Why must a cordless phone be away from other electronic devi

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?

 

[Don Bruder]

In article <m6kn519r272gqavjio87ov6c7p598bn9qv@4ax.com>,
curious@nospam.com wrote:

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's mostly about corporate cheapness and CYA - Like any device not
individually licensed by the FCC to use a particular frequency, "This
device must not produce any interference, and must accept any
interference it receives, even if the interference makes it malfunction"
applies to a 900 MHz phone. Computers, TVs, and microwaves (and to a
lesser but still significant extent) stereos and other gear can be HUGE
producers of RFI - Especially in the case of computers, more than plenty
to completely swamp the cheap-as-we-can-possibly-make-it front end on a
typical home-grade cordless phone.

Phone makers don't want to spend more on shielding than they absolutely
must, so they try to convince Joe User that their problems with
interference are exactly that: their problems, and attempt to avoid any
responsibility for either reducing the interference, or making the phone
properly in the first place, by specifying that the phone may not be
located anyplace where interference is even slightly likely to be
generated.

If they could get away with "This phone must not be located within 10
miles of anything else that plugs in or uses batteries" without blowing
themselves out of the water, they'd put that in the book, too. Since
they can't, they settle for "away from all electronics" and the old
standby "It ain't our fault you put it near an (unplugged, there purely
for decoration) old blender on your kitchen counter" response to
customer complaints about how poorly the phone works.

In theory, having the phone near the computer can cause trouble, mainly
with the phone's reception. In practice, if it works for you, put it
where you want it. If it doesn't work, find someplace else to put it
where it DOES work.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[CWatters]

<curious@nospam.com> wrote in message
news:m6kn519r272gqavjio87ov6c7p598bn9qv@4ax.com...

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?

No it's most probably the other way around. The computer might cause
problems for the phone eg swamping the radio reciever.

 

[JANA]

Computers, monitors, and microwave oven power supplies can radiate out a
fair amount of radio frequency interference known as RFI. This is also the
same for the clocking circuits, and digital signals being used in the
boards. Most modern appliances and devices use some type of switching power
supply, and digital processing systems of some type.

Even if an appliance or computer is well shielded to block the RFI to an
acceptable amount, there is always some that is able to radiate out. The AC
line cord, and interconnect wires can also act as a sort of antenna, even
though they are electrically referenced to ground, and may have RFI traps.
The harmonics from the frequencies generated are very high, and thus the
shielding that is used for these devices is not fully adequate, or able to
do its job perfectly. The standards must always allow for some leakage, or
the appliances would not be affordable, or practical to manufacture on a
mass basis.

As for your phone, the amount of RFI you can have from a home appliance, or
computer, can be strong enough to cause interference. This can be the same
for most other communication devices.

I have seen a two-way communications radio cause interference to a computer
that was about 15 feet away. I have also seen computers cause interference
to cordless phones, and to ordinary radios.

As for having damage to a cordless phone, it would have to be exposed to
extremely strong radiation. This radiation would have to be so strong that
it would be dangerous for a person to be near by to the radiation source. I
would worry more about the cordless phone causing interference to the
computer. This may cause corrupt data if anything at all.

With a cordless phone, both the handset and base are transmitter and
receiver devices. They are both susceptible to receive, and or to transmit
signals, that can cause interference to other devices.

The bottom line is that I would not be worried about a computer, microwave
oven (unless the phone is put inside), or monitor, or TV set causing damage
to your cordless phone.


--

JANA
_____


<curious@nospam.com> wrote in message
news:m6kn519r272gqavjio87ov6c7p598bn9qv@4ax.com...
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?

 

[Vidar Lřkken]

curious@nospam.com wrote:

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?

Hmm, I don't really see a big reason for that. Your computer cabinet
will act (partly) as a faraday cage, and block out radio frequency.
I've haid one motherboard that went haywire due to a mobile phone, but
then the mobile phone was lying _on_ the motherboard, and I suspect the
bios to have been corrupted.
A cordless phone _on top_ of you PC could introduce noise on your
monitor, this you'll have to test, but monitors don't take damage from a
few minutes of low energy RF.
Nor does a PC.
Only thing is that the phone can get shorter range, since a pc might
output RF.
I suspect this is the reason, as it includes microwaves and such, wich
don't take damage in any damn way from RF (they're pretty bad themself
when coming to RF).
Anyway, you won't destroy your pc, nor your phone by trying is my guess,
but you might get worse quality and/or range.
So, I'd go with it if you like having it there

--
MVH,
Vidar

www.bitsex.net