1. What is an satellite LNB?

LNB stands for "Low Noise Block Converter". It is the part of your Satellite dish that hangs off of the arm and looks like a flashlight. It is what captures the digital signal from the satellite.

2. How does an LNB work?

There are 32 transponders on the 101 degree satellite (main satellite) that send channels. They are numbered 1-32. Each transponder sends a group of channels. An LNB on a satellite dish can look at either odd or even transponders at any given time. It cannot see both at the same time. If you change the channel to one that is on an odd transponder, then the LNB switches to look at the odd...if you change to a channel on an even transponder, then the LNB switches to look at the even.

3. How does the LNB know which side (even or odd transponders) to look at?

This is done by voltage changes that your DirectTV receiver sends. 

4. What is a Dual LNB?

A Dual LNB is just two LNB's...each connection can operate independently of each other so you can have two receivers each looking at different stations on different transponders. They both look at the same satellite (101 Degree satellite). A single LNB only has one coax connection and cannot be used with more than 1 DirectTV receiver.

5. What is the difference between the "Round" 18" dishes and the "Elliptical" 18"x24" dishes?

The 18" dish had a Dual LNB that looks at one satellite. The satellite is positioned at 101 degrees and sends all the main programming that is offered in the DirectTV packages. The 18x24" dish has TWO Dual LNBs and is set up to see two satellites... the 101 degree and the 119. The 119 degree satellite sends additional programming such as the NASA channel, ParaTodos Spanish programming, other foreign language programming and HDTV channels.

You could also use two Round 18" dishes, one pointed at the 101 degree satellite and the other pointed at the 119 satellite to do the same as the Elliptical dish. You would connect the four cables from the two dishes to a multiswitch as explained in the Multiswitches FAQ section.

6. Can I use a splitter to add more receivers or add dual Tuners to my DirectTiVo?

NO....this is where multiswitches come into play. You cannot use regular splitters. From the explanation of LNBs above, you should understand that if I split an LNB with a regular splitter, then I will have two receivers using the same LNB and fighting over looking at odd or even transponders. One or both receivers will only be able to see half of the channels.

7. How does DirecTV work? 

Way up high in the sky near the equator are DirecTV broadcasting satellites. They send out signals and somehow through the use of dish antennas, cables, multiswitches, and receivers, you watch the channels provided by DirecTV. For more detailed explanation of how it all works, see below.

8. What 101W and other numbers during installation? 

DirecTV satellites are in a geostationary orbit. This basically means that they go around the earth in exactly 24 hour periods, and therefore stay in the same place in the sky all the time. The only place they can do both of those is above the equator (physics.. you can't escape it). So, generally, positions are referred to by the longitude of the place they are above. Longitude, on the globe, are the lines that run from pole to pole. 101 West is the orbital position directly above, you guessed it, 101 West longitude. At 24,000 miles above the planet, this is a bit of a wide area, a couple hundred miles or so across. So, there's not one satellite there, but several. But to your dish, it's all the same. In order for your dish to see them, it has to point at them. That's why aiming is so critical. Less than a degree off and you see a completely different section of the sky. DirecTV also maintains satellites at 119 West.

9. What is the difference between Round and Oval dishes? 

Round dishes are the simplest. They point at one place in the sky. For DTV, this is 101W, of course. All the main DTV channels are sent from here. Quite a lot of local channels are sent from here as well. So, what's the oval dish for? The oval dish actually see a range of positions. 

See, the signal coming from the sky looks almost like a point source. Imagine a bunch of lines drawn from a point in space to your round dish. The lines are all parallel, so when they hit your dish, they bounce in different directions. Your round dish is a curve, so all those lines bounce to come together. The point where they all come to is where the LNB is. It's at the focal point.

The oval dish, however, doesn't focus in one place, but several. You don't point the oval dish at 101W or at 119W (DirecTV's two major orbital locations). Actually, you point it at 110W, a point directly in between. Now, imagine the lines coming from 101W. The dish isn't pointing at 101W, but the lines still hit it. But, they reflect a bit to the side. You might notice that that is where the LNB on your oval dish is placed, off to one side. The other LNB is placed to the other side (119W is on the other side of the dish). Actually, if you look at the dish at a 9 degree angle (from the front of the dish) you'll see that it looks round. So actually, the oval dish is really round, when you consider it from those angles. Neat, huh? Depending on where the LNB is located in front of the dish, it's looking at a different point in the sky.

10. I heard I can use two round dishes, how do I do that? 

Remember the only thing special about the oval dish is that it has two LNB's looking at different places. So, if you have two round dishes, one pointed at 101W, the other at 119W, and you use the same kind of multiswitch that comes with the oval dish, then you see the exact same thing. There's nothing inherently special about the oval dish except that it's pointing at two places in the sky. A lot of people use two round dishes to get a minor signal improvement, or more frequently because getting a couple of round dishes can be cheaper. All you need is a 4xN or 5xN multiswitch and to aim the things the right way.

11. What is a Spot Beam? 

A spot beam is a often used term now, and it affects what local stations you can possibly receive. The normal satellites send out a signal pretty indiscriminately. It simply is a microwave transmitter beaming data across the US. The spot beam is the same thing, but it points at a reflector that has a narrower focus. The upshot of this is that depending on where you are in the country, you won't see the beams pointing away from you. That is, the satellite sends a beam similar to a flashlight beam at one spot of the country. A 100-200 mile wide spot.

Why use spot beams? Because there's only a limited amount of space up there. They can't broadcast anything they want, the FCC would kill them. They only have so much bandwidth/frequency space. To make the most use out of it all, they rebroadcast on the same frequencies in different spots. This is *perfect* for sending local channels. So on frequency "3" they might send locals to Birmingham, Atlanta, and Denver and so forth. All on that same frequency. This reuse can be done because they're not sending Denver's channels to Atlanta (it would be a waste since they can't legally sell them there anyway). Because each spot on the ground only sees what's being sent to them, the other spots using the same frequency doesn't get interfered with by the other spots. Any spot map you look at will have overlapping spots. Any spots that overlap must use two different frequencies, but any spots that don't overlap can use the same frequencies.

12. What are 119W spot beams? 

They're planning on putting spot beams up in 119W too (DirecTV 7S). Right now they're only in 101W. These will be local channels for more/new markets. To get these, you will need to have an oval dish (or the equivalent, two rounds). 

13. What about 110W? 

The 110W beam is not used for much. A few local markets in the Carolinas used to require it. Right now it's used mainly for HDTV programs. But mainly this is to keep their space on those satellites in usage while they figure out what to do with it. To get 110W channels, you need an oval dish with a third satellite adapter or a Triple LNB Phase III Dish like the GainMaster from Channel Master. This adapter hooks into the 119W LNB and uses some of the unused 119W frequency signals. You could also put a round dish pointing at 110W and use the same kind of adapter/signal combiner.

14. What is SAT-C Kit used for? 

A Sat-C kit is a special adapter available as a kit to receive the 110W and comes with everything to need to hook it up to the oval dish. It goes in between the other LNB's. It's also a special LNB, so you can't use it as a single LNB or regular Dual LNB. Also, a regular single or dual LNB will not work as a Sat-C LNB.

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