Kantronics KPC–3 Plus User Manual page 67

Digipeating
Everything we have done so far will only be heard by those within range to hear your
signal. With packet radio it is possible to go farther than that. The DIGIPEAT parameter
in the TNC comes defaulted ON. This makes your TNC a possible relay station, or
digital repeater —digipeater, or just digi for short. In many VHF communities one or
more of these is put up in a good, high location and referred to as a dedicated digi. The
TNC and radio is all that is needed for the digital repeater to do its job. A computer
would be needed if you wanted to change a parameter, but it would not need to stay
there for the digi to work. The higher the antenna, the more effective a digi will be, but
remember, every TNC has the capability of being a digipeater.
If we turn the MRPT command ON we will begin to see more than just the ―from‖ and
―to‖ stations of the monitored packets. We will also see the callsigns of those stations
that have been used as digipeaters. This list of stations is often called a path. Here is an
example of what you might see:
NØKN>KBØNYK, IAH*,LAG,AUS:
Hi there
In this example, NØKN is talking to KBØNYK, using the digipeaters IAH, LAG and AUS.
The asterisk beside IAH tells you that you are hearing that digipeater. You will notice
that IAH, LAG and AUS are not real callsigns. The TNC provides a parameter
(MYALIAS) to set up an alias, which is often easier to remember than a callsign. To
make this connection NØKN would have typed the following command to his TNC:
C KBØNYK V IAH,LAG,AUS
V is short for via and up to 8 digis may be used. You must specify digis in the order they
will be encountered along the path from your station to the station you wish to connect
to. A space must be typed after the ―C‖ and on both sides of the ―V‖, but digis are
separated by commas. A path can also be used with the Unproto command:
U CQ V NOM,LCH,SLI,BIX
Unproto sets up the path for anything that is subsequently typed in the Convers Mode
where no connection exists. CONNECT issues a connect request to the specified
station, via the specified path. Then a virtually error-free conversation can take place
between them.
When digipeating, the packet goes all the way from the first station, through all relay
stations, to the destination station. Then the response also has to take this same path in
reverse. Chances for collisions and, therefore, for retries are multiplied with every digi
used. This is often called end-to-end acknowledgment. Another way to get from one
place to another is to connect to a ―node‖. A node will take care of the acknowledgment
between it and the next node or end user. See the KA-Node section for more
information. Ask your local packeteers about other types of nodes which may be
operational in your area, such as K-Net, TheNet, NET/ROM, G8BPQ, and ROSE.
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