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Transcript

  • 1.
    • Amplitude Modulation
  • 2. Basic AM
    • Modulation
      • Amplitude
      • Spectrum
        • Carrier
        • Sideband
      • Modulation index
        • 0 < m < 1
        • How to measure?
          • Modulated carrier vs baseband signal
        • What happens when m>1?
  • 3. Waveforms
    • Base Band and Modulation
      • m = 100%
      • m = 120%
        • Math
        • Real
  • 4. Spectrum
    • Double Side Band Full Carrier
      • Spectrum
        • LSB, USB, Carrier
  • 5. Efficiency
    • Efficiency in Using Bandwidth?
      • Two side bands
    • Efficiency in Using Power?
      • Carrier
      • Side band
      • Information in side band
      • Carrier for synchronization
  • 6. Variations of AM
    • Bandwidth Efficiency
      • Single Side Band
      • Vestigial Side Band
    • Power Efficiency
      • Reduced Carrier
      • Suppressed Carrier
    • Complication
      • Circuits: generation, tuning, detection
      • Filter, tone variation, carrier recovery
  • 7. AM Radio
    • Source
      • Audio, 20-20 kHz
    • Carrier Frequency
      • 525 – 1705 kHz
    • Performance
      • 5 kHz bandwidth
      • 250-500 km range
      • 50 µV sensitivity
  • 8. AM Radio
  • 9. Commercial AM Radio
    • Circuit Diagram
  • 10. Commercial Radio
    • Circuit Board
  • 11. Block Diagram
  • 12. Crucial Components
    • RF Amplifier
      • High dynamic range
    • Autodyne Oscillator and Mixer
      • Tuning
    • Loop Antenna
      • LC resonator
    • Intermediate Frequency Amplifiers
      • 455 kHz
      • Tank circuit (double tuner) with flat center band
    • Diode RF Rectifier
      • Envelope detection
    • Automatic Gain Control
      • Strong vs weak stations
    • Audio Amplifier
    • Speaker
  • 13. Heterodyne
    • Incoming RF
      • RF amplifier
      • Bandpass filter
    • Local Oscillator
    • Mixer
      • Nonlinear device or balanced mixer
      • Bandpass filter
      • Signal proportional to local oscillator strength
    • Intermediate Frequency (AM at 455 kHz)
      • No further tuning
    • EMI from Local Oscillator
  • 14. Detection
    • Baseband Signal
    • Coherent Detection
      • AM modulation
      • Local oscillator
      • Mixer
      • LP filter
      • AC coupling
      • High sensitivity for low S/N
  • 15. Envelope Detection
    • Circuit
      • RF rectifier
      • Filter
      • RC time constant
      • Simple for high S/N
    • Waveform
  • 16. Detection
    • Square Law Detector
      • Modulation
      • Nonlinearity
      • RF filter
      • Low pass and AC coupling
  • 17. Performance
    • Sensitivity
    • Fidelity or Bandwidth
    • Dynamic Range
    • Selectivity
      • Adjacent channel
    • Image Rejection
      • IF
    • Spurious Response
      • Harmonics
    • Squelch
    • Noises
      • Static noise from transmission media
      • Motor boating noise from drift in frequency
  • 18. Lab and Projects
    • Virtual Laboratory
      • http://www.mathworks.com/matlabcentral/fileexchange/loadCategory.do
      • (Search: FM AM)
      • Matlab project
        • http://www.cse.ucsc.edu/classes/ee151/Winter01/
      • Software Radio (http://www.wpi.edu/Pubs/E-project/Available/E-project-042805-113037/unrestricted/DASR_MQP_REPORT.pdf)
    • Simple AM Projects
    • Experiments
      • Agilent 33120 AM modulation
      • MC1496
        • http://www.onsemi.com/pub/Collateral/AN531-D.PDF
  • 19. AM Transmitter
    • History
    • Block Diagram
    • Automatic Level Control
      • m < 1
  • 20. AM Modulator
    • Balanced Mixer
    • Other Circuit
      • Base band signal modulates oscillator current
  • 21. Power Amplifier Impedance Matching
    • Maximize Power to the Load
    • Impedance
      • Z = V / I
    • Change V – I Relation
      • Transformer
        • High current, low voltage
        • Low current, high voltage
      • RLC Networks
        • Frequency dependent impedance
  • 22. Impedance Matching
    • MIT Open Courseware
      • http://ocw.mit.edu/NR/rdonlyres/Electrical-Engineering-and-Computer-Science/6-776Spring-2005/025E9FB7-46C3-4718-98EA-CBD23EEC9D98/0/lec4.pdf
    • Berkeley RLC Pi and T LC Network Calculator
      • http://bwrc.eecs.berkeley.edu/Research/RF/projects/60GHz/matching/ImpMatch.html
    • Role of Antenna
      • Impedance transformation between circuit and free space
  • 23. Short Wave Radio
    • Terrestrial Coverage, HAM
      • http://n5xu.ece.utexas.edu/hamradio/
    • Regenerative Receiver Project
      • http://www.electronics-tutorials.com/receivers/regen-radio-receiver.htm
  • 24. HAM
    • http:// www.arrl.org/hamradio.html
    • http://www.qsl.net/dl4yhf/
      • Spectral analysis of audio signals
    • http://www.ac6v.com/
      • Antenna projects
    • http://www.radio.org/linux/
      • Linux HAM
  • 25. AM Stereo
    • Two Channels
      • L+R
      • L-R
    • Quadrature Amplitude Modulation
      • Sin, Cos: orthogonal
      • Increase Information Capacity Without Increasing Bandwidth
    • Motorola CQUAM System
      • Details
      • Chip
  • 26. Modern Application of AM
    • Advanced Television Systems Committee (ATSC)
    • 8-VSB Digital Signaling
  • 27. AM Noise Analysis
    • DSBFC Signal and Noise
      • Baseband signal power:
      • Carrier power:
      • Noise spectral density:
      • Double sideband bandwidth:
      • Total noise power:
    • Coherent Detection
      • In phase noise only
      • S/N
  • 28. AM Noise Analysis
    • Envelope Detection
      • Signal Dominant Regime
        • Similar to coherent detection
      • Noise Dominant Regime
        • Noise large
        • Signal small with random phase
    • Numerical Analysis
  • 29. AM Review
    • AM Waveform
    • Modulation Index Limit
    • Double Sideband, Full Carrier
    • Detection Circuits
      • Coherent detection
      • Envelope detection
    • Variations
      • SSB, RC or SC
      • Vestigial sideband
    • AM Transmitter
      • Impedance matching
      • Efficiency