4.9.9 Morse ID in Packet
In most countries, packet is an accepted mode of identification so
this command should be left OFF. In some countries, however, a Morse
ID is required when packet is used and so the MID command should be
enabled.
4.9.10 Sharing Packet Channels with Voice Operation
Although it is seldom needed, the PK-900 does have an input for
SQUELCH information from a transceiver on the RADIO connectors. This
input should be used and the SQUELCH command set if the packet channel
is to be shared with voice operation.
4.9.11 Disabling Transmit Operation
Occasionally for test purposes it may be desired to disable the PTT
circuit in the PK-900. This is done with the XMITOK Command.
4.10 Seldom Used Commands
The following commands operate in Packet, but are seldom needed.
They are listed for reference and described in the Command Summary.
AFilter BBSmsgs CONPerm CPactime DCdconn Flow HEAderln
MDMon MRpt MXmit
4.11 Packet Lite HF Packet Protocol Extension
Amateur radio needs a better communications mode for HF operation.
Baudot and ASCII have no provision for error detection. AMTOR FEC and
ARQ are more resistant to errors, but do not carry the full ASCII
character set. 300 baud AX.25 packet is undesirable because the long
transmissions are prone to bit errors, any one of which invalidate the
whole frame. PACTOR is a recent protocol improvement.
Packet Lite is, as its name suggests, an abbreviated form of packet.
It is designed as a transparent extension to the AX.25 protocol that
reduces the "overhead" of all HF packet frames without digipeaters.
Packet Lite does not solve HF packet's problems, but it should provide
some throughput improvement on HF where it is desperately needed.
AEA's engineering department is interested in hearing from Packet Lite
users with any comments or suggestions on improving the protocol.
A Brief Description of the Packet Lite Protocol
The main feature of Packet Lite that reduces overhead is that it uses
an address field of only 4 bytes. A standard AX.25 header without
digipeaters uses 14 bytes of addressing. Shortening the packet frame
header lessens the possibility of any given frame taking a hit.
Packet Lite reduces the length of an I-frame slightly, but its real
strength is the shortening of the acknowledgment frames, resulting in
1/93 4-38
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