Fundamentals of Communications (XE37ZKT), Part I Pulse...
Transcript of Fundamentals of Communications (XE37ZKT), Part I Pulse...
![Page 1: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/1.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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Fundamentals ofCommunications
(XE37ZKT), Part I
Pulse Code Modulation,Amplitude Shift Keying
Josef Dobes
6th
![Page 2: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/2.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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1. Outline
• Pulse Modulations
– Pulse Width Modulation (PWM)
– PAM, PPM, PCM, ...
![Page 3: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/3.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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1. Outline
• Pulse Modulations
– Pulse Width Modulation (PWM)
– PAM, PPM, PCM, ...
• Pulse Code Modulation (PCM)
• Examples of PCM Codes
• Nyquist Rate
• Quantization Noise
![Page 4: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/4.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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1. Outline
• Pulse Modulations
– Pulse Width Modulation (PWM)
– PAM, PPM, PCM, ...
• Pulse Code Modulation (PCM)
• Examples of PCM Codes
• Nyquist Rate
• Quantization Noise
• Three Types of Keying (ASK, FSK, PSK)
![Page 5: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/5.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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1. Outline
• Pulse Modulations
– Pulse Width Modulation (PWM)
– PAM, PPM, PCM, ...
• Pulse Code Modulation (PCM)
• Examples of PCM Codes
• Nyquist Rate
• Quantization Noise
• Three Types of Keying (ASK, FSK, PSK)
• Amplitude Shift Keying (ASK)
– LF/HF Spectra
– 4-ASK
![Page 6: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/6.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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2. Pulse Width Modulation
Signal is compared to a sawtooth wave producing a pulse widthproportional to amplitude.
![Page 7: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/7.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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2. Pulse Width Modulation
Signal is compared to a sawtooth wave producing a pulse widthproportional to amplitude.
There are many similar cases (PAM, PPM, ...). However, the mostimportant one is PCM. (See the sampling and quantization concept).
![Page 8: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/8.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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3. Pulse Code Modulation
3.1. Sampling and Quantization
−3.19 000
−2.28 001
−1.37 010
−0.455 011
0.455 100
1.37 101
2.28 110
3.19 111
Quan
tiza
tion
leve
ls
t
x(t) Sampled values Quantized values
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Sampling period
−4
−3
−2
−1
0
1
2
3
4
110 110 111 110 011 010 011 100 100 011 010PCM sequence
![Page 9: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/9.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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4. Some PCM Codes
![Page 10: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/10.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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5. Nyquist Rate
Due to the sampling, the spectra are repeated with the samplingfrequency:
Thus, the spectra may overlay if fs < 2fm. In such a case, theoriginal signal cannot be completely reconstructed. To do so, thesampling frequency must fulfill the condition
fs = 2fm,
where fm is the maximum LF modulating frequency.
![Page 11: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/11.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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6. Quantization Noise
Average quantization noise power:
σ2 =q2
12,
where q is the quantization interval. (See the quantization errorconcept, where σ = 0.91 V).
![Page 12: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/12.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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6. Quantization Noise
Average quantization noise power:
σ2 =q2
12,
where q is the quantization interval. (See the quantization errorconcept, where σ = 0.91 V).
Signal peak power:
V2p =
L2q2
4,
where L is number of quantization intervals. (See the quantizationerror concept, where L = 7).
![Page 13: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/13.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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6. Quantization Noise
Average quantization noise power:
σ2 =q2
12,
where q is the quantization interval. (See the quantization errorconcept, where σ = 0.91 V).
Signal peak power:
V2p =
L2q2
4,
where L is number of quantization intervals. (See the quantizationerror concept, where L = 7).
Signal power to average quantization noise power:(S
N
)q
=V2
p
σ2= 3L2.
![Page 14: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/14.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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−3.19 000
−2.28 001
−1.37 010
−0.455 011
0.455 100
1.37 101
2.28 110
3.19 111
Quan
tiza
tion
leve
ls
t
x(t) Sampled values Quantized and Hold q(t)
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Sampling period
−4
−3
−2
−1
0
1
2
3
4
t
Quantization error q(t) − x(t)
ε(t
)
110 110 111 110 011 010 011 100 100 011 010
![Page 15: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/15.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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7. ASK/FSK/PSK Keying
7.1. Amplitude Shift Keying
![Page 16: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/16.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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7.2. Frequency Shift Keying
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Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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7.3. Phase Shift Keying
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Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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8. Amplitude Shift Keying
8.1. LF/HF Spectra
![Page 19: Fundamentals of Communications (XE37ZKT), Part I Pulse ...poseidon2.feld.cvut.cz/personal/dobes2/(6)PCM-Keying.pp4.pdf · ASK/FSK/PSK Keying Amplitude Shift Keying Home Page JJ II](https://reader031.fdocuments.net/reader031/viewer/2022021723/5cd2b4af88c993e80a8c6ad1/html5/thumbnails/19.jpg)
Outline
Pulse Width . . .
Pulse Code Modulation
Some PCM Codes
Nyquist Rate
Quantization Noise
ASK/FSK/PSK Keying
Amplitude Shift Keying
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8.2. 4-ASK
Actually, this is a form of combining the ASK and PSK...