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PK-232 MBX – OPERATING MANUAL PACKET-RADIO
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o Start reducing TXDELAY by units of 5 each time making sure the other station is still
digipeating ALL your UNPROTO packets. Eventually you will find a value where the
other station can no longer copy your packets to digipeat them.
o When this happens, increase TXDELAY in units of one or two until the other station
again digipeats ALL of your packets. This will be the optimum setting of TXDELAY.
After TXDELAY is adjusted as indicated above you may want to adjust the audio delay
(AUDELAY) as indicated in the Command Summary.
The next sections of this chapter will discuss some of the more advanced Packet fea-
tures including Multiple Connects, Packet Timing and Protocol, and HF Packet Opera-
tion.
4.4.8.2 AXDELAY and AXHANG
Although it is not common, Packet can be used through voice repeaters.
When sending packets through an audio repeater you may require a longer key-up de-
lay than is normally needed for direct communications.
The AXDELAY command adds more key-up delay in your PK-232 so that the repeater
can lock-up. The AXHANG command sets the time your PK-232 assumes is needed for
the repeater to drop.
4.5 Packet Protocol Basics
Here we will talk a little about the AX.25 Packet protocol. You do not need to understand
this to use Packet, but it is helpful in understanding the Packet protocol parameters.
There are two modes of packet transmissions Connected mode and Unconnected mode.
Most of the time when you use Packet, you will be conversing with another Packet station in
Connected mode. Still the Unconnected or Unprotocol mode comes in handy for beacon
transmissions and roundtable conversations.
All packets are constructed basically the same. Packets contain source and destination call-
signs (and any digipeaters if they are used), as well as information identifying the type of
packet. This packet identification can be seen with the MONITOR command discussed ear-
lier. All packets contain an error check code called the CRC. This ensures that when a packet
is received, it will not contain a single error. The command PASSALL can disable the CRC er-
ror check, but this should only be done for experimental purposes.
4.5.1 Unconnected Packets
In order to allow amateurs to send message beacons and to call CQ, the AX.25 protocol
has the ability to send packets that are intended for more than one specific Packet station
to see. Since all packets must have a destination "callsign", the PK-232 sends Unprotocol
packets TO the callsign of CQ. This can be changed with the UNPROTO command, but
most people like this since it makes an easy way to call CQ.
4.5.2 Connected Packets
When you Connect to another station, the AX.25 Packet protocol ensures that the station
to whom you are connected receives all the packets that you send. Similarly, the protocol
ensures you will receive all the packets that the other station sends to you. The following
describes briefly how the protocol does this.