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73.809 Interference protection to full service FM stations

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Summary

This section outlines the rules on how a full power station can complain about interference by an LPFM station and what the FCC considers as legal interference.

(a) defines legal interference to a commercial station as predicted interference within the full power FM station's city grade contour or their community of license. (This is ironic considering that a full power station must provide city grade coverage over the entire city of license therefore making the latter reference redundant.). For non-commercial stations, it's anywhere in the city of license that is also within the service contour. However with all that aside, actual interference is considered where the LPFM is interfering with the regularly used signal of the full power station.

(b) gives the LPFM the right to demonstrate that their station will not cause interference.

(c) states that when the full power FM complains of interference, they must notify the LPFM and the FCC. The LPFM must cease broadcasting within 24 hours. It also states that if the full power station is uncooperative, the LPFM is absolved of the complaint and may continue operations.

(d) states that if the LPFM station is broadcasting spurious signals outside of their designated frequency (such as on the aviation band, etc.), they must suspend operations immediately but are permitted to run short tests to verify any remedial action taken to clear the interference.

(e) states that any time operation is suspended for interference or spurious emissions, a full report must be made to the FCC.

Text of Current Rule

(a) If a full service commercial or NCE FM facility application is filed subsequent to the filing of an LPFM station facility application, such full service station is protected against any condition of interference to the direct reception of its signal caused by such LPFM station that operates on the same channel or first-adjacent channel provided that the interference is predicted to occur and actually occurs within:

(1) The 3.16 mV/m (70 dBu) contour of such full service station;

(2) The community of license of such full service station; or

(3) Any area of the community of license of such full service station that is predicted to receive at least a 1 mV/ m (60 dBu) signal. Predicted interference shall be calculated in accordance with the ratios set forth in § 73.215 paragraphs (a)(1) and (a)(2). Intermediate frequency (IF) channel interference overlap will be determined based upon overlap of the 91 dBu F(50,50) contours of the FM and LPFM stations. Actual interference will be considered to occur whenever reception of a regularly used signal is impaired by the signal radiated by the LPFM station.

(b) An LPFM station will be provided an opportunity to demonstrate in connection with the processing of the commercial or NCE FM application that interference as described in paragraph (a) of this section is unlikely. If the LPFM station fails to so demonstrate, it will be required to cease operations upon the commencement of program tests by the commercial or NCE FM station.

(c) Complaints of actual interference by an LPFM station subject to subsections (a) and (b) must be served on the LPFM licensee and the Federal Communications Commission, attention Audio Services Division. The LPFM station must suspend operations within twenty-four hours of the receipt of such complaint unless the interference has been resolved to the satisfaction of the complainant on the basis of suitable techniques. An LPFM station may only resume operations at the direction of the Federal Communications Commission. If the Commission determines that the complainant has refused to permit the LPFM station to apply remedial techniques that demonstrably will eliminate the interference without impairment of the original reception, the licensee of the LPFM station is absolved of further responsibility for the complaint.

(d) It shall be the responsibility of the licensee of an LPFM station to correct any condition of interference that results from the radiation of radio frequency energy outside its assigned channel. Upon notice by the FCC to the station licensee or operator that such interference is caused by spurious emissions of the station, operation of the station shall be immediately suspended and not resumed until the interference has been eliminated. However, short test transmissions may be made during the period of suspended operation to check the efficacy of remedial measures.

(e) In each instance where suspension of operation is required, the licensee shall submit a full report to the FCC in Washington, D.C., after operation is resumed, containing details of the nature of the interference, the source of the interfering signals, and the remedial steps taken to eliminate the interference.

Rule History

Adopted in Original Order
Amended in Sep 2000 Order
Amended in Dec 2007 Order
Amended in Nov 2012 Order

(a) It shall be the responsibility of the licensee of an LPFM station to correct at its expense any condition of interference to the direct reception of the signal of any subsequently authorized commercial or NCE FM If a full service commercial or NCE FM facility applicaiton is filed subsequent to the filing on an LPFM station facility application, such full service station is protected against any condition of interference to the direct reception of its signal caused by such LPFM station that operates on the same channel or first-adjacent channel second-adjacent channel or intermediate frequency (IF) channels as the LPFM station, where interference is predicted to occur and actually occurs within:

(1) the 3.16 mV/m (70 dBu) contour of such full service stations;

(2) the community of license of a commercial full service FM station; or

(3) any area of the community of license of an NCE FM such full service station that is predicted to receive at least a 1 mV/m (60 dBu) signal. Predicted interference shall be calculated in accordance with the ratios set forth in Section 73.215(a)(1) and (2) of this Part. Intermediate Frequency (IF) channel interference overlap will be determined based upon overlap of the 91 dBu F(50,50) contours of the FM and LPFM stations. Actual interference will be considered to occur whenever reception of a regularly used signal is impaired by the signals radiated by the LPFM station.

(b) An LPFM station will be provided an opportunity to demonstrate in connection with the procession processing of the commercial or NCE FM application that interference with the 3.16 mV/m contour of such station as described in subsection paragraph (a) is unlikely. If the LPFM station fails to so demonstrate, it will be required to cease operations upon the commencement of program tests by the commercial or NCE FM station. 1

(c) Complaints of actual interference by an LPFM station subject to subsections (a) and (b) within the 3.16 mV/m contour of a commercial or NCE FM station must be served on the LPFM licensee and the Federal Communications Commission, attention Audio Services Division. The LPFM station must suspend operations within twenty-four hours of the receipt of such complaint unless the interference has been resolved to the satisfaction of the complainant on the basis of suitable techniques. An LPFM station may only resume operations at the direction of the Federal Communications Commission. If the Commission determines that the complainant has refused to permit the LPFM station to apply remedial techniques that demonstrably will eliminate the interference without impairment of the original reception, the licensee of the LPFM station is absolved of further responsibility for the complaint.

(d) It shall be the responsibility of the licensee of an LPFM station to correct any condition of interference that results from the radiation of radio frequency energy outside its assigned channel. Upon notice by the FCC to the station licensee or operator that such interference is caused by spurious emissions of the station, operation of the station shall be immediately suspended and not resumed until the interference has been eliminated. However, short test transmissions may be made during the period of suspended operation to check the efficacy of remedial measures.

(e) In each instance where suspension of operation is required, the licensee shall submit a full report to the FCC in Washington, D.C., after operation is resumed, containing details of the nature of the interference, the source of the interfering signals, and the remedial steps taken to eliminate the interference.