Timewave PK-232MBX, Руководство по эксплуатации

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PK-232 MBX – OPERATING MANUAL PACKET-RADIO
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3. WA1ABC>WB2XYZ [C, P] 01 3E 38 58 32 {Packet Lite attempt}
…
In this case, the non-Lite station notices the non-standard bytes following the control byte
but sends no response at all. If this occurs, you must turn the command LITE OFF and try
to connect again to the distant station. No adverse effects are caused by this, but trans-
parency with standard AX.25 is lost when the receiving station does not acknowledge a
Packet Lite connect request in some manner.
We know that TCP/IP, NET-ROM and DRSI stations ignore Packet Lite Connect requests.
These stations are normally found on VHF, but to be safe, the LITE command should be
turned OFF when not in use.
4.10.3 Packet Lite Protocol Enhancement Summary
The following describes the Packet Lite protocol extension in detail for those interested in
the technical details. It is not necessary to read or understand the following section to use
the protocol.
Here is a summary of a Packet Lite exchange, where WALABC calls WB2XYZ:
Connect:
W B 2 X Y Z -0 W A 1 A B C -0 SABM 01 3E 38 58 32
destination | source | CTRL PID | short address
The destination and the source are both 7 bytes long. Everything up to the CTRL byte
(SABM) is standard AX.25 version 2.0. The 'Protocol ID" of 01 hex is Packet Lite's reserved
value, which provides a way of interpreting the following bytes. This leaves room for other
extensions to AX.25 in the future. The short address bytes are the right-justified bytes of
the address field that WA1ABC proposes to use in subsequent Packet Lite frames with
WB2XYZ. In this case, the AEA implementation of the short address is illustrated. 3E38 is
a compressed version of the destination WB2XYZ and 5832 is a compression of WA1ABC.
However, any combination of 26 bits may be used (see "Technical Details" below).
Connect acknowledgment:
W A 1 A B C -0 W B 2 X Y Z -0 UA 01 58 32 3E 36
destination | source | CTRL PID | short address
WB2XYZ replies to WA1ABC. Again, everything up to the CTRL byte (UA) is standard
AX.25. The 'PID' of 01 and the short address confirm that WB2XYZ has accepted the
Packet Lite connection. The short address is again the right-justified representation of the
address field that WB2XYZ will be using in subsequent Packet Lite transmissions. In this
case WB2XYZ has accepted the short address field suggested by WA1ABC, and has shown
his acceptance by echoing the address back in reverse order (5832 = WA1ABC and 3E38
= WB2XYZ). AEA products always accept the short address from the SABM frame; how-
ever, the Packet Lite protocol allows the sender of the UA frame to propose a different
combination of 26 bits, to avoid conflicting with another Lite QSO. In either case, the
sender of the original SABM must accept the 26 bits in the UA frame, reversing the ad-
dress order for its own transmission.
Transmission of data:
7C F0 B0 65 10 F0 Test <CR>
3E38 shifted 5832 shifted [I, P; 0, 0]
short dest. short source CTRL PID text