Analog Data Digital Signals Converting Analog Data Digital

Analog Data, Digital Signals • Converting Analog Data, Digital Signals is known as DIGITIZATION • 2 Ways of converting Analog Data into Digital Signals – Pulse Code Modulation (PCM) – Delta Modulation (DM)

Analog Data, Digital Signals • Pulse code modulation (PCM) is based on the sampling theorem, which states that If a signal f(t) is sampled at regular intervals of time and at a rate higher than twice the highest signal frequency, then the samples contain all the information of the original signal. The function f(t) may be reconstructed from these samples by the use of a low-pass filter.

Analog Data, Digital Signals -> PCM -> Here the entire analog data sample is divided into 16 levels based on amplitude. -> for each level a 4 bit data is assigned -> for example Level 0 = 0000 Level 1 = 0001 Level 2 = 0010. . Level 15= 1111

-> Without nonlinear encoding Stronger signal and weaker signal are treated to be the same -> result is Stronger signal concentrated well BUT weaker signal is not much concentrated SO LOSS OF QUALITY -> With nonlinear encoding Stronger signal and weaker signal are NOT treated to be the same -> result is Stronger signal concentrated well AND weaker signal is ALSO much concentrated SO NO LOSS OF QUALITY

Analog Data, Digital Signals -> DM -> Here relative data generation is done -> if (amplitudecurrent>amplitudeprevious) then { step size == + delta data bit == 1 } Else { step size == - delta data bit == 0 } Due to enormous slope overload noise in DM(Delta Modulation), -> PCM is better than DM