DATA AND SIGNAL

DATA AND SIGNAL

1. ·

   • Analog data
     • continuous
   • Analog Signal
     • have an infinite number of values in a range
     • periodic
       • simple
         • sine wave
           • parameters
             • Peak amplitude
             • Frequency
             • Phase
           • Sine Wave Plot
             • Time-domain plot
             • Frequency-domain plot
     • composite
       • simple sine wave with different frequencies, amplitudes, and phases
       • Bandwidth ------> Range of frequency

2. ·

   • Digital data
     • discrete states
   • Digital Signal
     • Only limited number of value
     • can have more than two level
     • Signal Level (bps)
     • Transmission
       • Baseband Transmission
         • Sending a digital signal over a channel without changing the digital signal to an analog signal
         • Requires a low-pass channel ---> a channel with a bandwidth that starts from zero
       • Broadband Transmission
         • Changing the digital signal to an analog signal
         • Requires bandpass channel ---> a channel with a bandwidth that does not start from zero
       • Transmission Impairment
         • Attenuation
           • loss of energy
             • use amplifier
         • Distortion
           • Signal changes its form or shape
         • Noise
           • unwanted eletrical or electromagnet energy that degrades the quality of data and signals
             • Thermal Noise
               • random motion of electron
             • Induced Noise
               • from source such as motors
             • Impulse Noise
               • spike that come from power line
             • Crosstalk
               • effects of one wire on other wire
           • Signal-to-noise Ratio

3. Signal

   • Periodic
     • completes a pattern within a measurable time frame (period)
     • repeats pattern over subsequent identical periods
   • Nonperiodic
     • signal changes without exhibiting a pattern or cycle repeat over time

4. Data Limit

   • Data Rate Limit
     • factors
       • The bandwidth avaible
       • The level of the signal
       • The quality of the channel (the level of noise)
     • Theoretical formulas
       • Nquist formula
       • Shannon formula

5. Perfomance

   • Transmission Time
   • Queing Time
   • Propagation Time
   • Latency(delay)

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