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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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10th Sep 2019, 11:54 am | #21 |
Octode
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,765
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Re: Digital 'cassette' recorder
Fascinating build here, really like the idea.
What "sample rate" is used to sample the audio, And also bit depth of the ADC? Assuming those are valid terms to use here In short, what audio quality can be expected? |
10th Sep 2019, 8:31 pm | #22 |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Digital 'cassette' recorder
PsychMan,
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! Last edited by Karen O; 10th Sep 2019 at 8:37 pm. Reason: Mention that it's monophonic |
10th Sep 2019, 9:47 pm | #23 | |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Digital 'cassette' recorder
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11th Sep 2019, 11:17 am | #24 |
Nonode
Join Date: Mar 2010
Location: Dukinfield, Cheshire, UK.
Posts: 2,038
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Re: Digital 'cassette' recorder
What a fascinating project, Karen. And the look is wonderful, rather like something one would see in a 70's school, knobs an' all.
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Andy G1HBE. |
11th Sep 2019, 1:25 pm | #25 | |
Octode
Join Date: Jun 2013
Location: Fleet, Hampshire, UK
Posts: 1,765
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Re: Digital 'cassette' recorder
Quote:
Its inspiring stuff. I might have to have a go at something similar myself with Arduino boards. I have used PICs a long time ago, and might revisit, but I find Arduinos a lot simpler to throw things together if you have less patience I hadnt considered using them for audio before, but with ethernet modules as well, Id be interested to experiment with sampling audio and sending it over ethernet to a device for playback |
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12th Sep 2019, 1:33 am | #26 | |
Heptode
Join Date: Jul 2012
Location: Daylesford, Victoria, Australia
Posts: 675
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Re: Digital 'cassette' recorder
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The Waves That Rule Britannia |
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12th Sep 2019, 11:41 am | #27 | |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Digital 'cassette' recorder
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12th Sep 2019, 1:39 pm | #28 |
Nonode
Join Date: Feb 2005
Location: Worcestershire, UK.
Posts: 2,535
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Re: Digital 'cassette' recorder
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