Narrowbanding FAQs
Monday, April 05, 2010 | Comments
FCC officials agreed to answer technical questions submitted by MissionCritical Communications readers. Following are questions from readers and answers from FCC technical and policy experts.
Question: Will 150 – 160 and 450 – 460 itinerant frequencies also be subject to 12.5-kilohertz requirements?
Answer: The various itinerant frequencies are subject to varying requirements. Regarding the VHF high band, some of the itinerant frequencies — often previously referred to as the “color dot” channels — were moved from Part 90 to the Multi-Use Radio Service (MURS) under Part 95 (see WT Docket No. 98-182 and 47 CFR Part 95, Subpart J and 47 CFR 95.632) and some remained in Part 90. Of those itinerant frequencies that remained in Part 90, most were created as narrowband channels in the refarming proceeding and may only be assigned for narrowband use. 151.640 MHz is limited to 6.25-kilohertz operations, and 151.5125, 151.700, 151.760, 154.5275 and 158.4075 MHz are limited to 12.5-kilohertz operations. The remaining two VHF high band itinerant channels 151.505 and 158.400 MHz are subject to the narrowbanding rules, and stations must narrowband by Jan. 1, 2013.
The rest of the VHF high band itinerant channels were moved to the MURS. Under those rules (see 47 CFR 95.632), 151.820, 151.880 and 151.940 MHz are authorized for 12.5-kilohertz channels, and 154.570 and 154.600 MHz are authorized for 25-kilohertz channels. However, notwithstanding those requirements, rule section 95.1317 provides for grandfathered operation of previously granted Part 90 licenses on those frequencies. The rule states that “[s]tations that were licensed under Part 90 of the commission’s rules to operate on MURS frequencies as of Nov. 13, 2000, are granted a license by rule that authorizes continued operations under the terms of such nullified Part 90 authorizations, including any rule waivers.” Therefore, stations operating on 25-kilohertz MURS channels prior to Nov. 13, 2000, may continue wideband operation, and all stations may operate using 25-kilohertz channels on 154.570 and 154.600 MHz.
The UHF itinerant channels weren’t moved to the MURS and are subject to the Jan. 1, 2013, narrowbanding deadline. These channels are: 451.800, 456.800, 464.500, 464.500, 469.500 and 469.550 MHz. All other UHF itinerant channels were created as narrowband channels in the refarming proceeding and have always been subject to narrowband use. 451.80625, 451.81875, 456.80625 and 456.81875 MHz are limited to 6.25-kilohertz operations, and 451.8125 and 456.8125 MHz are limited to 12.5-kilohertz operations.

Question: Are the VHF low band frequencies (30 – 50 MHz) affected by narrowbanding? Does the FCC have future plans for these frequencies or will they be left as is?
Answer: The VHF low band isn’t subject to the narrowbanding rules, and the commission has no current plans to change the rules for these channels. If the FCC were to consider changes for these channels, it would be done through a notice and comment rulemaking proceeding.

Question: Are the frequencies subject to narrowbanding by the Jan. 1, 2013 deadline?
Answer: Yes.

Question: Can an end user re-certify my MastrII/Micor transmitters for narrowband? Can I do the recertification using field grade service monitors, or will I need the services of an FCC certified lab?
I want to modify several VHF MSF5000 base stations and repeaters using the Communications Specialists 12.5-kilohertz kits. What do I need to do to comply with the FCC regulations? What is the procedure that I need to follow to recertify my equipment? Do I have to send the equipment to the FCC?
Answer: If a kit is used to modify a radio to bring it into compliance with the narrowband rules, the radio must be recertified to show compliance with those rules. Regardless of who actually modifies the radio and the equipment used to do so, the party that submits the new application for equipment approval becomes the responsible party for that radio. That party would be required to place the new FCC ID label on the device. If this party is also a distributor or a manufacturer, the party could modify the same radios in a similar manner and place the new FCC ID label on the modified radio. If a different party were to use the same kit to modify a radio, they would need to submit that modified radio for a new certification and become the responsible party for those modified radios.
For guidance on how to apply for an FCC equipment authorization, refer to guidance at The modified devices need to be certified.

Question: The FCC, in public notice DA 09-2589, stated that under certain circumstances previously certified multimode equipment can be manufactured or imported after Jan. 1, 2011. Specifically, the public notice stated that the equipment certification for previously certified multimode equipment containing a wideband 25-kilohertz mode will continue to be valid, and such equipment may continue to be manufactured and imported, only if the modes of operation are enabled primarily through software rather than firmware or hardware, and users aren’t provided with the programming software necessary to activate the wideband 25-kilohertz mode. Based on this, please clarify the following.
Are manufacturers required to modify radios so that previous versions of programming software with 25-kilohertz capability can’t be used? This assumes the previous version of programming software is replaced by a new version with no 25-kilohertz capability and the previous version is no longer sold.
Answer: Manufacturers must ensure that equipment manufactured or imported after the transition date has the 25-kilohertz capability disabled. If this is done through programming software, then the appropriate software must be modified to comply with this requirement, and the previous version of the software must be updated or replaced.

Question: Is it permissible for users to program radios sold after Jan. 1, 2011, with previous versions of programming software and enable 25-kilohertz operations?
Answer: No, it isn’t permissible for users to program or reprogram radios sold after Jan. 1, 2011, to enable the 25-kilohertz mode of operation.

Editor’s Note: If you have a technical question regarding VHF or UHF narrowbanding, e-mail, and we will request an answer from the FCC and run the information as soon as possible. You can also contact the FCC directly via Robert Kenny, FCC spokesman, 202-418-2668,

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