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ADDING APRStt MESSAGE SUPPORT FOR FT-51R and TH-78 HT's     9 Oct 2008 ----------------------------------------------------------------------                                                                 WB4APR  The Yaesu FT-11R, FT-41R, & FT-51R and Kenwood TH-78 HT's all contain  a DTMF message TX and RX display system.  The messages are typically  12 (or 6 in the TH78) bytes long but can be combined into up to 10  such messages for a full length of 60 bytes of uppercase message text.  We can use these radios for RECEIPT of APRS local information of value to the traveler and for paging.  For example, they can display these  things:  1) FFFFFF the locally recommended APRS frequency Object 2) CCCCCC the callsign of any LOCAL-DIRECT APRS user in range 3) The CALLSIGN and FREQUENCY of anyone with a TM-D710 radio 4) MESsASGES from APRS users addressed to FT51-TH78 5) Any other message, or special info we care to parse for.  It is assumed that this FT51/TH78 Gateway process will be added to  the general APRStt code for ease of distribution and maintenance.  To help us refer to this capability, we can call it the HT51/78 processor.  Here is how it works.    First of all, since there are going to be a lot of DTMF tones flying  around, it is receommended that the HT51/78 gateway have its own  local frequency dedicated to these radio users.  The DTMF format used by these radios is:  NNN#MMMMMMMMMMMM#  Where NNN is a DTMF GROUP code that all 51/78 users monitor and where MMMMMMMMMMM is up to 6 bytes of text entered using the two-key method of these radios.  That is, press the desired letter  key, ABC, DEF, GHI, etc and then press the "A" key if the letter was  the first one listed on the key.  Or press "B" key if it was the  second letter, or press the "C" key if it was the third or press the "D" key if it was the numeral for that key.  Notice that these radios not only monitor the NNN group code, but can also have their own individual codes.  So an APRS message can be sent to an INDIVIDUAL radio as long as the HT51/78 processor has a pre-list of what the XXX individual code is for each HT51/78 users callsign.  Even group codes for WX or Skywarn, or EOC or any number of sub message groups can be handled!  APRS PARSING:  The HT51/78 processor code looks on the APRS channels for the  following kinds of packets and then transmits the 6 bytes as indicated.  1) Any packet heard DIRECT:  It sends the CALLSIGN 2) Any FFF.FFF OBJECT:  It sends the FFFFFF 3) Any user with FFF.FFFMHz in his text: Sends CALLSIGN and FFFFFF 4) Any group message sent to "FT51-TH78" it parses into approximate     6 byte chunks (looking for SPACEs where it can find them) and sends     all of these chunks on the HT51-78 frequency. 5) Individual messages from APRS to individual FT51 or TH78 radios!  This allows these radios to be used to monitor for APRS activity and to be paged or sent messages from the APRS system!  In fact, this gateway can be implementd so simply, that it could be put on a PIC chip and placed on a mountain top for full coverage wide area limited APRS operation with these 1995's vintage radios.  Bob, Wb4APR