Cable Modem and Splitter Problem

[BigJimbo]

Okay my friends dad wired a TV in the office and ran a splitter off the wall jack which runs to the modem and the TV. The modem "Cable" light vary rarely turns solid (from blinking state). Do you think its the splitter? I don't live there so I dont know if that just started recently or since he put the TV in there.

I've heard in the past that a splitter could affect the cable modem is this true?

 

[imported_Bunter]

Cable modems are more signal-strength sensitive than TVs. If he can, I'd highly recommend splitting the cable connection where it comes into the house, and dedicate one of those splits to the modem. That way the modem gets the best connection it can. The other can be further split for TVs. If he can't do that, he probably need a signal amplifier.

Have him try connecting the modem to the jack by itself and see if the signal is strong enough without the TV. At least that will narrow down the problem.

 

[Cheetah8799]

If he only has 2 devices, it should be ok. But if he has like 4 TVs all split off of the main cable line, then there may be problems with the signal strength in the cable.

I'm sure someone with more cable knowledge can correct me, but I think it doesn't matter where you split the cable connection. When split at any point, all of the connections on that cable are degraded the same amount. I think there is a loss in total strength as well with each split.

Anyway, avoid splitting the cable too many times. More than 3 or 4 is a problem for sure, unless if you have a good cable coming to your house.

 

[imported_Bunter]

Installers have told me to split the modem out at the earliest point to avoid it going through multiple splitters. Apparently you want the data line going through as few connections as possible.

 

[BigJimbo]

Yea at my house we had them route a new line for the cable modem ie 2 lines comming in.

When i hooked the modem directly to the wall It worked but he doesnt beleive that is the problem. I just wanted to see if anyone could confirm this was correct

 

[dcheng]

I live in a house that has funky pre-1990 coax runs. In order to get my cable modem to work, we were limited to 2 rooms in the house, and we had to drop one of the splitters. Now anytime there is work done in the neighborhood, I almost always lose my connection and have to call in to have them rejigger (technical term) the load coming to my house.

Anyway, all that is to say that during the initial install, the tech told me that each splitter only affects the lines coming off the splitter, so the ideal place to have the splitter is as close to the de-marc, then dedicate one line for the cable modem. The standard splitters degrade the signal by about 3.5dB. The other thing to watch for is whether the splitter is able to pass the higher frequencies since the data portion runs in the higher frequecies.

If you're forced to use an amplifier (which the installer tried), you need to get one of the ones that is rated for two-way communication. One of the problems with these amplifiers is that they also degrade the signal getting to the cable modem, as well as the signal coming FROM the cable modem. Most cable modems put out a max of about 57dB of power. If you barely get a signal, putting an amplifier to boost your receive signal can add just enough degradation to the send signal that the 57dB is no longer enough to get sync on the provider's end. Depending on the model of cable modem, you may be able to check the power levels of your modem from whatever interface it uses. For example, I seem to recall that my cable modem (Motorola Sufboard 4100) was putting out 56 or 57dB or power, which means that if I add another splitter or amplifier in the cable modem path, I no longer sync.

Now, I do not work for the cable compaies, nor do I know that much about cable modem technology, so take all this with a grain of salt.