uses SOCK_PACKET facilities to provide a network monitor of all AX.25
UI text traffic heard by the system. It is based on
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
master has been running for a while and a new
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.
Allow for the monitoring of outgoing frames as well as incoming ones.
Choose "raw" mode which allows non-printable data through.
Monitor only those frames received on a particular port, by default all
AX.25 interfaces are monitored.
"Master" mode. Retain monitored data for the number of minutes specified
option in a shared memory segment.
Retain monitored packets going back the given number of minutes.
Default is 30.
title string. Default is "Live data from Linux."
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."
Set up one
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
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
documentation, and then use
to run javAPRS:
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
expands the Mic-E packet into one or two MIM packets as follows: