Timewave DSP-232, Operating Manual, Page: 166 / 271

Chapter 9 AMTOR Operation
If the changeover time from transmit to receive in your radio set-up is too long, the ack signal from the distant
station will arrive before your radio has switched back to receive. However, if the transmitting station is further
away, the transmission time over the propagation path will delay the arrival of the signal until after your radio has
switched to receive. For this reason, you may be able to link with stations across the world easier than across town.
If the receiving station’s changeover from transmit to receive is too slow, the transmitting station delay between
“PTT” and “data send” can be extended. See
ADELAY
to adjust the DSP’s AMTOR timing characteristics to
compensate for this.
If switching-time problems persist, you may have to make changes in the radio to eliminate excessive time delays:
♦
Remove large decoupling capacitors from the Push-To-Talk line to allow faster PTT (transmitter)
activation;
♦
Improve power supply decoupling, especially in audio stages.
♦
Don ’t use the squelch control.
Another solution is for either you, or the other station, to change the timing value in
ADELAY
.
In case you can’t solve your radio’s switching-time problems, call AEA for assistance.
Maildrop Operation
One of the unique features of the DSP-232 is that it allows AMTOR as well as Packet and PACTOR access to its
MailDrop; messages can be dropped off and picked up in any combination of these modes as long as your mode
(Packet, PACTOR, RTTY, etc.) matches the calling station’s. Make sure that you understand
Chapter 7 - MailDrop
Operation and the basic AMTOR operation described earlier in this chapter before putting your AMTOR Maildrop
on the air.
TMAIL
controls other stations’ access to your AMTOR and PACTOR MailDrop in the same way that the
MAILDROP command controls Packet access. See TMAIL for more information about MailDrop accessibility.
The AMTOR Maildrop has been designed with a “Watchdog” safety feature so that it can operate independently
with little attention. If a remote station is linked with your AMTOR Maildrop and no traffic is passed for 5 minutes,
the link will drop and your transmitter will shut off.
At this writing however, unattended operation below 30 MHz isn’t legal for US amateurs unless they hold a Special
Temporary Authorization (STA) from the FCC for this purpose. This restriction may soon change, but until then US
amateurs must be sure to always have control of their HF transmitters when any automatic device such as the DSP
MailDrop is in operation.
With this in mind, we’ve designed the AMTOR Maildrop so that it can be turned on or off at any time during an
ARQ link simply by turning
TMAIL ON
or
OFF
. This allows you to make your Maildrop available to any station
you’re linked with at a moment’s notice. This could come in handy should you want to forward a message from an
AMTOR station into the Packet or PACTOR network. See the
CODE 2
command for upper and lowercase text in
AMTOR.
LED Status and mode Indicators
The front panel LED display provides mode and status information at a glance. This is especially useful in AMTOR
operation. See the following table for the light patterns you’ll see when you operate your DSP in its different
AMTOR modes.
Action Keystroke On-Screen Text Front Panel LEDs
Enter AMTOR mode and
to listen to FEC
transmissions
AM
Opmode was ( old mode )
Opmode now AMtor
Amtor/FEC
September, 05 9-7