Episode 2019-09 - Modulation

Hello and welcome to the next edition of the Mike Wills Podcast! This is the Dog Days of Podcasting edition for {insert date here}. I am WX0MIK and my name is Mike Wills. This season, we are covering amateur (or ham) radio.

  • Modulation is what enables us to communicate information using radio signals.
  • Bandwidth
    • We now know that a frequency can have a strength and amplitude
    • Signals are actually spread over a range of frequencies. From less than 300 Hz to over 3000 Hz.
    • Most of the modes have pre-defined bandwidth and in fact, in some cases, the FCC dictates that bandwidth you can use.
  • Modulation
    • Adds information to the signal.
    • A signal without information is unmodulated
    • Can be analog or digital
    • Two types are AM and FM
  • Continuous Wave (CW) or Morse Code - This is the simplest form of modulation using dits and dahs.
  • Amplitude Modulation - varying the power and amplitude of a signal to add speech or data.
  • Single Side Band (SSB) - Take an AM signal and use only 1/2 of the signal. There is then an upper sideband (USB) and a lower sideband (LSB).
  • Frequency and Phase Modulation (FM and PM) - Mostly used interchangeably.
  • Bandwidth of Modulated Signals
    • SSB is low bandwidth and thus can travel much further. CW is even lower yet and thus better yet for long distances.
    • CW uses 150 Hz
    • SSB digital uses 500 to 3000 Hz
    • SSB voice uses 2 to 3 kHz
    • AM voice uses 6 kHz
    • AM broadcast uses 10 kHz
    • FM voice uses 15 to 15 kHz
    • FM broadcast uses 150 kHz
  • There are some variations and rule surround this, but generally this is that case. The book will explain when this changes.

Thank you for listening. 73 from WX0MIK.

  • podcast/ddop/public/episode_201909.txt
  • Last modified: 2019/08/10 03:17
  • by mikewills