User Tools

Site Tools


podcast:ddop:public:episode_201909

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.

Notes

  • 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.

Wrap Up

Thank you for listening. 73 from WX0MIK.

Contact Information

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