Last week we looked at securing our fixings and preparing for the alignment of your satellite dish. Let’s move on the alignment process:
In this example we’re going to use the Whyte Technologies office as our example installation site.
Attach your satellite dish to your previously fixed mounting, evenly tighten the pole camp to the point that the grip is enough to hold the dish in position without it sliding down. You should now be able to move your satellite dish’s azimuth (east to west) and it will hold in place when you let go.
On the side of your dish mount you will notice an elevation scale and the locking bolts for elevation, again tighten these evenly so that the dish will hold its elevation when adjusted up and down.
Secure your LNB in the LNB clamp tightened sufficiently to allow adjustment while holding position when you let the LNB go.
From the Whyte Technologies offices (Latitude 51.6579° Longitude -0.0219°) the direction of the Astra 2 fleet of satellites at 28.2° east can be found at:
Azimuth True: 145.6°
Azimuth Mag: 146.1°
LNB Skew: -13°
Your look angles will be different and I’d recommend using Dish Pointer to get your general line of sight and your dish setup data for your installation location.
In this case we’re interested in Azimuth Magnetic (Mag) for use on a compass (or compass phone app). Elevation, for use with an inclinometer (again there are phone apps that can help). The LNB Skew adjustment can be made roughly at this point using the scale shown on the LNB (usually found on the LNB casing behind the cap). One other important adjustment is focus as your LNB will be able to be adjusted towards and away from the dish surface, this can be optimised too to further improve performance.
Using your look angle information you will be able to point your satellite dish in the general direction of Astra 2 at 28.2° east. It’s generally best to aim a little high and off to the east or west a little, the reason for this is that it’s better to drop into the required position (elevation) rather than push up.
While searching for Astra 2 ensure your dish has a clear line of sight and avoid shadowing the signal path to the satellite dish.
Connect your satellite meter/spectrum analyser with Astra 2 selected on a known transponder. To search for Astra 2 were going to sweep slowly from east to west and at the end of each sweep drop the elevation a little. As we’re targeting a satellite that’s 39046km away this needs to be done slowly. To get an idea of how slowly this is about 5 seconds per centimetre.
You will achieve a low level lock on the satellite reasonable quickly. At this point were going to start peaking the dish to optimise our signal. Once you have obtained the best levels you can with your meter lightly nip the azimuth bolts (dish clamp) on the dish while watching your satellite meter/spectrum analyser do this applying even pressure, you will notice that each turn of the nut will affect the levels received as you will be pulling the dish when tightening the bolts. The same process can be applied to elevation, remember we mentioned that it’s better to drop into a satellite position and as you tighten the elevation bolts sure enough your satellite dish elevation will drop (some of you may have a Az-El mount that has a vertical bolt and locking nuts for azimuth adjustment, again start a little high and drop in). While making these adjustments keep an eye on your satellite meter/spectrum analyser during the peaking process. Once your satisfied that the signal levels and quality you’re receiving are the best they can be tighten up your azimuth and elevation bolts applying even pressure, watching your satellite meter/spectrum analyser as you do so.
For Skew adjustment we will be using the Pre BER scale function of your satellite meter/spectrum analyser. Select a Vertical Low transponder and note the current levels you’re receiving and make a fine adjustment of the Skew of the LNB (clockwise and counter clockwise) you will notice a peak point where the signal and quality (Pre BER) is as best as it can be. Then select a Horizontal Low and perform the same procedure, you should find that you are within half a millimetre of your previous peak level position as linear polarisation has an orthogonal offset. You can also apply the same procedure to Horizontal High and Vertical High (you will find subtle differences as there are European and UK downlink beams from the Astra 2 fleet of satellites) we’re looking for the best overall performance. Now that we’ve set up the Skew the final adjustment is Focus. Here we’re moving the LNB towards and away from the dish surface, again looking to optimise the signal strength and quality with small adjustments. Once done tighten the LNB clamp. With your meter connected make one final check that everything is tight.
Next week we’ll be looking at completing the satellite dish installation so that our work up the ladder or on the roof is done.