Kantronics KPC-9612 Plus, Руководство пользователя

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Your Packet Unit is a Terminal Node Controller (TNC)
Packet radio modems, or packet modems, are generally referred to as TNCs. This
“label” or “moniker” was adopted when the Tucson Area Packet Radio Group
(TAPR) developed their first “TNC-1" packet radio modem kit in the early
1980s. The TNC is the workhorse of packet radio. As a listening device it hears
an audio signal from the radio, changes the data to digital form, determines if the
data is a good packet and sends it to whatever device is attached, usually a com-
puter. As a relay device it also checks the packets it receives and determines if
the packets need to be resent, then does so if appropriate. As a sending device it
receives digital data from the computer, packetizes it and changes it into audio
tones which are sent out to the radio. The rules the TNC uses to do all of this is
called a protocol.
Protocol for Amateur Packet Radio: AX.25
The most commonly used protocol in amateur packet radio is AX.25. The details
of the inner workings can be found in a book titled “AX.25 Amateur
Packet-Radio Link-Layer Protocol”, which is available from the ARRL. Most
TNC users will not need to or care to go into the details. The TNC takes care of
the nitty gritty work for you, although there are parameters you can set that deter-
mine how efficiently some of that work is done.
Command Mode
In order to change parameters, or give any other instructions to the TNC, you
must be in Command Mode. This is the mode you will be in when you first turn
on the TNC or after resetting it.
Once you have left Command Mode for any reason, there is a parameter called
COMMAND that determines what special character you will use to return to
Command Mode. This comes defaulted as a <Ctrl+C> (i.e., while holding down
the control key, press “C”, then release both keys).
Whenever you enter Command Mode the TNC will send a prompt to your screen
that looks like this:
cmd:
Modes of Operation Packet Mode of Operation
User’s Guide 108 KPC-9612 Plus v 8.2