View Full Version : Cell phone interferes w/ HD signal strength...

12-02-2007, 05:41 PM
Had a tech over today to replace one of my cable cards and look into a sporadic signal dropping problem I've been having.

Turns out that my cellphone (AT&T Wireless) interferes with the signal on the HD channels -- I'm using Astound Broadband in the SF Bay Area. Watching the signal strength meter it hovers around 80 and then when I make a call on my phone it drops down into the 20s...

Anyone have any ideas other than switching cable/cell services?

12-02-2007, 06:58 PM
I'm in the bay area and have Comcast for broadband internet and cable, and AT&T wireless, and no issues. GSM phones can cause interference (try placing your GSM phone near you home cordless phone and you'll hear an interesting noise), but I've not had an issue with HD reception.

12-02-2007, 07:04 PM
I'm using Astound Broadband in the SF Bay Area. That's an odd problem for cable TV. Very odd. I looked up the site to see if maybe it was a wireless variation, but it does appear to be cable. Also, I noticed this when I went there:Digital Video Recorder (DVR): Forget TiVoŠ, Astound offers you digital video recording for a fraction of the price Isn't that nice of them? :down:

12-02-2007, 08:27 PM
Not odd at all. I had RCN in SF (before Astound bought them) and had *exactly* that behavior whenever my Treo was too near the Motorola 6412 cable box. It got a lot worse when I made a call.

As for why this might be more pronounced on Astound's network that Comcast? One reason is that Astound's cable plant goes up to 855 mhz, where comcast's doesnt. (Isn't one of the GSM bands right around 850Mhz?)

I would suspect that the interference might be more prominent on some channels than others, but I never experimented. I just kept my phone away from the TV.

You could ask astound to replace the wire in your house with quad-shield and see if that helps, I suppose.

12-02-2007, 08:47 PM
The interference is w/ the cables and not the Tivo? I wired all the cable lines myself and have easy access to them, so that might be an easy fix.

Does anyone have any experience w/ the quad RG6 from monoprice?

Also, the in-wall cable goes to an outlet box, is that a possible source of interference?

12-02-2007, 08:50 PM
Is it just when your phone gets too close to the box or is it the cable too?

If it's just the box you can build yourself a faraday cage for it. :)

12-02-2007, 08:56 PM
The problem between GSM handsets and electronic equipment is that when in a call, the transmitter is pulsing, transmitting in its time slot and off at other times. A CDMA handset, OTOH, transmits continuously across a relatively broad frequency band (1.25MHz), and rarely interferes with electronic equipment.

12-03-2007, 09:08 AM
I know you are talking about cable but over the air is even worse. My cell phone (att) makes watching the digital/hd signal on my hdtv almost impossible. If I get a call the screen goes blank and even when I don't I will see blocks at random times. I will often put my cell in another room to fix the problem. Like what has already been stated that is one of the worst things about GSM networks. My car speakers will put out noise from interference caused by my phone.

12-03-2007, 11:33 AM
My phone interferes with basically everything. My car stereo, my computer speakers, my home phone, my OTA reception, my sound system...