What is SSB modulation?

I understood the standard amplitude modulation where the audio signal is combined with the carrier wave and the result from the image is pretty obvious, but for the SSB modulation, I do not understand why the carrier wave and one of the side bands are not needed. The result looks the same as the carrier wave. Does it mean that only the carrier wave is transmitted in SSB modulation?

The diagrams don’t tell you enough.

In AM, the two sidebands are mirror-images of each other. The sound plus the carrier on one side and the sound minus on the other.

If you play enough games, you can reduce or eliminate one of the two sidebands. Conventional broadcast television works like this. The picture is AM, but not all of the lower sideband is transmitted to save channel space.

OK, so we don’t need both sidebands, how about the carrier? You don’t need that, either if you can predict exactly, precisely where it was. This is carrier re-injection that the ham radio people use. In their case, the carrier frequency is on a knob and you can hear the decoded pitch of the voice go up and down from rumbly bass thumping to squeaky cartoon sound as the adjustment is made. When you get close to the original with your made-up carrier, the voice settles down to semi-normal.

The voice wont be perfect unless you can determine exactly where the original carrier was.

SSB Suppressed Carrier is massively efficient. Half the sideband power, no carrier, and half the bandwidth. That’s why the hams like it.

There is one advantage of straight, simple AM. You can get a simple crystal radio and headphones to listen to it. No batteries and no power. Hang a wire in the trees, hook everything up, and listen. I think I still have mine here somewhere.


Correct me if I am wrong but isn’t this actually kind of FM instead of AM? Because I have seen that SSB modulation sort of modify the frequency of the carrier, like if I want to transmit a 1khz audio source using a 17khz carrier radio wave, USB will transmit 18khz while LSB transmits 16khz.

isn’t this actually kind of FM instead of AM?

No. FM is a whole different dog. FM produces infinite sidebands while it’s working and there are certain modulation conditions where the carrier will seem to vanish in favor of a pile of sidebands. It’s possible to “clean up” FM by limiting and clipping the carrier. That’s how an FM radio seems to be so clean. Music without interference and electrical trash—and all that is normal.

We should settle on exactly what you’re talking about. When most people say SSB, they really mean Single Side Band Suppressed Carrier. Do you?

17khz carrier radio wave

My Spidey Sense is telling me we’re secretly building a case for Subliminal Messaging. Are we?