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       aprsmon - monitor APRS AX.25 traffic for javAPRS


       aprsmon [-a] [-m] [-r] [-k minutes] [-p port] [-t title] [-i infofile]


       Aprsmon  uses  SOCK_PACKET  facilities  to  provide a network monitor of all AX.25 UI text
       traffic heard by the system.  It is based on listen(1).

       Aprsmon collects (-m) or displays standard AX.25 UI text frames in  a  format  similar  to
       that  output  by  a  standard  TNC  in  "Monitor  ON" mode and is intended to be used with
       programs like javAPRS which wish to see a TNC data stream over a TCP connection.  When the
       aprsmon  master  has been running for a while and a new aprsmon slave starts up, first all
       saved up reports are sent, then a title line indicating the  beginning  of  live  data  is
       sent, and new reports are sent as received.

       Compressed  position  and  telemetry  reports  as  generated  by  the APRS Mic Encoder are
       translated into the conventional uncompressed APRS Micro-Interface-Module  (MIM)  telemtry
       format  so  that  these stations are visible in javAPRS.  Reports containing a TheNet X1J4
       beacon header are also edited to strip off  the  header  making  these  nodes  visible  in
       javAPRS as well.


       -a        Allow for the monitoring of outgoing frames as well as incoming ones.

       -r        Choose "raw" mode which allows non-printable data through.

       -p port   Monitor  only  those  frames received on a particular port, by default all AX.25
                 interfaces are monitored.

       -m        "Master" mode.  Retain monitored data for the number of minutes  specified  with
                 the -k option in a shared memory segment.

       -k minutes
                 Retain monitored packets going back the given number of minutes.  Default is 30.

       -t title  Sets  the javAPRS or aprsd title string.  Default is "Live data from Linux." For
                 use with aprsd the format must be something like  "aprsmon  v2.4.4  padd  padb."
                 pada  and  padb  can be anything, and are ignored but you *must* have 4 words in

       -i infofile
                 Infofile is the path to the file that  the  aprsmon  master  writes  the  shared
                 memory segment and semaphore id's into.  Default is "/var/ax25/"


       Set  up  one aprsmon master running on your system to collect historical data going back a
       while.  You will probably want to set up an /etc/rc.d/init.d script for this.

       aprsmon -a -m&

       Add an entry into /etc/services with the port number you want javAPRS to connect on.   For

       aprs      14439/tcp # APRS monitor on 144.39

       Add an entry into /etc/inetd.conf for this service:

       aprs stream tcp nowait root /usr/sbin/aprsmon aprsmon -a

       To test, simply "telnet localhost aprs".  To use with javAPRS, set, for example,

       <PARAM name = "dataFile1" value = "netc:14439:localhost">
       in  your HTML file as described in the javAPRS documentation, and then use appletviewer to
       run javAPRS:
       appletviewer mydemo.html

Mic-E to MIM Translation

       The Mic-E reduces the duration of packet noise on a voice frequency by encoding  its  data
       in  a  compressed  form,  some  of  which is binary.  Some APRS-decoding software, notably
       javAPRS, is unable to deal with this data.  To solve this problem aprsmon expands the Mic-
       E packet into one or two MIM packets as follows:


       ddhhmm    is the UTC day and time the packet was received by the host running aprsmon.

       DDMM.hhN  is the latitude.

       /         is the symbol table selection (/ or \).

       DDDMM.hhW is the longitude.

       $         is the symbol.

       cse,spd   are course and speed.

       E         is the type of Mic-Encoder:

                 E - TAPR Mic-Encoder
                 T - Kenwood TH-D7

       m         is the status message number, and

       status    is the status message number expanded as follows:

                 0 -  Off duty..
                 1 -  Enroute...
                 2 -  In Service
                 3 -  Returning.
                 4 -  Committed.
                 5 -  Special...
                 6 -  PRIORITY..
                 7 -  EMERGENCY.

                 are the values of the telemetry channels.


       /etc/ax25/axports /var/ax25/


       call(1),           listen(1),           beacon(1),          ax25(4),          axattach(8),,,, MIC-


       Alan Crosswell,