In 1992 the FCC adopted the forthcoming narrowbanding requirements known as “refarming”. The basic purpose of this action was to enhance spectrum efficiency in the VHF and UHF land mobile bands.
Narrowbanding will allow the spectrum a better use of the frequencies already in place by reducing the existing 25 KHz channels to 12.5 KHz splits. That process is just around the corner and the following information will outline the upcoming process and hopefully allow you to make the necessary plans for the future in terms of licensing and timing of new product purchases.
What is Narrowbanding?
Currently most radio systems operate on wideband channels of 25 KHz. Licensees in the private land mobile VHF and UHF bands must modify their FCC licenses and convert their radio equipment to operate on channel bandwidths of 12.5 KHz or less. Any equipment that is not capable of operating on channels of 12.5 KHz or less will need to be replaced.
What does Narrowbanding mean?
If you use the analogy of three radio channels being like a three lane expressway, it would be like adding two more traffic lanes in between the existing lanes without adding any width to the highway. In other words, the old highway had three lanes in 30’, and the new one has five lanes in the same 30’ width.
If someone adds a new narrowband channel next to an existing wideband channel, there is a possibility for interference, because the new channels overlap part of the wideband channel. There is very little room for error. Converting to narrowband early minimizes the possibility of this issue.
Key Dates:
January 1, 2011: The FCC will no longer accept applications for new VHF or UHF systems that operate on wideband channels (25 KHz or more).
January 1, 2011: The FCC will no longer accept applications for modification of VHF or UHF systems that operate on wideband channels (25 KHz).
January 1, 2013: All existing licenses must operate on channels with a bandwidth of 12.5 KHz or less (narrowband). Failure to comply with the January 1, 2013 deadline results in cancellation of license.
Radio equipment manufacturers have been aware of the pending narrowband mandate since 1997 and most of the equipment purchased in the last five years will be capable of changing to narrowband operation simply by reprogramming.
Implementing the migration to narrowband requires re-licensing all existing radio channels to modify the technical parameters of the license to narrowband emission designators. The existing radio frequencies licensed will remain the same. There are no new frequencies allocated because of a switch to narrowband.
The actual migration process requires reprogramming every RF link, base, mobile and portable radio as well as any pagers at the time chosen for the change over. During the process, it is possible that some radios will still be operating wideband while others are operating on narrowband. During this change over, wideband radios talking to narrowband radios will sound distorted because they will transmit twice as much information as the narrowband radios are prepared to receive. Narrowband radios talking to wideband radios will sound clear but only about ½ volume because they are transmitting only ½ of the information a wideband radio is prepared to receive. Because of this unavoidable scenario, it is desirable to modify all radios in as short a time frame as possible.
Once the equipment is converted, there may still be issues with communications to radios in other departments or adjacent counties that decide to do their changeover on a different schedule. Radios can be programmed channel by channel with some channels operating wideband and others on narrowband. Some radios may end up being reprogrammed multiple times as various departments switch to narrowband on different schedules.
This is the time to start initial planning for implementing the narrowband mandate. Some initial steps to take are:
- Inventory the radio equipment in use to determine what will need replacement
- Discuss optional systems
- Discuss a timetable for implementation
- Discuss financing
- Discuss the impact on interoperability.
We are available to come to meetings to answer questions and provide more information if you like. Please let us know if we can be of assistance in any way.
