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Lately, I feel a little like Paul Revere. I ve been traveling around trying to warn people, The FCC is coming! The FCC is coming! So far, there seems to be little interest in making preparations for narrowbanding, which is a little like not worrying about your tax preparation until April 16. But if your personnel are using radios on VHF (150 174 MHz) or UHF (421 512 MHz) frequencies, then this mandate applies to you.
An interim timetable for narrowbanding has been widely publicized. On Jan. 1, 2011:
- Any new system application must be designed for 12.5 kHz deviation or less.
- Modifications of existing licenses that expand an authorized contour of a 25 kHz station are prohibited.
- Manufacturing of new equipment that operates on 25 kHz will be prohibited.
The purpose of the interim deadline is to encourage licensees to begin planning and budgeting, as well as developing migration strategiesbeforethe deadline.
The final deadline is Jan. 1, 2013. The requirements are:
- All existing licensees must operate on a 12.5 kHz bandwidth channel or less. This does not imply that any licensee will receive two 12.5 kHz channels to replace a previously licensed 25 kHz channel. Licensees must apply for new narrowband licenses or modify their existing licensebeforethis deadline.
Consequences
It's important that you understand that your system operation will, in all likelihood, be affected by narrowbanding. The most noticeable item will probably be a reduction in coverage that will affect mobiles, portables and base stations. Agencies that use pagers to alert field units should know that these will also be affected.
Why will system coverage be reduced? There are some scientific explanations for range reductions, but a simple explanation is that your transmitter deviation will be reduced by half. Your voice power will be reduced. Your radio receiver, which can t be narrowbanded, will still be expecting to receive a signal at full deviation.
What will fill this newly created empty space? Noise. Noise from power lines, spark plugs, electronic cash registers, atmospherics and distant stations. Your voice signal is now competing with all of these other sources for your radio s attention. Your receiver will have a hard time separating your voice from all of this noise. As a result, you will experience a reduction in coverage. In some areas, this reduction could be significant.
Preparation
What can you do to get ready for this change? First, make a comprehensive plan to deal with the issues. Include a list and a timetable. Update your FCC licenses. Next, I suggest you conduct a complete system inventory. If you don't have an asset control system in place, now s a good time to start one. Inventory every piece of radio equipment you have in service. Record the manufacturer, model, serial number and date of purchase, if possible. Don't forget to count the portable stored in the captain's desk drawer. This list will tell you what equipment can be modified and what must be replaced.
Next, I suggest you perform a complete inspection of all base stations, repeaters and voting receivers. Pay special attention to antennas, feed lines, lightning arrestors, connectors and proper grounding. Look for anything that might allow unwanted signals or noise to enter your system. Replace parts as needed.
Cost
Now you're ready to prepare a budget to replace some items.Remember: You re only two budget cycles away from the deadline. Keep your budgetary decision-makers informed: Council and commission members don t like surprises. You may have a great relationship with some vendor(s), but it's highly recommended that you have your equipment list reviewed by a neutral third party. You may want to replace base stations and voting receivers first; they re the backbone of your system.
There's a rumor going around that suppliers may be stocking up on equipment to sell as interim solutions. The transmitter will meet the new requirements but the receiver won't, meaning this equipment will have to be replaced again, probably sooner rather than later.
Some rural areas may be far enough away from major cities to be able to use older, wideband receivers beyond the deadline. There s less interference in these areas due to adjacent channel noise, co-channel interference and other types of noise associated with the urban environment. In this case, using a unit with a wideband receiver may be acceptable for a while. Before taking action, conduct a comprehensive coverage test of your service area that will provide a basis for future reference.
The bottom line: The narrowbanding deadline is fast approaching. Now's the time to get started.
Charles Tayloris an APCO Life Member with more than 30 years of experience in public safety land mobile radio and is retired from the Ventura County Communications Department. Contact him via e-mail atmrcharles@dslextreme.com.
Note:This article was adapted from one originally published in January 2010Public Safety Communications, the official magazine of APCO International.
