Bandwidth and data rate

1
Bandwidth and data rate

• Bandwidth range of frequencies with most of the
  energy in the signal
• with a bandwidth of 2w Hz, w bps can be expected
• Signal electric or electromagnetic
• encoding of data
• Transmission (tx) communication of data by the
  propagation and processing of signals

2
Analog and digital data tx
3
(No Transcript)
4
Analog tx a means of transmitting analog signals
without regard to their contents Digital tx
transmission of digital data Trend digital
transmission for digital signals
5
Why digital transmission?

• Advanced digital technology cost down
• Repeater data integrity
• Easy multiplexing utilization
• Easy encryption/decryption security
• Multimedia support integration

6
Transmission impairments

• Attenuation reduction of signal strength
• increasing function of distance and frequency
• (repeater/amplifier) (equalizer)
• Delay distortion major limitation to bps
• signal speed is highest at the center frequency
• (equalizer)

7
Transmission impairments(2)

• Noise
• thermal noise
• Intermodulation noise
• Crosstalk electrical coupling
• Impulse noise

8
Transmission media
9
Data encoding

• Encode data into signal
• D-data into D-signal
• D-data into A-signal
• A-data into D-signal
• PCM(pulse code modulation), DM(delta -)
• based on the sampling theorem sample regularly
  at a rate higher than twice the signal frequency
• A-data into A-signal AM, FM, PM, QAM

10
(No Transcript)
11
ASK
FSK
PSK
12
Asynchronous transmission
13
Synchronous transmission
(preamble)
(postamble)