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Cell Phone Interference

Interesting. Yes. It is possible the TV power supply is being interferred with. However, if this is caused by the cell phone in close proximity, I would certainly expect the behavior to exhibit while the cell phone is ringing.

It is unlikely that there is a significant change in cell phone RF output power, regardless of signalling vs. voice channel. It may change some, but not enough to matter. (i.e., the difference in antenna response vs. frequency, etc.. Really, not enough to be concerned with.)

Perhaps the TV is at fault and it has nothing to do with the cell phone? Could be a problem in the TV's power supply, or the power quality of the branch circuit it is using has a problem. (such as: abnormal line harmonics, bad neutral, bad grounding or bonding, etc..)

You "might" be able to deduce this by trying to replicate the TV problem by selectivly turning ON and OFF certain high-drain appliances in the home, especially those with motors. Air Conditioner, Clothes Dryer (on high heat), Refrigerator, Hot Water Heater, and/or Hot Tubs, Pool Pumps, well water pumps, etc... if you happen to have those.

Based on your last reply, I am beginning to think the problem is not with the cell phone proximity. It just sounds like a coincidence. (??)

To answer one other question, cell phones do not normally "collect and periodically retransmit" data back to the cell site. Some do, but they are very specialized devices. Not your run-of-the-mill consumer handsets.

-mpm

Reply to
mpm
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I had a flashing back on one of my older phones. It sensed any RF and flashed, thus i knew when it was transmitting..

My current motor Razr seems to run the battery down real fast at times when I enter the place where i am currently at, where there is no reception. It seems to get in some mode where it must be doing a lot of transmitting where there is no reception. Sounds dumb.

Of course teh cell phone will use full power when its in a poor location, and can't back off power like in a good location.

greg

Reply to
GregS

And I can easily hear GSM phones signalling if I'm on a normal phone. Or on the car radio as the GSM phone switches between cell-sites

There's an interesting collection of real-world EMC problems at

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Barry

Reply to
Barry Lennox

It does, actually. Caught it yesterday, was checking if the caller ID worked and went to the TV to check that as well, it was messing up the TVs SMPS allright.

Hey, I would know that.

Would you believe I have twice opened and fixed this (cheap) TV, once it had a dried electrolythic cap which was mounted too close to a heating 7805 regulator and once I don't remember what, after a lightning which had killed the Ethernet controller (and not the coax PHY buffer...) of my Nukeman, the TV and the cable modem, got the latter replaced and the other two fixed.

But the case for the cellphone is proved now, anyway. It messes up the power supply (IIRC the one which makes the 5V stays on all the time, not sure about the others, I think the sweeps supplies were off but I am no more than 60% sure of that, lightning event was a year ago). About 30 cm (1ft) from the board is close enough, I am not sure the missus will allow me to try any closer (she keeps the phone in the other corner of the room since it got under suspicion ....:-).

Dimiter

Reply to
Didi

Sounds right. When far from the tower, the tower will instruct the cell phone to increase it's output power to improve the signal. (And lower when you're in close to avoid overloading the cell site's receiver multicouplers.) So, if you're in an area of poor coverage, you have at least 2 things eating away at battery life:

Temporary signal fades, which drive the need for more frequent updates, and, High RF power ouput instructions from the cell site.

-mpm

Reply to
mpm

What do you mean "it"? I've observed the effect on numerous receivers, some quite expensive (which isn't a guarantee of quality) and several quite sensitive.

As someone suggested, its probably overloading the receivers' front end or IF sections. But that qualifies as interference.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
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Reply to
Paul Hovnanian P.E.

Now, picture this kind of interference mesing up a pacemaker or other medical electronics.

-- Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com

------------------------------------------------------------------ Karate is a form of martial arts in which people who have had years and years of training can, using only their hands and feet, make some of the worst movies in the history of the world. -- Dave Barry

Reply to
Paul Hovnanian P.E.

It could also be caused by an external device overloading and generating spurious signals.

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Michael A. Terrell
Central Florida
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Michael A. Terrell

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