PK-232 MBX Operating Manual - N3UJJ

PK-232 OPERATING MANUAL
PACKET RADIO
Second, all Packet Lite connections emulate AX.25 version 2.0 (RR polling
instead of retrying I-frames). This is necessary for the 10 minute
identification described below. Also, the main reason version 1 continues
to be used on HF is that on a retry a (RR,P) polling frame is BO long that
one might as well just send the I-frame again. Packet Lite's polling and
ack frames are so short that the AX.25 version 2.0 polling method is now
worth doing.
4.10.1 Enabling Packet Life
To begin using Packet Lite, first make sure you have made all the proper
HF Packet settings discussed earlier in this chapter. Be especially
careful to ensure VHF is OFF and HBAUD is set to 300.
Once these settings have been made, to enable the Packet Lite protocol
extensions, turn the PK-232 command LITE ON. You must not be connected to
any other stations or you will not be allowed to change the LITE command.
Initiating a Packet Lite Connection
Once all the above settings have been made, simply issue the standard
CONNECT request as described earlier in the chapter.
If the station you are connecting to also has the command LITE ON, a
Packet Lite connection will result and you and the distant station should
enjoy a more reliable QSO than others on the same frequency.
4.10.2 Compatibility With Standard AX.25 Stations
If the station you connect to does not have the Packet LITE protocol
extensions, there are three known possibilities of what will occur.
1. WAlABC>WB2XYZ [C,P] 01 3E 38 58 32 {Packet Lite attempt}
WB2XYZ>WAlABC (UA,F) {standard ack}
In this case, the non-Lite station sees the [C,P] control byte but ignores
the non-standard bytes following it. It replies with a standard UA frame,
and the connection proceeds as standard AX.25.
2. WAIABC>WB2XYZ [C, P] 01 3E 38 58 32 {packet Lite attempt}
WB2XYZ>WAlABC (FR): 3F 00 03 {Frame Reject}
WAIABC>WB2XYZ (C, P] {Standard attempt}
WB2XYZ>WAlABC (UA, F) {Standard ack}
In this case, the non-Lite station notices the non-standard bytes
following the control byte and issues a FP-MR (Frame Reject) to signify
that a protocol violation has taken place. The PK-232 receives the FRMR
and automatically reverts to standard AX.25, sending the connect retries
without the Lite PID and address bytes.
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