Splitters 1ghz vs 2ghz to run video and internet from same coax - AVS Forum
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post #1 of 8 Old 09-21-2009, 10:00 AM - Thread Starter
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I only have one coax outlet on the main floor of my new place and currently my comcast digital HD tuner box (from which I get HD digital cable) is hooked up to it. I would like to get comcast's cable internet as well but I really want to put the modem on my entertainment stand next to my cable box.

My question is this: Can I use a coax splitter to plug both my tuner box and cable modem into the same coax? And if so, any recommendation for which one to get (1ghz vs 2ghz, does it matter?)?

Thank you in advance for any help you would be willing to provide! I know absolutely nothing about coax and cable frequencies!
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post #2 of 8 Old 09-21-2009, 10:02 AM
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1 ghz is enough for cable....

As for being able to split it for your internet, most likely will not be a problem, however if their is not enough signal then you could have problems with the TV pixilating and/or the internet dropping offline..
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post #3 of 8 Old 09-21-2009, 10:19 AM - Thread Starter
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Quote:
Originally Posted by Angus.Young View Post

1 ghz is enough for cable....

As for being able to split it for your internet, most likely will not be a problem, however if their is not enough signal then you could have problems with the TV pixilating and/or the internet dropping offline..

Ok great, thanks. So if I discover there is a problem, a signal amplifier may help?
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post #4 of 8 Old 09-21-2009, 04:37 PM
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Quote:
Originally Posted by Jwmart View Post

Ok great, thanks. So if I discover there is a problem, a signal amplifier may help?

It's a certain type of amp called a bi-directional drop amp. Very low gain but it allows your STB and modem needed two-way communication.

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post #5 of 8 Old 09-23-2009, 09:21 PM
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The cable modem "upstream" is below 50Mhz and downstream can be about anywhere, but cable systems typically do not use above 850MHZ... (A little more info why a 2GHz splitter is a waste of money).

When the cable guy gets lazy, they do put modems and boxes on the same run from the demarc point, but that is NOT the proper install method. They should be using a -12dB tap as the very first thing in the system to run to your modem. Lots of legacy and new reasons to do this including tube TVs IF interfering with upstream etc.

The suggestion of a two way amp is a good one if you have trouble, problem is where to put it. An amp should be placed as close to the source as possible (where cable enters your home) to help with cable TV reception - but if the problem ends up being upstream issues, it is best placed closer to the modem. So, if you really get desperate, you can actually put in two - a downstream where cable enters your home and a special upstream only amp next to the cable modem.

Good luck
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post #6 of 8 Old 09-24-2009, 12:37 AM
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[quote=When the cable guy gets lazy, they do put modems and boxes on the same run from the demarc point, but that is NOT the proper install method. They should be using a -12dB tap as the very first thing in the system to run to your modem. Lots of legacy and new reasons to do this including tube TVs IF interfering with upstream etc.


Good luck
David[/QUOTE]

It will really depend on the system you are in.. not as some people like to call everyone lazy without ever having done.. or ever knowing how to do the job properly.

Different cable systems = different rules

lots of places if you were to put a 12 db tap in place your modem would NEVER lock up...
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post #7 of 8 Old 09-26-2009, 07:06 PM
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OK, as a continuation of another question, this thread popped up in my search for the solution. I assume the demarc point, is the point where the underground Comcast cable from the Comcast pedestal enters my home. At that point, I pulled two RG6Q cables to my central room. As a related note, the pedestal is new, the cable drop off of the pole is new, and I am the only customer on that pedestal.

Here is my latest question. David, thanks for pointing me in the right direction but just to be clear;

I have sixteen RG6Q cable feeds to 16 TVs, Tivos in my house. I may have one extra, that is the only one that may or may not be hooked up to a TV, making the total 15.

I have two Motorola BDA-S4 Cable Modem TV HDTV Amplifiers. I expect Comcast will provide the same wireless cable modem/VOIP setup as in my guest house.

Is there any advantage to having each TV video run come directly off one of the outputs on the signal boosters? Will there be any advantage/disadvantage to using 2 way splitters to take the eight outputs to sixteen (enough needed) besides cost? (and extra $100 for two more). I also can use CDA-4As if they are better then the Motorola's. I have attached the spec sheet on the Motorola below.

I studied the diagram and went through the signal loss of using splitters. It seems like the further down the chain the amplified splitters are, the better. Also, it would seem that using four amplified splitters ($200) for up to 16 amplified outputs would be best.

OK, here is where I am a bit lost. The cable into the building will go to a splitter, one side could be split to four amplified splitters, the other side will go to the Comcast cable modem/VOIP unit. Does this side need to be amplified also? What is a good quality splitter? Does Home Depot or Lowe's carry these or should I order? I can have most items in 1 day through Amazon. If you had to pick the exact splitter for this install, what would you use?


In time, a more expensive unit will be planned, for right now getting video, Internet, and phone working is a priority. I do have a 6 zone sound system, but that will be later once this other stuff is working.


LL
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post #8 of 8 Old 09-26-2009, 10:54 PM
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Quote:
Originally Posted by rhiatlanta View Post

OK, here is where I am a bit lost. The cable into the building will go to a splitter, one side could be split to four amplified splitters, the other side will go to the Comcast cable modem/VOIP unit. Does this side need to be amplified also?

The first thing that needs to be known are your signal levels. EXACTLY how is your cable modem currently connected and what are your upstream and downstream power levels as found at http://192.168.100.1?

With an input level of +10dBmV, a standard 15dB gain drop amp can feed 24 outlets at 100 feet away, so 16 outlets should be no problem. A 4-output drop amp is nothing more than a standard 15dB gain drop amp with a 4-way splitter on the output. Just put a 4-way splitter on each output of one of those BDA-S4s to give you 16 outlets. Just what is done at the input of the amp will be determined by the signal level you obtain from your cable modem.

CIAO!

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