TELECOM Digest OnLine - Sorted: Re: Why Must a Cordless Phone be Away From Electronic Devices?

Re: Why Must a Cordless Phone be Away From Electronic Devices?

Tony P. (kd1s@nospamplease.cox.reallynospam.net)
Sat, 16 Apr 2005 13:37:38 -0400

In article <telecom24.158.11@telecom-digest.org>, Wesrock@aol.com
says:

> In a message dated Tue, 12 Apr 2005 02:02:56 -0400, curious@nospam.com
> writes:

>> I just got a 900 MHz DSS cordless phone, and I had the perfect spot
>> for it, right on top of my tower computer case. But then I noticed
>> that the manual says that the base unit must be placed away from all
>> electronic equipment, including PCs, stereos, TVs, and microwaves.
>> What is the reasoning for this? Could the magnetic fields generated
>> by the speakers in the phone cause any problems?

> It will do no harm to the computer. But the other electronic
> equipment may interfere with the cordless phone transmission and
> reception.

> We had a 900 mHz cordless that sat right under a TV and had no
> problem. But when it finally gave up the ghost we replaced it with
> another cordless, which turned out to be 2.4 gHz. We then found out
> that 2.4 gHz is much more seriously affected to the point that it was
> unusable. We returned it, since that was exactly where we wanted the
> cordless.

> It is reported than 4.8 gHz is even more badly impaired by other
> electronic equipment.

In the case of a computer, even with the metal cases there are some
serious harmonics radiating from the machine that could potentially
interfere with the cordless phone.

That being said, all consumer electronic devices are Part 15 devices:

§ 15.5 General conditions of operation.

(b) Operation of an intentional, unintentional, or incidental radiator
is subject to the conditions that no harmful interference is caused and
that interference must be accepted that may be caused by the operation
of an authorized radio station, by another intentional or unintentional
radiator, by industrial, scientific and medical (ISM) equipment, or by
an incidental radiator.

In other words, consumer electronic gears is a magnet for interference.

In your case though I bet the problems you're having with a 2.4GHz phone
have more to do with the more likely 802.11 gear, and somewhat less
likely from wireless devices and controllers.

For example, my Pelican Spirit wireless game controller is absolutely
worth crap around here. Too many wireless networks.

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