Modulations Amplitude Shift Keying ASK (OOK)

BW for ASK Nbaud is baud rate

 Ex. Given a BW of 10,000 Hz (1, ,000) for a full-duplex ASK. Find the carriers and the BW in each direction. Assume there is no gap between the bands in two directions. What is the maximum baud rate and bit rate?

Frequency Shift Keying (FSK)

BW for FSK

 EXample: Find the maximum bit rates for an FSK signal if the bandwidth of the medium is 12,000 Hz, and the difference between the two carriers must be at least 2000 Hz. Transmission is in full-duplex mode.

Phase Shift Keying (PSK)

PSK Constellation diagram

4-PSK

4-PSK Constellation diagram

8-PSK

BW for PSK  The same as ASK  Ex. Given a bandwidth of 5000 Hz for an 8-PSK signal, what are the baud rate and bit rate?

 PSK is not susceptible to the noise degradation that affects ASK, nor the BW limitations of FSK.

Quadrature amplitude modulation (QAM)

BW for QAM  The same as ASK and PSK.

Multiplexing  multiple links on 1 physical line  common on long-haul, high capacity, links  have FDM and TDM alternatives

Frequency Division Multiplexing

FDM System Overview

FDM Voiceband Example

Wavelength Division Multiplexing  FDM with multiple beams of light at different freq  carried over optical fiber links

Synchronous Time Division Multiplexing

TDM System Overview