1. Basic Concepts Modulation & Detection Zdzisław Papir Modulation Purposes of using modulation Demodulation Demodulation vs. Detection The whole picture – transmission system Classification of modulations

2. Definition of Modulation Modulation & Detection Zdzisław Papir Modulation involves three signals: information carrying signal = modulating signal x(t) carrier c(t) modulated signal φ(t) Modulation is mapping of the information signal into one of the parameters of the carrier. The output signal is called the modulated signal. MODULATOR φ(t)φ(t) x(t)x(t) c(t)c(t)

3. Amplitude Modulation Modulation & Detection Zdzisław Papir MODULATOR

4. Amplitude Modulation Modulation & Detection Zdzisław Papir t

5. Baseband Modulation (Line Code) Modulation & Detection Zdzisław Papir + – Transition graph for Millers code

6. Baseband Modulation (Line Code) Modulation & Detection Zdzisław Papir + – 1000110000111

7. Baseband Modulation (Line Code) Modulation & Detection Zdzisław Papir + – S( ) Power density spectrum Bipolar NRZ code Millers code Biphase code

8. Spectra of information signals Modulation & Detection Zdzisław Papir Voice - baseband – up to several kHzs Sound - baseband – up to tens of kHzs Video – baseband up to several MHzs Raw data – baseband up to...?

9. Purposes Modulation & Detection Zdzisław Papir #1 Access to different parts of the electromagnetic spectrum Microwave - MHzs Copper plant – baseband up to 10 MHz Fiber – narrow frequency window at THzs Sattelite - GHzs

10. Purposes Modulation & Detection Zdzisław Papir #2 Better noise immunity of transmission TRANSMITTERRECEIVER TRANSMISSION CHANNEL noise modulation detection improvment of the Signal to Noise Ratio (SNR) SNR (modulation & detection) > > SNR (baseband system) SNR

11. Purposes Modulation & Detection Zdzisław Papir #3 Frequency or Time Division Multiplex of transmission channels Frequency (FDM)Time (TDM)

12. The free lunch does not exist Modulation & Detection Zdzisław Papir #1 Access to different parts of the electromagnetic spectrum #2 Better noise immunity of transmission #3 Frequency or Time Division Multiplex of transmission channels #4 SPECTRUM WIDENING B [Hz] or W [rad/s] – spectrum of the modulated signal f m [Hz] or ω m [rad/s] – spectrum of the modulating signal spectrum widening coefficient

13. Definition of Demodulation Modulation & Detection Zdzisław Papir Modulation is MAPPING the information signal onto the carrier. MODULATOR φ(t)φ(t) x(t)x(t) c(t)c(t) DEMODULATOR φ(t)φ(t)x(t)x(t) c(t)c(t) Demodulation is STRIPPING the information signal from the carrier.

14. Definition of Detection Modulation & Detection Zdzisław Papir DETECTION φ(t)φ(t) x(t) + noise c(t)c(t) Detection is STRIPPING the information signal from the carrier in a noisy environment.

15. The Whole Picture Modulation & Detection Zdzisław Papir TRANSMITTERRECEIVER TRANSMISSION CHANNEL noise modulation detection

16. Transmitter Modulation & Detection Zdzisław Papir LPFMOD BPF Information signal Modulated signal LPF– Lowpass Filter BPF– Bandpass Filter MOD– Modulator Carrier

17. Receiver Modulation & Detection Zdzisław Papir BPFDEMOD LPF Information signal Modulated signal LPF– Lowpass Filter BPF– Bandpass Filter MOD– Modulator Carrier

18. Transmission Channel Modulation & Detection Zdzisław Papir The common assumption is that the transmission channel disturbes the signal being transmitted with the Additive White Gaussian Noise. AWGN – Additive White Gaussian Noise

19. Modulation & Detection Zdzisław Papir LPFMOD BPF Transmission System BPFDEMOD LPF

20. Modulation & Detection Zdzisław Papir LPFMOD BPF Transmission System Quality BPFDEMOD LPF

21. Modulation & Detection Zdzisław Papir Classification of Modulations MODULATOR φ(t)φ(t) x(t)x(t) c(t)c(t) Digital - Analog Analog waveform – sin or cos waveform (A) Digital waveform – sequence of pulses (D)

22. Modulation & Detection Zdzisław Papir Classification of Modulations carrier information signal D D A A Sampling theorem PAMPFM PDM Keying ASK PSK FSK MSK GMSK Line codes NRZMiller HDB PRS AM FM SSB QAM Classics