detect tone

i have a computer microphone and i want to be able to detect a tone at
a specific frequency from the recording from the microphone. i want
the program to work with background sound. What methods are available ?

On 28 Jul, 12:09, amcneilly <amcnei...@gmail.com> wrote:
> i have a computer microphone and i want to be able to detect a tone at
> a specific frequency from the recording from the microphone. i want
> the program to work with background sound. What methods are available ?

It depends a bit on what what you mean by 'tone'.

If you mean 'monochromatic signal at the specified
frequency' then the task is simple: Use a narrow-band
band-pass filter centered at the frequency, and measure
the energy at the output of this filter relative to the
energy of the unfiltered signal.

If you by 'tone' means 'a tone played by some musical
instrument' then this might be very hard.

Rune

Thanks for your reply.


The tone should be monochromatic. as i am producing a pure tone of a
specified frequency.

How would i calculate the energy of a waveform?



On Jul 28, 11:21=A0am, Rune Allnor <all...@tele.ntnu.no> wrote:
> On 28 Jul, 12:09,amcneilly<amcnei...@gmail.com> wrote:
>
> > i have a computer microphone and i want to be able to detect a tone at
> > a specific frequency from the recording from the microphone. i want
> > the program to work with background sound. What methods are available ?
>
> It depends a bit on what what you mean by 'tone'.
>
> If you mean 'monochromatic signal at the specified
> frequency' then the task is simple: Use a narrow-band
> band-pass filter centered at the frequency, and measure
> the energy at the output of this filter relative to the
> energy of the unfiltered signal.
>
> If you by 'tone' means 'a tone played by some musical
> instrument' then this might be very hard.
>
> Rune

> How would i calculate the energy of a waveform?

You can use RMS value on the output of the filter (over a window).

gopi

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On Jul 28, 6:09=A0am, amcneilly <amcnei...@gmail.com> wrote:
> i have a computer microphone and i want to be able to detect a tone at
> a specific frequency from the recording from the microphone. i want
> the program to work with background sound. What methods are available ?

Try reading Vlad's paper

http://www.abvolt.com/research/Multitone%20detect-IEEE.pdf


Clay

On Jul 28, 6:09=A0am, amcneilly <amcnei...@gmail.com> wrote:
> i have a computer microphone and i want to be able to detect a tone at
> a specific frequency from the recording from the microphone. i want
> the program to work with background sound. What methods are available ?

I'd probably just use a Goertzel DTFT at the tone frequency.

Darrell

amcneilly wrote:

> i have a computer microphone and i want to be able to detect a tone at
> a specific frequency from the recording from the microphone. i want
> the program to work with background sound. What methods are available ?

If you want to impress your professor, use LM567.


Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com

On Jul 28, 10:53=A0am, Vladimir Vassilevsky <nos...@nowhere.com> wrote:
> amcneilly wrote:
> > i have a computer microphone and i want to be able to detect a tone at
> > a specific frequency from the recording from the microphone. i want
> > the program to work with background sound. What methods are available ?
>
> If you want to impress your professor, use LM567.
>
> Vladimir Vassilevsky
> DSP and Mixed Signal Design Consultanthttp://www.abvolt.com

And it will directly drive an LED to let you know when the frequency
is present.

On Jul 28, 11:21&#4294967295;am, Rune Allnor <all...@tele.ntnu.no> wrote:
> On 28 Jul, 12:09,amcneilly<amcnei...@gmail.com> wrote:
>
> > i have a computer microphone and i want to be able to detect a tone at
> > a specific frequency from the recording from the microphone. i want
> > the program to work with background sound. What methods are available ?
>
> It depends a bit on what what you mean by 'tone'.
>
> If you mean 'monochromatic signal at the specified
> frequency' then the task is simple: Use a narrow-band
> band-pass filter centered at the frequency, and measure
> the energy at the output of this filter relative to the
> energy of the unfiltered signal.
>
> If you by 'tone' means 'a tone played by some musical
> instrument' then this might be very hard.
>
> Rune

Would a monochromatic tone a specific frequency be a pure sin wave?

Thanks for your help. I have successfully detected my 20 khz tone
using Goertzel algorithm using Matlab.

What i would like to do now is change the sender signal and the
detection algorithm to help reduce the problem of detection of
background sound. The goal is to detect from a microphone a signal
from a transmitter with minimal interference from background sound. i
can tolerate a low percentage of false positives.

What i was thinking is mixing a 20 khz tone and 19 khz . i am a novice
to DSP.  What approach would you guys recommend?



On Jul 30, 4:53&#4294967295;pm, amcneilly <amcnei...@gmail.com> wrote:
> On Jul 28, 11:21&#4294967295;am, Rune Allnor <all...@tele.ntnu.no> wrote:
>
>
>
>
>
> > On 28 Jul, 12:09,amcneilly<amcnei...@gmail.com> wrote:
>
> > > i have a computer microphone and i want to be able to detect a tone at
> > > a specific frequency from the recording from the microphone. i want
> > > the program to work with background sound. What methods are available ?
>
> > It depends a bit on what what you mean by 'tone'.
>
> > If you mean 'monochromatic signal at the specified
> > frequency' then the task is simple: Use a narrow-band
> > band-pass filter centered at the frequency, and measure
> > the energy at the output of this filter relative to the
> > energy of the unfiltered signal.
>
> > If you by 'tone' means 'a tone played by some musical
> > instrument' then this might be very hard.
>
> > Rune
>
> Would a monochromatic tone a specific frequency be a pure sin wave?