HDTV VoIP and Internet: Even the Cable Guy is Stumped

November 19, 2007 6:12 PM

Set up for cable, internet and VoIP in a three-level townhouse. Current set up is all farked up.

Situation: three-level townhouse. His office on second floor. My office on lowest level, in the basement. I have a tv hooked up to cable, with no box, basic channels. The first floor has our 50" tv, with the digital cable box, the modem and router for our wireless internet and the modem for our VoIP (Vonage, if it matters).

We're getting serious pixelation on our HD channels, less so on non-HD channels. The screen breaks up horribly on HD channels, and the sound hiccups. Some channels are worse than others. Whenever we use the phones, it gets unwatchable.

Cable comes into the house through the basement and splits. One goes to my tv, and the other goes up to the first floor, then splits again to feed the internet and VoIP.

The Comcast Guy came out today to troubleshoot the pixelation. He changed out every junction, tightened everything, and tested the signal from the main Comcast box. Signal coming into the house is strong. Signal going to my tv is strong. Signal going to first floor to big tv is strong before the split to the modems, etc. There was some improvement overall, indicating a possible loose connection, but as soon as we tried the phone the big tv screen actually froze.

Comcast Guy suggests that maybe the signal is being diluted at the splits on the first floor, and that we should move the modems / router to the lower level on the cable with my tv, since it's not HD and would take less signal strength to get a good picture. However, we can't get a good wireless signal to the second floor for the internet if the router is on the lower level. The VoIP and internet modems / router have to be next to each other for cabling, or so we believe.

What to do, Hive Mind? Any suggestions?

posted by Corky to Technology (9 answers total)

You can stretch CAT5 328 ft. before you need a repeater -- the modem and router don't have to be near each other.
posted by hjo3 at 6:18 PM on November 19, 2007

However, we can't get a good wireless signal to the second floor for the internet if the router is on the lower level.

Well, if this is the only issue (that is, if following the comcast guy's advice solves all the other problems) then couldn't you just plug in the modem where he suggests and run a long cable to where-ever is the best placement for the router?
posted by winston at 6:20 PM on November 19, 2007

Move the modems and router to the lower level as suggested, and put a wireless repeater on the first floor so you can get good wireless signal on the second.
posted by bac at 6:20 PM on November 19, 2007

Move the cable modem as suggested, and send your interpipes connection up to the second floor through the electrical loop. A pair of "HomePlug" devices do it pretty well at my in-laws' house.
posted by genghis at 6:21 PM on November 19, 2007

However, we can't get a good wireless signal to the second floor for the internet if the router is on the lower level. The VoIP and internet modems / router have to be next to each other for cabling, or so we believe.

High gain antennas, bridges, and repeaters give you a lot of wireless options.

These items dont have to be next to each other. You can run cat-5 cable safely for 100 feet.
posted by damn dirty ape at 9:00 PM on November 19, 2007

Did he test the signal AFTER the splitter on the 2nd floor? That may be where your problem lies. I had this same issue - the seasoned Comcast tech who finally fixed it ended up putting in a signal amplifier before my splitter. He also told me that the new digital stuff has been causing a mess with signals all over the place - I got the feeling that the equipment Comcast has in a lot of buildings isn't always capable of providing a strong signal to everyone.

Also, browse to http://192.168.100.1/signal.htm and post what your upstream and downstream power levels are. I don't know what the "proper" levels are, but my signal is 5dBmV downstream, 46dBmV upstream, and I get 8Mbps down / 1.2 Mbps up at the moment.
posted by chundo at 9:34 PM on November 19, 2007

you need your cable to do a homerun for the modem. forget wireless signal and get powerline adapters. the homerun will isolate the modem. the power line adapters will connect everyone in the house without dealing with wireless signal degradation.
posted by Davaal at 11:35 PM on November 19, 2007

chundo's (unlinked) link doesn't work for my modem. The OP may just want to start off at http://192.168.100.1 and browse around to find where it lists your signal strength.
posted by philomathoholic at 12:25 AM on November 20, 2007

The phone is supposed to operate on a different frequency than the frequencies video lies on. If using the phone is causing video droppage, a possibility that the phone is operating outside of its allowed spectrum.

If it's a Moto box, hit the power button, then select. It'll come up with a diag screen. Go to option 3, which is most likely OOB status. Take a look at the SNR. It should say "good," but the actual levels will vary quite a bit. If it says poor, then you've already found the problem. If not, use your phone. If it drops to poor while using the phone, you've just confirmed that your phone is causing the problem.

All that aside, I'm pretty sure it's bad wiring/levels. Everything was/is split is wrong. Splits cost 4.5dBmv per output (ie: two-way has 4.5dBmv loss, four-way has 18dBmv loss) which means that your basement will have the best signal, while everything else will sort of suck.

As far as cable-land stuff, this is all pretty basic, and I'm genuinely surprised the cable guy couldn't figure any of this out. Have them send another person out.
posted by onedarkride at 5:11 AM on November 20, 2007