Introduction

Diseqc motors offer a cheap and convenient method for tracking the Clarke Belt with your satellite dish. They can be easily aligned if you take a few initial precautions and follow the steps outlined below.

Installing the Motor

1. Check the pole - ensure that the mounting pole is perfectly straight with a level or inclinometer. If the pole is not level, your dish will not properly track the arc of satellites.

2. Attach the Diseqc motor to the pole - tighten the motor fittings.

3. Set the elevation angle on the motor - the elevation angle on the motor will be based on the latitude of your location. The manual for the motor will tell you what to set this angle to or alternatively, you can use the following table:


Motor elevation & declination angles

Latitude	Elevation	Declination
50	39	6.6
51	38	6.7
52	37	6.8
53	36	6.9
54	35	7.0
55	34	7.1

For example, Athlone, which has a latitude of 53 degrees, will require an elevation angle of 36 degrees. The angle can be set according to the markings on the side of the motor. Some motors even include the latitude markings as an additional aid.


Setting the elevation angle



4. Attach the dish to the motor shaft - make sure the dish is at right angles to the motor and pole.

5. Set the adjusted declination angle on the dish - your latitude will also determine the declination angle - see above. Most diseqc motors use a special adjusted declination angle formula (based on the tilt of the rotating motor shaft) which will again be specified in your manual. For example, Athlone, with latitude of 53 degrees, will require a declination angle of approximately 7 degrees. A Moteck SG-2100, a common diseqc motor, uses the formula 30 – declination angle. So for Athlone the adjusted declination angle is 23 degrees (i.e. 30-7) when using an SG-2100. This angle can be set according to the markings on the side of the dish.


Setting the adjusted declination angle



Note: If you have a different model of motor, it will use a different formula for the adjusted declination angle.

Aligning the motor - the 'True South' approach

This method relies on aligning the motor with true south using a satellite which is positioned at or near true south for your location. In this case, we will use Atlantic Bird 2 located at 8 West as our reference for true south.

1. Slightly loosen the motor fittings - this will enable you to just rotate the motor about the pole. Don't loosen the fittings too much or it will complicate matters.

2. Connect up a satellite meter or alternatively tune the receiver - make sure to tune to an active transponder - the CNN transponder (11010, H, 27500) is a good choice.

3. Rotate the dish and motor until you see activity on the signal meter - rotate slowly both the dish and motor on the pole until the signal meter is at a maximum. A compass or the position of the sun may be useful in locating true south.

Rotating the dish and motor


4. Tighten the fittings - once the satellite has been found and the signal is at a maximum, tighten the motor fittings to the pole to ensure everything is firmly locked in position.

Note: For people located on the east coast of Ireland, Atlantic Bird 3 at 5 West may provide better tracking. In that case, use the same procedure as above, but with the France 2 transponder (11591, V, 20000) as your reference.

Aligning the motor - the USALS approach

USALS (aka GotoX or Diseqc 1.3) allows you to quickly and accurately align your dish. As most receivers are now USALS compatible, this method provides much better tracking of the Clarke Belt than the 'True South' approach. This is due to the fact that it is more precise to align your dish at the eastern or western extremes of the arc than at the top of the arc (i.e. near true south).

1. Enter you latitude and longitude into the receiver - enter your location coordinates into the the USALS menu of your receiver.


Typical USALS menu



2. Drive the motor to a satellite towards the east or west - select a satellite in the USALS menu and drive or GOTO that satellite. A good choice is Turksat at 42E as it has a strong signal over Ireland.

3. Rotate the dish and motor until you see activity on the signal meter - loosen the pole fittings slightly and rotate slowly both the dish and motor on the pole until the signal meter is at a maximum. If you don't have a signal meter, then watch the quality meter on the satellite receiver which has been tuned to an active transponder. For Turksat, the TRT 1 transponder (11920, V, 24440) is suitable.

4. Tighten the fittings - once the satellite has been found and the signal is at a maximum, tighten the motor fittings to the pole to ensure everything is firmly locked in position.

Testing your alignment

Once you believe the motor has been properly aligned, it's a good idea to confirm with a few tests. We will use 5 satellites which are spread across the Clarke Belt.

Extreme East Turksat 42E - TRT 1 : 11920, V, 24440
East Hotbird 13E - Al Jazeera : 11034, V, 27500
South Atlantic Bird 2 8W - CNN : 11010, H, 27500
West Hispasat 30W - Retevision : 12547, V, 30000
Extreme West Intelsat 9 58W - Aastha Channel 2 : 11477, H, 26462


If you run into problems, firstly recheck the pole is level - this is critical for proper tracking. Double check your elevation and declination angles and ensure the motor axis is properly aligned with true south. The following diagram will help you to locate any faults.