Timewave DSP-232, Operating Manual

Page: 168 / 271

Chapter 9 AMTOR Operation
answering machine message you’ve set up for incoming calls. Set
WRU ON
or
CUSTOM
to $0200 to activate your
Auto-AnswerBack message.
To record your AAB message, enter “
AAB
(24-character text)”.
Example:
cmd:
AAB WF7A - VASHON ISLAND , WA
...and yes, spaces between words count as characters.
AChg Immediate Command
Mode: AMTOR, PACTOR Host: AG
ACHG
is an immediate command used in AMTOR or PACTOR by the receiving station to interrupt a sending
station’s transmissions.
As the receiving station, you usually rely on the transmitting station—your partner in the ARQ “handshake”—to
send “+?” to make the changeover. However, in ARQ (Mode A), you can use the
ACHG
command to interrupt the
sending station’s transmission. Use the
ACHG
command only when it’s really needed—it’s akin to interrupting
someone while they’re talking.
ADelay n Default: 4 (40 msec.)
Mode: AMTOR, PACTOR Host: AD
“
n ” 1 to 9 specifies transmitter key-up delay in 10 mS increments.
ADELAY is the length of time, in tens of milliseconds, between the time the DSP activates the transmitter’s PTT
line and when the ARQ data actually begins to flow. The
ADELAY
command allows you to adjust a variable delay,
from 10 to 90 mS, to handle the PTT delay of different transmitters.
In most cases, the default value of
4 (40 mS) is adequate for the majority of the popular HF transmitters. If the
AMTOR or PACTOR signal strength is good and you observe periodic errors caused by the loss of phasing (shown
by re-phase cycles in the middle of an ARQ contact) during contacts, it may be necessary to adjust the
ADELAY
value.
♦
Be sure that errors and rephasing effects are not caused by the other station before changing your
ADELAY
.
♦
If changing your ADELAY values doesn’t improve link performance, reinstall your original value and ask the
other station to try changing its
ADELAY
setting.
Because the ARQ AMTOR mode allows 170 mS for the signal to travel to the distant station and back, increasing
ADELAY will reduce the maximum working distance. The maximum theoretical range of an ARQ contact is limited
to about 16,000 miles (25,500 kilometers). Using some of that time as a transmit delay leaves less time for signal
propagation, thus the maximum distance available is reduced.
Regardless of the setting of
ADELAY , ARQ (mode A) AMTOR may not work well over very short distances like
one or two miles. However, in very short distance work ARQ shouldn’t be necessary to achieve error-free copy,
anyway.
AList
Immediate Command
Mode: AMTOR Host: AL
ALIST
is an immediate command that switches your DSP into the ARQ Listen mode.
In AMTOR Listen (and PACTOR Listen) modes, monitored link attempts are displayed like this:
>W1AW <C>
The callsigns are shown one per line and are meant to resemble the way the TNC monitors connect frames in
packet. Since neither mode supports identification within the calling blocks, no source callsign can be shown.
September, 05 9-9