2. Phase Shift Keying (PSK)

• A range of techniques used in the medium to high speed modems which transmit digital information by a change in the phase of the carrier.
• Is another form of angle modulated, constant-amplitude digital modulation.
• PSK is similar to conventional phase modulation except that with PSK the input is a binary digital signal and a limited number of output phases are possible.

    2.1 Binary Phase Shift Keying (BPSK)

•         Uses 180 degrees of change to represent 0's and 1's . This results in a very robust signal which can be handled by low-cost equipment.
• At this level one baud or symbol still transfers only one bit.
• Carrier 1600 or 1700 Hz

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