Question

a. Analyse the effect of number of amplitude levels in ASK and QAM systems in terms of (12 Marks) b. Why inter symbol interference (ISI) is a major cause that result in bit errors in baseband 3. complexity of system, error performance and speed of data transfer.

Answer 1

ASK system [effect in amplitude level] ask[amplitude shift keying] is a digital modulation technique defined as the process of shifting of amplitude of carrier signal between two levels if the carrier signal will be transmitted if the signal value is 1 signal will be transmitted if the signal value is 1 otherwise signal value 0 will be transmitted the message signal be binary sequence of 1's and 0's v_m = {v_m if signal is 1 0, if signal is 0 \r\n ask uses finite number of amplitudes and assigned a unique pattern of binary digits rightarrow ask is very susceptible to noise interference, noise usually affects the amplitude Therefore ask is the modulation technique most affected by noise and cause an error in the signal rightarrow although there is only one carrier frequency, the process of modulation produces a complex signal that is a combination of many simple signals each with a different frequency rightarrow data transfer speed in ask depends upon.