Transcript Figure 6.7: Distorsion

Figure
6.7:
Distorsion
Figure 6.4
FDM (Frekvensdelningsmultiplex, frequency division multiplex)
Exempel på FDM-teknik: ADSL-modem,
kabel-TV-modem, trådlös kommunikation.
Figure 6.5
FDM demultiplexing example
Figure 6.19
T-1 line for multiplexing telephone lines
Bandbredd = övre
gränsfrekvens – undre
gränsfrekvens
Digital modulation
• För att överföra N bit/symbol krävs M=2N
• Vid M symboler överförs N=log2 M
bit/symbol.
• Baudrate fs= antal symboler per sekund.
Enhet: baud eller symboler/sekund.
• Symbollängd Ts= 1/fs. fs= 1/Ts
• Bitrate R = datahastighet. Enhet: bps eller
bit/s.
• R= fslog2 M
Figure 3.6
Sine wave examples (continued)
Figure 3.9
Three harmonics
Figure 3.10
Adding first three harmonics
Figure 3.11 Frequency spectrum comparison
Point-to-point communication
Layer
7
Layer
6
Mikrofon
Högtalare
Source coding
Digitalizating
compression
0110
Error management
Layer
2
NACK
ACK
0110010
Source decoding
0110
.
Error control
0100010
0110010
Bitfel
Layer
1
Flow control
Flow control
Modulation
Demodulation
Aliasing
Quantization noice
Digital modulation methods
Binär signal
ASK = Amplitude
Shift Keying (AM)
FSK = Frequency
Shift Keying (FM)
PSK = Phase Shift
Keying (PSK)
Spread spectrum
DS-CDMA = Direct Sequence Code Division
Multiple Access
Chip sequencies
Figure 13.15
Encoding rules
Figure 13.16
CDMA multiplexer
Figure 13.17
CDMA demultiplexer