Digital Modulation oleh Warsun Najib Digital Modulation Digital
Digital Modulation oleh Warsun Najib Digital Modulation
Digital Modulation Three basic forms of digital modulation Analog Digital AM Amplitude ASK FM Frequency FSK PM Phase PSK 10/30/2020 Digital Modulation 2
Amplitude Shift Key 11111010001101010010111 t t (logic 1) (logic 0) 10/30/2020 Digital Modulation 3
Amplitude Shift Key[1] The ASK waveform for one pulse (logic 1) In order to find an Energy Spectrum of Energy Spectrum The Autocorrelation technique is used Delay sinc 2 function Therefore Energy Spectrum of ASK 10/30/2020 Digital Modulation 0 4
Power Spectral Density Detection of ASK : detect 10/30/2020 present (logic 1) or absent (logic 0) Digital Modulation of the carrier 5
Frequency Shift Key 11111010001101010010111 t t Output for 1 Output for 0 10/30/2020 Digital Modulation 6
Power Spectral Density 0 Frequency separation Note: To prevent significant overlapping of the bandpass of two filters in detection process frequency separation 10/30/2020 Data rate Digital Modulation 7
Power Spectral Density[1] The Actual shape of Power Spectral Density of FSK Detection of FSK Bandpass Filter is used to detect f 1 (1) and f 2 (0) In general for frequency separation; ; 10/30/2020 or Digital Modulation where m is an integer 8
Phase Shift Key 11111010001101010010111 t t ~ ~ 10/30/2020 Digital Modulation 9
Power Spectral Density 10/30/2020 Digital Modulation 10
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) carrier Local oscillator e. g. Crystal oscillator known as Voltage Control Oscillator VCO 10/30/2020 Digital Modulation 11
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