FCC approves FM for CB Radio

Many thanks to SWLing Post contributor, Ron who shares the following news via the Southgate ARC:

FCC signals FM CB will be permitted on 27 MHz

63 years after the introduction of Class D 27 MHz AM CB Radio the FCC has agreed to permit FM to be used

From FCC Memorandum Opinion and Order on Reconsideration WT Docket No. 10-119, issued July 15, 2021:

What the Memorandum Opinion and Order on Reconsideration Would Do:

• Grant Cobra’s Petition requesting that the Commission allow FM as an optional modulation scheme for all existing 40 CB Radio Service channels (with AM remaining mandatory).

• Grant Motorola’s Petition requesting that the Commission allow automatic or periodic location and data transmissions in the GMRS and FRS. The Commission’s rules currently permit the transmission of location information and brief text messages initiated by a manual action and automatic responses of location information.

• Grant Medtronic’s Petition requesting the correction of typographical errors and rule changes in the Part 95 Personal Radio Services Rules Report and Order that inadvertently altered the substance of the Medical Device Radiocommunications Service (MedRadio) rules

The FCC say:

After considering this additional information, we conclude that allowing manufacturers to add FM as an optional modulation scheme will not substantially change the fundamental nature of the CB Radio Service and will improve the user experience, as described by Cobra and President. How people use the service will not materially change or be expanded. Further, Cobra states that AM is a “well established” operating mode that is unlikely to disappear, even if we permit operations in FM mode.

Continuing to mandate AM capability while permitting dual modulation will provide benefits to CB radio users who will have an additional modulation option, while maintaining the basic character of the service.

The addition of FM as a permitted mode will not result in additional interference because users who hear unintelligible audio on a particular channel can simply select another channel or switch modes.

Read FCC Memorandum Opinion and Order on Reconsideration WT Docket No. 10-119

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14 thoughts on “FCC approves FM for CB Radio

  1. John K5MO

    “The addition of FM as a permitted mode will not result in additional interference because users who hear unintelligible audio on a particular channel can simply select another channel or switch modes.”

    This is classic “bureaucrat speak” of the finest vintage!

    I’m surprised they didn’t say “no interference will be caused because the users who hear “unintelligible audio” (aka: Interference) can always turn the radio off”


  2. Dennis Dura

    I didn’t see any mention in the Docket about adding FM to a dual mode radio with AM/SSB now. If so, it’ll be easy for a few of the manufacturers that already offer 10 meter rigs with all three… Anytone and the variety of names they use on the same radio.

  3. Tha Dood

    YES!!!! It’s indeed about time to do NBFM on 27MHz CB’s in the USA. Should be less interference, lower power on the radio output finals, better S/N Ratios, possibly longer battery life on portables, etc. I see a big Win / Win here. But, you don’t have to wait on Cobra, there’s a dude in the UK that is making CB FM boards to modify your existing rigs, https://www.ebay.com/itm/283737307487 I’ve already bought two of these. Now, to decide which rigs to add FM too. They appear very straight forward and cleverly designed.

  4. K5MPH

    Its about time the FCC is sometime way behind times in all this radio stuff and what we call a hobby,this may bring a new life into CB radio………..

    1. Ryan

      thanks for the links!
      It seems the link for the confidential history of ham radio is the same for the CB radio. Could you please tell me which issue it is in, I would love to read it

    2. Michael Black

      May 1969 Electronics Illustrated, page 68 “Skeletons in CB’s Closet”. Some history of what 27MHz was used for before CB.

      Don’t forget that about 1947, there is as “CB” at 450MHz. But equipment too expensive at that frequency and time, so it didn’t get many users. GMRS is kind of descended from it.

      Canada waited a few years after the US before creating a “General Radio Service” that was mostly the same as CB in the US. I thought FM was allowed, but it’s been a long time. A significant difference was a few channels were not allowed in Canada, so a tiny 11 metre ham band continued. It didn’t get removed until April 30th 1972, when the missing channels became CB. I don’t think there were antpy Canadian made CB sets, so it relied on sets for the US market. Since there were 23 channel sets before 1972, I wonder if people were really good about not using those extra channels.

  5. 13dka

    Well… that took a while. 🙂

    In Germany, the first 12-channel (500mW) radios with FM came in 1977, an expansion of the band to 22 channels in 1981 brought the first mode limitation to FM for the new channels, based on concerns about interference through AM. In 1983 the regulator allowed 40 channels FM with 4W and the old 12 channels in between with 1W AM, the 8-fold TX power compared to the initial regulations clearly helped with the adoption of the formerly much despised mode.

    10 years later, the only channel still being used in AM on a regular basis was CH9, FM wasn’t so bad after all: People had realized that you could get away with much higher illegal power levels than you ever could in AM. 🙂

  6. rtc

    Keep in mind that 60 years ago (1958) the “state of the art” was still tube based and FM gear
    was bulky and expensive.That’s why the first generation CB gear was crystal controlled single channel with
    a super-regen tunable (broad) receiver.
    A quick search of the internet shows that most CB websites feel that Cobra and President are just looking to
    sell new radios with the FM mode.
    We’ll see.

  7. mangosman

    In Australia, this was an option a long time ago and was dropped because very narrow band FM performance approaches AM in the 27 MHz. We have 476.4250 and 477.4125 MHz FM CB radio which is now much more popular than 27 MHz. These UHF frequencies are used in the Americas and Europe for TV.
    In the 27 MHz band, SSB (12 W)/AM (6W) is used instead. The use of SSB means a doubling of the available channels compared to AM and FM. The range is increased because all of the battery power is used for the voice signals and not wasted on an AM carrier and for FM the power output of the transmitter is constant. With SSB silence means no power transmitted and the greater the volume of the sound the greater the power transmitted.

    As Desmond mentioned CB radio is very old, and has been replaced by digital two way radios in many professional situations such as the emergency services, mining companies….. The advantage is that they have selective calling better sound, 20 % increase in coverage and upto 50 % longer battery life.
    Check out two way radios for the VHF high band and UHF.

  8. Desmond Walsh

    Reading the FCC document I cannot see any reason why they did not adopt NBFM for CB 50 years ago. Lots of lines about FRS, UHF etc but little about 27MHz . Anyway it may interest a few people.
    Des Walsh EI5CD


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