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USER'S GUIDE
FRACK
The
the originating station retransmits the packet.
RETRY
The
ing station abandons further retries and terminates the connection. The maximum num-
ber of packet transmissions is
retransmission. Setting
FRACK
is automatically corrected for the additional time required for digipeating. The
time interval before your PK-232 retransmits an unacknowledged packet is
n
where
is the number of digipeaters used for this connection.
5.5.4.4.
DWAIT
Digipeated packets require an end-to-end acknowledgment. Digipeaters don't acknowl-
edge the packets they relay. If a link includes several digipeaters, the chances of loss of
either the original packet or the acknowledgment increase drastically.
To help alleviate this problem, an automatic wait time can be imposed on any station
not transmitting a digipeated packet. Stations waiting for a clear channel to transmit
packets wait for this time interval after the channel clears before transmitting. This wait
does not apply if the station is transmitting one or more digipeated packets. This usu-
ally gives the digipeater a clear chance at the channel.
DWAIT
The
peating is not being done by anyone in your local area, this parameter can be set to 0
(zero). In any event it should be set to the same value by all members of a local area
packet group.
To minimize unnecessary retries, the PK-232 applies a collision-avoidance strategy to all
packets except those being digipeated. On the second and subsequent transmissions of
a given packet, your PK-232 waits an additional random time after detecting a clear
channel before transmitting. This prevents repeated collisions of transmissions by the
same two stations. The random time in a multiple (0 to 15) of the
For the first transmission of a packet, the time between your PK-232's detection of loss
of carrier and activation of the PTT line is:
For retries of the same packet, the interval is:
where
r
is a random number from 1 to 15. Therefore, the longest amount of time
added randomly is 0.094 ×
the longest time added is 2.8 seconds.
PK232UG Rev. B 9/86
command (FRame ACKnowledge time sets the time lapse allowed before
command sets the maximum number of retransmissions before the originat-
RETRY
RETRY
to 0 (zero) specifies an infinite number of retries.
FRACK
Retry interval =
command sets your PK-232's wait time in ten-millisecond intervals. If digi-
DWAIT
Wait time =
× 10 milliseconds
DWAIT
Wait time = (
TXDELAY
+ 1; the initial transmission does not count as a
n
× (2 ×
+ 1) seconds
TXDELAY
+
r
×
) × 100/16 milliseconds
seconds. For the default value of
5-10
ADVANCED PACKET OPERATION
TXDELAY
time.
TXDELAY
= 30,
101
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