# SWM + DECA + Cable Modem - Design



## vyslouzil (May 12, 2008)

I understand this is not a supported method for SWM, however I have been running this setup since mid 2008 with zero issues. I'm looking to integrate DECA into this setup, however my Holland STVC splitter/combiner does not pass the 500-600Mhz on the SAT port. Does anyone have any idea how I can get to the proposed state? I'm wondering if replacing the STVC's with SWS-2's will do the track..but are SWS-2 fully bi-directional, or do they filter out everything except for the SWM communication?

Working setup..no DECA:









Proposed setup..doesn't work due to STVC splitters blocking DECA:









Would appreciate any ideas..I'm unfort stuck stacking my cable modem on top of my SWM signals due to my home wiring/limitations.

FYI: My cable modem uses ~30MHz and ~843MHz ..so there is room in there for it.
STVC specs: http://www.hollandelectronics.com/catalog/upload_file/Filters-Diplexers.pdf


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## veryoldschool (Dec 10, 2006)

"simply put": you're screwed.
The Cable modem and the DECA work in the same bands, so you'd need to filter DECA from the cable modem and hope you don't have two frequencies that are too close or overlap, "and then" diplex out the DECA from the SAT feed and feed them separately, which might require a PI to power each DECA.


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## vyslouzil (May 12, 2008)

I thought DECA runs on 500-600MHz? My cable modem runs on 30MHz and 840-860MHz.


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## veryoldschool (Dec 10, 2006)

vyslouzil said:


> I thought DECA runs on 500-600MHz? My cable modem runs on 30MHz and 840-860MHz.


Then the bandstop will block DECA from your cable, and you still need to:


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## DogLover (Mar 19, 2007)

Couldn't he add a Band Stop Filter to the input of the SWS-8? Wouldn't that block keep the DECA limited to only the IRDs? Then he'd just need to run another coax fromthe SWS-8 to a DECA for the network, that could connect to a switch in any room he as both ethernet and coax?

Or am I missing something?


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## veryoldschool (Dec 10, 2006)

DogLover said:


> Couldn't he add a Band Stop Filter to the input of the SWS-8? Wouldn't that block keep the DECA limited to only the IRDs? Then he'd just need to run another coax fromthe SWS-8 to a DECA for the network, that could connect to a switch in any room he as both ethernet and coax?
> 
> Or am I missing something?


If all the DECA connections were at/off the last 8-way, then "sure".


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## vyslouzil (May 12, 2008)

I don't follow.. None of the frequencies should be even close to overlapping.

SWM - 2.3 MHz return, and 974 MHz - 1892 MHz send
Cable Modem - 30 MHz return, and 840-850 MHz send
DECA - 500 MHz - 600 MHz bi-directional

Other than the Holland STVC splitters I use, what is preventing all of these technologies from co-existing on a single cable? At the moment, it appears if the STVC didn't block out below 950 MHz on the SAT port, then DECA would work..

What am I missing here?


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## JosephB (Nov 14, 2005)

In your proposed setup, why do you have two DECAs connecting to the network? Drop the DECA connecting to the network on the left side of the diagram, put a bandstop filter on the input to the SWS-8 that is going to all of the IRDs, and it should work without any other modifications. If you can get all of your DECA stuff on that one splitter, then you don't have to worry about the rest of the coax network. Just put a filter on the splitter to isolate the DECA frequencies and you should be good to go.


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## espaeth (Oct 14, 2003)

Shouldn't the cable modem be on the right, with the provider on the left? That would really clear up a lot of confusion in the diagram if that's the case.


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## veryoldschool (Dec 10, 2006)

espaeth said:


> Shouldn't the cable modem be on the right, with the provider on the left? That would really clear up a lot of confusion in the diagram if that's the case.


It doesn't really matter which way the cable signal is traveling.
"the key is", to not send the DECA through the diplexers at all. Skip this and keep the DECAs all connected to the 8-way splitter and it should work.


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## espaeth (Oct 14, 2003)

veryoldschool said:


> It doesn't really matter which way the cable signal is traveling.
> "the key is", to not send the DECA through the diplexers at all. Skip this and keep the DECAs all connected to the 8-way splitter and it should work.


Indeed, but the way he has it drawn to get a connection back to his Internet access you'd need DECA to pass to the left where the cable modem is.

If the cable modem is on the right with the receivers, this becomes a significantly less complicated problem.


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