1. Sistem Telekomunikasi, Sukiswo, ST, MT Sukiswo sukiswok@yahoo.com
Digital Modulation
Sukiswo
Sistem Telekomunikasi, Sukiswo, ST, MT

2. Sistem Telekomunikasi, Sukiswo, ST, MT
Outline
ASK
FSK
PSK
Sistem Telekomunikasi, Sukiswo, ST, MT

3. Sistem Telekomunikasi, Sukiswo, ST, MT
Digital Modulation
Three basic forms of digital modulation
Analog Digital
AM Amplitude ASK
FM Frequency FSK
PM Phase PSK
Sistem Telekomunikasi, Sukiswo, ST, MT

4. Sistem Telekomunikasi, Sukiswo, ST, MT
Amplitude Shift Key t
(logic 1)
(logic 0)
Sistem Telekomunikasi, Sukiswo, ST, MT

5. Amplitude Shift Keying[1]
Sistem Telekomunikasi, Sukiswo, ST, MT
Amplitude Shift Keying[1]
The ASK waveform for one pulse (logic 1)
In order to find an Energy Spectrum of
The Autocorrelation technique is used
Delay
Energy Spectrum
Therefore Energy Spectrum of ASK
sinc2 function
Sistem Telekomunikasi, Sukiswo, ST, MT

6. Power Spectral Density
Sistem Telekomunikasi, Sukiswo, ST, MT
Power Spectral Density
Detection of ASK : detect present (logic 1) or of the carrier
absent (logic 0)
Sistem Telekomunikasi, Sukiswo, ST, MT

7. Frequency Shift Keying
Sistem Telekomunikasi, Sukiswo, ST, MT
Frequency Shift Keying t
Output for 1
Output for 0
Sistem Telekomunikasi, Sukiswo, ST, MT

8. Power Spectral Density
Sistem Telekomunikasi, Sukiswo, ST, MT
Power Spectral Density
Frequency separation
Note: To prevent significant overlapping of the bandpass of two
filters in detection process
frequency separation Data rate
Sistem Telekomunikasi, Sukiswo, ST, MT

9. Power Spectral Density[1]
Sistem Telekomunikasi, Sukiswo, ST, MT
Power Spectral Density[1]
The Actual shape of Power Spectral Density of FSK
Detection of FSK Bandpass Filter
is used to detect f1 (1) and f2 (0)
In general for frequency separation; ; or
where m is an integer
Sistem Telekomunikasi, Sukiswo, ST, MT

10. Sistem Telekomunikasi, Sukiswo, ST, MT
Phase Shift Keying t ~
Sistem Telekomunikasi, Sukiswo, ST, MT

11. Power Spectral Density
Sistem Telekomunikasi, Sukiswo, ST, MT
Power Spectral Density
Sistem Telekomunikasi, Sukiswo, ST, MT

12. Detection of PSK Phase Reversal Key (PRK)
Sistem Telekomunikasi, Sukiswo, ST, MT
Detection of PSK Phase Reversal Key (PRK)
Since information is in the phase, only synchronous detection is possible
Receiver:
To data detection
Matched filter detection
carrier
Synchronize
(coherent)
Local oscillator e.g. Crystal oscillator
known as Voltage Control Oscillator VCO
Sistem Telekomunikasi, Sukiswo, ST, MT