Timewave DSP-232, Operating Manual, Page: 79 / 271

Chapter 5 Packet Operation
Monitoring the Packet Networking Switches
There are other types of frames used by networking switches that the DSP doesn’t normally display. These frames
can be seen with
MPROTO
—turning it on allows all AX.25 frames to be displayed. Some packets you might see
with
MPROTO ON
will contain information that may interfere with the display on your terminal or computer
causing it to look “funny”. For this reason,
MPROTO
’s default is
OFF
.
Selective Monitoring
After you’ve monitored channel activity for awhile, you may decide there are only a few stations you want to copy.
To “screen” stations for monitoring purposes, use
MTO and MFROM . With the MBELL command, you can even
be alerted when a certain station transmits on the frequency. These commands work in conjunction with MONITOR
and MCON commands.
MFILTER
Some terminals and computer programs are sensitive to certain characters that may appear in monitored packets.
You’ll know this is happening if occasionally the cursor on your screen moves to strange places, causing the
received copy to be garbled.
The DSP default for
MFILTER
is
$80
which prevents most control characters from interfering with your display.
Monitor Without Callsign Headers
Sometimes you may want to monitor certain stations without having to look at the packet callsign headers. This can
be useful when monitoring message traffic from a large PBBS. The
MBX command allows you to choose the
callsign of a station, or a pair of stations, you want to monitor without having to see packet headers.
Beacon Operation
In the early days of packet, the beacon was useful to show your presence on the packet channel. With the growth of
packet, many users feel that beacons have outlived their usefulness and interfere with traffic. Use your beacon with
discretion.
The DSP can send an automatic “beacon” message at a specified time interval. A beacon can send special
announcements, or let others know you’re on the air. To enable beacon operation:
♦
Enter your beacon message in BTEXT .
♦
Set the beacon interval using the BEACON EVERY or AFTER command.
♦
A beacon frame is sent to the path set in UNPROTO .
As a reminder, if you set the
BEACON
timing at a value considered too small for busy channels (less than “90”),
you’ll see:
WARNING: BEACON too often
Packet Transmit Timing
The DSP has a number of built-in timers used to control the packet protocol and transmit timing. The default values
have been set at the factory to provide reasonable performance, but the values may not be optimum for your local
area. Most protocol parameters should be adjusted only after carefully reading about them later in the chapter. You
should adjust TXDELAY for your transmitter as described below.
Radios vary in the time it takes it to switch from receive to transmit. If your DSP’ starts sending data before your
transmitter is up to power, the packet will not be received properly at the distant end.
TXDELAY
controls the delay
between your transmitter’s key-up and the moment when your DSP’ starts sending data. The default value of
30
corresponds to a time of 300 mS and works with most VHF/UHF FM transceivers. With modern transceivers,
TXDELAY can often be reduced from its default value which will improve packet performance in your area. You
should perform the following procedure to optimize TXDELAY for your station:
1) Find another station who can reliably digipeat your signals.
2) Set
your
UNPROTO
path to
TEST
via the call of the station that will digipeat your signals. For example:
U TEST V WO6P .
5-18 September, 05