How to Align a Satellite Dish Antenna
Since all satellites for TVRO and DTH (Direct To Home) are in geostationary orbit, they are positioned on an imaginary arc (now called the Clarke Belt in honor of Arthur C. Clarke) about 22,500 miles above the equator. This means a satellite dish always points upwards and in the direction of the i.e. generally southwards.
From the table below will provide you the suggested dish size corresponding to the Effective Isotropically Radiated Power (EIRP) and value can be determined from the Satellite’s foot print.
Dish sizes are minimum for “Top Grade” reception
(Minimum 25 degrees LNB for C-Band, 0.6 dB LNB for Ku-Band)
SMATV – Satellite Master Antenna Television
For example, you are interested to receive the program “Pinoy Extreme Philippines”. This Free-to-Air (FTA) program can be found at ABS 1 satellite in the horizontal polarity. You can go to this website, www.lyngsat.com to know more about the said free-to-air program. Considering that your headend is in Luzon, based on the satellite’s foot print the EIRP is around 36 dBW.
Figure 2. ABS 1 Satellite’s A(Standard) Beam | 31-38 dBW
From Table 1, with an EIRP of 36 dBW, you need a 3.5 m (approx.12 ft.) diameter dish antenna in order to receive a top grade reception. Take the values from the SMATV column because you are going to re-broadcast the signal. If it is for home use, you can take the values from the DTH size column.
Terminology: Elevation and Azimuth
The up and down angle is called “Elevation”.
The east and west rotation angle is called “Azimuth”.
Offset Dishes: A word of Warning
An offset dish may appear to point downwards!
Offset dishes may appear to be pointed low towards the horizon, when in fact they are aiming at much high elevation as shown in the above diagram.
How to determine the look angles of a Satellite?
There are many ways of getting the look angles of a Satellite. One method is by mathematical computation wherein you need the Satellite’s orbital location and also your headend’s latitude and longitude. Sometimes these parameters are not readily available and it takes you quite sometime in determining the Satellite’s look angles. I suggest that you use this method which does not involve computation but rather requires you to browse the Internet.
You can go to this website, www.dishpointer.com and it will bring you to the Satellite Finder/Dish Pointing calculator with Google maps. Just input your location i.e. San Fernando, Pampanga and select from the list of Satellites available that you are interested in, and then click go. Figure 5 shows the graphical result of the Dish Pointer.
If you’ve never aligned a dish before, it can be very frustrating, especially if you don’t have a signal meter of some sort. You may well end-up thinking the receiver is faulty. Digital channels are either “on” or “off” and do not fade in or out gradually like analogue signals, further adding to the difficulty. Waving a dish about in the deluded hope that you will somehow find the correct location without either setting the elevation angle or knowing the azimuth angle is a complete and utter waste of time. However, if you follow the steps outlined below you will succeed… eventually!
1. Attach the F-connectors – Make sure that the cable and F-connectors are properly fitted. The inner core of the coax cable and the outer braid must never come in contact with each other.
2. Set the elevation angle – Considering panning your Satellite dish to ABS 1, the said satellite is located 75.0 degrees east and also this is where Pinoy Extreme is transmitted from. For Pampanga, the dish elevation for ABS 1 is approximately 35.3 degrees (from the dish pointer). Using your angle meter (shown in figure 7), set the elevation angle of the Satellite dish.
Most offset dishes have an elevation scale on the mounting bracket which allows you to adjust the dish to the correct elevation as shown in Figure 6.
Figure 6. Usually found in Off-set dish antennas Figure 7. Angle meter
Set this to approximately 35.3 degrees and then tighten the nut.
For satellite other than ABS 1, a list of the different satellites can be found at www.lyngsat.com.
3. Tune your receiver – If you don’t have a signal meter, you will have to use your receiver’s on-screen meter. Firstly, make sure you are tuned to an active channel or transponder and that all the parameters are correct – Frequency: 3829 Mhz, Symbol Rate: 11111 Msps, Polarization: Horizontal (FEC Auto or 3/4). For MPEG 4 programs, you should be aware if the receiver supports or compatible with the video format otherwise the signal quality will not be shown.
You may have to enter the Set-up/installation menu in order to have a constant display of the meter.
Figure 8. On-screen meter
Note that the Signal Quality level is the important guide, not Signal Strength level!
4. Aim the dish –A compass can be used to get a rough idea of where to aim the dish but remember to keep the compass away from the metal dish. The Dishpointer tool in Figure 5 above is especially helpful.
Figure 9 Magnetic compass
Alternatively, you can use a calculated sunpass time for the satellite i.e. the time at which the sun’s azimuth is the same as the satellite. A detailed explanation on how to locate a satellite using the position of the sun is provided.
5. Rotate the dish – Slowly move the dish east or west incrementally until you observe some activity on the receiver meter settings. If you rotate the dish too quickly, you will run past the satellite as there is a usually a small lag before the receiver quality meter reacts. When you do see activity on the meter, rotate the dish about that point until the level is at a maximum. Lock the dish into place.
6. Optimize the elevation – With the dish pointing in the right direction, readjust the elevation as per 2 until the quality is at a maximum.
7. Set the skew angle – As you face the dish, rotate or twist the LNB clockwise for an easterly satellite or anti-clockwise for a westerly satellite until the quality is again maximized. This can make a very significant improvement to the signal quality and should not be overlooked!
8. QED – Finished! If some channels are missing, then do a channel search to update the receiver’s database.