Why do cordless phones give feedback?

[larrymoencurly]

Why has almost every analog cordless phone (not cell) I've tried gives
some whistling feedback when I talk into it? Don't they either use
separate frequencies for the transmission and reception or something
like echo cancellation? The only phone that didn't was a cheap AT&T
49 MHz model that Consumer Reports said was really good, but I kept
losing it because it didn't have a paging function.

I'm using analog because they're about the only 900 MHz phones
available here that don't sound distorted, and I don't want 2.4 GHz or
5.2 GHz because they seem to blank out when wireless networking
equipment or microwave ovens are used.

 

[the Wiz]

larrymoencurly@my-deja.com (larrymoencurly) wrote:

Why has almost every analog cordless phone (not cell) I've tried gives
some whistling feedback when I talk into it? Don't they either use
separate frequencies for the transmission and reception or something
like echo cancellation? The only phone that didn't was a cheap AT&T
49 MHz model that Consumer Reports said was really good, but I kept
losing it because it didn't have a paging function.

Probably has something to do with the position you're holding the phone in - as
in it's not against your ear - something that's very common if you're trying to
use the phone "hands free" by tilting your head towards your shoulder.

I have one of those cheap AT&T phones that works pretty well, but WILL give a
feedback squeal if it's placed near a hard surface. The re4ason it doesn't
squeal in normal use is that the microphone isn't very sensitive - people often
ask me to "speak up" when I'm on the cordless phone but never when I'm on the
corded phones..

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[Brent]

On 8 Apr 2004 21:40:50 -0700, larrymoencurly@my-deja.com
(larrymoencurly) wrote:

Why has almost every analog cordless phone (not cell) I've tried gives
some whistling feedback when I talk into it? Don't they either use
separate frequencies for the transmission and reception or something
like echo cancellation? The only phone that didn't was a cheap AT&T
49 MHz model that Consumer Reports said was really good, but I kept
losing it because it didn't have a paging function.

I'm using analog because they're about the only 900 MHz phones
available here that don't sound distorted, and I don't want 2.4 GHz or
5.2 GHz because they seem to blank out when wireless networking
equipment or microwave ovens are used.

5.8 (not 5.2) Ghz shouldn't interfere with either of those. 2.4Ghz
interferes with the microwave because microwave and WLAN because they
also operate at 2.4Ghz. Some of the newer 2.4Ghz phones say they will
not interfere with WLAN. I've seen a Vtech that says this.

 

[zack]

On Fri, 09 Apr 2004 10:57:17 -0500, Brent <inverted@mail.com> wrote:

5.8 (not 5.2) Ghz shouldn't interfere with either of those. 2.4Ghz
interferes with the microwave because microwave and WLAN because they
also operate at 2.4Ghz. Some of the newer 2.4Ghz phones say they will
not interfere with WLAN. I've seen a Vtech that says this.

My microwave does not interfere with my 2.4ghz cordless phone unless I
put the phone about 6 inches away from it.. If you get interference
when your phone is more than 2 feet away, then you probably have a
very old microwave and should get it tested for leakage.

 

[larrymoencurly]

the Wiz <look@message.body> wrote in message news:<qeec7053beer3s7nuhtifhedio10a59vg1@4ax.com>...

Why has almost every analog cordless phone (not cell) I've
tried gives some whistling feedback when I talk into it?

Probably has something to do with the position you're holding
the phone in - as in it's not against your ear - something
that's very common if you're trying to use the phone "hands
free" by tilting your head towards your shoulder.

That was one of the first things I thought it was, but even pressing
my ear hard against the phone has never helped.

I have one of those cheap AT&T phones that works pretty well, but
WILL give a feedback squeal if it's placed near a hard surface.
The reason it doesn't squeal in normal use is that the microphone
isn't very sensitive - people often ask me to "speak up" when
I'm on the cordless phone but never when I'm on the corded phones..

The cheap 49 MHz AT&T 4336 that gave me no problems seemed to have a
fairly sensitive microphone, or at least it amplified my own voice
plenty back into the earpiece. Consumer Reports said that another
model with a pager, 4337, was very similar, but they were completely
wrong -- very different internal circuitry, noticeable distortion, and
lots of feedback.