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Old 10th Sep 2019, 8:31 pm   #22
Karen O
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Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 670
Default Re: Digital 'cassette' recorder

Good question!

I was aiming for a similar frequency response and SNR to an ordinary cassette recorder, back in the day. I chose a sample rate of 31.25kHz to achieve a 10kHz bandwidth (with a little room for filter roll-off), and an SNR of 50dB or so. I used 10 bit samples, mostly because the PIC's ADC is ten bits.

Although 8 bits would give theoretically 48dB SNR, there is an undesirable effect whereby the noise seems to 'come up' as a sound decays. It's kinda like a 'fffffff' sound during the decay of say, a piano note. 10 bits seems to stop that.

Oh, and it's mono of course!
Karen O

Does Dr Who use Old New Stock parts for his/her Tardis?

Last edited by Karen O; 10th Sep 2019 at 8:37 pm. Reason: Mention that it's monophonic
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