11 Mar
2005
11 Mar
'05
10:17 a.m.
>>>> "Jules" == Jules Richardson
<julesrichardsonuk at yahoo.co.uk> writes:
Jules> On Fri, 2005-03-11 at 07:51 +0000, Philip Pemberton wrote:
> ...
> Shift register + counter + high speed RAM. Could even do it with
> an FPGA if you wanted. Buffering an entire track with 8x
> oversampling is going to be hellishly memory intensive though.
Jules> Well if worst-case is 1mbps data rate at 300rpm and 8x
Jules> oversample, isn't that (8 * 10240 * 1024) / 5 = 1677722 bits
Jules> of memory maximum needed?
Jules> (div by 5 because 300rpm gives you a whole track in 1/5 of a
Jules> second)
Jules> So 256KBytes of RAM should always be enough to buffer a whole
Jules> track, regardless of what physical drive or media you use.
Even if you want 8 bits per sample, that's still only 1.5 MB, and the
data rate is 7.5 MB/s (since a track is 200 ms by your calculation).
That's a trivial bandwidth requirement; anything better than antique
DRAM will do the job easily, and the space requirement is tiny, too.
I'm wondering if you can do this job with a microcontroller similar to
a PIC, running the sampling loop in software. If not quite, it should
be pretty close.
paul