Re: 12 and 16-bit oscilloscopes

"Tom Bruhns" <k7itm@xxxxxxx> writes:

Mike Monett wrote:
"Tom Bruhns" <k7itm@xxxxxxx> wrote:

[...snip good info]

(Practically all audio ADCs these days are delta-sigma type, with a lot
of digital filtering and decimation going on inside.)

Cheers,
Tom

Can you tell us which boards had response to DC?

Which ones would you recommend for an inexpensive low-end pc scope?

Hi Mike,

Sorry if I wasn't clear about that. I was doing a survey (and not a
terribly complete one at that) of high resolution ADC parts that would
be useful in a digitizer that went to at least 80kHz bandwidth. I
can't tell you about any of the boards; I don't have info on what ADCs
they actually used. There may be good reasons to sample audio faster
than 44.1ks/s, but extending the digitized bandwidth much beyond 20kHz
is probably not very high on the list.

I would love to make a "scope" based on something like the
AD7660. It's a 24 bit 2.5MHz sigma delta ADC
<http://www.analog.com/en/prod/0,,AD7760,00.html>.

I was thinking

- USB powered
- buffer data in local SDRAM
- Hi-speed USB interface
- local SDRAM chip to buffer samples
- *all* samples streamed to controller PC
- PC does post processing for "triggering", averaging, spectrum analysis

--

John Devereux
.

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