Satellite and cable on the same line?

[gar598]

I'm trying to see if it's possible to run cable (internet) and DirecTV coming in using the same coax cable.. I've read some reports of people using diplexers for this but it seems this may cause signal latency, etc. The ideal solution would be to run another line which unfortunately is not possible (so they tell me) - this is a condo building and the wiring is run under the floor.

Thanks.

 

[bobdole369]

Cable signal runs from 5-1000mhz. Satellite TV may possibly interfere as it runs 950-2150 MHz.

Note that the cable system always broadcasts everything available on the line - unless you are trapped out at the distro closet. This is less and less common as digital boxes are the norm and analog tv signal over cable is being phased out. So even though you might not have "TV Service" you will see ALL the digital channels on your line. And while Internet might only be transmitted/received on 30mhz or so of that cable, it will be very full down low.

Noting that a diplexer cannot possibly introduce latency. It's a passive device, its a simple filter that says "hi freq go this way" "lo freq go that way". Its only a bunch of caps and inductors of the right value. It won't do anything but slightly reduce (usually by 6db) the signal towards the upper or lower edge - ant thats usually just fine.

So the short answer - it depends on your cableco and what frequencies they are using for Internet. The diplexer solution is the most likely to work well.

DBS freq range according to Wikipedia
http://en.wikipedia.org/wiki/Satellite_television

In the United States, service providers use the intermediate frequency ranges of 950-2150 MHz to carry the signal to the receiver. This allows for transmission of UHF band signals along the same span of coaxial wire at the same time. In some applications, (DirecTV AU9-S and AT-9) ranges the lower B-Band and upper 2250-3000 MHz, are used. Newer LNBFs in use by DirecTV referred to as SWM, use a more limited frequency range of 950-1800 MHz.

DOCSIS frequency range according to Bradyvolpe.com
http://bradyvolpe.com/docsis-101/docsis101_rf-fundamentals/

Typically the range of frequencies that are delivered to our homes for television signals is 54 MHz to as high as 1000 MHz (though many current systems only support 750 MHz or 860 MHz).

 

[Plugers]

Comcast internet channels in my area are 579mhz-603mhz(ch 83-87), although it is still on 749mhz(ch 115) in a few areas not migrated to the new (DOCSIS 3) channels yet.