[aprssig] FW: HT/mic DTMF standards

Robert Bruninga bruninga at usna.edu
Wed Oct 8 11:16:46 EDT 2008

The TH-78 HT's have both DTMF Messaging TX and RX.  Although the
message window is only 6 letters wide, it is an interesting
application to APRStt.  

How many of you have a TH-78?

Even 6 byte messages can be very useful.  See how we use 6 digit
APRS keypad data from D7's for score reporting at scout
events... www.aprs.org/aprsevent.html

Update to the APRStt table of existing radio DTMF pads.  I added
a column to indicate the number of DTMF memories.  The ## means
the number of digits in each memory.  If your HT has ALPHA on
the keys and is not on here, please tell us.  Also if your DTMF
memory length is less than 16 also tell us.
 Radio   mem #  Alpha  Encoding
 ------- --- -- -----  ------------------------------
 TH-D7   10  16 1=qz   multi-press A=next-letter
 TM-D700 10  16 1=qz   multi-press A=next-letter
 TM-D710 ??  ?? 1=qz   multi-press C=next-letter
 FT-51R  ??  16 1=QZ   ?????
 TH-78   10  15 1=QZ   TX & RX two-key-using A/B/C
                       6 letter messages and paging
 TH-79a  ??  16 none   No Alpha at all. 
 FT470   ??  ?? 7=PQRS ?????
 VX-7R   ??  16 7=PQRS ?????
 VX-8R   ??  ?? 7=PQRS multipress  "mode"=next-letter
 Cell Phones    7=pqrs multipress  PAUSE=next-letter
 Echolink...    1=QZ   two-digits-per-letter-fixed

 APRStt proposed 7=pqrs multi-press A=next-letter

Also, tell us what the above FT's and VX7R do with the
alphabetic keys?  Do they spell some menu responses?  DTMF
messaging?  What?

Notice, that I am leaning towards the final definition for
APRStt as shown above.  The only open item is what key to use
for the "next-letter" key.  I'm leaning towards "A" since all
radios except the D710 are compatible with it, and maybe we can
change the D710 (though it doesn't matter, since APRStt is not
needed with a D710 since it can send APRS directly).

> K1RFD (author of EchoLink) seems willing 
> to consider possibly supporting MULTI-PRESS
> in addition to his two-key method at some 
> time in the future to come more in line with 
> cell phone use... So it looks to me like
> the APRStt standard should be:
> Multi-press(lower case first), with 7=pqrs, and A=next-letter
> See the APRStt web page www.aprs.org/aprstt.html  
> It is evolving, so some sections are out of date 
> as we nail these issues down...
> And for ABBREVIATED CALLSIGNS, once the system 
> has received your pre-loaded DTMF fully spelled 
> callsign, then F5SMZ suggests that using the 
> SUFFIX is the least complex way of entering a 
> shorter call as long as it does not conflict 
> with anyone else on that same APRStt frequency.
> IE, "APR" (27A777) instead of "WB4APR" 
> (922444427A777).  Where the "A" key is used 
> as the "next-letter" separator if adjacent 
> letters are on the same key.  
> Bob, WB4APR

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