AM () (4-1) · 2011. 8. 20. · FM Discriminator -2 . (Supper Heterodyne) L1 C1 TR1 ( ) 455KHz...
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Transcript of AM () (4-1) · 2011. 8. 20. · FM Discriminator -2 . (Supper Heterodyne) L1 C1 TR1 ( ) 455KHz...
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Receivers
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AM 455 KHzFM 10.7 MHz
455 KHz 42 MHz33.4 MHz
)(38.9 MHz)(5.5 MHz)video(.
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Local oscillator 455KHzAM10.7 OR 9.1MHz
FM
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455KHzAM10.7 MHzFM(.
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IF(
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C1L1
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455KHzAMTR2
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C2L2.C1C2)(
455KHz1000KHz1455KHz,Mixer
4
RF Out
Oscillator
mixer
RF
Am
plif
ier
C1
C2
L1
L2
TR1
TR2
87
14551000=455 KHz1455+1000=2455 KHz
1000 KHz1455 KHz
IFIntermediate frequency
455KHz455KHz RF
AGCAutomatic Gain Control
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AGCTR1
IF1 IF2 IF3
IF INA
udio
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D1C1 RF
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Push Pull
Volume
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Q6
Q7
Speaker
AudioIN
90
Modulation
:
1-CWContinuous wave modulation )Analog(,,
PM,FM,AM
2-Pulse Modulation)Digital(
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3-Coding )Analog()Digital(
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91
1-CWContinuous wave modulation
AMAmplitude Modulation RF carrier
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30MHz
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92
SSBSingle side band
6 KHz±3 KHz1MHz1,003,000997,000MHz
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800
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Hz Hz
Hz
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FMRF carrier
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PMphase
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Digital A/DAnalog to Digital .
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PDM / PTM / PWM / PLMPulse – Duration / Time / Width / Length Modulation
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96
Pulse - Code Modulation PCM
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TCMTrellis – Code Modulation Gottfried Ungerboeck1980
3-Coding
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97
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98
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99
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PLL
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