Amplitude Shift Keying (ASK)

• Here amplitude is varied keeping frequency and phase constant

1. BASK (Binary Amplitude Shift Keying)

• ASK is normally implemented in two levels
• Also known as on-off keying (OOK)

2. Multilevel ASK

• Here we can have more than two levels
• It is not implemented with pure ASK, but QAM

Frequency Shift Keying (FSK)

• Here frequency is varied keeping amplitude and phase constant

Binary FSK

• We take two carrier frequencies
• First carrier to be 0 and second carrier to be 1

Phase Shift Keying (PSK)

• Here phase is varied keeping frequency and amplitude constant

Binary PSK

• We have two signal elements, one with phase of 0° and other with phase of 180°