by Harold Hallikainen
San Luis Obispo, CA
As I write this in early November, I'm enjoying one of the remaining warm days here in San Luis Obispo. Please excuse any saltwater or grains of sand that may creep into the paper as I write here at the beach.
Last month we questioned the FCC's reasoning in not establishing a low power FM service, similar to what was done with television. This was a first look at freedom of speech issues brought up by various unlicensed FM broadcast stations. Several of these stations have been fined and ordered shut down by the FCC. Many continue in operation and are taking their cases to court. This month we'll look at some of the arguments raised in the case of William Leigh Dougan (unlicensed station KAPW, Phoeniz, AZ) v. FCC.
According to filings from KAPW, the FCC issued a Notice of Apparent Liability for $17,500 for the operation of one-half watt unlicensed FM station. The FCC also claims that a request to inspect the station was refused.
KAPW questions the FCC's jurisdiction over his station since it did not interfere with other licensed broadcasters or "otherwise enter into interstate commerce." The case also questions the "appeals process" available to those who receive a forfeiture order from the FCC. KAPW is attempting to have a court review the forfeiture order. The FCC is seeking to have the petition for review with this particular court dismissed on the basis that the FCC Forfeiture Order has not "injured" Mr. Dougan. Dougan's attorney argues that the FCC could, if it wished, never turn the case over to the Justice Department for collection, leaving Dougan with an outstanding Forfeiture Order and no chance for his day in court. While the appeals process might be interesting, we'll concentrate on the possibility of a license-free low power broadcast service. Should the rules be amended to allow such a service?
As pointed out last month, the FCC has argued that it is more spectrum efficient to license fewer high power stations instead of many low power stations since the coverage area to interference area ratio of high power stations is greater than that for low power stations. With such an allocations scheme, however, gaps occur where lower stations would fit without interference, yet higher power stations would not fit. If, for simplicity, we assume an omnidirectional horizontal radiation pattern and make the prohibited overlap areas tangent, a small area without overlap occurs between the stations. For example, if three stations each have an "interference radius" of 100 kilometers, and they are packed as closely as possible, it is possible to fit another station with an interference radius of 15 kilometers between the intersections of the other interference circles. Is it spectrum efficient to not authorize stations to fill these gaps? If freedom of speech is applied to broadcasting, does the FCC have a "compelling governmental interest" to prohibit low power stations that can operate without interference to existing stations?
Determining the location of these "holes in the spectrum" and the maximum power that may be radiated and not result in interference (as currently defined by regulations on prohibited overlap) is an interesting problem. The FCC could "find the holes" and define a maximum ERP and HAAT for each hole. As the antenna was moved from the "center of the hole", its power would have to be reduced to prevent interference. As an alternative, the FCC could define a simple procedure for determining where a low power station could operate without causing interference and a private organization could publish a list of frequencies and powers available, or, better yet, could write software that would determine the frequency and maximum ERP/HAAT combination that could be operated at a user specified latitude and longitude. Such software could be sold with FCC approved transmitters at retail stores, such as Radio Shack. These stations would be required to protect licensed stations (as determined by the software) and would not receive any interference protection.
Unfortunately, it would be easy for someone to accidentally or purposely misadjust the equipment such that it DOES cause interference to licensed stations. Such a problem might be cause for the FCC to continue to license ALL stations, including those operating at extremely low power. This would be similar to just authorizing local origination on FM translators.
Another way to prevent interference to licensed stations would be to set aside channels exclusively for the use of unlicensed stations. While it's a bit late to do this for FM, it could be done with the expanded AM band. If a new band is finally used for digital audio broadcasting, and the adopted technology allows for independent transmitters for each station (perhaps through the use spread spectrum techniques), a few channels (or different pseudorandom number codes for spread spectrum) could be set aside for unlicensed operation.
The FCC DOES allow unlicensed broadcasting in the AM and FM broadcast bands, but with extremely limited coverage. In the AM broadcast band, intentional radiation is allowed if the field strength is limited to 24000/F(KHz) microvolts per meter measured 30 meters from the radiator (15.209). An exception is allowed for educational institutions where the measurement point is extended to the perimeter of the campus. A 1 MHz signal that is 24 microvolts per meter 30 meters from the antenna will probably not be heard very far away.
Unlicensed operation in the FM band is limited to a field strength of 250 microvolts per meter measured 3 meters from the antenna. This works out to 165.8 picowatts per square meter, which would be 18.7 nanowatts into an isotropic radiator. KAPW's 500 milliwatts appears to violate this requirement!
It will be interesting to see how the courts decide in the various unlicensed broadcast station cases. Perhaps technology has invalidated some precedents such that some sort of microBroadcasting can be authorized. I'll look forward to your comments!
Harold Hallikainen is president of Hallikainen and Friends, a manufacturer of transmitter control and telemetry systems. He also teaches electronics at Cuesta College, San Luis Obispo and recently returned from the Harvest Moon Dance Festival. He can be reached at 805 541 0200. He can also be reached on internet at harold@hallikainen.com.