Phase Shift Key Modulation
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Advantages of Phase Shift Keying modulation.
Ability of transmitting digital data through public telephone lines. The telephone line was designed to receive, switch and transmit analog signals in a voice frequency rate about 300-3400 Hz. These digital devices are attached to the network via a Modem, which converts digital data into analog signals and vice versa. PSK is one of the three modulation techniques used by modems to convert digital data into analog signals and vice versa.
More efficient use of bandwidth can be achieved if each signaling element (symbol) represents more than one bit. Instead of a phase shift of 180 degrees as followed in PSK, a common encoding technique known as Quadrature Phase Shift Keying (QPSK) uses phase shift of multiples of 90 degrees. Thus each signal element represents two bits rather than one. This scheme can be extended. It's possible to transmit three bits at a time using eight different phase angles, with each signal of more than one amplitude...