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TELE-satellite International — The World‘s Largest Digital TV Trade Magazine
— 1 -12/2012
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www.TELE-satellite.com
Two-axis Motor Control
A fixed satellite antenna can only re-
ceive one satellite, no matter what you
do. If more satellites are to be received,
the antenna has to be turned and this
is typically done with actuator motors
or horizon-to-horizon motors. Both of
these systems track an imaginary arc
across the sky where all the satellites
can be found. Setting up one of these
systems is time consuming and comes
with a lot of trial and error.
Even when the antenna is correctly
aligned and is then able to align itself
with all the receivable satellites, this
joy often doesn’t last too long. The big-
gest enemy is wind; it can easily knock
the antenna out of alignment. It doesn’t
take much, and before you know it, the
antenna is no longer aligned with the
satellite arc.
Then, of course, the satellites them-
selves might not be exactly where
they’re supposed to be, either because
they aren’t positioned correctly in space
or because they’re old and can’t main-
tain their correct position anymore.
Professional satellite operators and
satellite DXers, those that are very
hard core hobbyists, use dual axis mo-
tors with which the antennac can be
moved not only in the azimuth direc-
tion (left/right), but also in the eleva-
tion direction (up/down). This makes it
possible to align the antenna perfectly
on any satellite.
For this workshop we came up with
something rather special and unique: is
it possible to mimic a professional two-
axis motorized antenna system using a
pair of standard DiSEqC motors?
These motors can be found in any
satellite shop and they work very well
Dual Motor
Antenna Control
for Small Dishes
Vitor Martins Augusto
with many different satellite receivers
that support the DiSEqC 1.2 protocol.
The Technical Data portion of a TELE-
satellite receiver test report always
identifies if a receiver supports the DiS-
EqC 1.2 protocol.
Next we’d like to refresh your memo-
ry on the operating principles of a DiS-
EqC motor, that is, a motor with a single
axis. In general, these motors are very
easy to install. First you’d need the lon-
gitude and latitude of your location. You
can easily find this information by en-
tering the name of the closest city into
Google along with the words longitude
and latitude.
The first result will usually give you
what you need. Here in the city of Porto
in northern Portugal, “Porto Longitude
Latitude” was entered into Google with
the following results: 41.1N latitude and
8.6
W longitude.
The only thing missing was the dec-
lination (the inclination of the motor to
vertical). Some motor manufacturers
such as Moteck include an elevation ta-
ble in the package from which the in-
clination can be read off based on the
latitude.
Moteck makes it even easier for the
user: on the website
www.gaaps.com
.
The twin LNB on the dish has one output
going to Motor 1 and the second output
going to Motor 2. The satellite receiver is
connected via a DiSEqC 2/1 switch.