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Analog and digital data

Analog and digital data. Skills : none IT concepts : analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size trade off. This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License. Where does this topic fit?.

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Analog and digital data

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  1. Analog and digital data Skills: none IT concepts: analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size trade off This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.

  2. Where does this topic fit? • Internet concepts • Applications • Technology • Implications • Internet skills • Application development • Content creation

  3. Digital and analog clocks Start clocks Which clock is digital? Which analog? Which clock is the closest analog to the physical world?

  4. A digital clock 12:00:00 12:00:01 12:00:02 12:00:03 etc. Digital data is discreet and jumpy, not smooth and continuous

  5. Physical sensors → electric signals Light level Pressure Sound waves Acceleration Position of a knob Orientation Proximity Gasses in the air Magnetic field

  6. For example, a microphone Varying voltage Sound waves

  7. Computers require digital data Computer 10010110 (150) 11001001 (201) 11000111 (199) … Analog to digital converter Analog data Digital data

  8. The input is continuous, analog data Sample the signal at regular intervals v2 v1 v7 . . . . . . S7 S3 S1 S2

  9. v2 v1 v9 Each sample produces a number

  10. v2 v1 v9 Each sample produces a number A jagged approximation of the original, continuous signal

  11. More frequent sampling results in a better fit

  12. Each sample produces a number But How big (how many bits) is each number?

  13. What time is it between seconds? Round off to the nearest second

  14. 60 steps More steps (higher resolution) means smaller round-off errors 12 steps 4 steps

  15. Digitizing introduces round-off errors 5 4 3.6 3 2.2 2 1 0

  16. 3 More steps (intervals) between the minimum and maximum values means smaller round-off errors 0 7 0 15 0

  17. More bits per sample → more possible steps

  18. The quality/file size tradeoff Increase sample rate → quality ↑ file size ↑ Increase sample size → quality ↑ file size ↑

  19. Computers can output analog data Computer 10010110 (150) 11001001 (201) 11000111 (199) … Digital to analog converter

  20. v2 v1 v9 Generate a somewhat jagged analog signal by approximating the value between samples with straight lines

  21. Electric signals → change physical world Sound Light Flow rate Temperature Turn things on and off

  22. v2 v1 v7 . . . . . . S7 S3 S1 S2 A few questions The value of sample 9 would be between the values of which two samples?

  23. Without looking back, what two factors determine the quality or goodness of fit of a digitized signal to the original analog signal?

  24. Where does this topic fit? • Internet concepts • Applications • Technology (electronics) • Implications • Internet skills • Application development • Content creation

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