Ref am

728 views

Published on

Published in: Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
728
On SlideShare
0
From Embeds
0
Number of Embeds
7
Actions
Shares
0
Downloads
10
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Ref am

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

×