Technician Class Lesson 2.2, Modulation

Here’s the video to introduce Lesson 2.2 from the ARRL Ham Radio License Manual.

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7 Responses to Technician Class Lesson 2.2, Modulation

  1. Owen Weislow says:

    I looked at the modulation video before reading the chapter and I must say the video was quite confusing. You used a lot of terminology, when describing your equipment, that did little but complicate your explanations. I think an explanation of terms and an in depth description of your equipment would be useful at the beginning. Like many a scientist or engineer, you tend to forget that you are talking to neophytes and although you may know the ins and outs of the subject matter, you audience does not

  2. Dave says:

    Hello Marge, in properly modulated AM, each sideband carries identical information—it’s just that one of the sidebands is “upside down” (the lower sideband). And no information is carried in the carrier (which is not exactly true, because the carrier serves as a phase reference). Single sideband has only one sideband and no carrier. In order to receive this information, the receiver inserts a “carrier” as a frequency reference for demodulation (this used to be called the beat frequency oscillator—BFO—though today we use the term “product detector”). Hope that helps. 73, Dave

  3. marge says:

    Your discussion of frequency and modulation helped me understand it. Now I’m a bit stuck on Modulation, like how AM has a carrier and two sidebands and then there’s single sideband. The way I’m picturing AM is like a sandwich although the meat (the information) is actually in the bread and the middle just carries the bread. So then how can a SSB signal work, with just the carrier and one sideband. If it can be sent that way, why would they use the carrier with two sidebands. Thank you so much for doing these videos!

  4. Dave says:

    Yes, FM is frequency modulation. Did I say something wrong in the video?

  5. Clay Clark says:

    Isn’t FM frequency modulation?

  6. dave says:

    Dennis, I’m having problems with my ISP – very slow speeds – too slow for video. But I checked the video and let the entire thing download before playing, and it seems to be fine. I checked it on my Chrome browser. Let me know if you’re still having trouble. If need be, I can re-render and re-upload. 73

  7. Dennis says:

    This video seems to always stop at 4:48, and won’t go any further.

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