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73.827 Interference to the input signals of FM translator or FM booster stations

Submitted by on

Summary

This section addresses the protection of third adjacent channel translator input signals as required by the LCRA. Establishes a potential interference area (PIA) of 2 km around the translator or 10 km around the translator when the LPFM is within a path that is +/- 30 degrees from the path the translator and primary station. If the LPFM is within the PIA, an LPFM applicant can use a formula that appears in the MITRE report.

This rule also states that LPFM stations must protect the input of translators if the input path was in use or even proposed prior to the application (or in the case of original LPFM applications, after the date that the public notice announcing the (2013) window, June 17, 2013).

Text of Current Rule

(a)  Interference to the direct reception of the input signal of an FM translator station.  This subsection applies when an LPFM application proposes to operate near an FM translator station, the FM translator station is receiving its input signal off-air (either directly from the primary station or from a translator station) and the LPFM application proposes to operate on a third-adjacent channel to the station delivering an input signal to the translator station.  In these circumstances, the LPFM station will not be authorized unless it is located at least 2 km from the FM translator station.  In addition, in cases where an LPFM station is located within +/- 30 degrees of the azimuth between the FM translator station and its input signal, the LPFM station will not be authorized unless it is located at least 10 kilometers from the FM translator station.  The provisions of this subsection will not apply if the LPFM applicant:  

(1)  demonstrates that no actual interference will occur due to an undesired (LPFM) to desired (station delivering signal to translator station) ratio below 34 dB at all locations,

(2) complies with the minimum LPFM/FM translator distance separation calculated in accordance with the following formula:  du = 133.5 antilog [(Peu + Gru – Grd – Ed) / 20], where du = the minimum allowed separation in km, Peu = LPFM ERP in dBW, Gru = gain (dBd) of the FM translator receive antenna in the direction of the LPFM site, Grd = gain (dBd) of the FM translator receive antenna in the direction of the primary station site, Ed = predicted field strength (dBu) of the primary station at the translator site, or

(3)  reaches an agreement with the licensee of the FM translator regarding an alternative technical solution. 

Note to paragraph (a):  LPFM applicants may assume that an FM translator station’s receive and transmit antennas are collocated.

(b) An authorized LPFM station will not be permitted to continue to operate if an FM translator or FM booster station demonstrates that the LPFM station is causing actual interference to the FM translator or booster station’s input signal, provided that the same input signal was in use or proposed in an application filed with the Commission prior to the release of the public notice announcing the dates for an LPFM filing window and has been continiously in use or proposed since that time.

(c) Complaints of actual interference by an LPFM station subject to paragraph (b) of this section must be served on the LPFM licensee and the Federal Communications Commission, Attention: Audio Division, Media Bureau.  The LPFM station must suspend operations upon the receipt of such complaint unless the interference has been resolved to the satisfaction of the complainant on the basis of suitable techniques.  Short test transmissions may be made during the period of suspended operations to check the efficacy of remedial measures.  An LPFM station may only resume full operation 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.

Rule History

Adopted in the Sep 2000 Order.
Amended in the Nov 2012 Order.
Amended in the Sep 2013 Order.

(a) Interference to the direct reception of the input signal of an FM translator station. This subsection applies when an LPFM application proposes to operate near an FM translator station, the FM translator station is receiving its primary station input signal off-air (either directly from the primary station or from a translator station) and the LPFM application proposes to operate on a third-adjacent channel to the primary station delivering an input signal to the translator station. In these circumstances, the LPFM station will not be authorized unless it is located at least 2 km from the FM translator station. In addition, in cases where an LPFM station is located within +/- 30 degrees of the azimuth between the FM translator station and its primary station input signal, the LPFM station will not be authorized unless it is located at least 10 kilometers from the FM translator station. The provisions of this subsection will not apply if the LPFM applicant:

(1) demonstrates that no actual interference will occur due to an undesired (LPFM) to desired (primary station delivering signal to translator station) ratio below 34 dB at all locations,

(2) complies with the minimum LPFM/FM translator distance separation calculated in accordance with the following formula: du = 133.5 antilog [(Peu + Gru – Grd – Ed) / 20], where du = the minimum allowed separation in km, Peu = LPFM ERP in dBW, Gru = gain (dBd) of the FM translator receive antenna in the direction of the LPFM site, Grd = gain (dBd) of the FM translator receive antenna in the direction of the primary station site, Ed = predicted field strength (dBu) of the primary station at the translator site, or

(3) reaches an agreement with the licensee of the FM translator regarding an alternative technical solution.

NOTE TO PARAGRAPH (a): LPFM applicants may assume that an FM translator station’s receive and transmit antennas are collocated.

(a) (b) An authorized LPFM station will not be permitted to continue to operate if an FM translator or FM booster station demonstrates that the LPFM station is causing actual interference to the FM translator or FM booster station's input signal, provided that the same input signal was in use or proposed in an application filed with the Commission prior to the release of the public notice announcing the dates for an LPFM filing window and has been continiously in use or proposed since that time at the time the LPFM station was authorized.

(b) (c) Complaints of actual interference by an LPFM station subject to paragraph (a) of this section must be served on the LPFM licensee and the Federal Communications Commission, attention Audio Services Division. The LPFM station must suspend operations upon the receipt of such complaint unless the interference has been resolved to the satisfaction of the complainant on the basis of suitable techniques. Short test transmissions may be made during the period of suspended operation to check the efficacy of remedial measures. An LPFM station may only resume full operation 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.