By Stephen Dunifer
In every FCC action brought against micropower broadcasters Part 15 has always been cited. Given the FCC’s own definitions this is a blatant misapplication of their own regulatory structure.
First let us examine the definition of a FM broadcast station under Part 73:
FM broadcast station. A station employing frequency modulation in the FM broadcast band and licensed primarily for the transmission of radio-telephone emissions intended to be received by the general public. (§ 73.310 FM technical definitions.)
Note the operative phrase “to be received by the general public”. Even though micropower stations are non-licensed their emissions are intended to be received by the general public. Further, they operate in the FM broadcast band and employ frequency modulation. Therefore, they are an FM broadcast station as defined by 73.310.
Going on to Part 15: Clearly, the FCC is trying to say that micropower stations are intentional radiators and therefore subject to Part 15. Examination of the part 15 definitions will yield CB radios, receivers, computers, CPU boards, cordless phones, etc. but not an FM broadcast station. The scope of Part 15 is:
§ 15.1 Scope of this part.
(a) This part sets out the regulations under which an intentional, unintentional, or incidental radiator may be operated without an individual license. It also contains the technical specifications, administrative requirements and other conditions relating to the marketing of part 15 devices.
(b) The operation of an intentional or unintentional radiator that is not in accordance with the regulations in this part must be licensed pursuant to the provisions of section 301 of the Communications Act of 1934, as amended, unless otherwise exempted from the licensing requirements elsewhere in this chapter.
(c) Unless specifically exempted, the operation or marketing of an intentional or unintentional radiator that is not in compliance with the administrative and technical provisions in this part, including prior Commission authorization or verification, as appropriate, is prohibited under section 302 of the Communications Act of 1934, as amended, and subpart I of part 2 of this chapter. The equipment authorization and verification procedures are de-tailed in subpart J of part 2 of this chapter.
Examination of 15.1 yields some interesting facts. First, the FCC claims that micropower stations are illegal because they are not licensed. Yet, 15.1 clearly states its scope applies to intentional radiators operated without a license. Therefore, the person using such a device is not required to have a license as long as the device meets the technical guidelines set forth for intentional radiators. Secondly, if it does not meet these requirements then the operator must be licensed pursuant to 301, section 73, which covers licensing of transmission facilities.
An intentional radiator is defined by Part 15 as:
(o) Intentional radiator. A device that intentionally generates and emits radio frequency energy by radiation or induction. (§ 15.3 Definitions.)
Nowhere in this definition do we note any similarity to the definition of a FM broadcast station as defined by Part 73. A Mr. Microphone is not an FM broadcast station. Given the extremely low signal strength allowed, no Part 15 device would have the capability to reach the general public in any meaningful way. For illustration these levels are as follows for the FM band.
§ 15.239 Operation in the band 88-108 MHz.
(a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered on the operating frequency. The 200 kHz band shall lie wholly within the frequency range of 88-108 MHz.
(b) The field strength of any emissions within the permitted 200 kHz band shall not exceed 250 micro-volts/meter at 3 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in § 15.35 for limiting peak emissions apply.
(c) The field strength of any emissions radiated on any frequency out-side of the specified 200 kHz band shall not exceed the general radiated emission limits in § 15.209.
§ 15.209 Radiated emission limits; general requirements.
(a) Except as provided elsewhere in this subpart, the emissions from an intentional radiator shall not exceed the field strength levels specified in the following table:
** Except as provided in paragraph (g), fundamental emissions from intentional radiators operating under this section shall not be located in the frequency bands 54-72 MHz, 76-88 MHz, 174-216 MHz or 470-806 MHz. However, operation within these frequency bands is permitted under other sections of this part, e.g., §§ 15.231 and 15.241.
(b) In the emission table above, the tighter limit applies at the band edges.
(c) The level of any unwanted emissions from an intentional radiator operating under these general provisions shall not exceed the level of the fundamental emission. For intentional radiators which operate under the provisions of other sections within this part and which are required to reduce their unwanted emissions to the limits specified in this table, the limits in this table are based on the frequency of the unwanted emission and not the fundamental frequency. However, the level of any unwanted emissions shall not exceed the level of the fundamental frequency.
Signal levels as stated above are very low and represent a power level of 10 milliwatts or less. By using such low standards and applying them to micropower broadcast stations it prejudices the uninformed reader. This is accomplished by saying, for example, that a micropower station had a signal strength of 1,000,000 microvolts per meter at 3 meters from the antenna when the stated limit for part 15 is 250 microvolts per meter at 3 meters from the antenna. Such wide differences make it appear the micropower station is wildly beyond the bounds of acceptable signal strength. Yet, Part 15 does not apply to broadcast stations according to the FCC’s own definitions.
Going back to Part 73, the following are the basic technical requirements:
§ 73.317 FM transmission system requirements.
(a) FM broadcast stations employing transmitters authorized after January 1, 1960, must maintain the bandwidth occupied by their emissions in accordance with the specification detailed below. FM broadcast stations employing transmitters installed or type accepted before January 1, 1960, must achieve the highest degree of compliance with these specifications practicable with their existing equipment. In either case, should harmful interference to other authorized stations occur, the licensee shall correct the problem promptly or cease operation.
(b) Any emission appearing on a frequency removed from the carrier by between 120 kHz and 240 kHz inclusive must be attenuated at least 25 dB below the level of the unmodulated carrier. Compliance with this requirement will be deemed to show the occupied bandwidth to be 240 kHz or less.
(c) Any emission appearing on a frequency removed from the carrier by more than 240 kHz and up to and including 600 kHz must be attenuated at least 35 dB below the level of the unmodulated carrier.
(d) Any emission appearing on a frequency removed from the carrier by more than 600 kHz must be attenuated at least 43 + 10 Log10 (Power, in watts) dB below the level of the unmodulated carrier, or 80 dB, whichever is the lesser attenuation.
(e) Preemphasis shall not be greater than the impedance-frequency characteristics of a series inductance resistance network having a time constant of 75 microseconds. (See upper curve of Figure 2 of § 73.333.) [51 FR 17028, May 8, 1986]
All FM broadcast stations must meet the requirements of 73.317 b-d regarding emissions beyond the carrier frequency. Such standards should be applied to micropower stations as well. If we take for, example, a micropower station with an output power of 25 watts, the ratio between the power of the carrier and any emission removed from the carrier frequency by more than 600 kHz is, in decibels equal to 43 + 10Log10(25). Note that is a ratio of carrier frequency power to the power of the unwanted emission not a brick wall level for out of band emissions of 150 microvolts per meter at three meters distance as specified by Part 15.209 for intentional radiators operating from 88-108 mHz..
Just to round things out, the following are the standards of good engineering practice for non- commercial FM stations.
§ 73.508 Standards of good engineering practice.
(a) All noncommercial educational stations operating with more than 10 watts transmitter output power shall be subject to all of the provisions of the FM Technical Standards contained in subpart B of this part. Class D educational stations shall be subject to the definitions contained in § 73.310 of subpart B of this part, and also to those other provisions of the FM Technical Standards which are specifically made applicable to them by the provisions of this subpart.
(b) The transmitter and associated transmitting equipment of each non-commercial educational FM station licensed for transmitter output power above 10 watts must be designed, constructed and operated in accordance with § 73.317.
(c) The transmitter and associated transmitting equipment of each non-commercial educational FM station licensed for transmitter power output of 10 watts or less, although not required to meet all requirements of § 73.317, must be constructed with the safety provisions of the current national electrical code as approved by the American Standards Association. These stations must be operated, tuned, and adjusted so that emissions are not radiated outside the authorized band causing or which are capable of causing interference to the communications of other stations. The audio distortion, audio frequency range, carrier hum, noise level, and other essential phases of the operation which control the external effects, must be at all times capable of providing satisfactory broadcast service. Studio equipment properly covered by an underwriter’s certificate will be considered as satisfying safety requirements. (Secs. 4, 5, 303, 48 Stat., as amended, 1066)
Only one conclusion can be drawn from this examination of the FCC regulations. Every time the FCC has cited a micropower broadcaster under part 15 it has done so either in complete ignorance of its own regulatory structure or has done so in an intentional and willful manner with confusion, intimidation and misdirection being the primary goal.
—Stephen Dunifer is the founder of Free Radio Berkeley.
Stephen Dunifer's Briefing Paper
By Stephen Dunifer