My cable modem is causing my lowest TV channel to be fuzzy..

S

SonicTron

Snopes is My Fact Checker
Joined
Mar 9, 2000
Messages
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OK this is weird. And hasn't happened until recently.

My Surfboard 5120 modem has started causing extreme static on channel 3 when its plugged in. BUT ONLY when:

1) it is fully connected to the cable provider
2) there is a lot of data transfer happening (it gets much more intensely staticy)


For example, if the modem is plugged in but no systems are turned on, there is no static. If I'm on the pc and I am navigating sites with heavy image load, there are white static lightningbolts shooting across the screen for a few moments. If I am downloading torrents, there is NONSTOP static shooting across the screen and a crackling sound.

The channel is still there...and the image between the static lines shooting across the screen are not affected. The quality is still there but its like lightningbolts of white static and crackling are shooting across the screen, making watching that channel very unpleasant.

I'm going to replace all the wires and maybe the 900mhz splitter I have in place. But still I would like to know what is the cause of this, so maybe someone out there can help me :)

Edit: also, this ONLY happens on Channel 3. Channel 2 is unaffected, and all channels over channel 3 are unaffected. ONLY CHANNEL 3!! What the heck ?! =P

cable from the wall goes to the splitter, then one cable plugs directly into the TV and the other directly into the Modem.

ALSO other TV's in the house are affected. But the static is much much less noticeable on those TV's when there is high data transferring.
 
Heres my modem info while under heavy data duress

Downstream Value
Frequency 597000000 Hz
Signal to Noise Ratio 32 dB
QAM QAM256
Network Access Control Object ON
Power Level -10 dBmV
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
Upstream Value
Channel ID 6
Frequency 32000000 Hz
Ranging Service ID 2201
Symbol Rate 2.560 Msym/s
Power Level 58 dBmV



Heres what it looks like with nothing going on

Downstream Value
Frequency 597000000 Hz
Signal to Noise Ratio 32 dB
QAM QAM256
Network Access Control Object ON
Power Level -10 dBmV
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
Upstream Value
Channel ID 6
Frequency 32000000 Hz
Ranging Service ID 2201
Symbol Rate 2.560 Msym/s
Power Level 58 dBmV


I think they are exactly the same..
 
I'd call your cable service provider and get them on it. If you have to, I'd politely remind them that there are lots of choices for TV and broadband connectivity. My guess is that they'll be all over it.

Good luck - :cool:
 
I had a similar problem not too long ago, but it was more than one channel and only affected the TV with the digital cable box. Some lines were replaced and a signal amplifier was added inline, and the problem went away.

But as BlindedByScience said, call the cable provider, they'll get it sorted out.


 
I had the same problem with a DVR that I had a while ago. The cable company send the first guy over who was convinced the problem was the cable box. They swapped the box but the problem remained. The second guy put up a signal amp on the line and things were great after that.
 
Someone with more cable experience can correct me if I'm wrong, but generally cable modems operate at higher frequency's than that of Channel 3. (Totally dependent on the ISP's HFC network)

Generally the channel's/frequency's they are using to operate the cable modem will be un-accessible. (For example channel 100, operating at 1000mhz for downstream and channel 50, operating at 50mhz for upstream)

Basically what I'm saying is, I don't see how the cable modem is affecting your TV. Cable Modems are more susceptible to signal level changes than TV's, due to the specific range they have to operate in. (In the HFC network i've worked on, it was -15 to +15 upstream, +36 to +58 downstream)

I do however agree with the other guys. Call the cable company, they will sort it out.

The only thing I can think of off the top of my head is a issue with channel 3 and the frequency it operates at. They may be getting some signal bleed into channel 3's frequency from another frequency that the cable modem is operating at. (i.e 3.0mhz for channel 3, and 3.1mhz for the cable modem) Thus causing the issues.
 
The transmit frequency of your modem is 32Mhz which is t-channel 11 and part of the return path spectrum. So that would be a stretch for that to cause problems on channel 3, which is around the 60-66mhz area.

Is this happening to all of the TV's in your house? Is this TV on a splitter with the cable modem?

It is possible that the modem could be going bad, as they modems are cheap, and their tuners have been known to transmit over wider frequency at higher outputs than normal. Also keep in mind on the transmit side, it's not a constant transmission, like the receive, it is very bursty, unless your modem is bad.

Try moving your modem to a different outlet, and check all the connections behind your tv. If there is a splitter, you might change it as it could be going bad.
 
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