sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring House with too many TV's and not enough Signal strength.

OK So right now I've got the main line coming in from the cable company under the house.

There is a powered drop amp, which has the following ports: 3.5db drop port, and three 7db drop ports.
From there I have the 3.5db drop port traveling probably about a hundred feet back under the house the way it came in from the road, up the side of the house and into my room where I have my cable modem.

In my room -- comes in the wall, I have a 3ft cable going to a splitter w/ 3.5db drop per port, one going to the cable modem, another going to another splitter w/ the TV and the TV tuner card in my computer.

Back downstairs -- I have a DVR on one of the 7db drop lines, another 7db drop line coming up the wall of the house to a splitter that goes to 2 different rooms, and am soon installing another line to go to my grandmothers room as she just moved in with me w/ a full time care-giver.

Mostly everything looks OK, but the cable modem drops atleast 10 times a day for 10-15 second intervals, sometimes more... which is a serious pain in the arse as you can imagine.

So I'm wondering what I could install, and where to install it, in order to prevent the cable modem from droping it's connection.

Any help would be appreciated as I'm more of an RJ45/Ethernet Networking guy, and haven't done much with Coax. Thanks!

Did the cable company install that amp? Normally you want your modem feed to be connected with a two way (3.5db per drop) splitter before the amp. Most amps aren't two way compatible (send & receive). Then you would normally dedicate that one line drop strictly for your modem. I realize you are going a long way with that run to your room so it may not be convenient to install a 2nd line for your tv and tuner card. I would try it the way you have it with that splitter in your room, but with that feed before the amp.

First place I would look is the splitters, are they rated 1000mhz or better, all empty ports terminated, and are all connectors on correctly, look carefully inside each one for a small whisker from the braid, if you see one replace the connector......Here are a couple links to help you to dig down into the modem you have and check for incoming signal strength
and some tips on trouble shooting:

https://homepage.ntlworld.com/robin.d.h.walker/cmtips/signal.html#caution
https://www.dslreports.com/forums/all

Hope this helps and post back how things are going....

Thanks for the suggestions, and yes all my splitters are bi-directional (2way) and 5-1000mhz rated. I didn't think about putting a splitter in before the amp but I'll try that. Also, would putting a line amp in before the splitter help or no?

Line amps are not normally a good idea on the modem line at all. The problem is that the non commercial grade ones don't have the circuitry in them to distinguish between data and noise.

Ditto

I got board one day and recabled my house with a Comcast guy, He provide me with an Amp. LAter I got a cable modem, I had to seperate a leg off before going into the Amp to run the modem. (no the Amp didn't make it go faster )

OK well I went with suggestions and put a 3.5db splitter in FRONT of the amp, so I have a line going from the splitter to my room, a 3 foot cable going to another 3.5db split, one 3ft line going to the cable modem, another 25ft line going to the TV / TV Tuner in the computer.

The other line goes directly to the drop amp which distributes to the rest of the house.

We'll see how this goes.

I'm surprised no one has mentioned that the standard for CATV house wiring (just as it is for telephone) is the star configuration. Each location should have a separate RG-6 "home run" back to a central location.

In your case I assume that the location of your home run amp would be a suitable location, much as you did with the run to your cable modem.

Not only does this make servicing easier but it's easier to maintain equal signal levels on all the runs.

So I suggest that as long as you are in the cable running mood make sure you are using an RG-6 type cable and rerun everything.

Other than that I think the advice you were given is good especially about the amplifiers and where to split off the run to the cable modem. To do this whole thing right you really need to measure the signal levels then determine if you need an amplifier and if so what gain.

By the way, if you are using a Motorola Surfboard cable modem you can communicate with it by typing 192.168.100.1 in your browser. I only know Motorola, others may be the same.

It will show you the signal levels of the digital carrier (around 600Mhz) it is receiving as well as the return signal level it is producing. This can be a good troubleshooting tool to diagnose modem problems. If you can't bring up your modem in your browser to begin with you have connectivity problems in your network. If the receive signal level is below -10 or -15 db you may have problems with the your cable connections or the drop itself.

-Hal

No I didn't know about the 192.168.100.1 but I have an RCA Digital|Broadband modem and it works too.

/edit/

--- Cable Signal Details ---
Forward Path:
Signal Acquired at 633.000 MHz
SNR: 32.7 dB
Received Signal Strength: -8.6 dBmV
Bit Error Rate: 0.000 %
Modulation: 256 QAM


Return Path:
Connection: Acquired
Frequency: 21.0 MHz
Power Level: 35.0 dBmV
Channel ID: 3
Modulation: 16 QAM


Data Service Details
Provisioned Address: Yes
Provisioned Time: Yes
Provisioned Configuration: Yes
Registered: Yes
BPI: Enabled

This info will probably mean more to you guys than it will to me, so tell me if something's off and let me know how to fix it if you can.

[This message has been edited by vaximily (edited September 01, 2005).]

All that matters here is the Cable signal details. The signal level of -8.6dbmv is a bit on the low side and should indicate why you were having problems before with multiple splitters in the line. Each 2 way reduces the signal by 3.5db. All splitters are multiples of 2 ways cascaded in one case so a 4 way would reduce the signal by 7db.

The BER couldn't be better though.

If you want to see what the best you can do is, temporarily connect your modem directly to the cable drop. Bring it there and run a cat5 line back to your computer assuming that you don't have a laptop and are using an ethernet connection.

Note also that the signal level indicated is only the digital carrier at 633 Mhz. The television channel video and aural carriers range from 55 to maybe 750 Mhz and their levels are unrelated to the level displayed by your modem so again you need a signal level meter to diagnose problems and determine what you need to do in the way of any amplification.

-Hal