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What is FM mode on a CB radio?


FM (Frequency Modulation) mode has been utilized in other countries for many years and is even one of the main modes of communication due to the excellent sound quality, however, was illegal in the United States.  In the United States, CB radios only operated in AM (Amplitude Modulation) or SSB (Single Side Band) mode.  Back in 2016, efforts were made to petition the FCC (Federal Communication Commission) to allow FM usage in CB radios in the United States.  In September 2021, the FCC approved this change and it is now legal to operate a CB radio in FM mode in the United States.

Benefits of FM Mode 

  • The main benefit is improved sound quality at close range which can improve the user experience.  FM allows for a clearer sound with less background noise which can benefit CB users with clearer and more productive communication. If you’d like to experience how AM vs. FM sounds, click the link below to watch a short video:
  • According to Cobra®, it "offers the best available sound quality due to the "capture effect," meaning that one strong signal is selected, and other signals are suppressed".
  • Offers another mode for CB radio - historically, CB radios were limited to AM (Amplitude Modulation) and SSB (Single Side Band) modes.
  • Can be used with existing CB setups.  Does not require changes to your antenna system.
  • FM mode operates within the same standard AM frequencies used for CB radios 26.965 – 27.405MHz.
  • You can still communicate on AM as you've always done.

Potential Concerns

  • Users will not be able to talk to regular AM CB users if they are in the FM mode.
  • Shorter range than AM and SSB modes.
  • Lack of knowledge regarding the new mode might lead to user confusion.

"So, what mode should I use?"

It will depend on your particualr needs.  Do you need range or clearer communication? The good news is that all of the CB radios with FM mode that we offer will come with both modes so you can pick the best mode of communication when you want to.  

For example, if the sound is muffled on a local AM channel, you might switch to FM mode to strengthen the signal and improve clarity and volume on that frequency. However, if communicating with others at longer distances, AM frequencies could be more reliable.

Dual AM/FM Mode CB Radios at CB World!

As of today, CB World offers AM CB radios and some CB radios with both AM/FM modes.  For FM mode, we have Cobra® and President Electronics brands. Here is a link to our current offering of AM CB radios that include the FM mode option: