Tips for Aligning Satellite Dishes
Posted by Hans de Ruiter
I have just spent a ridiculous amount of time setting up a satellite TV system for receiving Freeview, free satellite TV for New Zealand. A lot of this time was due to my own lack of experience, and the difficulty in knowing whether something is really working, or not aligned. Here are a few tips for anyone else wishing to set this up themselves. This is not a complete guide, just some ideas that should save time. It assumes that you are installing a Ku band dish for digital TV, but a lot of the advice applies to any satellite dish.
Before Installing the Satellite Dish
- Buy/borrow a satellite finder. Do NOT rely on just the satellite finder that is built in to the receiver.
Some receivers are advertised as having a built in satellite finder. What this means is that it can emit the same annoying sound that a satellite finder does. However, it will only indicate the signal strength of the current transponder that it is tuned to. If you have incorrect settings (e.g., the wrong LNB oscillator frequency) then you could have the dish pointed at the satellite and not know it. More importantly, the satellite finder is much more sensitive and, therefore, does not have to be aligned as precisely. This will save you much time and frustration.
- Buy/borrow a spirit level.
Taking the time to get the dish mounting mast perfectly vertical will save time later. If you are using a motor, this is essential.
- Buy/borrow a compass and be sure to adjust it for the local offset for magnetic north.
It will be much easier to find the satellite if the dish is already pointing in roughly the right direction. Magnetic north and true north are at different locations, and the offset varies from place to place.
- Write down the Local Oscillator (LO) frequency of the LNB. NOTE: A universal LNB has two LOs.
I made the mistake of mounting the dish complete with LNB before noting the LO frequency, which just happened to be different from most "standard" LNBs for the KU band. As a result, the satellite receiver was looking for the signals at the wrong frequencies. The box that the LNB comes in usually does not list this information.
- Unless you have access to the right crimping tool (i.e., a coax cable crimp tool, not a normal crimp tool), it is much easier to use the screw on connectors.
- Use dishpointer.com in order to find out where to point the dish.
- Using the dishpointer.com data, check that there are no obstacles blocking the view of the desired satellite(s).
The high frequencies used by satellites are line-of-sight only. What this means is that you will not be able to receive from a satellite that you do not have a clear view of (by which I mean clear sky; you won't be able to see the satellite with the naked eye). Note that most Ku band satellite dishes have the LNB mounted offset from the centre, so they appear to be looking lower than they really are (typically by 20°-30°).
Installing the Satellite Dish
Make sure that the mounting pole is vertical using the spirit level before attaching the satellite dish.
The more accurate you are earlier on, the easier it will be to find that satellite.
- Make sure that the you have compensated for the offset between magnetic north and true north.
Dishpointer.com provides a magnetic azimuth compass reading, so it may be easier to use that. However, a compass that has be pre-adjusted should use the true offset. If the arrow is not pointed at 0°, then it may have been adjusted.
- Do NOT trust the elevation/lattitude markings on the satellite dish.
Obviously the markings are a good reference, but they can be off by over 5°. In my case, the elevation adjustment mechanism was very loose, and I finally found the satellite 5-10° lower than the markings on the dish. I have read that some people manually check the elevation, but remember to look-up and compensate for the LNB mounting offset (e.g., a dish with a 28° LNB offset should be pointed 28° lower than the actual elevation).
- Check if the LNB as a mark on it indicating the horizontal polarization angle.
Satellite signals can be vertically and horizontally polarized (and circularly polarized too, but this is less common for TV). There is also a "skew" angle for the satellite which should be used to adjust the angle of the LNB. If the LNB is rotated to the wrong angle, then a weak signal, or no signal could be received. I made the mistake of assuming which way the horizontal antenna was oriented, and payed for it later (see the section below called "Some Transponders are not Working").
- Be as accurate as possible with alignment.
The closer the dish is to the correct alignment, the easier it will be to lock on to the satellite. This includes the azimuth (compass angle), elevation (how high), and LNB skew (rotation of the LNB in its mount).
- Even with the satellite finder connected, it is still useful to have the satellite receiver and TV visible/audible from the satellite dish during alignment.
The satellite finder is great for telling you whether the dish is pointed at a satellite, but it won't tell you which satellite; that is where the satellite receiver's signal level and quality indicators come in.
Aligning the Satellite Dish
- Start with the satellite finder sensitivity turned right up; it will make a noise when the dish is pointing close to a satellite, and the needle will swing to the right.
- Check if the LNB is working (see "Is my LNB Broken?" below) before starting.
- Once it starts beeping (squealing really), turn down the sensitivity of the satellite finder, and rotate the dish (very slowly) a bit more until it starts beeping again.
You should not have to move more than a degree from the initial point at which it started beeping. If you do, try turning in the other direction. This process is repeated until the dish is aligned.
- Try to align the azimuth first, and then adjust the elevation, and then the LNB skew.
If you cannot find the satellite at one elevation, perform a grid like search swinging back and forth with the elevation adjusted by 1° increments per sweep.
- New Zealanders should start their sweep a little to the east, so that Optus D1 is the first satellite that they find (assuming that you want to watch freeview).
Optus D1, C1, and D2 are quite close together, and it is easy lock on to the wrong one.
- Make sure that the satellite receiver has the correct LNB LO frequency(ies) set.
As was mentioned above, the receiver must have the right LO frequency, or it will be searching for signals in the wrong place.
- Once you have a reasonable lock, check the signal level and quality on the satellite receiver, with it tuned to the desired satellite.
If you are not receiving a signal despite the satellite finder indicating the presence of a satellite, then the dish is aligned with the wrong satellite.
- The LNB skew can make a big difference.
I ended up with being able to receive signals from some transponders, but not others. This turned out to be due to the LNB not being rotated to the correct angle. See the section below called "I Can Only Receive Some Transponders but not Others" for more details.
- Check that all transponders have a signal.
This assumes that the satellite receiver has been preprogrammed with the channels on the target satellite. If not, the satellite receiver should have the ability to scan for transponders.
Is My LNB Broken?
After scanning the sky for a while (without the satellite finder), and finding nothing, I started to wonder if the LNB might be broken. Searching through the internet, the best advice seemed to be: "point the dish at a satellite, and check if you get a signal." How on earth can you do this if you don't even know if the dish is aligned! Well, I have found out a relatively easy way to check if a Ku band LNB is broken: a satellite finder that is turned up to maximum should start squealing if you put your hand in front of the LNB (in front of the end that should be pointed at the dish). Alternatively, pointing the LNB at the ground should have the same effect. Your hand and the ground are sources of noise which the LNB should pick up, resulting in the signal detected by the satellite finder. If the satellite finder does not make a noise, then the LNB is likely broken.
It is unusual to receive an LNB that is dead, but it does happen. This test is also useful if satellite reception suddenly stops, since this could be caused by a number of different things; it could be caused by a dead LNB, a broken cable, the wind pushing the dish out of alignment, etc.
I Can Only Receive Some Transponders but not Others
This is a problem that I had, which initially had me confused. I was receiving strong signals from some transponders, whilst some others (which had channels that I wanted to see), were completely dead. To make things even more confusing, those very same transponders had worked not too long agon. It turned out that I had rotated the LNB slightly (adjusted the skew), resulting in a lost signal. In fact, my initial skew setting was significantly out from where it should be, and I had switched from a standard LNB, to a universal one. Universal LNBs seem to have stronger polarization characteristics, which can result in a better signal, but also requires better alignment.
This blog entry has become much longer than I had expected, but it contains a good summary of the kind of issues that can come up during satellite dish alignment, and how to avoid them. I hope that it will save other people some time and frustration. There are plenty of satellite installation "how-tos" on the internet, but none of them prepared me for the issues that I encountered.
Blog » Tips for Aligning Satellite Dishes
Blog » Tips for Aligning Satellite Dishes