14
8.8 Setting motorized satellite dish
Proper work of Ferguson receiver ensures motorized system by USALS company Stab. To connect
the installation of the dish with motorized system USALS, connect the output of USALS to LNB IN
on rear panel of Ferguson receiver. The motor is what actually moves the antenna between the
various satellite positions and is installed in between the antenna mast and the antenna mount. It
is designed such that the axis of rotation is aligned with the North Star. This type of mount is often
referred to as a Polar Mount. As a result, azimuth and elevation do not have to be adjusted
individually. Instead, the antenna rotates on only one axis. The antenna motor is installed on the
already existing vertical mast. The local latitude position of the location is then setup on the
motor’s scale thus aligning the axis of rotation in the correct position. Similar to a fixed antenna
installation, the elevation scale on the antenna mount must be set for a satellite as close to south
as possible. In the southern hemisphere you would be looking for a northern-most satellite. The
selected satellite should lie within 5° of your southern-most position; the southern-most position
being equal to your local longitude. For example, if your local longitude is 73° west, then the
satellite you select should be located /- 5° of 73° west, or within the range 68° to 78° west.
USALS greatly simplifies the antenna setup. Ferguson receiver simply asks you for your local
geographical coordinates and calculates the satellite positions on its own using a complex
mathematical formula. The receiver then drives the motor directly to the selected satellite position.
Once you have a signal, you need only finely adjust the antenna mount and horizontal position (on
the mast itself) for maximum signal. If the initial southern setting was slightly off, it would now be
corrected. Once the first satellite is perfectly set, all the other satellites in the arc would also be
automatically set as soon as the orbital position of these additional satellites is entered into the
receiver.
Without USALS, the alignment of the antenna system is somewhat more difficult. DiSEqC 1.2 drives
the antenna to the selected satellite position in almost the same way. But since the local
geographical data is missing, the motor drives to a satellite position based on the prime meridian
and the equator. Therefore, when aligning the motor for the first time – and then again later
on with all the other satellite positions – alignment with the actual satellite position has to be
achieved with the motor commands “move east/west”. Because of these difficulties,
manufacturers of these motors make available helpful software on their web sites that
enable you to easily calculate the true position of a satellite.
