Monday, May 17, 2010

Legal Pirate Radio

There's always a lot of news about pirate radio. It's always hot topic in the news; from the hapless hippies of the bay area, the well puckish college kids, to the freakish-Orwellian overkill of the Florida ATF raids. Suffice it to say, there's always something to be said about it, especially by those that don't know anything about it.But one of the least reported facts is that pirate radio can be legal. For the record what I mean by "pirate" is unlicensed. There are two categories: low power AM and campus radiation. Here are the rules on these unlicensed systems. If you follow these rules, you can legally broadcast without a license! Have fun, but check your field strength measurements!

§ 15.219 Operation in the band 510-1705 kHz. HERE

A. The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts.

B. The total length of the transmission line, antenna and ground lead(if used) shall not exceed 3 meters.

C. All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification
may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by measuring the radiated emissions.

§ 15.221 Operation in the band 525-1705 kHz. HERE

A. Carrier current systems and transmitters employing a leaky coaxial cable as the radiating antenna may operate in the band 525-1705 kHz provided the field strength levels of the radiated emissions do not exceed 15 uV/m, as measured at a distance of 47,715/(frequency in kHz) meters (equivalent to Lambda/2Pi) from the electric power line or the coaxial cable, respectively. The field strength levels of emissions outside this band shall not exceed the general radiated emission limits in § 15.209.

B. As an alternative to the provisions in paragraph (a) of this section, intentional radiators used for the operation of an AM
broadcast station on a college or university campus or on the campus of any other education institution may comply with the following:

1. On the campus, the field strength of emissions appearing outside of this frequency band shall not exceed the general radiated emission limits shown in § 15.209 as measured from the radiating source. There is no limit on the field strength of emissions appearing within this frequency band, except that the provisions of § 15.5 continue to comply.

2. At the perimeter of the campus, the field strength of any emissions, including those within the frequency band 525-1705 kHz, shall not exceed the general radiated emission in § 15.209.

3. The conducted limits specified in § 15.207 apply to the radio frequency voltage on the public utility power lines outside of the campus. Due to the large number of radio frequency devices which may be used on the campus, contributing to the conducted emissions, as an alternative to measuring conducted emissions outside of the campus, it is acceptable to demonstrate compliance with this provision by measuring each individual intentional radiator employed in the system at the point where it connects to the AC power lines.

C. A grant of equipment authorization is not required for intentional radiators operated under the provisions of this section. In lieu thereof, the intentional radiator shall be verified for compliance with the regulations in accordance with subpart J of part 2 of this chapter. This data shall be kept on file at the location of the studio, office or control room associated with the transmitting equipment. In some cases, this may correspond to the location of the transmitting equipment.

D. For the band 535-1705 kHz, the frequency of operation shall be chosen such that operation is not within the protected field strength contours of licensed AM stations.