Section 74.1204 - Protection of FM broadcast, FM Translator and LP100 stations(a) An application for an FM translator station will not be accepted for filing if the proposed operation would involve overlap of predicted field contours with any other authorized commercial or noncommercial educational FM broadcast stations, FM translators, and Class D (secondary) noncommercial educational FM stations; or if it would result in new or increased overlap with an LP100 station, as set forth: (1) Commercial Class B FM Stations (Protected Contour: 0.5 mV/m) | Frequency separation | Interference contour of proposed translator station | Protected contour of commercial Class B station |
| Co-channel | 0.05 mV/m (34 dBu) | 0.5 mV/m (54 dBu) |
| 200 kHz | 0.25 mV/m (48 dBu) | 0.5 mV/m (54 dBu) |
| 400 kHz/ 600 kHz | 50.0 mV/m (94 dBu) | 0.5 mV/m (54 dBu) |
(2) Commercial Class B1 FM Stations (Protected Contour: 0.7 mV/m) | Frequency separation | Interference contour of proposed translator station | Protected contour of commercial Class B1 station |
| Co-channel | 0.07 mV/m (37 dBu) | 0.7 mV/m (57 dBu) |
| 200 kHz | 0.35 mV/m (51 dBu) | 0.5 mV/m (57 dBu) |
| 400 kHz/ 600 kHz | 70.0 mV/m (97 dBu) | 0.7 mV/m (57 dBu) |
(3) All Other Classes of FM Stations (Protected Contour: 1 mV/m) | Frequency separation | Interference contour of proposed translator | Protected contour of any other station |
| Co-channel | 0.1 mV/m (40 dBu) | 1 mV/m (60 dBu) |
| 200 kHz | 0.5 mV/m (54 dBu) | 1 mV/m (60 dBu) |
| 400 kHz/ 600 kHz | 100 mV/m (100 dBu) | 1 mV/m (60 dBu) |
(4) LP100 stations (Protected Contour: 1 mV/m) | Frequency separation | Interference contour of proposed translator
station | Protected contour of LP100 LPFM station |
| Co-channel | 0.1 mV/m (40 dBu) | 1 mV/m (60 dBu) |
| 200 kHz | 0.5 mV/m (54 dBu) | 1 mV/m (60 dBu) |
Note to paragraph (a)(4): LP100 stations, to the purposes of determining overlap pursuant to this paragraph, LPFM applications and permits that have not yet been licensed must be considered as operating with the maximum permitted facilities. All LPFM TIS stations must be protected on the basis of a nondirectional antenna.
(b) The following standards must be used to compute the distances to the pertinent contours: (1) The distances to the protected contours are computed using Figure 1 of § 73.333 [F(50,50) curves] of this chapter.(2) The distances to the interference contours are computed using Figure 1a of § 73.333 [F(50,10) curves] of this chapter. In the event that the distance to the contour is below 16 kilometers (approximately 10 miles), and therefore not covered by Figure 1a, curves in Figure 1 must be used.(3) The effective radiated power (ERP) to be used is the maximum ERP of the main radiated lobe in the pertinent azimuthal direction. If the transmitting antenna is not horizontally polarized only, either the vertical component or the horizontal component of the ERP should be used, whichever is greater in the pertinent azimuthal direction.(4) The antenna height to be used is the height of the radiation center above the average terrain along each pertinent radial, determined in accordance with § 73.313(d) of this chapter.(c) An application for a change (other than a change in channel) in the authorized facilities of an FM translator station will be accepted even though overlap of field strength contours would occur with another station in an area where such overlap does not already exist, if: (1) The total area of overlap with that station would not be increased:(2) The area of overlap with any other station would not increase;(3) The area of overlap does not move significantly closer to the station receiving the overlap; and,(4) No area of overlap would be created with any station with which the overlap does not now exist.(d) The provisions of this section concerning prohibited overlap will not apply where the area of such overlap lies entirely over water. In addition, an application otherwise precluded by this section will be accepted if it can be demonstrated that no actual interference will occur due to intervening terrain, lack of population or such other factors as may be applicable.(e) The provisions of this section will not apply to overlap between a proposed fill-in FM translator station and its primary station operating on a first, second or third adjacent channel, provided That such operation may not result in interference to the primary station within its principal community.(f) An application for an FM translator station will not be accepted for filing even though the proposed operation would not involve overlap of field strength contours with any other station, as set forth in paragraph (a) of this section, if grant of the authorization will result in interference to the reception of a regularly used, off-the-air signal of any authorized co-channel, first, second or third adjacent channel broadcast station, including previously authorized secondary service stations within the 45 dBu field strength contour of the desired station. Interference is demonstrated by:(1) The required minimum number of valid listener complaints as determined using Table 1 to § 74.1203(a)(3) of this part and defined in § 74.1201(k) of this part;(2) A map plotting the specific location of the alleged interference in relation to the complaining station's 45 dBu contour;(3) A statement that the complaining station is operating within its licensed parameters;(4) A statement that the complaining station licensee has used commercially reasonable efforts to inform the relevant translator licensee of the claimed interference and attempted private resolution; and(5) U/D data demonstrating that at each listener location the undesired to desired signal strength exceeds -20 dB for co-channel situations, -6 dB for first-adjacent channel situations or 40 dB for second- or third-adjacent channel situations, calculated using the methodology set out in paragraph (b) of this section.(g) An application for an FM translator or an FM booster station that is 53 or 54 channels removed from an FM radio broadcast station will not be accepted for filing if it fails to meet the required separation distances set out in § 73.207 of this chapter. For purposes of determining compliance with § 73.207 of this chapter, translator stations will be treated as Class A stations and booster stations will be treated the same as their FM radio broadcast station equivalents. FM radio broadcast station equivalents will be determined in accordance with §§ 73.210 and 73.211 of this chapter, based on the booster station's ERP and HAAT. Provided, however, that FM translator stations and booster stations operating with less than 100 watts ERP will be treated as class D stations and will not be subject to intermediate frequency separation requirements.(h) An application for an FM translator station will not be accepted for filing if it specifies a location within 320 kilometers (approximately 199 miles) of either the Canadian or Mexican borders and it does not comply with § 74.1235(d) of this part.(i) FM booster stations shall be subject to the requirement that the signal of any first adjacent channel station must exceed the signal of the booster station by 6 dB at all points within the protected contour of any first adjacent channel station, except that in the case of FM stations on adjacent channels at spacings that do not meet the minimum distance separations specified in § 73.207 of this chapter, the signal of any first adjacent channel station must exceed the signal of the booster by 6 dB at any point within the predicted interference free contour of the adjacent channel station.(j) FM translator stations authorized prior to June 1, 1991 with facilities that do not comply with the predicted interference protection provisions of this section, may continue to operate, provided that operation is in conformance with § 74.1203 regarding actual interference. Applications for major changes in FM translator stations must specify facilities that comply with provisions of this section.55 FR 50694, Dec. 10, 1990, as amended at 56 FR 56170, Nov. 1, 1991; 58 FR 42025, Aug. 6, 1993; 65 FR 7649 , Feb. 15, 2000; 65 FR 67304 , Nov. 9, 2000; 65 FR 79780 , Dec. 20, 2000; 84 FR 27741 , June 14, 2019; 86 FR 13664 , Mar. 10, 2021 84 FR 27740, 6/14/2019; 84 FR 29806, 8/13/2019; 84 FR 37142, 8/13/2019; 84 FR 27741, 6/14/2019; 86 FR 13664, 3/10/2021