Narrowbanding

KEY DATES

January 1, 2011 - All new applications for frequency assignments must have a maximum bandwidth of 12.5 Kilohertz.

January 1, 2011 - All modifications to existing licenses that expand the service contour of existing licenses must have a bandwidth of 12.5 Kilohertz or less.

All manufacturing of 25 Kilohertz equipment is to cease on January 1, 2011.

January 1, 2013 - All current licensees must be fully operational on 12.5 Kilohertz equipment. Failure to comply with the January 1, 2013 deadline results in license cancellation.

<a href="http://www.7is7.com/otto/countdown.html?year=2013&month=1&date=1&hrs=0&ts=24&min=0&sec=0&tz=-300&lang=en&show=YMWdhms&mode=t&cdir=down&bgcolor=%23A9B0B7&fgcolor=%23000080&title=Countdown%20To%20FCC%20Mandated%20Narrowbanding">Countdown To FCC Mandated Narrowbanding</a>

A Brief History of Narrowbanding

In 1992 the FCC adopted the forthcoming narrowbanding requirements known as "re-farming". 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 comer 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.

Implementing FCC-mandated Narrowbanding

Public safety agencies need to aggressively develop a strategy to meet narrowband deadlines to avoid cancellation of existing wideband FCC authorizations. Although the migration deadline may seem far off, the long lead time and interim deadlines make it necessary for agencies to plan well in advance.

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 cut-over. During the process, it is possible that some radios will still be operating wideband while others are operating on narrowband. During this cut-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 half volume because they are transmitting only half 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 areas that decide to do their cut-over 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 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.

WCI can Help!

Williams Communications, Inc. can help you with planning, licensing, and system implementation of your narrowband upgrades. Contact a consultant today to begin getting your LMR system in compliance with FCC regulations.