Basic Radio Signal Modulation

456

05:07:46

I have been enjoying an older Elements of Radio Servicing publication.  Free download at: 

 http://www.antiqueradios.com/archive.shtml

Top is AM signal and in time watching max voltage setting numbers on bar below wave forms you will see a slow rise and fall of blue modulating wave.  ABOVE and BELOW the steady 1 volt 600 kHz carrier frequency.

Bottom circuit is FM signal.  Click on green 78 kHz AC source (modulator).  Watch frequency changes  rise ABOVE and BELOW the 80 kHz carrier frequency.  (I made the carrier and modulator waves close in frequency to show frequency changes in simulator.  If this was 400 hz. modulation the FM signal would have to rise above and fall below 80 kHz. 400 times a second.

published 9 years ago

hurz

9 years ago

To your top circuit only... A modulator itself needs a nolinear element. Adding sinwaves is NOT a modulator itself! In best case, its a modulated spectrum. BTW, your WEB link is very fuzzy. What do you reference exactly to?

lmccoig

9 years ago

My EveryCircuit on computer is through Google Chrome app bar and not loaded on desktop, if that is what you mean?

hurz

9 years ago

I followed your link, but it does not direct to a webpages which explains your circuit. It is a link to a collection of more links related somehow to radio technology.

lmccoig

9 years ago

Link goes to .pdf files of Elements of Radio Servicing publication. I found information in Chapter 5 pages 25 and 26 and in Chapter 6 on page 30. It made FM modulation clearer to me than many other explanations and I wanted to try to simulate idea described.

hurz

9 years ago

Share the link to the .pdf if you wish to follow your idea

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