Re: Modem is 56k and the bandwidth supplied is 64k...
Posted 16 December 2011 - 07:36 AM
56,000 bits per second was the data rate. The other 8,000 bits is for framing/stop/start bits. For a very long time the rate of a voice channel has been 64,000 bits per second.
The number comes from (freq. sampled x 2) x 8 bit samples. The freq. sampled is in the range of 300 - 3400 hz and is allocated 4000hz in the system. So 4000 x 2 x 8 = 64,000. This is called the Nyquit rate, and based on the works of Nyquist and Shannon.
This post has been edited by dbasnett: 16 December 2011 - 07:50 AM