[aprssig] APRStt 4 digit grid squares...

Steve Dimse steve at dimse.com
Sun Feb 15 19:11:07 CST 2015


If it were me, I'd say one digit for hemispheres (e.g. alphabetical 1-NE, 2-NW, 3-SE, 4-SW), 2 digits for lat and 3 for lon. Six digits instead of four, but it is unambiguous, easy to remember, easy to parse, and covers the entire world - in other words, completely un-Bob-like. This grid square way is like repeating every mistake in the APRS protocol at once, so of course Bob will use it.

And even if Bob picked this idea, then he would realize that I only use 1 bit of the MSB for longitude, and 2 bits for hemisphere, so there are 5 bits that could be kludged, and it would get messy again...

Steve K4HG

On Feb 15, 2015, at 6:55 PM, Jeff Dugas (Mobile) <N5TEV at CompuServe.com> wrote:

> Thanks Bob, got it.
> 
> So, would I assume correctly that this system would preclude someone from operating APRS-TT Maritime Mobile from an area not covered by one of the designated areas?
> 
> No quibble - just trying to ensure I understand how it all works.
> 
> Jeff
> N5TEV
> 
> -----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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