PIC 18Fxx2 PWM output

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Hi everybody,
 what quality of sound i will have for speech on 10 bits PWM, '.wav' 22 kHz,16
bit?
 Please any estimation, especially negative.

Thanks in advance.

Re: PIC 18Fxx2 PWM output
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bit?
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Well, it's sort-of, not-so umm, a bit better than, arr kind-a, you see...
What do you expect to hear?
The resolution determines noise and distortion, while the sample
frequency limits the maximum speech frequency.
Take a sample, recode it on your PC and estimate the quality yourself.

HTH,
Michael





Re: PIC 18Fxx2 PWM output
Hi Michael,
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 Clear sound are wanted. All examples i saw PWM wasn't used as codec.
It needn't to invent square wheel if somebody did with bad result. On
PC for sound are worked any program, hardly the samples transform
directly. Of course i must be more industrious & to study theme, but
it need the large time.
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I can't understand, is this some laughter on me?

Best  regards
Victor

Re: PIC 18Fxx2 PWM output
You will find it's a lot easier to filter the PWM carrier frequency if you
use say 8 bits @ 80kHz (which should be possisble given the specs you
stated). The speech will seem clearer even though the resolution is only 8
bits.

I'd definitely recommend a low cost speech codec if you need decent quality.

One more thing - take care when you update the PWM values - some PWMs are
double buffered and some are not. If not, you will see PWM glitches when the
software updates the PWM value. Buffered PWMs reload the new value at a
known counter value, usually 0.

-Andrew


Whytech
MSP430 / PIC / AVR tools, SMD prototyping adaptors
Imagecraft MSP430 C compilers
http://www.whytech.com.au


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kHz,16 bit?
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Re: PIC 18Fxx2 PWM output
Hi Andrew,
i don't understand something, want to direct apply but haven't mail.
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What mean 'filter' here?

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I use now TLW codec but haven't clear voice. Therefore in desperate
seek most cheap decision.

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 Are timer(counter) rigid connect with PWM & are rejected new values
early?

Best regards
Victor

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