APRStt User Guide                                        19 May 2008
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OVERVIEW:

APRStt lets any user with a DTMF keypad and radio to send out an
identification report into the global APRS system.  By transmitting
such a pre-saved DTMF burst, the user will appear in the APRS 
system with all of these attributes:

 DATE/TIME  - With a time stamp of when heard
 POSITION   - in the vicinity of the repeater that heard him
 FREQ/TONE  - frequency and tone of that repeater
 NODE# ETC  - any other unique info such as VOIP node number

Seeing this, anyone in the local area, or anywhere in the world on
APRS could call him right back by voice to make contact.  A user 
sending his APRStt callsign will appear just like any other APRS 
user for example on the FINDU.COM system.  After sending a DTMF 
callsign a user should see himself appear on this URL:

 http://map.findu.com/MYCALL*

APRStt FORMAT:  The APRStt formats can contain all kinds of APRS
information, messages and even email, but at the introductory
level we are only after one thing.  That is the stations callsign.
This document only references this most basic APRStt but most
universal application.

APRStt CALSIGN:  To avoid errors, the user should permanently set 
his APRStt callsign into a DTMF memory in his radio so that it 
can be send rapidly and conistently.  The format is as follows:

 ##AcccccccccccKD

Where ## always begins an APRStt burst (kind of a PREP key)
Where A indicates a callsign will follow
Where cccccccc is the callsign using text messaging technique
Where K is a checksum to minimize errors
Where D signals the end with the "D" (or OK) key

CALLSIGN-SSID:  By default, an APRStt callsign will be assigned an 
SSID of -12 so that these callsigns are easily destinguished from
other callsigns from the same station on the air. 

APRSTT USAGE:  It is recommended that users dedicate at least
three DTMF memories for their data.  The first DTMF memory is 
usually set up for a complete report so that it can be sent 
easily with a single key press.  This complete format only 
contains the fully spelled callsign as shown above.  This makes
sure that the repeater logs the callsign correctly.

DTMF Memory 1:  ##AccccccccKD
Exmaple WB4APR: ##A9220427A770D  (checksum 30 = "0"

SHORTCUT:  Once you have identified with your full callsign,
you can make subsequent transmissions with only the right three
characters (or numbers) of your callsign.  So for me it would 
be "APR" and that would spell out in DTMF as a callsign as:

    ##A27A773D  (checksum 23 = 3)

The APRStt engine will decode that to "APR" and scan its list
of active APRStt users and to a RIGHT-END-MATCH.  If there is
a match, then that is sufficient.  If there is a conflict, then
additional characters are needed, but still right justified.
Being a shorter string, you can now store not only your callsign
but also your symbol type and optionally a one-byte comment string.
This way you can have a separate string in your HT and Mobile
that will include the symbol for each.

DTMF Memory 2:  ##AsssssKD  or ##Asssss*SCKD
Example WB4APR: ##A27A773D  or ##A27A77*126D

This is the same as memory #1 but the string is a short-cut
and it can contain the SYMBOL and COMMENT digits (1 and 2 
respectively shown above).  The SYMBOL digit represents one of 
the following:

APRStt SYMBOLS:  There are 9 APRStt symbols:
  1 house  4 truck    7 HT or human
  2        5 SUV      8 Boat
  3        6 Special  9 Car

APRStt COMMENTS:  THe comment digit is used to indicate one of the
following standardized APRS comments:

  0 Off duty    3 Returning  6 Priority  9 Custom 2
  1 Enroute     4 Committed  7 EMERGENCY
  2 In Service  5 Special    8 Custom 1


DTMF STATUS TEXT:  For the nimble fingered station, there is also
the capability of entering free-field status text into his report.
In that case, he would send a special DTMF memory 3 with his 
short-cut callsign that ends with the A key.  This signals the 
APRStt repeater that additional text will follow in the next 10
seconds.  The format for DTMF MEMORY 3 indicating that comment
text or additional data will follow is:

DTMF Memory 2:  ##AsssssKAD
Example WB4APR: ##A27A773AD

THen the additional information in this case is manually keyed in
and preceeded with the "C" key and the text is spelled in the
same text-style as the callsign ending with the "D".  For example 
the string "C2221D" would add "CQ" onto the end of your position 
report.

   ...CtttttttttttttD

You could even program additional DTMF memories with some common
phrases you mgith want to send.  For example:

   ...C4338063302803333D

Would spell out to be "GET ME AT 3" and be captured on the global
APRS system and available to mom or data via either RF or on the
FINDU.COM or other APRS systems.

With these simple formats, you can join the world of APRS!

ALPHANUMERIC TEXT ENTRY:

You spell a callsign using normal text messaging  techniques. Looking 
at the 2 key on your keypad, this key can represet ABC or 2 depending 
on how many times you press it.  So the letter A is a single press.  
The letter B is 22 and the letter C is 222.  To enter the numberal 
"2" in a text string requires four presses as in 2222.

The only additional thing you must remember is that in order to send
two letters that share the same key in a row, you also have to send 
the "A" key as a key separateor.  SO to send the text string of 
"ABC" you would have to send 2A22A222.  But if wanted to send the
letters "ADG" you would only need to press "234" since the letters
are on different keys.


Bob, Wb4APR