TRUY N THÔNG SỀ Ố
DIGITAL COMMUNICATION
Week 2
1
2
•Format: The first important step in any
DCS:
–Transform the information source to a form
compatible with a digital system
•Pulse modulate: (đi u ch xung)ề ế
–Transform the digital messages to baseband
waveforms
–Baseband = signal whose spectrum extends
from (or near) DC some finite value (< a
few MHz)
3
Encode Transmit
Pulse
modulate
Sample Quantize
Demodulate/
Detect
Channel
Receive
Low-pass
filter Decode
Pulse
waveforms
Bit stream
Format
Format
Digital info.
Textual
info.
Analog
info.
Textual
info.
Analog
info.
Digital info.
source
sink
Formatting and transmission of baseband signal
4
Content
1. Formatting Textual Data (Character
Coding)
2. Messages, Characters, and Symbols
3. Formatting Analog Information
4. Sources of Corruption
5. Pulse Code Modulation
6. Baseband Modulation
5