Radio interference

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For a amateur radio course for FRO covering radio interferance and prevention

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Radio interference

  1. 1. Radio Interference<br />
  2. 2. Overview<br />What is it?<br />Radio Interference<br />Preventing<br />
  3. 3. What is it?<br />Unwanted signals<br />Effect electronic circuits<br />
  4. 4. Radio Interference<br />International Electrotechnical Commission<br />1933 set up International Special Committee on Radio Interference<br />EU<br />EMC Directive (89/336/EC)<br />Immunity<br />Emissions<br />
  5. 5. Radio Interference Types<br />Narrow band<br />TX equipment<br />Broad band<br />Power lines<br />Motors<br />Computers and TV<br />Antenna<br />Outside of antenna cable<br />Unbalanced<br />Power supplies<br />
  6. 6. Radio Interference Sources<br />Transmitting equipment<br />Harmonics<br />Wrong frequency<br />Faulty electronic equipment<br />Sun<br />Auroras<br />Splatter<br />
  7. 7. RX interference sources<br />Clipping<br />Square wave<br />Harmonics<br />Clipping from<br />Power<br />Microphone<br />
  8. 8. Preventing<br />Filter<br />Don’t over drive the system<br />Use baluns<br />RF choke<br />Faraday Cage<br />Cables<br />Electric Earth<br />
  9. 9. Preventing<br />Baluns<br />Matching between balanced and unbalanced lines<br />Conver between 300/450 W lines and 75 W coax<br />
  10. 10. Preventing<br />Baluns<br />Wound around a iron core<br />
  11. 11. Preventing<br />RF choke<br />inductor<br />
  12. 12. Preventing<br />Faraday Cage<br />Metal cage or mesh<br />Can block radio waves<br />Small gapes depending on wavelength<br />
  13. 13. Preventing<br />Cables<br />Twisted pair<br />Cancelling out<br />Coax<br />Inner conductor<br />Outer “shielding” conductor<br />
  14. 14. Preventing<br />Electrical earth<br />

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