Splitting Coax: How Much Is To Much?

DepotDepot The ModFather Join Date: 2002-11-09 Member: 7956Members
in Off-Topic
<div class="IPBDescription">Db loss, high noise ratios, etc.</div>Yesterday I helped a lady convert her computer setup from 56k to high speed cable. It wound up being an all day project for one reason or another, and I found out she has a TV in like, every room in her house. Therein lies the problem, and is the nature of my questioning.

There is one main heavy-duty coax from the street to a heavy-duty splitter. Three cables leave the splitter, one of them going to another splitter. Two cables leave this splitter, one of them goint to the computer's cable modem (and, I need to install a new 3-out splitter here, to run coax to the kitchen, which I robbed to get to the computer).

Comcast says my signal strength at the modem is normal, but the noise ratio is high. Her speed is also a lot slower than mine, and we're supposed to have identical packages (Comcast offers 3 speeds here). I am thinking all of these splitters are causing an issue.

How often can you split coax before it's a problem? Are some splitters better than others, and are all meant for external (outdoors use)? What would <b>YOU </b>do in this situation, to get the best signal to the computer? <img src="style_emoticons/<#EMO_DIR#>/confused-fix.gif" style="vertical-align:middle" emoid="???" border="0" alt="confused-fix.gif" />
Off Topic Disagree Agree Awesome

Comments

  • puzlpuzl The Old Firm Join Date: 2003-02-26 Member: 14029Retired Developer, NS1 Playtester, Forum Moderators, Constellation
    edited November 2006
    It depends on the quality of the splitters, and how much attenuation they introduce. A docsis cable modem needs between -10 and +15 dBMv power on the modem receiver and it needs an SNR of about 20dB depending on the downstream modulation. If you are getting the right signal power but poor SNR then it might be something you can solve. Each time you split the signal, you introduce noise and attentuation. Some powered splitters provide amplication and some filtering to clean up the signal, but this isn't suitable for docsis. The best thing to do is to take the signal as early as possible and connect it to the cable modem to see if the noise problems go away. ideally the first split should be two-way, one for data, and one for tv. You can then split the tv signal as often as you like, but each split will reduce the signal quality and the resultant picture quality.

    What model cable modem do you use?
    Off Topic Disagree Agree Awesome
  • DepotDepot The ModFather Join Date: 2002-11-09 Member: 7956Members
    Thanks puzl, that all makes sense. What I can do is connect the modem to the first split instead of the second, and take another snr reading. If it's significantly lower, we'll have to do some re-routing.

    The cable modem is a Motorola, SB5120 I believe. I have one here and have no qualms with it. It's also by far the most popular modem around these parts, available at Best Buys now for $59.00 with a $20.00 mail in rebate. I think this is the same one Comcast uses if you rent one from them.
    Off Topic Disagree Agree Awesome
  • OmegamanOmegaman Join Date: 2004-01-11 Member: 25239Members
    The fact that I understood more than half of this techno-babble makes me very proud. <img src="style_emoticons/<#EMO_DIR#>/smile-fix.gif" style="vertical-align:middle" emoid=":)" border="0" alt="smile-fix.gif" />
    Off Topic Disagree Agree Awesome
  • DepotDepot The ModFather Join Date: 2002-11-09 Member: 7956Members
    I think what I need is to hook a one-to-four splitter onto the main line. Two of the four feed the living room and main bedroom TVs, #3 runs to another one-to-two splitter around the corner of the house, and #4 runs directly to the cable modem. The one-to-two splitter will feed TVs in the kitchen and spare bedroom.

    Now, what am I looking for exactly in good one-to-four and one-to-two splitters?
    Off Topic Disagree Agree Awesome
  • ultranewbultranewb Pro Bug Hunter Join Date: 2004-07-21 Member: 30026Members
    The usual solution is to throw more money at it and an rf amp is the easiest can't miss method.

    example: <a href="http://www.ramelectronics.net/html/rf-cable-satellite.html#amp" target="_blank">http://www.ramelectronics.net/html/rf-cabl...ellite.html#amp</a>
    Off Topic Disagree Agree Awesome
  • CForresterCForrester P0rk(h0p Join Date: 2002-10-05 Member: 1439Members, Constellation
    Hey Depot, check <a href="http://www.dslreports.com/faq/cabletech" target="_blank">this</a> out. They have lots of information about wiring, and getting the best signal quality for cable modems and TV.
    Off Topic Disagree Agree Awesome
  • DepotDepot The ModFather Join Date: 2002-11-09 Member: 7956Members
    <!--quoteo(post=1581811:date=Nov 28 2006, 10:27 PM:name=ultranewb)--><div class='quotetop'>QUOTE(ultranewb @ Nov 28 2006, 10:27 PM) [snapback]1581811[/snapback]</div><div class='quotemain'><!--quotec-->
    The usual solution is to throw more money at it and an rf amp is the easiest can't miss method.

    example: <a href="http://www.ramelectronics.net/html/rf-cable-satellite.html#amp" target="_blank">http://www.ramelectronics.net/html/rf-cabl...ellite.html#amp</a>
    <!--QuoteEnd--></div><!--QuoteEEnd-->
    <!--quoteo(post=1581813:date=Nov 28 2006, 10:56 PM:name=CForrester)--><div class='quotetop'>QUOTE(CForrester @ Nov 28 2006, 10:56 PM) [snapback]1581813[/snapback]</div><div class='quotemain'><!--quotec-->
    Hey Depot, check <a href="http://www.dslreports.com/faq/cabletech" target="_blank">this</a> out. They have lots of information about wiring, and getting the best signal quality for cable modems and TV.
    <!--QuoteEnd--></div><!--QuoteEEnd-->
    Thanks guys, checking out both links. <img src="style_emoticons/<#EMO_DIR#>/wink-fix.gif" style="vertical-align:middle" emoid=";)" border="0" alt="wink-fix.gif" />
    Off Topic Disagree Agree Awesome
Sign In or Register to comment.