NAME

       aprsmon - monitor APRS AX.25 traffic for javAPRS

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

       -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 title string.  Default is "Live data from Linux."

       -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/aprsmon.info."

javAPRS CONFIGURATION

       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
       example:

       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:

       @ddhhmmzDDMM.hhN/DDDMM.hhW$cse/spd/E>mon/Mm/status
       T#MIC,aaabbbcccdddeeefffComments

       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.

       aaa,bbb,ccc,ddd,eee,fff
                 are the values of the telemetry channels.

FILES

       /etc/ax25/axports /var/ax25/aprsmon.info

SEE ALSO

       call(1),          listen(1),          beacon(1),           ax25(4),           axattach(8),
       http://www.bridge.net/~sdimse/javAPRS.html, http://www.tapr.org, http://www.aprs.net, MIC-
       E.TXT,TELEMTRY.TXT,PROTOCOL.TXT

AUTHOR

       Alan Crosswell, n2ygk@weca.org