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Splitters and SWM Signal

Discussion in 'DIRECTV Installation/MDU Discussion' started by sysakpa, Jan 8, 2013.

  1. sysakpa

    sysakpa New Member

    Jan 8, 2013
    I am pretty new to this industry so this question will probably be easy for most to answer.

    What exactly is a SWM signal and how is it different from the signal a conventional multiswitch uses and outputs?

    If not already answered from your description above, why can one use a splitter after a SWM but not use a splitter after a conventional multiswitch? I was told that it does not even have to be a SWM splitter.
    From my basic knowledge I was told that the different voltages that receivers send to the LNB would "interfere" with eachother after passing through the splitter on its way to the LNB. Does this "interference" occur only when the voltages are different or does it occur even if they are the same?

    Why is this "interference" not an issue with a SWM? Is it because each line from this multiswitch can carry up to 8 tuners?

  2. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

    Dec 9, 2006
    Non SWiM uses 13 & 18 volts to both power the LNB and select which polarization is needed for the channel. It also uses a tone to change which LNB.

    SWiM is a completely different method. Each receiver sends a request over a 2.3 MHz signal to the SWiM, and the SWiM then tunes to the transponder and converts the signal to one of eight frequencies for the receiver. These eight frequencies are all different, so they can be carried on the same coax without interfering, so the coax can be split.

    A crude way to explain this is the SWiM is a pre-tuner before each receiver.
  3. dielray

    dielray Legend

    Aug 5, 2009
    To add more information:

    A transponder is just a downlink frequency range. Each transponder can hold a number of channels.

    The difference between multiswitch and SWM is how the signal is organized.

    A multiswitch Ka/Ku system breaks the signal coming from the satellites into 4 parts. There are many transponders in any one part, even though a tuner will only ever use one transponder. The transponders that are in one part cannot be mixed and matched with another part. For example, a 13 volt part will only carry odd numbered transponders and will never carry even numbered transponders. This is the "interference" you were talking about. If you split this type of system, it will only work for as long as they are both looking at the same part. If you have two tuners requesting different parts only one wins out, leaving the other one searching for satellite or displaying the wrong channel.

    SWM allows any 8 transponders to be chosen and passed down one cable. This is basically mixing and matching transponders. This type can be split because even if a tuner is looking at a certain transponder, another tuner can always see the transponder it's looking for.
  4. carl6

    carl6 Moderator Staff Member DBSTalk Club

    Nov 15, 2005
    Seattle, WA

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