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[TowerTalk] HF remote controlled stations

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Subject: [TowerTalk] HF remote controlled stations
From: ("Dick Green".)
Date: Tue, 3 Jun 1997 12:24:54 -0400
>  Which software is doing the job ?
>   Is the software able to indicate the forward & reflected
>   output power on same window ?

In the case of the AlphaPower 87A, the software is built-in to the
amplifier. You only need an ASCII terminal or a simple terminal program
running on a PC to communicate with the Alpha. The 87A uses a typical
command line interface. For example, if you type the command 'PWR<ENTER>',
it will display forward power. There is no command to display the forward
and reflected power at the same time, but there are two separate commands
used for this purpose, one for forward and one for reflected. The command
set allows you to control every function of the amp (including power on/off
and standby/operate.) The amp was specifically designed for the type of
remote control you have in mind.

> * what antenna switch matrix can be remote controlled in
>   same manner ( I know only the AlphaPower ). Is Alpha
>   supplying a common software for the 87A and antenna
>   switch ? Can they be controlled at same time ? 

Alpha's DAS antenna switch is daisy-chained to the 87A so it can be
controlled over the same RS-232 interface. There are two ways to change
antennas. The simplest way is to set the transceiver to the desired
frequency and transmit. The 87A detects the frequency change by sampling
the RF and automatically switches both the amp and the antenna switch to
the correct band segment settings and antenna. This takes less than a
second and no part of your transmission is lost (it will pass the RF
through from the transceiver until the switching is complete.) You can also
use specific RS232 commands to switch bands and antennas (e.g., if you
issue the 'band 1' and 'ant 3' command, the 87A switches to 160 meters and
antenna number 3.)

> * Is there any software package available today capable to
>   integrate on same data stream all the transceiver features
>   and commands, the TX/RX audio, the amplifier on/off switch
>   and bandswitch, antenna selecting switch and rotator control ?
>   or I have to use 2-3 separate links ?

I don't know of any software that can do this. The problem is that there
are a lot of different command interfaces to support out there, and a
limited market for this application. Each device has a separate RS232
interface. The best (and perhaps only) way to really solve this problem is
to use put a computer in the remote shack and operate it from packet or a
telephone modem (this is your control link.) You will need one port for the
packet or phone modem, one port for the transceiver, one port for the amp,
and one port for the rotator. Then you need software that can accept
commands over the packet or phone link, select the appropriate port, and
pass commands to the desired device. I know of no software that is
engineered to do this (although it may exist.) However, you can write your
own using a terminal program with a built-in scripting language.

Some scripting languages are powerful enough to do this, while others may
not be. The nice thing is that you don't have to write a bunch of complex
communications software to run the ports. A relatively simple script can be
written to monitor the packet or phone modem port for commands you issue
remotely. Then it switches to the desired devices, passes on your commands,
and returns status from the devices (if any.) I wrote such a script in
order to make coax power loss measurements at my antenna without any help.
I use a miniature portable packet station (Baycom TNC, HT, HP 100LX palmtop
computer, and a battery) to communicate with a computer and packet setup in
my shack. The transceiver is the Kenwood TS-950SDX. I can issue commands
that tell the computer to set various transceiver modes and frequencies,
turn on the amp, set the amp to operate, and transmit on/off (or operate
the Kenwood's built-in memory keyer or voice record/playback.)

I used a product called MLINK. That was my choice because I co-designed and
sold it for over ten years, so the script was easy for me to write.
Unfortunately, this program may be difficult to obtain since it is sold
exclusively to businesses and is not sold through typical retail channels
(I sold the company and product, both of which ended up in the hands of
Computer Associates -- you could try contacting them.) Another good choice
would be TERM, from Century Software in Salt Lake City. There are probably
a bunch of other ASCII communications programs with scripting languages,
but you have to pick one that has a language powerful enough for this

As for the TX/RX audio, I don't know how that would work (I'm not familiar
with the Kachina transceiver.) Seems to me that the best way would be to
hook up the transmit and receive audio to a phone patch and use a phone
connection for that part (and use packet for control.) You could also use
VHF, but that's probably more expensive (it would be best to use two
full-duplex dual banders.) If you want to send CW, you would probaby have
to wire up a keying line to the shack computer's LPT line and write some
software that sends CW. That's not particularly easy to do!

That's my take on the situation. I have a feeling it might be less
expensive to isolate your home shack from the RF interference (like, build
a metal cage around the room and filter the heck out of the power lines.)

73, Dick, WC1M

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