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Danja

join:2012-08-05
Columbus, IN

[Signals] Signal strength for modem (can I use a splitter)

Hello,

I'd like to hook up both a set top box and a modem to a single coax jack. Unfortunately, when I tried this using a GE splitter from Walmart, I got very poor streaming video performance through the modem. I'm wondering if there's a splitter or amplifier available that would alleviate this problem. Here are the specs of the modem (SB5100, taken straight from the manual):

Downstream:
-15 dBmV to + 15 dBmV
Upstream:
+8 dBmV to +53 dBmV

Here is what the modem sees when it's hooked up directly to the coax jack:

Downstream
Signal to noise: 35-36 dB
Power level: -9 dBmV
Upstream
Power level: 34 dBmV

And here is what it sees when it's hooked up through the splitter:

Downstream
Signal to noise: 34 dB
Power level: -14 dBmV
Upstream
Power level: 38 dBmV

It seems that even straight from the wall jack my signal strength is on the low end of what the modem can take, and when I hook up the splitter it degrades it to the edge of the operating envelope. What are my options? Should I buy a high quality splitter such as from Monster or CableVision? Should I get some kind of signal amplifier?

Any help would be appreciated.



beachintech
There's sand in my tool bag
Premium
join:2008-01-06
kudos:5

You need to have a tech come out to fix your signal issue. It's very lopsided.

Are you putting a 2 port splitter on there or bigger?
--
Ex-Tech at the Beach.
I speak for myself, not my former employer.



tshirt
Premium,MVM
join:2004-07-11
Snohomish, WA
kudos:4
Reviews:
·Comcast
reply to Danja

Your signals are too low (probably, modems are NOT prescion meters and can be off by several points) on the downstream side.
If you can't eliminate a splitter (or 2) by using a different jack call for a tech.
Do NOT waste money on a consumer grade amp, they rarely work well with HSI (they are intend to help TV signals) If an home amp is required CmCast will supply a professional model, more likely they would change your tap value or re-adjust a line amp.
Even more likely is replacing some cables, the splitter(s) or the house drop will fix the problem.

Expand your moderator at work


ropeguru
Premium
join:2001-01-25
Mechanicsville, VA

1 edit

Re: [Signals] Signal strength for modem (can I use a splitter)

He is wanting to split the coax cable signal. Ethernet hubs don't have anything to do with that.

Just trying to avoid confusion ...



pclover

join:2008-08-02
Santa Cruz, CA

1 edit

Etherent hubs have NOTHING to do with coax and cable.

Yes, I would get a tech out there.

Any idea if your house is wired with RG59 or RG6 cable?


Danja

join:2012-08-05
Columbus, IN
reply to Danja

Thanks for the help guys. I had Comcast send a tech out and the signal downstream has been boosted to 0 dBmV after applying the splitter. It still drops occasionally but much less than before, and at this point I suspect at least part of the problem is outside the scope of Comcast. Thank you all for your help.