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Lesson 7: Signals and Emissions

Lesson 7 of 10, syllabus topic T8. The exam asks 4 questions from this topic, one from each of its 4 groups.

Signals and emissions explain how voice, Morse code and data ride on a radio wave, building on frequency and bandwidth.

What you will learn

  • T8A Basic characteristics of FM and SSB; Bandwidth of various modulation modes: CW, SSB, FM, fast-scan TV; Choice of emission type: selection of USB vs LSB, use of SSB for weak signal work, use of FM for VHF packet and repeaters
  • T8B Amateur satellite operation: Doppler shift, basic orbits, operating protocols, modulation mode selection, transmitter power considerations, telemetry, satellite tracking programs, beacons, uplink and downlink mode definitions, spin fading, definition of “LEO”, setting uplink power
  • T8C Operating activities: radio direction finding, contests, linking over the internet, exchanging grid locators
  • T8D Non-voice and digital communications: image signals and definition of NTSC, CW, packet radio, PSK, APRS, error detection and correction, amateur radio networking, DMR, WSJT modes, Broadband-Hamnet

1. Read

  1. Operating on HF: Which sideband to useHelps with T8A
  2. Learning Morse code: Why CW is still usedHelps with T8A
  3. Working amateur satellites: Uplink, downlink and mode namesHelps with T8B
  4. Working amateur satellites: Low Earth orbit and pass timingHelps with T8B
  5. Working amateur satellites: Doppler shiftHelps with T8B
  6. Operating on HF: Contests and field activitiesHelps with T8C
  7. Digital modes: FT8 and FT4Helps with T8D
  8. Digital modes: PSK31 and RTTYHelps with T8D
  9. Digital modes: Packet and APRSHelps with T8D
  10. Digital modes: Digital voiceHelps with T8D
  11. All 47 T8 questions with their answers and explanationsEvery group, with the rule or source behind each answer

2. Explore

  • Morse code trainer

    Play the same word at 10 and then at 20 words per minute. A dit lasts 1200 divided by the speed in milliseconds: 120 ms at 10 wpm, 60 ms at 20 wpm.

  • Grid square locator

    Look up your grid square. Contest and FT8 operators exchange these locators.

    This is exam question T8C05.

3. Practice

Practice one group at a time. A group is ready when you have answered every one of its questions and learned at least 80 percent of them; a question counts as learned when your last three answers to it were correct. To review quickly, go through this lesson’s questions as flashcards.

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