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I need to design a DSP system that can detect tones in the 40kHz range
and that can last from 1ms - 10ms. I expect to use an 8 bit ADC at
300kbps.

So my basic questions are:

1) What is the simpliest DSP that could be used to implement this?
(dsPIC? etc.)
2) What algorithms should I be looking at?

Thanks in advance.

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dosextender wrote:

> I need to design a DSP system that can detect tones in the 40kHz range
> and that can last from 1ms - 10ms. I expect to use an 8 bit ADC at
> 300kbps.
> 
> So my basic questions are:
> 
> 1) What is the simpliest DSP that could be used to implement this?
> (dsPIC? etc.)
> 2) What algorithms should I be looking at?
> 
> Thanks in advance.

Tell us more.
How many different tones might there be?
Do you need to distinguish between them?
Do you need to detect more than mere presence?
How much noise do you expect?
What important question didn't I ask?

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

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> How many different tones might there be?

In the beginning I expect to have 2 tones. (Possibly more later on)

> Do you need to distinguish between them?

Yes most definitely.

> Do you need to detect more than mere presence?

Yes I will also have to detect the length of the tone.

> How much noise do you expect?

From very little to saturation. 

> What important question didn't I ask?

I hope to find this out based on above ;-)

Thanks again.



Jerry Avins <j...@ieee.org> wrote in message news:<40fea56b$0$5640$6...@news.rcn.com>...
> dosextender wrote:
> 
> > I need to design a DSP system that can detect tones in the 40kHz range
> > and that can last from 1ms - 10ms. I expect to use an 8 bit ADC at
> > 300kbps.
> > 
> > So my basic questions are:
> > 
> > 1) What is the simpliest DSP that could be used to implement this?
> > (dsPIC? etc.)
> > 2) What algorithms should I be looking at?
> > 
> > Thanks in advance.
> 
> Tell us more.
> How many different tones might there be?
> Do you need to distinguish between them?
> Do you need to detect more than mere presence?
> How much noise do you expect?
> What important question didn't I ask?
> 
> Jerry

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On 21 Jul 2004 14:52:54 -0700, e...@yahoo.com (dosextender)
wrote:

>> How many different tones might there be?
>
>In the beginning I expect to have 2 tones. (Possibly more later on)
>
>> Do you need to distinguish between them?
>
>Yes most definitely.
>
>> Do you need to detect more than mere presence?
>
>Yes I will also have to detect the length of the tone.
>
>> How much noise do you expect?
>
>From very little to saturation. 
>
>> What important question didn't I ask?
>
>I hope to find this out based on above ;-)

   Look up DTMF tone detection. Your frequency range is much higher,
but the well-established methods of reading DTMF might be applicable.
   Would each of these two tones be various discrete frequencies? Or
would they vary continuously?
   DTMF signalling uses one of four frequencies for the "low" tone and
one of four other frequencies for the "high" tone.  There are
standards for things such as minumum detect time and the max amount of
second-harmonic signal (the tones are supposed to be low-distortion
sine waves) so that voice isn't mistaken for DTMF, though occasionally
this happens anyway.

   DTMF generation and detection are relatively easy tasks for modern
DSP's, but your requirement of 40kHz tones and 300ksps sampling rate
makes it more challenging. I might approach this by writing some C
code to do the detection (it should be portable without too much pain
to different manufacturer's C compilers), and see how many cycles it
takes to run on different DSP's.

>Thanks again.

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On 2004-07-21 19:18:35 +0200, Jerry Avins said:

> Tell us more.
> How many different tones might there be?
> Do you need to distinguish between them?
> Do you need to detect more than mere presence?
> How much noise do you expect?
> What important question didn't I ask?
> 
> Jerry

If (2) is answered with a "yes", how close together are these tones in 
frequency?
-- 
Stephan M. Bernsee
http://www.dspdimension.com

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you could try some good wavelet options. this is quite useful, more
chances of success especially when you need more resolution.

amar

Stephan M. Bernsee <s...@dspdimension.com> wrote in message news:<2...@uni-berlin.de>...
> On 2004-07-21 19:18:35 +0200, Jerry Avins said:
> 
> > Tell us more.
> > How many different tones might there be?
> > Do you need to distinguish between them?
> > Do you need to detect more than mere presence?
> > How much noise do you expect?
> > What important question didn't I ask?
> > 
> > Jerry
> 
> If (2) is answered with a "yes", how close together are these tones in 
> frequency?

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I expect the tones (initially) to be at 37.5K and 40K. 


Stephan M. Bernsee <s...@dspdimension.com> wrote in message news:<2...@uni-berlin.de>...
> On 2004-07-21 19:18:35 +0200, Jerry Avins said:
> 
> > Tell us more.
> > How many different tones might there be?
> > Do you need to distinguish between them?
> > Do you need to detect more than mere presence?
> > How much noise do you expect?
> > What important question didn't I ask?
> > 
> > Jerry
> 
> If (2) is answered with a "yes", how close together are these tones in 
> frequency?

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One important thing to note here is the timign requirement that is 1
ms / 10 ms that means that the freq band in which detection can be
made without ambiguity is 1 MHz to 0.1 MHz. Therefore it seems that
the tones ought to be atleast 2*0.1 MHz appart if they need to be
detected without ambiguity, if bandpass filters are to be used.


Stephan M. Bernsee <s...@dspdimension.com> wrote in message news:<2...@uni-berlin.de>...
> On 2004-07-21 19:18:35 +0200, Jerry Avins said:
> 
> > Tell us more.
> > How many different tones might there be?
> > Do you need to distinguish between them?
> > Do you need to detect more than mere presence?
> > How much noise do you expect?
> > What important question didn't I ask?
> > 
> > Jerry
> 
> If (2) is answered with a "yes", how close together are these tones in 
> frequency?

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