On Fri, 2006-12-01 at 10:02 -0800, Hasan Khan wrote:
> Hi,
> I need to transmit a digital signal over a distance of about 150ft.  I did some research on google and  I am thinking of transmitting the signal over RS485 twisted pair standard.  The signal will be digitized audio done by a PIC.  Supposing audio ranges from 20Hz to 4KHz, and sampling at 8KHz, RS485 should be able to handle the bandwidth easily.
> 
> My questions, first, is there anything fundamentally wrong with this approach?  

Not that I can see. Assuming single channel, 8 bit audio, your data rate
is 64kbps, should be a piece of cake with RS485. Just use real RS485
drivers and you should be OK.

> Second, will RS485 work reliably without loss of data over 150ft of twisted pair?

"Zero loss of data" is impossible, every real world link might "loose"
an odd bit. The issue is how much of this can you take. Off hand, RS485
running at 64kbps over 150ft for audio should be fine. If however you
need near 100% reliable reception you're going to have to add some error
detection/correction. Not a big deal, but something to keep in mind.

TTYL

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