0195136047.pdf

15.3 DIGITAL COMMUNICATION SYSTEMS 723

Digital

recorder

A/D

converter

Studio

LR

Modulator

Laser

recording

Master disc

Replication

Channel

1.25 m/s

Digital

control

and display

information

Channel

encoder

Up-sampling

and

interpolation

D/A

converter

LR

Demodulator

Compact disc

Channel

decoder

Figure 15.3.12General block diagram of

a CD digital audio system.

Communication

satellite

Earth

Reference

Station 2 station

Station 1

Station N

...

Figure 15.3.13Communication links of several earth stations

communicating through a satellite.

t=0tot=Tb, since the operation of any other interval will be similar. The desired ASK signal
is given by

sASK(t)=

{

Accos(ωct+φc), 0 <t<Tb, for 1

0 , 0 <t<Tb, for 0

(15.3.17)