOHA channel and rules of
the game which will be to only transmit no more often than once every 15
seconds.  And have success only ONCE per pass and then back-off.

Bob, WB4APR


Original Message-----

>
> Robert Bruninga <bruninga at usna.edu> wrote:
>
> Those get their first digit from the 3 orange squares off the East coast
> of the USA.
>
> On Sun, Feb 15, 2015 at 3:11 PM, Jeff Dugas (Mobile) <N5TEV at compuserve.com
> > wrote:
>
>> Bob,
>>
>> On the map, how does it work for the 3-square red box (1-2-3) in the area
>> over Indonesia?
>>
>> Jeff
>> N5TEV
>>
>> -----Original Message-----
>>
>> Robert Bruninga <bruninga at usna.edu> wrote:
>>
>> Thanks everyone, for all the GRID ideas.  But here is what we think we
>> have decided to go with for the worldwide 4 digit DTMF Grid map we will use
>> on QIKcom-2.
>>
>>
>>
>> http://aprs.org/qikcom-2.html
>>
>>
>>
>> It uses a table from 00 to 99 to map to the first two ALPHA characters.
>>
>>
>>
>> Bob, WB4aPR
>>
>>
>>
>> *From:* aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] *On
>> Behalf Of *George Vastianos
>> *Sent:* Saturday, February 14, 2015 5:13 PM
>> *To:* TAPR APRS Mailing List
>> *Subject:* [aprssig] Σχετ: proposal for APRStt grid loc. Σχετ: 60 Grid
>> Square............
>>
>>
>>
>> Oh SORRY!
>>
>>
>>
>> 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
>>
>>
>>
>> THANKS AGAIN!
>>
>>
>>
>>
>> ------------------------------
>>
>> *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.
>>
>> 73
>>
>> sv8gxc
>>
>>
>>
>> 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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>
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