Well, maybe I'm babbling here, but let's go ahead and design our own system for
the thrill of it...

Assuming you want cd quality stereo sound and 32 channels running simultaneously
on one twisted pair, then you need:

14400 samples per second, 16 bits per sample, and 64 channels (32 stereo
channels).  So you need to be able to move 14,745,600 bits of data through the
cable.  Now, it is audio, and you really don't need to have it exact, so let's
say that about 100 times a second you send a break which lasts for one chunk(16
bits) which will give you only 14300 samples per second, but won't be audibly
noticable.  Then you'll be able to synchronize the receivers.  Add the overhead
of a start bit and a stop bit (for every 16 bits), and you end up needing to
send 16.6Mbps through a twisted pair.  All you need on the receiver end is a
chip which counts chunks (can't call it a byte, it's a 16 bit chunk) and puts
every 32nd chunk on alternating ADCs.

I haven't read up on rs-485 recently, but I doubt you'll be able to reliably use
a run of the mill rs-485 transceiver for it.  You may even want to look at an
ethernet driver.  At any rate, this entire system depends on a constant supply
of data from the transmitter at a constant speed.  No need to deal with
'assembling' packets of data or buffering anything.  It's more of a multiplexing
system than anything.

-Adam

John Perkinton wrote:
> For some reason, even though the audio quality is unsurpassable through the
> existing system, my boss wants me to design a digital audio version. This is
> going to be a nightmare, he wants 32 stereo channels, down one pair of
> cables. Everyone says its impossible including a few of my friends who work
> for Philips, but cable TV does it using Nicam so why can't I.
>
> Any ideas, or should I just look for another job, as I only get paid #17,000
> a year, and end up working about 75 hours a week with little or no holidays,
> no paid overtime. If you have any ideas please don't hesitate to contact me.
>
> Please also let me know of any projects you have done, and I'll let you know
> some other mad things I've done with PIC's.
>
> John Perkinton.