How to Calculate Line Speed Or Bit Rate For One Channel.

How to Calculate Line Speed Or Bit Rate For One Channel.

Before that, I will tell you about Nyquist Theorem:
-In 1993, Harry Nyquist derived the minimum sampling frequency required to extract all information in a continuous, time-varying waveform.

-The Nyquist sampling theorem establishes the minimum sampling rate(fs) that can be used for a given PCM signal. For a sample to be reproduced accurately in a PCM receiver, each cycle of the analog input signal (Fmax) must be sampled at least twice.

-So, the sampling theorem states that for a limited bandwitch (band limited) signal with maximum frequency Fmax the equally spaced sampling frequency (Fs) must be greater than twice of the maximum frequency Fmax:

                      Sampling rate, fs = 2(fmax)

Example Question :

The human voice normally contains frequencies from 0 to 4000Hz. According to Nyquist Theorem, the sampling frequency (fs) is normally chosen to be twice of the highest frequency of a human voice and line speed or bit rate for one channel.

Answer:

                                     Sampling rate, fs = 2fmax
                                                                             = 2 x (4000 Hz)
                                                                  =8000Hz

line speed or bit rate for one channel= sampling rate x 8bit
                                                  =8000 Hz x 8bit
                                           = 64000bps
                                        =64 kbps

Why we use 8 bit?

One  bytes of data is transmitted during the time interval assigned to a particular channel. One channel transmits 8 bits and the halts (stop) while the next channel transmit 8 bits. The third channel then transmits its data word and so on.

Based On:

Politeknik Ibrahim Sultan Noted

By

Miss Rohana Binti Hasan.