Chapter 5 AM FM and Digital Modulated Systems

Chapter 5 AM, FM and Digital Modulated Systems

In this chapter, we will study the techniques of bandpass communications. 1. Analog baseband signal (AM, FM, etc) 2. Digital baseband signals (OOK, BPSK, etc. ) 3. Multiplexing (TDM, FDM, CDM)

Basic Model for Bandpass Communication Source Destination

Amplitude Modulation

Generation of High-Power AM by Pulse Width Modulation

Costas Loop

Squaring Loop

Spectrum for USSB Signal

Generation of SSB Signals

VSB Spectra

Angle Modulation

Angle Modulator Circuits RFC : Radio Frequency Choke

FM with m(t) = Sinusoidal Signal

Bessel functions: n = 0 , 1, 2, 3, 4, 5, 6

Magnitude spectra for FM or PM

Spectrum of WBFM Signal

Spectrum of Wideband Binary FSK

Pre-emphasis and De-emphasis

Frequency Division Multiplexing

FM Stereo System

FM Broadcasting

Binary Modulated Bandpass Signals

Digital Bandpass Signals

PSD

Detection of OOK

Detection of BPSK

From Frequency Shift Keying section to the end of Chapter 5, the math is quite complex. Thus, we will focus on the concepts and understanding how various techniques work. Section 5. 10 will be covered briefly. Section 5. 11 will not be covered. Note that Chapter 5 is concerned with the technology. Do not focus too much about the mathematical details.

Frequency Shift Keying

FSK Modem FSK is very popular for telephone modems.

Example FSK Data

Spectra of FSK Data

PSD for Complex Envelope of FSK

Detection of FSK

Quadrature Phase Shift Keying (QPSK) (4 Level PSK)

Quadrature Amplitude Modulation (QAM) (Multi Level AM)

Generation of QAM

MSK, GMSK, QPSK, and OQPSK

Direct Sequence Spread Spectrum

Autocorrelation and PSD for an m-Sequence PN Waveform

Approximate PSD of BPSK-DS-SS Signal

Frequency-Hopped Spread Spectrum