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Differential Phase Shift KeyingDifferential Phase Shift Keying (DPSK) is a method of Keying in networking. Instead of a fixed assignment, each data bit is coded as a Phase Change. Encoding rule at transmitter In the beginning, add a reference bit 0 as the present-encoded bit. Compare the present data bit with the present-encoded bit, if different, next encoded bit is 0, else, next encoded bit is 1. Output waveform has 0 degrees phase shift if present-encoded is bit '0', else, 180 degrees phase shift. At receiver Compare the carrier at present time slot with that at a time slot 1-bit before. If different, decode data bit as 0, if not different, decode data bit as 1. Reference carrier is not required for demodulation. Also, phase distortion problem is minimized as demodulation relies on detection of phase change rather than a particular phase value. Source: Hong Kong Institute of Vocational Education(Tuen Mun) Related Topic: Phase Shift Keying
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