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Author Topic: Sound/Code decoder  (Read 1286 times)
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Kova
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« on: September 12, 2007, 09:30:49 09:30 »

Hi all,
sorry for my english  Embarrassed
I have a question Smiley.

I have a buzzer that emits many different sounds and, also, 3 error codes:

1┬░) Bip Bip Bip at 440Hz
2┬░) Biiip Biiip Biip at 700Hz
3┬░) Biiiip Biiip Biiiip at 1150Hz

I want to decode these 3 error codes.
I can't touch nothing (the buzzer, the amp) than I must use a little mic to capture the sound/code.

Besides, the buzzer is situated in a crowded place with people that speaks, screams etc.

Is it possible to do?  Roll Eyes

Thanks a lot and sorry, another time, for my english  Cry

Bye
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samir
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« Reply #1 on: September 12, 2007, 10:34:49 10:34 »

Hi all,
sorry for my english  Embarrassed
I have a question Smiley.

I have a buzzer that emits many different sounds and, also, 3 error codes:

1┬░) Bip Bip Bip at 440Hz
2┬░) Biiip Biiip Biip at 700Hz
3┬░) Biiiip Biiip Biiiip at 1150Hz

I want to decode these 3 error codes.
I can't touch nothing (the buzzer, the amp) than I must use a little mic to capture the sound/code.

Besides, the buzzer is situated in a crowded place with people that speaks, screams etc.

Is it possible to do?  Roll Eyes

Thanks a lot and sorry, another time, for my english  Cry

Bye
may me you can use digital passband freq
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zeus
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« Reply #2 on: September 12, 2007, 04:16:45 16:16 »

Use NE 567 tone decoder/pll for each frequency. It will provide impulse duration for required freq.
http://www.x-robotics.com/downloads/pdfs/NE567_SE567_2.pdf
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flash65
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« Reply #3 on: December 17, 2007, 02:49:03 14:49 »

You can use a simply PLL as LM567 one for frequency of decoding. If you need more info ask me.
regards
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hoda
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« Reply #4 on: February 23, 2008, 11:38:07 23:38 »

To avoid surrounding noise you must first use a band pass filter for each error frequency then the signal can be further proccessed using tone decoder or using microcontroller
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tuvoj
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« Reply #5 on: March 07, 2008, 08:16:39 08:16 »

The 567 is discontinued by several manfs and is hard to work with---try the Rohm BA1604==improved!

Cheers-Tuvo
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Trishool
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« Reply #6 on: March 09, 2008, 03:17:45 15:17 »

Hi all,
sorry for my english  Embarrassed
I have a question Smiley.

I have a buzzer that emits many different sounds and, also, 3 error codes:

1┬░) Bip Bip Bip at 440Hz
2┬░) Biiip Biiip Biip at 700Hz
3┬░) Biiiip Biiip Biiiip at 1150Hz

I want to decode these 3 error codes.
I can't touch nothing (the buzzer, the amp) than I must use a little mic to capture the sound/code.

Besides, the buzzer is situated in a crowded place with people that speaks, screams etc.

Is it possible to do?  Roll Eyes

Thanks a lot and sorry, another time, for my english  Cry

Bye

If you are using a Microcontroller you can use its timer to generate different frequency as you whish and tie it to a speaker after power amplifier stage .

So far as decoding a frequency via a mike pickup you need a noise rejection layer , it would be good to implement this with the microcontroller and tune it in the real application area for rejection band.

Ts
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mhayball
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« Reply #7 on: March 13, 2008, 12:24:28 00:24 »

I have successfully used a PIC to decode tones right up to 16kHz with no problems.  You can use the 'count' command in Picbasic - I use it twice in a row with a small delay.  The first count is used to detect the tone coming in, and then the second count is to literally count the pulses in a fixed period of time, around a few milliseconds.  My current progam detects 13 different tones and works great.  You must use an external crystal oscillator however - do not use the internal oscillator as it will not produce an accurate count of the tone.  If you need a sample of code I can put this up on the forum.  Only thing is this depends on level of tone being input.  If it is too small you will need an LM386 to boost the tone level so the PIC can 'see' the tone pulses.
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Kova
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« Reply #8 on: March 13, 2008, 07:16:40 07:16 »

If you need a sample of code I can put this up on the forum.

Sure....if you can, please post the code Smiley Smiley
Bye!
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mhayball
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« Reply #9 on: March 18, 2008, 10:45:07 22:45 »

Here is the code, however I have taken it direct out of a larger program I have developed.  You will need to spend some time understanding the variables but if you have any questions just ask.  FIN is your pin on the pic for tone input, F is a variable to store the pulse count, J is used to record the previous tone count for comparision to F, A(I) is a storage array for the number of tones you want to read in and record.

                                 
   Count FIN,4,F                              
   IF (ABS(F-J))>1 Then                         
      Pause 2                                       Count FIN,4,F                           
      A(I)=F                                       Pause 1      

This is used in a loop, so you need to increment the value of I each time to store the next tone pulse.  I set this up to read tones at 100-120msec length so you may not need the pause to be so low.  This is based on 4MHz xtal oscillator.                           
                                 
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