quality of service on a pair of wires = 1 / the quality & speed you desire
--->
Robert H. Hanson LAN/WAN Consultant - Internet Service Provider
Otis Orchards, Wa. Cutting Edge Communications www.cet.com
(509) 927-9541 finger: info@cet.com or email: roberth@cet.com
On Wed, 2 Oct 1996, Jeff Weisberg wrote:
>
>
> | By Shannon's law(?), a local caller (one A->D conversion) actually can
> | push at most 28K through the pipe (1/2 the sampling rate). Slightly higher
> | rates can be achieved if the analog device matches the sampling rate at
> | the Central Office.
>
> close....
>
> it's Nyquist's law that says that a signal bandlimited to B
> requires a sampling rate of 2B.
> our sampling rate is 8kHz. ergo, our signal is limited to (a
> theoretical maximum of) 4kHz.
>
> Shannon's law tells us that the Capacity of our channel
> (in bits/sec) is
> C = B*log2(1 + SNR)
>
> where our noise is (mostly) due to quantization (to 8 bits)
>
>
> --jeff
>