NCJ Number
191789
Journal
Law and Order Volume: 49 Issue: 8 Dated: August 2001 Pages: 39-41
Date Published
August 2001
Length
3 pages
Annotation
This article discusses the causes of police radio interference and describes the efforts of Nextel Communications to address interference issues.
Abstract
The fundamental cause of radio interference relates to the way the 800 MHz frequency band was allocated for licensing by the Federal Communications Commission (FCC). When the FCC divided up the available radio spectrum, the majority were using similar transmission methods and intended to communicate with their users through a fairly consistent level of desired signal levels and background noise. As the demand for wireless services increased explosively in the 1980's and 1990's, more providers started using digital technology to provide greater security and squeeze more simultaneous conversations and data streams into a finite number of channels. Public safety radios rely on a clear channel to work reliably. When a receiver detects a signal on the assigned frequency, it opens the squelch, which tunes out normal background noise and amplifies the signal so the user can hear it. If the radio is close enough to a cell site, the public safety user's radio either won't "hear" desired incoming transmissions from other users or won't be able to receive direction from the controlling computer regarding switching the channel. The net result is that some public safety radios can be rendered useless if they are close enough to an interfering specialized mobile radio site. Because Nextel's system makes the greatest use of these interleaved frequencies, the company is often blamed for the interference problems. Larry Krevor, vice president of government affairs for Nextel, has stated that "Our policy is to remedy any interference problems, even if it means going the extra mile to take care of public safety. We can raise the site antenna, substitute channels, institute filtering, or look for a longer term fix. We're desirous of being part of the solution, rather than being the problem." The issues are different for different markets, so interference problems can only be solved with collaborative efforts among public safety organizations, wireless providers, equipment manufacturers, the FCC, and other affected government agencies.