Digital modulation

1. Digital Modulation

2. In digitalmodulation, an analog carrier signal
is modulated by a discrete signal.
Digital modulation methods can be
considered as digital-to-analog conversion,
and the corresponding demodulationor
detection as analog-to-digital conversion.

3. •The most fundamental digital modulation
techniques are based on keying:
PSK (phase-shift keying): a finite number of
phases are used.
FSK (frequency-shift keying): a finite number of
frequencies are used.
ASK (amplitude-shift keying): a finite number of
amplitudes are used.

4. FSK
•Frequency-shift keying(FSK) is a frequency
modulationscheme in which digital
information is transmitted through discrete
frequency changes of a carrier wave.

5. Fig: binary FSK

6. ASK
•Amplitude-shift keying(ASK) is a form of
amplitude modulationthat represents digital
dataas variations in the amplitudeof a carrier
wave.

7. PSK
•Phase-shift keying(PSK) is a digital
modulationscheme that conveys databy
changing, or modulating, the phaseof a
reference signal(the carrier wave).