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Chapter 2 Fundamentals of Data and Signals

Chapter 2 Fundamentals of Data and Signals. Introduction - Data and Signals. Data Signals. Analog versus Digital. Analog Digital. Noise. All Signals Have Three Components. Amplitude Frequency Phase. Amplitude.

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Chapter 2 Fundamentals of Data and Signals

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  1. Chapter 2Fundamentals of Data and Signals

  2. Introduction - Data and Signals • Data • Signals

  3. Analog versus Digital • Analog • Digital

  4. Noise

  5. All Signals Have Three Components • Amplitude • Frequency • Phase

  6. Amplitude • The amplitude of a signal is the height of the wave above or below a given reference point.

  7. Frequency • The frequency • the number of times a signal makes a complete cycle within a given time frame.

  8. Spectrum and Bandwidth • Spectrum • Bandwidth • e.g. The average voice has a frequency range of roughly 300 Hz to 3100 Hz. • The spectrum is • The bandwidth is

  9. Phase • The phase of a signal is the position of the waveform relative to a given moment of time or relative to time zero. • A change in phase can be any number of angles between 0 and 360 degrees. • Phase changes often occur on common angles, such as 45, 90, 135, etc.

  10. Signal Strength • All signals experience loss (attenuation) due to friction in transmission. • Attenuation is denoted as a decibel (dB) loss. • dB is a relative measure. • Decibel losses (and gains) are additive. Total: -5dB loss

  11. Digital Data with Digital Signals –Encoding • NRZ-L • NRZ-I • Manchester • Differential Manchester • 4B/5B Digital Encoding

  12. 1s Baud Rate and BPS • Baud rate • BPS Baud rate = BPS =

  13. 4B/5B Digital Encoding • Yet another encoding technique that converts four bits of data into five-bit quantities. • The five-bit quantities are unique in that no five-bit code has more than 2 consecutive zeroes. • The five-bit code is then transmitted using an NRZ-I encoded signal. • overhead

  14. Digital Data with Analog Signals - Modulation • Amplitude Modulation

  15. Digital Data with Analog Signals - Modulation • Frequency Modulation • Phase Modulation • Quadrature phase modulation • Quadrature amplitude modulation

  16. Analog Data into Digital Signals • Pulse Code Modulation • The analog waveform is sampled at specific intervals and the “snapshots” are converted to binary values • Higher sampling rate, or more quantization levels, improve the resolution, but will also increase the cost

  17. Analog Data into Digital Signals • Delta Modulation • An analog waveform is tracked using delta steps • Output 1 to represent a rise in voltage, and a 0 to represent a drop.

  18. Analog Data with Analog Signals • Analog signals serve as carriers • Modulated into different amplitude (AM) or frequencies (FM)

  19. A secure encoding technique that uses multiple frequencies or codes to transmit data. Spread Spectrum Technology

  20. Data Codes • The set of all textual characters or symbols and their corresponding binary patterns is called a data code. • There are two basic data code sets • ASCII • EBCDIC

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