0195136047.pdf

696 COMMUNICATION SYSTEMS

sFM(t) f(t)

R D

R D

L 1

L 2

Re

Message

FM signal signal

(a)

(b)

(c)

(d)

Amplitude response

Linear region

Amplitude response

Amplitude response

Bandpass filters Envelope detectors

Re

Ce

Ce

C 1

C 2

f 1

f 1

f

f 2

f

f

|H 1 (f)|

|H 2 (f)| |H 1 (f)|

|H(f)| = |H 1 (f)| − |H 2 (f)| |H 1 (f)|

−|H 2 (f)|

Linear region

Figure 15.2.15Balanced discriminator with the corresponding frequency response.