EA8URF - Turnaround time of hamradio transceivers.

Submitted by EA8URF on Thu, 2025-07-10 06:34

Good info about the turnaround time of hamradio transceivers.

The TXDelay and the RX recovery time of a radio should be lower than
30 msec in order to allow optimum PACTOR performance regardless
of the distance between the two PACTOR controllers.
The sum of delays (including the propagation delay) and switching times on
both sides must not exceed 180 msec.
The PTC-IIxxx have two parameters which allow some adjustment to the require-
ments of a radio: TXDelay and CSDelay, the minimum for both settings is
5 msec, the maximum 80 msec. Of course, the possible maximum distance
between two systems is smaller in case of high TXD and CSD values.
CSDelay determines how long the short Control (ack/nack) blocks are de-
layed and thus determines the ARQ timing. High CSD values are required
if the TX->RX switching time (RX recovery) of the MASTER (initiates
the link and waits for ack/nack in the short RX gap between connect
packets) is large and the distance between the two systems is short.
PACTOR provides a special "longpath" (set a "!" in front of a call sign
when connecting) "option" which adds 150 msec to the RX gap. The efficien-
cy of the link lowers to about 90% but also slow radios can be used with
"long path option".

Recovered from "PACTOR" iogroups.
Author: SCS-PACTOR-Team.

73's

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