Cell Phone Interference? - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 8 Old 09-29-2008, 04:59 PM - Thread Starter
Senior Member
 
xlr231's Avatar
 
Join Date: Feb 2007
Location: Fort Wayne, IN
Posts: 252
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 10
Does anyone else have a problem with their cell phone causing interference with with their HDTV reception?

Anytime I make or receive a call the picture freezes and the signal drops out on WFFT. It doesn't effect any other channels. The phone is a GSM (850/900/1800/1900MHz) T-Mobile phone that is supposed to operate at 1900MHz here. According to the FCC WFFT operates in the 602-608 MHz band so I don't know why it would interfere.

Any ideas why this happens?
xlr231 is online now  
Sponsored Links
Advertisement
 
post #2 of 8 Old 09-30-2008, 02:05 AM
Member
 
louie826's Avatar
 
Join Date: Dec 2006
Location: Visalia, Central CA
Posts: 195
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I don't know why, but I just want to add that I also have interference issues on my TV on any digital channel. It happens when I turn on or off my cell phone, or an incoming call arrives to the phone.

All of the digital channels on my TV come in through QAM or unscrambled digital cable channels.
louie826 is offline  
post #3 of 8 Old 09-30-2008, 07:39 AM
Advanced Member
 
nybbler's Avatar
 
Join Date: Sep 2006
Posts: 697
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
It's probably the dreaded GSM buzz, though it doesn't make a lot of sense that it would affect only that channel; the GSM buzz is at 217Hz.

Easiest way to fix it is to move the phone away from the TV; some people apparently have had success with ferrite beads; you'd put one around every cable going into the TV that doesn't already have one.
nybbler is offline  
post #4 of 8 Old 09-30-2008, 09:21 AM
AVS Special Member
 
Falcon_77's Avatar
 
Join Date: May 2007
Location: OC, CA
Posts: 2,602
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by nybbler View Post

It's probably the dreaded GSM buzz, though it doesn't make a lot of sense that it would affect only that channel; the GSM buzz is at 217Hz.

Is that what causes my phone to buzz when a co-worker's cell phone gets too close? It's very annoying, especially when I'm talking with clients. My VZ phone doesn't do this, but my old Nextel phone did.
Falcon_77 is offline  
post #5 of 8 Old 09-30-2008, 01:26 PM
AVS Special Member
 
m_vanmeter's Avatar
 
Join Date: Feb 2006
Location: Georgetown, KY
Posts: 5,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 21
radio frequency interference (RFI) caused by the slightly more powerful transmitter in the GSM phones. When turned on or off and when receiving a call, the cell tower negotiates with the phone for the necessary transmit power level to make the connection and complete the call. The same happens with a data transmission if your phone has a data package. GSM protocal phones seem more prone to this type of RFI than do CDMA phones used by Verizon and Sprint.
m_vanmeter is offline  
post #6 of 8 Old 09-30-2008, 03:31 PM
Member
 
jimmyv2000's Avatar
 
Join Date: Mar 2008
Location: Manchester NH
Posts: 117
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 11
Quote:
Originally Posted by Falcon_77 View Post

Is that what causes my phone to buzz when a co-worker's cell phone gets too close? It's very annoying, especially when I'm talking with clients. My VZ phone doesn't do this, but my old Nextel phone did.

my presonal phone Vz doesn't do this
my work phone AT&T buzzes alot and interferes with the radio too

JIMMY
jimmyv2000 is offline  
post #7 of 8 Old 09-30-2008, 08:10 PM
AVS Special Member
 
Falcon_77's Avatar
 
Join Date: May 2007
Location: OC, CA
Posts: 2,602
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by jimmyv2000 View Post

my work phone AT&T buzzes alot and interferes with the radio too

GSM can put out 1-2W? I remember seeing specs on my phone and it was close to 0.5W.

I talked to my co-worker and it is an AT&T phone.

So, what's going to happen when (if) phones try to use "white-spaces"?
Falcon_77 is offline  
post #8 of 8 Old 10-01-2008, 09:56 AM
Advanced Member
 
nybbler's Avatar
 
Join Date: Sep 2006
Posts: 697
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
During certain GSM operations the transmitter is pulsed with a 25% duty cycle at 217Hz. The 217Hz (and its harmonics) can couple directly into speaker amplifiers and cause the distinctive buzz. Presumably it can also couple into other circuitry and cause interference.
nybbler is offline  
Reply HDTV Technical

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off