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Welcome to B.A.R.K.’s TECHNICIAN CLASS

Welcome to B.A.R.K.’s TECHNICIAN CLASS. Run some Interference Protection # 14. Interference. Common Causes of Interference Fundamental Overload - Interference caused by very strong nearby signals Harmonics- Every transmitter creates harmonics. Harmonics are

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Welcome to B.A.R.K.’s TECHNICIAN CLASS

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  1. Welcome to B.A.R.K.’sTECHNICIAN CLASS Run some Interference Protection # 14

  2. Interference Common Causes of Interference Fundamental Overload- Interference caused by very strong nearby signals Harmonics- Every transmitter creates harmonics. Harmonics are multiples of the fundamental frequency. Example: Fundamental= 110 Hz 1rst harmonic= 220 Hz 2nd harmonic= 330 Hz 3rd harmonic= 440 Hz To reduce harmonic interference install a filter between your antenna and transmitter. Note that not all harmonics are of equal amplitude.

  3. Interference Spurious Emissions- any radio frequency not deliberately transmitted. Spurious emissions are often called “splatter”. A harmonic or other signal outside a transmitter’s assigned channel would be considered a spurious emission. The difference between harmonics and spurious emissions is that harmonics are multiples of the fundamental frequency, spurious emissions often are not multiples.

  4. Interference Distortion If you receive a report that your signal through the repeater is distorted or weak, the problem may be any of the following: Your transmitter may be slightly off frequency Your batteries may be running low You could be in a bad location

  5. The FCC regulates low-power, unlicensed devices under their • Part 15 rules. Part 15 devices include wireless telephones, • remote car starters, and wireless Internet routers. • If a "Part 15" device in your neighbor’s home is causing • harmful interference with your station you should: • Work with your neighbor to identify the device • Politely inform the neighbor of the rules and ask them to • cease using the device • Check your station to make sure it meets standards of • -good amateur practice

  6. Recognition and correction of problems If someone tells you that your transmissions are interfering with their TV reception: -First make sure that your station is operating properly -That it does not cause interference to your own television. When a neighbor reports that your radio signals are interfering with something in his home: The proper course of action to take is to check your station and make sure it meets the standards of good amateur practice.

  7. The most likely cause of telephone interference from a nearby transmitter is the transmitter’s signals are causing the telephone to act like a radio receiver. • A logical first step when attempting to cure an interference problem in a telephone is to install an RF filter at the telephone. • RF current on a coaxial cable shield can be reduced by installing a ferrite choke.

  8. Interference • If you set your microphone gain to high it could also cause • distortion. • If, when using your HT radio, you get reports of distortion: • Talk farther away from the microphone • Lower the volume of your voice • Lower the microphone gain

  9. -A fundamental overload, in reference to a receiver, is interference caused by very strong signals from a nearby source. • Receiver front-end overload is the result of interference caused by strong signals from a nearby source. • To reduce TV interference from a 2 meter transmitter use a band reject filter.

  10. Interference Noise Blanker When operating portable you might receive reports of a variable, high-pitched whine in your audio. The whine is frequently caused by your car’s alternator. Many portable radios have a “noise blanker” circuit that, when engaged, will reduce or eliminate the whine. Noise Blanker circuit

  11. Let’s Review !

  12. T7B10 What might be the problem if you receive a report that your audio signal through the repeater is distorted or unintelligible?A. Your transmitter may be slightly off frequencyB. Your batteries may be running lowC. You could be in a bad locationD. All of these choices are correct

  13. T7B10 (D)What might be the problem if you receive a report that your audio signal through the repeater is distorted or unintelligible?A. Your transmitter may be slightly off frequencyB. Your batteries may be running lowC. You could be in a bad locationD. All of these choices are correct

  14. T4B01 What may happen if a transmitter is operated with the microphone gain set too high?A. The output power might be too highB. The output signal might become distortedC. The frequency might varyD. The SWR might increase

  15. T4B01 (B)What may happen if a transmitter is operated with the microphone gain set too high?A.The output power might be too highB. The output signal might become distortedC.The frequency might varyD.The SWR might increase

  16. T7B01 What can you do if you are told your FM handheld or mobile transceiver is over deviating?A. Talk louder into the microphoneB. Let the transceiver cool offC. Change to a higher power levelD. Talk farther away from the microphone

  17. T7B01 (D)What can you do if you are told your FM handheld or mobile transceiver is over deviating?A. Talk louder into the microphoneB. Let the transceiver cool offC. Change to a higher power levelD. Talk farther away from the microphone

  18. T2B07 What should you do if you receive a report that your station’s transmissions are causing splatter or interference on nearby frequencies?A. Increase transmit powerB. Change mode of transmissionC. Report the interference to the equipment manufacturerD. Check your transmitter for off-frequency operation or spurious emissions

  19. T2B07 (D)What should you do if you receive a report that your station’s transmissions are causing splatter or interference on nearby frequencies?A. Increase transmit powerB. Change mode of transmissionC. Report the interference to the equipment manufacturerD. Check your transmitter for off-frequency operation or spurious emissions

  20. T4B05 Which of the following would reduce ignition interference to a receiver?A. Change frequency slightlyB. Decrease the squelch settingC. Turn on the noise blankerD. Use the RIT control

  21. T4B05 (C)Which of the following would reduce ignition interference to a receiver?A. Change frequency slightlyB. Decrease the squelch settingC. Turn on the noise blankerD. Use the RIT control

  22. T7B09 What could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter?A. Your microphone is picking up noise from an open windowB. You have the volume on your receiver set too highC. You need to adjust your squelch controlD. Noise on the vehicle’s electrical system is being transmitted along with your speech audio

  23. T7B09 (D)What could be happening if another operator reports a variable high-pitched whine on the audio from your mobile transmitter?A. Your microphone is picking up noise from an open window B. You have the volume on your receiver set too high C. You need to adjust your squelch controlD. Noise on the vehicle’s electrical system is being transmitted along with your speech audio

  24. T4A10 What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio?A. The ignition systemB. The alternatorC. The electric fuel pumpD. Anti-lock braking system controllers

  25. T4A10 (B)What is the source of a high-pitched whine that varies with engine speed in a mobile transceiver’s receive audio?A. The ignition systemB. The alternatorC. The electric fuel pumpD. Anti-lock braking system controllers

  26. T4A09 Which would you use to reduce RF current flowing on the shield of an audio cable?A. Band-pass filterB. Low-pass filterC. PreamplifierD. Ferrite choke

  27. T4A09 (D)Which would you use to reduce RF current flowing on the shield of an audio cable?A. Band-pass filter B. Low-pass filter C. PreamplifierD. Ferrite choke

  28. T4A05 What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter?A. Low-pass filterB. High-pass filterC. Band-pass filterD. Band-reject filter

  29. T4A05 (D)What type of filter should be connected to a TV receiver as the first step in trying to prevent RF overload from a nearby 2 meter transmitter?A. Low-pass filter B. High-pass filter C. Band-pass filterD. Band-reject filter

  30. T4A04 Where must a filter be installed to reduce harmonic emissions?A. Between the transmitter and the antennaB. Between the receiver and the transmitterC. At the station power supplyD. At the microphone

  31. T4A04 (A)Where must a filter be installed to reduce harmonic emissions?A. Between the transmitter and the antennaB. Between the receiver and the transmitterC. At the station power supplyD. At the microphone

  32. T7B03 Which of the following may be a cause of radio frequency interference?A. Fundamental overloadB. HarmonicsC. Spurious emissionsD. All of these choices are correct

  33. T7B03 (D)Which of the following may be a cause of radio frequency interference?A. Fundamental overloadB. HarmonicsC. Spurious emissionsD. All of these choices are correct

  34. T7B11 What is a symptom of RF feedback in a transmitter or transceiver?A. Excessive SWR at the antenna connectionB. The transmitter will not stay on the desired frequencyC. Reports of garbled, distorted, or unintelligible transmissionsD. Frequent blowing of power supply fuses

  35. T7B11 (C)What is a symptom of RF feedback in a transmitter or transceiver?A. Excessive SWR at the antenna connectionB. The transmitter will not stay on the desired frequencyC. Reports of garbled, distorted, or unintelligible transmissionsD. Frequent blowing of power supply fuses

  36. T7B06 What should you do first if someone tells you that your station’s transmissions are interfering with their radio or TV reception?A. Make sure that your station is functioning properly and that it does not cause interference to your own televisionB. Immediately turn off your transmitter and contact the nearest FCC office for assistanceC. Tell them that your license gives you the right to transmit and nothing can be done to reduce the interferenceD. Continue operating normally because your equipment cannot possibly cause any interference

  37. T7B06 (A)What should you do first if someone tells you that your station’s transmissions are interfering with their radio or TV reception?A. Make sure that your station is functioning properly and that it does not cause interference to your own televisionB. Immediately turn off your transmitter and contact the nearest FCC office for assistanceC. Tell them that your license gives you the right to transmit and nothing can be done to reduce the interferenceD. Continue operating normally because your equipment cannot possibly cause any interference

  38. T7B04 What is the most likely cause of interference to a non-cordless telephone from a nearby transmitter?A. Harmonics from the transmitterB. The telephone is inadvertently acting as a radio receiverC. Poor station groundingD. Improper transmitter adjustment

  39. T7B04 (B)What is the most likely cause of interference to a non-cordless telephone from a nearby transmitter?A. Harmonics from the transmitterB. The telephone is inadvertently acting as a radio receiverC. Poor station groundingD. Improper transmitter adjustment

  40. T7B05 What is a logical first step when attempting to cure a radio frequency interference problem in a nearby telephone?A. Install a low-pass filter at the transmitterB. Install a high-pass filter at the transmitterC. Install an RF filter at the telephoneD. Improve station grounding

  41. T7B05 (C)What is a logical first step when attempting to cure a radio frequency interference problem in a nearby telephone?A. Install a low-pass filter at the transmitterB. Install a high-pass filter at the transmitterC. Install an RF filter at the telephoneD. Improve station grounding

  42. T7B07 Which of the following may be useful in correcting a radio frequency interference problem?A. Snap-on ferrite chokesB. Low-pass and high-pass filtersC. Band-reject and band-pass filtersD. All of these choices are correct

  43. T7B07 (D)Which of the following may be useful in correcting a radio frequency interference problem?A. Snap-on ferrite chokesB. Low-pass and high-pass filtersC. Band-reject and band-pass filtersD. All of these choices are correct

  44. T7B08 What should you do if a "Part 15" device in your neighbor’s home is causing harmful interference to your amateur station?A. Work with your neighbor to identify the offending deviceB. Politely inform your neighbor about the rules that require him to stop using the device if it causes interferenceC. Check your station and make sure it meets the standards of good amateur practiceD. All of these choices are correct

  45. T7B08 (D)What should you do if a "Part 15" device in your neighbor’s home is causing harmful interference to your amateur station?A. Work with your neighbor to identify the offending deviceB. Politely inform your neighbor about the rules that require him to stop using the device if it causes interferenceC. Check your station and make sure it meets the standards of good amateur practiceD. All of these choices are correct

  46. Thank You ! Run some Interference Protection # 14

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