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I have a cable TV plus Internet coming into the house and into an 8-way splitter (CE Tech Home Command Center). From this splitter I have coax going to the cable modem plus 3 TV's. When I have my cable provider refresh my signal everything works fine for about two months. Then the interet gets gradually slower, and I have to have a signal refresh again. When I take the splitter out, the internet is back to full strength.

My question is how can the splitter gradually degrade the signal? It is just physical coax connections, no amplification or other electronics. I don't see how it can work on day 1 and gradually get slower.

Also, I could split the cable from outside, connect one to the modem and the other to the command center for the 3 TVs. Or I could buy a signal amplifier and boost the signal before it gets to the command center. Any recommendations on this?

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  • I can't speak to gradual degradation but you don't want to be splitting the signal that much without a powered splitter. I'd look into a powered splitter and see if that fixes things.
    – DA01
    May 28, 2014 at 1:11
  • One reason that your signal can degrade over time is changes in the network outside your home. Every time they add someone else to your local loop, your signal level goes down a fraction. The cable companies should be monitoring those levels; your cable boxes and modems report their signal levels back for precisely this reason. When they notice, then they either split the loop or they boost the transmit output for that loop. That's in a perfect world, though.
    – longneck
    Jul 6, 2016 at 18:22

3 Answers 3

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It sounds like you might just be dealing with a bad splitter, so my first recommendation would be to just replace the splitter.

There is a loss associated with every port on the splitter. If you look on the splitter, you'll probably see something like -4dB printed on each port. This is how much signal loss there is on that port.

Typically your cable modem will be connected to a splitter directly from the source feed, then all other TVs split from a secondary splitter.

Amplifiers usually just add noise and if there is a signal quality issue, it's best to work with your service provider to get the addressed.

Bad connector fittings on the end of the cable can make a huge difference, as can the length and quality of the cable used. By SOP, most cable installers would probably replace every RG6 compression fitting between the source and the modem.

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    A couple follow-on points: 1) the more outputs a splitter has, the more signal is lost, even if some of them are unused. 2) Higher quality splitters lose less signal. Look for the dB rating, as you say. 3) Some splitters are "unbalanced" meaning the outputs have different strengths. This may be useful for something like an internet modem, which you would want on the strongest signal.
    – Hank
    May 27, 2014 at 20:29
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    Unbalanced is known as a Tap. Charter recommends the first splitter be a tap with the low loss leg going to the cable modem.
    – Fiasco Labs
    May 27, 2014 at 20:40
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Sorry, can't comment yet due to "lack of reputation"

So here's an answer instead.

Steven makes a good point about signal loss at the splitter. You should do your best to use the smallest splitter possible, and one that is designated for digital frequencies (older ones weren't tested for interference here).

In the event that you cannot find a proper splitter, you should look into properly terminating the open ports:

https://www.amazon.com/Type-75-Ohm-Terminator-Pack/dp/B000AAN76Y

That's cheap and should well exceed the quantity you need.

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  • Aaaaand... I just realized this is a 2.5 year old question, and this is why I have no reputation... No bumping rule for unanswered questions? :|
    – user61305
    Oct 20, 2016 at 18:23
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You did not identify the cable modem type and model.
So only based on a Surfboard I reset my own monthly, The logs are cleared monthly.
But from studying the logs and talking with the engineers for our cable company, modems keep track of network conditions.
They will if repeated occurrence of interference occurs, both internal and external, that change one or more of the bonding channels used in a disruptive manor that channel can get bumped from usage. If enough disruption occurs to signals the modems will drop back to a slower through put.

I see the most trouble in our area when lightning storms and high winds occur (we have overhead lines). And then heavy issue when snowbirds return and leave causing techs to add-in or removal of service in area.

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  • So, a "signal refresh" by a cable company is more like an adjustment to the DB level they're sending you? If so, that, and your snowbirds bit, would completely explain why the signal degrades over time and can be fixed with a phone call.
    – Mazura
    Oct 20, 2016 at 22:49
  • I quit calling just log into modem and do a hardware reset. But. yes it resets levels, clears locked channels and such. Usually can do same by unplugging modem for about 5 minutes.
    – spicetraders
    Oct 20, 2016 at 22:57

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