Re: ColdFire QADC for voice audio?
- From: Vladimir Vassilevsky <antispam_bogus@xxxxxxxxxxx>
- Date: Mon, 29 Oct 2007 14:38:38 -0600
ghigbie@xxxxxxxxxx wrote:
We are considering using the 10 bit QADC on the ColdFire MCF5282 for
sampling up to 5 channels of voice audio with 8Khz to 16Khz sampling.
I am curious as to whether anyone has experience with this ADC for
voice audio applications and in particular whether they experienced
excessive digital noise, distortion, or other unforseen problems. The
alternative is to use external Codecs to digitize the audio be we are
willing to trade a certain amount of audio quality for lower power and
chip count.
I am not particularly familiar with the ADC of the Coldfire, however I have used the built-in 10bit ADCs of the other MCUs for the audio sampling. It is indeed possible to achieve the voice quality similar to that of the phone line. You will need to oversample the signal at least by the factor of two. An analog anti aliasing filter is required in front of the ADC; the 4th order filter is sufficient. It is also necessary to apply the preemphasis; that improves the quality a lot.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
.
- References:
- ColdFire QADC for voice audio?
- From: ghigbie
- ColdFire QADC for voice audio?
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