ABSTRACT
The pulse communication is one of the fastest area of electronic communication. Its concept goes back as far as to 1812 A.D., but its growth has been only in the last decade after availability of inexpensive I.C.s. In pulse modulation, pulses result from sampling the modulating signal wave. One of the chief advantages of pulse modulation is that if we combine pulse modulation with continuous wave modulation (AM, FM, PM), we can obtain “multi channel” communication system, a desirable feature for “data transmission”. In pulse time modulation, amplitude of the pulse is kept constant, where as width or position of the pulse is made proportional to the amplitude of the signal at the sampling instant. As amplitude is kept constant and does not carry any information, amplitude limiters can be used. In pulse width modulation, the width of the carrier pulse is varied according to the instantaneous value of the modulating signal, while the amplitude of the carrier remains constant.
