Spectrum Refarming
The FCC, Frequency Allocation, and Public Safety
John A. DiDonato and Alan T. Kealey
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John DiDonato is a Certified Engineer with RF Radiating Master Endorsement, National Association of Radio and Telecommunications Engineers (NARTE). He has been involved in the engineering, design, and implementation of land-mobile radio systems for federal, state, county, and municipal agencies for 17 years, and is currently owner of a wireless engineering consulting firm, "DiDonato Consulting Services, Inc." He can be reached via e-mail at: dcs@toad.net Alan T. Kealey is a Wireless Communications Engineer for the State of Maryland's Office of Information Technology. He has over eighteen years of experience maintaining and designing radio systems for various State Public Safety Agencies. |
| Photos: (select thumbnail to view detail image) |
 Prince George (MD) Fire Department Battalion Chief Tim Augustine radios orders during a 3rd alarm fire in District Heights, Maryland. Frequency "refarming" may affect radio users by narrowing bandwidth to allow for more available frequencies. Tom Carter |
This article can be found on
page 12 of the Nov/Dec 1997
issue of 9-1-1 Magazine.
After several years of cultivation, the FCC's Refarming seeds are ready to harvest. While it's too early to know the yield of this crop, it has great promise (and some challenges to be met). What is known is that it will affect many users of two-way radio systems.
What is this "Refarming," and how will it affect me? There are many questions about this topic, hopefully we can answer some of them. We will present the basic Refarming facts and how these changes could affect your radio communications operation.
Where??
First, Refarming does not affect all frequency bands. You are only affected if you operate in the following ranges:
150 MHz - 174 MHz (Nationwide)
421 MHz - 430 MHz (Only in Detroit, Buffalo, and Cleveland)
450 MHz - 470 MHz (Nationwide)
470 MHz - 512 MHz (11 cities, shared with UHF TV)
It does not affect frequencies below 72 MHz or 800 MHz and above.
What??
There are two fundamental changes in the Refarming Docket. The width of each channel (bandwidth) is reduced. Also, the spacing between each FCC channel assignment is reduced. These changes are listed in Table 1. The tricky part is how and where each of these occur.
When??
Well, the "when" is a little complicated.
In general, the new rules immediately reduce the spacing between channels. The FCC is already accepting VHF applications on the new channels. They started accepting applications for the new UHF channel assignments on October 17, 1997.
This does not mean that your old stuff has to be thrown away. There is no requirement date to force you off of your old channel. In real life, your wide-band receivers will start catching more interference as more of the new channels become active. If you are in a congested area, this could happen quickly; if you are in a rural area, it may take a while.
The real schedule crunch is on the vendors. As always, new products must be "Type-Accepted" by the FCC before they can be sold in the United States.
The Refarming Docket does not impact any radio models that were type-accepted prior to refarming. However, new products developed by vendors are subject to the new rules. Any new type-acceptances after February 14, 1997 must be capable of supporting at least one voice channel for every 12.5 KHz of bandwidth. Note that a 2:1 TDMA (Time Division Multiple Access) radio at 25 KHz bandwidth qualifies under this definition. Right now, there are about 18 vendors with type-accepted narrow-band equipment.
The docket also requires equipment that is type-accepted after January 1, 2005 to be able to handle one voice channel per 6.25 KHz of bandwidth.
It's important to note that vendors can continue to sell older equipment that was type-accepted before the deadline. Also, all new equipment may be multi-mode capable, and be able to operate on the old wider bandwidths.
What this means is that you can use your old channels, and buy equipment for them for the foreseeable future. The limitation is that you will not get any spectrum efficiency, but you will be exposed to higher interference potential by operating on the wider bandwidth.
What Else??
New Licensing Categories: This FCC action also changes some other stuff about frequency assignments. Most notable is the consolidation of the FCC's "services." There used to be about twenty different services, generally falling into four categories: Public Safety, Special Emergency, Industrial, and Transportation. They're now pulled together into just two: Public Safety and Industrial/Business. Now an applicant can apply for any available frequency in their qualifying pool. When you apply, the frequency coordinator that was responsible for a radio service before the consolidation retains approval of any frequencies assigned from that group. As an aside, these channels will be licensed as 11K3 (±3.0 KHz) not the 20K0 (±5.0 KHz) used on the existing channels
UHF Low Power Operation? You may have to move!! In public safety, the old low power offset channels will soon be primary high power channels. To meet the need for low power channels, the Public Safety Communications Council (PSCC) has established fourteen (14) new UHF channels designated as low power. These channels are listed in Table 2.
Trunking in VHF & UHF? Yes! Maybe!! Centralized trunking (using a control channel) will now be available without a waiver from the FCC if:
You have an exclusive service area (Note: the FCC has no way for you to do this below 470 MHz - we're still waiting on a ruling), or
You do not have an exclusive service area but have letters of agreement for all affected users of your frequency within 70 miles.
In addition, you need to have a channel loading of 50 units per channel in the Public Safety Pool or 90 units per channel for the Industrial/Business Pool.
Impact to New Users: The number of channels available to an applicant is increasing in two ways: Consolidation of services gives you access to pools that used to be unavailable to you, and the refarming itself provides new high power channels at 12.5 KHz spacing. Agencies that needed radio communications in the past but couldn't get channels will now have a chance to carry out their ideas.
Impact to Existing Users: Existing users will have to accept and adjust to the new rules. These agencies have designed their radio communications system using one set of conditions, and must now adjust to different conditions. The rate of growth will determine when and how much money these agencies will spend to overcome the problems of increased noise and interference. As the new channels become active, the adjacent channel activity will reduce the operating range and performance of present radio systems. In time, most existing radio systems must be enhanced, upgraded or replaced to maintain the performance required for Public Safety communications systems.
For users who now rely on the low power offset frequencies (FCC rule 90.267), the "when" is May 17, 1998. After that, you won't have protection from a new user on your channel at a higher power level. You'll have two options: 1) Re-license your existing frequency at a higher power level or 2) Move to one of the 14 reserved low power channels.
Either way, existing low power users will probably spend money for frequency coordination, frequency changes or both.
Service Providers: The FCC's reporting of the final crop yield for the Refarmed frequencies is a total of 706 new VHF and 2,820 new UHF channels that were previously unavailable for high power use. All these new channels will be a cash crop for many companies that provide equipment and technical services. Some of this will come at the expense of agencies that are just trying to maintain what they now have. The benefit is that it allows for expansion and growth to meet the demand for new channels in areas over-saturated with radio users.
Future license applications will depend more on principles of engineering and design than on fixed mileage separation. This means that future license applications will probably include more engineering documentation than has been true in the past (coverage maps, interference contours, etc.).
As existing systems degrade in the future because of the increasing number of new adjacent and co-channel users, occurrences of interference will be increasing. Providers of hands-on technical services can expect their skills to be in demand during the future.
Though not mandated, equipment operating on 5 KHz channels will be considered. This will provide even greater opportunity for service providers to offer increased channel capacity to users.
Summary
Refarming is not the answer for all the problems found in various Public Safety communications systems. It does offer some very good opportunities to construct new radio systems and augment existing ones. These frequency bands offer excellent propagation characteristics for many applications, so the chance to phase in new channels is a real bonus.
Trunking in these frequency bands allows the potential for cost saving by encouraging agencies to pool their resources while maintaining operational independence and promoting inter-operability.
The FCC is opening the door to let the radio users determine what will work best. Trunking, emission masks, 5 KHz spacing on VHF and pooling channels are the basic ingredients for building a new generation radio system. As radio users, consultants and manufacturers, we must supply the imagination and common sense to find the right mix of technology. One thing is sure though - there's a new crop of channels out there for those who need them!
