                FORMATS FOR USING APRS WITH DUMB TERMINALS

    Since most of the features of APRS can be used even if a station is not
running the APRS software, this file describes the exact APRS formats so that
they can be manually entered from dumb packet stations.  This might often be
the case from lightweight portable packet stations.  Frequently the need for
the map display is not out in the field where the portable packet stations
are, but at the headquarters, or net control point.  The following paragraphs
suggest ways to use dumb terminals or non-PC computers and TNC's in an APRS
network.

    All APRS communication is done using UI frames.  UI frames are
transmitted with all the error detection capability of standard packets, but
they are not automatically acknowledged.  The only disadvantage is that if a
collision occurs or there is interference on the channel, the UI frame is not
automatically retransmitted.  In APRS this is not a problem because all
information is repeatedly and redundantly transmitted.

    UI frames can be transmitted easily from a TNC in two ways.  First, by
loading the TNC Beacon Text with a desired message, the beacon is repeatedly
transmitted as a UI frame.  The period of retransmission is set using the B
parameter.  Most standard TAPR-2 TNC's use 10 second increments so that a
B_E_6 actually results in a beacon once every minute.  A value of 60 is once
every ten minutes.  The BText is the primary method used by APRS to broadcast
one line messages to all stations.

     The second way to send UI frames is to enter CONVERSE mode directly from
the cmd: mode without first establishing a connection.  This is done simply
by using either the CONV or K command.  In this mode you specify your
digipeater path by using the UNPROTO command.  Once in UNPROTO CONVERSE,
everything you type is still transmitted as normal AX.25 packets, except that
lines are only transmitted once and acknowledgments do not exist.  As long as
you do not experience a collision, these UNPROTO packets are just as good as
the connected protocol and are very effective at broadcasting information to
many other stations at once.

TO ADDRESS:   One caution; since APRS operates in a broadcast fashion and
does not use a connected protocol, the TO ADDRESS is not required.  To help
ignore non-APRS traffic which might also be on the channel, APRS stations use
the TO ADDRESS field as a type of filter.  APRS will only recognize UI frames
transmitted to the broadcast addresses of ID, CQ, QST, BEACON, MAIL, SKYWRN,
DFNET and APRS.  All other packets are ignored.  For this reason, you must
place one of these addresses in the TO ADDRESS field in your UNPROTO command.
APRS does have the ^O OTHER command to over-ride this filter temporarily.

APRS FORMATS:  Using either the BText or UNPROTO CONVERSE methods noted
above, APRS reports can still be transmitted manually.  To transmit a report
repetatively, enter it as a Beacon Text.  To report it once, simply type it
in the UNPROTO CONVERSE mode and hit carriage return.  The following formats
must be used exactly to have the desired effect at an APRS station.
Abbreviations are D for degrees (or DAY), M for minutes (Both lat/long and
time), h for hundredths (or Hours), N for North and W for West.  The
delimiter following the Longitude is used to indicate the type of APRS symbol
to be displayed (shown here as a $).  See the README.SYM file.


POSITION REPORT: To report the position LAT/LONG of your station you may
         either use the abbreviated format for a fixed station or the longer
         format for a mobile that includes the time of the position and an
         optional course, speed, and comments.  If the symbol for a Triangle
         is used (\) then APRS assumes the report is a DF line of bearing
         for direction finding.  To be compatible wiht TheNET node ID frames,
         as of version 2.09, the fixed format can occur anywhere in the BText.

   FIXED:   ...    !DDMM.hhN/DDDMM.hhW$comments
   MOBILE:  @DDHHMM/DDMM.hhN/DDDMM.hhW$CSE/SPD/comments
   DF:      ...    !DDMM.hhN/DDDMM.hhW\CSE/SPD/BRG/90Q/Comments ( Q=quality)
   GRDSQR:  [XXnnyy]comments to end of line
            [XXnn]comments to end of line
 
WEATHER REPORT:  APRS recognizes the underline symbol character to indicate
         that the report contains wind direction and speed information.
         This plots the station in dark blue and prevents APRS from assuming
         it is a moving mobile station.  The remainder of the comment line
         can contain any other pertinent weather information.  In APRS version
         2.07 there is an optional automatic Home weather station interface
         which automatically inserts your weather conditions into your Posit
         report.  It includes the optional Temp and Rain fields. 

         @DDHHMM/DDMM.hhN/DDDMM.hhW_CSE/SPD/T073/R000/WxStn (auto)
                                            Dxxx/Pxxx/Bxxx other optional
                                            fields for DewPt, Participation
                                            accumulation, and BaroPressure

OBJECT POSITION:  To report the position of something other than your own
         station, the same format for a mobile object is used but it is
         preceeded with a nine digit object name.  For shorter names, the
         9 character field must be padded with spaces:

         OBJECT   @DDHHMM/DDMM.hhN/DDDMM.hhW$CSE/SPD/comments

BROADCAST:  Simply send anything.  If you are using your TNC BText to
         repeatedly send the same message, it is preferred to include
         the day and time that you entered the the BText in the text
         so that recepients can tell how old the information is.

         @DDHHMM/comments...

MESSAGE: To direct a specific message to a specific station and have
         his bell ring and the message instantly flashed on his screen,
         use the following format, again padding the addressee call
         with spaces to a total of nine characters followed by a colon:
       
         W3XYZ____:one line message text......{3 (optional line counter)

         His station will acknowledge receipt with a responding message
         to you with only the letters ack in the message.

MSG ACK: If an APRS station sends you a message line, it will be repeated
         over and over until you send a responding ack.  To send an ack
         to station W3XYZ, simply enter his call padded to nine spaces
         and a colon followed by the letters ACK# where the # is the line
         number tacked onto the end of his message line with a ({).

         W3XYZ____:ack3    (APRS versions after 2.08 require the line #)


DUMB PACKET TERMINAL DF REPORTS:  Non APRS packet stations can also
automatically report their lines of bearing into the system by simply
entering a beacon text in the APRS format with their line of bearing.

 BText:  !DDMM.xxN/DDDMM.xxW\000/000/BRG/N0Q/DF report...

 Where:  DDMM.xxN is Latitude, DDDMM.xxW is Longitude
         \ (Backslash indicates a Triangle symbol for DFing)
         BRG is the DF bearing in degrees True
         N0Q is a Quality indicator where Q is a quality value (1-8) and
             N is an optional Number of HITS indicator. If N is 0, then it
             means nothing.  Values from 1 to 8 give an indication of the
             number of hits per period relative to the length of the time
             period.  So 8 means 100% of all samples possible, got a hit.
             The N is not processed, but is just another indicator from
             the automatic DF units.  By entering a 9 as the HIT indicator,
             you can indicate to other users that your report is manual.


USING AND DISPLAYING POSITION INFORMATION.  If all manual stations in an APRS
system carry a pre-printed map of the exercise or event area, not only can
they easily determine their own location for reporting, but they can also
plot the location of other stations and objects.  Usually, you do not need
the high technology of a GPS or LORAN receiver to know where you are.  Most
people can find themselves on a map and read the coordinates.  Then they
simply type them in to their BText and in a few minutes, everyone on the net
can see their exact location.  Similarly, by monitoring all of the APRS
beacons going back and forth, the dumb terminal user can still be equally
well informed of whats going on.

