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Transcript of Analog and digital data Skills: none IT concepts: analog to digital conversion, digital to analog...
![Page 1: Analog and digital data Skills: none IT concepts: analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649ceb5503460f949b7487/html5/thumbnails/1.jpg)
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.
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Where does this topic fit?
• Internet concepts– Applications– Technology– Implications
• Internet skills– Application development– Content creation
![Page 3: Analog and digital data Skills: none IT concepts: analog to digital conversion, digital to analog conversion, sample rate, sample size, quality-file size.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649ceb5503460f949b7487/html5/thumbnails/3.jpg)
Start clocks
Digital and analog clocks
Which clock is digital? Which analog?
Which clock is the closest analog to the physical world?
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12:00:0012:00:0112:00:0212:00:03
etc.
A digital clock
Digital data is discreet and jumpy, not smooth and continuous
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Light levelPressureSound wavesAccelerationPosition of a knobOrientation ProximityGasses in the airMagnetic field
Physical sensors → electric signals
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For example, a microphone
Sound waves Varying voltage
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Analog to digital converter
Computer
Computers require digital data
10010110 (150)11001001 (201)11000111 (199)…
Analog data Digital data
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The input is continuous, analog data
Sample the signal at regular intervals
S1 S2 S3 . . .
v1
v2
v7
S7 . . .
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Each sample produces a number
v1
v2
v9
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Each sample produces a number
v1
v2
v9
A jagged approximation of the original, continuous signal
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More frequent sampling results in a better fit
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Each sample produces a number
But
How big (how many bits) is each number?
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What time is it between seconds?
Round off to the nearest second
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60 steps
12 steps
4 steps
More steps (higher resolution) means smaller round-off errors
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4
3
2
1
0
5
3.6
2.2
Digitizing introduces round-off errors
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More steps (intervals) between the minimum and maximum values means smaller round-off errors
0
0
0
3
7
15
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Number of bits Number of possible steps
1 2
2 4
3 8
4 16
5 32
…
More bits per sample → more possible steps
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The quality/file size tradeoff
Increase sample rate → quality ↑ file size ↑
Increase sample size → quality ↑ file size ↑
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Digital to analog converter
Computer
10010110 (150)11001001 (201)11000111 (199)…
Computers can output analog data
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Generate a somewhat jagged analog signal by approximating the value between samples with straight lines
v1
v2
v9
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SoundLightFlow rateTemperatureTurn things on and off
Electric signals → change physical world
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A few questions
S1 S2 S3 . . .
v1
v2
v7
S7 . . .
The value of sample 9 would be between the values of which two samples?
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Without looking back, what two factors determine the quality or goodness of fit of a digitized signal to the original analog signal?
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Where does this topic fit?
• Internet concepts– Applications– Technology (electronics)– Implications
• Internet skills– Application development– Content creation