• SWM 101: How can you use SWM to watch programs in other rooms?



    One of the most compelling features of the modern home entertainment system is the ability to watch a program recorded in another room. It can be watched from another receiver, or in some cases watched from anywhere. If you're out of the house, you'll probably rely on DIRECTV's excellent mobile apps to stream straight from their servers, but inside the home you use a technology called Connected Home.

    Connected Home allows data to flow over a coaxial cable much like it would over a traditional Ethernet cable. The underlying technology is called MoCA and while it's different from other forms of networking, the effect is the same: data goes from place to place. Most people don't have Ethernet cable in every room so DIRECTV chose to build MoCA into its systems to make it easy for that information to flow.

    The thing you need to know about coaxial cables is that they are capable of carrying a massive amount of information. They're constructed to carry many frequencies at once, and each frequency range can carry its own digital data. Satellite TV uses frequencies from 950-2150MHz for its signals, while cable TV and over-the-air antennas use from 5-806MHz. That should mean that it's possible for both technologies to share the same cable, but that isn't true in practice.

    DIRECTV reserves the space from 475-625MHz for its connected home signal, the digital data that uses MoCA technology to get from place to place. That means it interferes with both cable and antenna setups and therefore it's impossible for antenna and SWM signals to share the same cable. But really that's not the point of this article... so let's get back to it: How does programming get from receiver to receiver?

    If you are sharing programming between DVRs, the DVR where it's stored sends the entire digital file in real time to the receiving DVR using MoCA. This doesn't interfere at all with your ability to use up to eight tuners on a single line, because MoCA data uses different frequencies than live satellite TV. There is a limit of one program at a time that can be streamed from a 2-tuner DVR, but that's due to the slower processor in those units. There is enough bandwidth in the MoCA signal for at least four programs to be streamed.

    If you're using a Genie client, that's where things get even more interesting. Unlike a receiver, a client can't actually interpret a satellite signal. The Genie DVR does all the work including adding menus and overlays and the client simply takes remote commands and sends them back to the DVR. The images coming from the DVR look just like you'd see them on the TV, menus and all. Again, live TV isn't affected because a different set of frequencies is used for this information as opposed to live satellite TV.

    MoCA can also be used for communicating between a DIRECTV receiver and the internet, or between the receiver and Ethernet-enabled devices on the network. DIRECTV doesn't approve of this use, but it's possible to use this DECA Broadband device to convert anything with an Ethernet connection so it will run through the coaxial cable instead. This is a great way to get an Ethernet connection to a room that needs it.

    One limitation of this technology is distance. Unlike Ethernet cables which have a practical limit of about 325 feet, coaxial cables carrying the same information only have a practical limit of about 150 feet, which isn't a problem in most homes but it can be an issue in larger installations. There really isn't an amplifier that's designed to deal with this issue, meaning that the only way to address it is proper planning.

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