[aprsspec] Checking with my APRS cousins

[Ev Tupis (W2EV)]

The PropNET project has a need to embed data in its frames sent to it's 
Internet system (not for use over the air).  Even so, I'm thinking is is best 
to be sure that it "breaks nothing" if somehow these frames were to find 
themselves on RF, and even on an APRS frequency by mistake.

We have figured out a way to embed more propagation-useful information into our 
TX frames through the development of our own PSK31-based client.

The thought is to embed the data in a "{PL" user defined datafield.  Sanity 
check: if everything after { is ignored by APRS clients/servers, etc...then 
there is no need to read the rest of this note.

Otherwise....

An example of a {PL field is shown below:

{PLDM42nf20041204102143MS3}

{P     = 2-byte designation for a PropNET user defined data element
L      = 1-byte designation for LIVEx protocol (our Internet Server
                 system is called LIVExchange)
DM42nf = 6-byte 6-cypher grid locator of the CATCHing station.
          I'm suggesting that CAPS and non-CAPS are literal
          to enhance human readability of the data
The following is a date/time stamp, indicateing when the frame was received in 
DM42nf:
2004   = 4-byte year (UTC)
12     = 2-byte month (UTC)
04     = 2-byte day (UTC)
102143 = 6-byte HHMMSS (UTC)
MS     = 2-byte Client "branding"
3      = 1-byte Client version designation, "BASE(62)" A-Z, a-z, 0-9
}      = maintains the "bookended" PropNET standard in other data elements

An example of an over-the-air frame as sent from WD4RBX-15 is below (lower-case 
for PSK31 efficiency):
wd4rbx-15>hy:>em85vf/G<PHG503046/^ABCD

hy = ALTNET indicating 10-meter operation
PHG= adoption of the extended PHG123456/ format to include more stuff of 
interest to PropNET (do a google search on PHGRA and take the top hyperlink)

If N7YG receives the frame, it will be reformatted as shown below, and 
forwarded to our LIVEx server as shown:
WD4RBX-15>HY,N7YG,TCPIP:>EM85vf/G<PHG503046/{PLDM42nf20041204102143MS3}

This tells me the following...
Using MS3 software, WD4RBX in EM85vf was heard on 10-m by N7YG in DM42nf at 
20041204102143z and sent to LIVEx.  The /G conveys the symbol that will 
represent WD4RBX on a map and the PHG tells us much about the circuit quality.

NOTE: This data will NOT intended to go back to RF in any way, shape or form 
given the way that the PropNET Internet system is designed.  Users get an 
"upload only" port and the data-parsing systems (on the Internet) get a 
"download only" port.  They will parse and display the results on a web page.

However...it *may* be possible that someday, a PropNET user may unintentionally 
power-up on an APRS frequency and connect to the APRS Internet Server system. 
It is doubtful, because we are hard-coding the server connection information 
into the client-side...but "hey, ya never know". :)

Any feedback on this?
Ev Tupis, W2EV