2008-06-10 05:29:18     Audio noise AD1854

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2008-06-10 05:29:18     Audio noise AD1854

Zaahir Khan (INDIA)

Message: 56919   

 

Hello All,

 

 

 

 

 

I am using BF561 ezkit, customised board.

 

Having AD1854 audio chip.

 

When we are running mp3 song. It sounds OK to us.

 

But when we are running 1k mp3 sine tone, getting tone & small noise, contineously comming.

 

AD1854 settings

 

I2S Justified mode,

 

L/RCLK   ----------->     41Khz

 

BCLK       ----------->       3.125 Mhz

 

Please help!!!!!

 

Thanks

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2008-06-10 10:01:39     Re: Audio noise AD1854

Robin Getz (UNITED STATES)

Message: 56929   

 

Zaahir:

 

how are you testing tone? with tone? it is a good idea to use the tone application with the correct sample frequency. In your case - this was "tone -f 41000 5000" play a 5kHz wave with 41kHz samples.

 

 

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2008-06-11 00:59:31     Re: Audio noise AD1854

Zaahir Khan (INDIA)

Message: 56957   

 

Hi Robin,

 

 

 

Thanks  for your reply.

 

I am using mp3play.

 

I have tried "tone" also as you suggested, still getting the noise.

 

I have attached the 1k.mp3 tone file.

 

Thanks

 

 

 

 

 

1k.mp3

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2008-06-12 00:09:28     Re: Audio noise AD1854

Zaahir Khan (INDIA)

Message: 57055   

 

Hi Robin,

 

 

 

I have tried for some mp3 tone file using mp3play

 

100Hz_44100Hz_16bit_30sec.mp3

 

250Hz_44100Hz_16bit_30sec.mp3

 

for these 2 tone files or these frequencies that noise not there.

 

But for

 

440Hz_44100Hz_16bit_30sec.mp3

 

this frequency and higher ones noise is there

 

We have probed the audio chip  output.

 

We found that for 100Hz & 250Hz  o/p was sine wave with some small glitchs on signal, but OK.

 

And for 440Hz a bunch of signal say 4 cycles  of  some small high  amplitude  &  other 4 cycles some less amplitude,

 

looks like some modulation. And this pattern getting repeated.

 

Please suggest!!!!

 

Thanks

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