Figure 6.7: Distorsion

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Figure 6.7 Distorsion
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Figure 6.4 FDM (Frekvensdelningsmultiplex,
frequency division multiplex)
Exempel på FDM-teknik ADSL-modem, kabel-TV-modem,
trådlös kommunikation.
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Figure 6.5 FDM demultiplexing example
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Figure 6.19 T-1 line for multiplexing
telephone lines
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Bandbredd övre gränsfrekvens undre
gränsfrekvens
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Digital modulation

• För att överföra N bit/symbol krävs M2N
• Vid M symboler överförs Nlog2 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

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Figure 3.6 Sine wave examples (continued)
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Figure 3.9 Three harmonics
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Figure 3.10 Adding first three harmonics
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Figure 3.11 Frequency spectrum comparison
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Point-to-point communication
Mikrofon
Högtalare
NACK
0110010
ACK
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Aliasing
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Quantization noice
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Digital modulation methods
Binär signal
ASK Amplitude Shift Keying (AM)
FSK Frequency Shift Keying (FM)
PSK Phase Shift Keying (PSK)
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Spread spectrum
DS-CDMA Direct Sequence Code DivisionMultiple
Access
Chip sequencies
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Figure 13.15 Encoding rules
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Figure 13.16 CDMA multiplexer
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Figure 13.17 CDMA demultiplexer