[amsat-bb] NOVA, Labjack and accutator utility working in XP in realtime

ok1vaw@volny.cz ok1vaw at volny.cz
Sun Sep 23 14:07:23 PDT 2007

Dear friends,
Maybe this can help to somebody who is solving the problem of control
of the antenna tracking as I was doing some time ago.
On the beginning there was a wish to be able to work the satellites.
I had a very old rotator with AC motor and pot (such as Kenpro, this
was sold in Germany under the Conrad brand with name Commander around
1989), which works still well. Then I solved a problem to control
the elevation. After refusing the possibility to buy and extra rotator
for elevation due to the high cost and impossibility to be used in my
conception, I have decided to use Accutator (Superjack).

After the years of different hardware changes (PCs, Pascal to Delphi,
Dos to XPs, A/D D/A card to Labjack U12) I have solution, which seems
to work with DDE to Nova (NLSA) in the realtime.
1. A realtime utility tracks the DDE server of Nova and waits for a current
change of elevation or azimuth.
2. The rotator pot for azimuth is measured by the Labjack (10bits resolution)
and by use of simple relay circuits the PC by use of digital IO of Labjack
controls the motor to right position.
3. The elevation control is much more sophisticated, because it must
read the pulses of the reed contact of the Superjack in the realtime
(about 5/sec) and recompute the pulse count for angle (quite non-linear
complicated form). Although it is not so straightforward and fast (=terribly
slow data reading due to using the XP about 100x lower) as it was in
the DOS/Pascal environment, but it can be used and it works.
4. So after some development, there is a very rough (I like to have still
the CRT type display by use of Wincrt unit for Delphi) program, which
works with Nova in the realtime and tracks the sats.
5. If somebody wants to ask for some details,how it was done, I am ready
to help. You can view my antenna farm on www.qsl.net/ok1vaw.

Regards, Vojtech, OK1VAW.
Sorry for my english.

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