Feedback Cancellation

">Pat wrote:
>> Thank you ladies and gentlemen for your responses.
>> 
>> Well I will try the adding of 1Hz to 5Hz and also will try the phasing
>> ideas. In this case all ideas are worth trying out. As for the problem
>> being delay, I have heard feedback coming out when a caller calls the
>> radio station while the volume of their radio receiver is high. That's
my
>> concern.
>> 
>> Some callers can call from long distances while some would call from
>> within the same town with the radio station, how do I manage the
feedback
>> control and callers are from different places, say the distances of up
to
>> 1600km. We know the delays of telephone lines and microwaves depend on
the
>> distance. Theproject is manageable for the same distances like in a
>> conference room but I am stuck in this case.
>> 
>> I thank you once again
>
>The feedback that disturbs you is not entirely the same as what limits 
>the gain in a PA system. Many advances have happened since I built the 
>frequency shifter more than 50 years ago, and now there are better ways.

>Most talk-show hosts remind callers to turn their radio volume down, and

>that seems to suffice. Can you tell us what specific problem needs to be

>addressed?
>
>Jerry
>-- 
>Engineering is the art of making what you want from things you can get."



My objective is to completely do away with the talk show hosts asking the
caller to turn down their volume. I want the caller to be free to talk and
have their volume relatively up without causing negative feedbak.

Thank you

"Pat" <chagondapat@yahoo.com> wrote in message
news:KYidnR32AY6-8FrZnZ2dnUVZ_vKdnZ2d@giganews.com...
>
> My objective is to completely do away with the talk show hosts asking the
> caller to turn down their volume. I want the caller to be free to talk and
> have their volume relatively up without causing negative feedbak.
>
> Thank you
>
Pat,
Why re-invent the wheel? A solution already exists. As I mentioned elsewhere
in this thread, you can buy a box for <$100 US that contains 12 banks * 2
channels (stereo) of parametrically defined filters. The primary purpose of
the box is to suppress narrowband energy that rises above a (user settable)
threshold of the total energy in the signal. In its default mode, it
automatically detects these feedback tones and quickly configures an
extremely narrow notch filter to kill the system gain at the offending
frequency. The effect on the overall audio quality is said to be nearly
imperceptible because the filter is only a few cents (100ths of a semitone)
wide. This is one brand; there may be others:

http://www.behringer.com/DSP1124P/index.cfm?lang=ENG

The box is designed for sound reinforcement (concerts) but I see no reason
it wouldn't work for what you want (live radio call-in).

Bob

Pat wrote:

   ...

> My objective is to completely do away with the talk show hosts asking the
> caller to turn down their volume. I want the caller to be free to talk and
> have their volume relatively up without causing negative feedbak.

Negative feedback is no problem at all. The problems arise from positive 
feedback and disorienting delay. Many "live" talk shows use a delay of 
several seconds to allow offensive words to be bleeped out. I don't see 
how you can get around that.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

>Pat wrote:
>
>   ...
>
>> My objective is to completely do away with the talk show hosts asking
the
>> caller to turn down their volume. I want the caller to be free to talk
and
>> have their volume relatively up without causing negative feedbak.
>
>Negative feedback is no problem at all. The problems arise from positive

>feedback and disorienting delay. Many "live" talk shows use a delay of 
>several seconds to allow offensive words to be bleeped out. I don't see 
>how you can get around that.
>
>Jerry
>-- 
>Engineering is the art of making what you want from things you can get.
>���������������������������������������������������������������������

Thank you very much. I want to come up with a design of my own. If the
wheel was invented already then it's pointless to reinvent it. Many
publications that I have read do not have a solution to that problem.