... A modulation is a process by which an information signal is converted to a sinusoid waveform for digital communication, such a sinusoid of duration T is referred to as a digital symbol. The sinusoid has just three features that can be used to distinguish it from other sinusoids: amplitude, frequency, and phase. Therefore, the modulation can be defined as a process whereby the amplitude, frequency, or phase of the RF carrier, or a combination of them, is varied in accordance with the information to be transmitted. The general form of the carrier wave, s(i), is as follows: s(t) = A(t) cos[?0 + ?(t)] Where A(t) is the time-varying amplitude, ?0 is the radian frequency of the carrier and O(t) is the phase, When the frequency, f, is used instead of ?, the relationship between them is ?+2?f The basic digital modulation/demodulation types as follows: o Phase Shift Keying (PSK) o Frequency Shift Keying (FSK) o ...

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