Last week, public-safety organizations and commercial wireless carriers jointly asked the FCC to establish clear rules that would prohibit the use of interfering wireless microphones in the 700 MHz band — spectrum that both first responders and commercial entities have wanted to use for years — in short order.

In the case of public safety, there are some narrowband 700 MHz systems in existence where there are no incumbent television stations. There have not been a lot of interference reports from public-safety systems to date, but there are relatively few of them operating now, and many of those are in locations that are not densely populated.

That user profile is expected to change dramatically after the scheduled completion of the digital television (DTV) transition in June, freeing the 700 MHz spectrum for use by all public-safety licensees throughout the nation, said Robert Gurss, director of legal and government affairs for the Association of Public-Safety Communications Officials (APCO).

"Our concern is that the number of users is going to dramatically increase, and that's when you're going to have problems [with interference from wireless microphones]," Gurss said during an interview with Urgent Communications.

Following directions from Congress, the FCC largely has avoided taking action on matters that are not part of the DTV transition. But Gurss noted that the wireless-microphone issue does relate to the DTV transition, a significant part of which is to deliver usable spectrum to public-safety and commercial licensees.

Without FCC action establishing clear rules that wireless microphones cannot interfere with primary users, disruptions to public-safety and commercial wireless transmissions in the 700 MHz band are "inevitable," according to the joint letter from three public-safety organizations and CTIA, the trade association for commercial wireless carriers.

In addition, such a situation would not be good for the users of the wireless microphones operating at 700 MHz, Gurss said.

"There's probably at least as much chance that we're going to interfere with them as they're going to interfere with us," he said.

Even if the FCC passes rules prohibiting wireless-microphone interference in the 700 MHz band, actually clearing the devices from the band promises to be difficult. The vast majority of wireless-microphone users — businesses, schools, community theaters and social organizations, for example — do not notify the FCC of their use. Many may not be aware what frequency the microphones use, and few would realize that the FCC passing a rule on this matter would affect them.

With this in mind, Gurss said local fire and building inspectors could ask about wireless-microphone usage as part of their normal inspections, and the matter could be included in the considerable community education conducted by firefighting agencies. Such an approach to deliver the message could be effective, but it will take quite a bit of time.

Of course, before that process can start, there needs to be a message that can be delivered. That's why public-safety and commercial wireless carriers want the FCC to act on the matter quickly, so such grassroots efforts have time to spread the word of the rule.

"It's only going to be effective if there is a very clear FCC mandate that [inspectors] can wave around," Gurss said.

Hopefully, the FCC will recognize this and act quickly to address the wireless-microphone issue.

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