Digital Communications: Fundamentals and Applications, 3rd Edition

Chapter 2

Formatting and Baseband Modulation

The block diagram shows that the information source flows into the format block, which is the first step of the process. The message symbols and digital input m subscript i are given to source encode block as source input, which then proceeds through encrypt, channel encode, and multiplex blocks. Channel symbols flow into the process between channel encode and multiplex blocks. Signals from the other sources are also introduced into the multiplex block. The digital output resulting from these steps is transferred into the pulse modulate block, and then to bandpass modulate, frequency spread, and ...