Kantronics KAM 98, Руководство пользователя

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close enough to receive the RF burst sent by NØGZZ,
and currently set to display messages on a computer
screen. So the “HELLO” message re-transmitted by
NØGZZ arrives at KBØNYK’s TNC, where it is pro-
cessed and recognized as an AX.25 packet addressed to
itself. Then KBØNYK’s TNC sends the message,
“HELLO,” to the computer screen for KBØNYK to
read. At the same time, KBØNYK’s TNC creates an
acknowledgment packet to send back to WØXI’s TNC,
reversing the address path it found in the “HELLO”
packet. When KBØNYK’s TNC detects that the radio
channel is clear, it keys the transmitter and sends the
packet back over the air.
Step 14. NØGZZ’s TNC now recognizes another packet which
has its callsign in the address path, requesting it to be
digipeated. NØGZZ’s TNC does so as soon as it can.
Step 15. WØXI’s TNC now hears a packet addressed to it. Since
the digipeated packet originally came from KBØNYK,
to whom he is connected, and since the packet contains
an acknowledgment for data that he had recently sent,
WØXI’s TNC can rest easy knowing that the data he
sent was properly received.
This concludes our close-up look at a single packet communication event, show-
ing how the various parts of packet radio work with each other. To simplify and
focus this example, various details and possible complications were ignored, but
this still shows the basic steps involved in establishing a connection and sending
the message “HELLO” from one person/station to another person/station.
This example covers one of many uses of packet radio. As covered in other sec-
tions of this manual, there are many ways to communicate with other stations.
Now that you have followed one particular message from one station to another,
it is useful to learn about the “packets” in packet radio.
Introduction Packet Communication
User’s Guide 28 KAM’98 v 8.3