Sec. 74.1204  Protection of FM broadcast stations and FM translators.

    (a) An application for an FM translator station will not be accepted 
for filing if the proposed operation would involve overlap of predicted 
field strength contours with any other authorized station, including 
commercial and noncommercial educational FM broadcast stations, FM 
translators and Class D (secondary) noncommercial educational FM 
stations, as set forth below:
    (1) Commercial Class B FM Stations (Protected Contour: 0.5 mV/m)

Co-channel........................  0.05 mV/m (34      0.5 mV/m (54     
                                     dBu)               dBu).           
200 kHz...........................  0.25 mV/m (48      0.5 mV/m (54     
                                     dBu)               dBu).           
400 kHz...........................  5.00 mV/m (74      0.5 mV/m (54     
                                     dBu)               dBu).           
600 kHz...........................  50.0 mV/m (94      0.5 mV/m (54     
                                     dBu)               dBu).           
------------------------------------------------------------------------

    (2) Commercial Class B1 FM Stations (Protected Contour: 0.7 mV/m)

Co-channel........................  0.07 mV/m (37      0.7 mV/m (57     
                                     dBu)               dBu).           
200 kHz...........................  0.35 mV/m (51      0.7 mV/m (57     
                                     dBu)               dBu).           
400 kHz...........................  7.00 mV/m (77      0.7 mV/m (57     
                                     dBu)               dBu).           
600 kHz...........................  70.0 mV/m (97      0.7 mV/m (57     
                                     dBu)               dBu).           
------------------------------------------------------------------------

    (3) All Other Classes of FM Stations (Protected Contour: 1 mV/m

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...........................  10 mV/m (80 dBu)   1 mV/m (60 dBu). 
600 kHz...........................  100 mV/m (100      1 mV/m (60 dBu). 
                                     dBu)                               
------------------------------------------------------------------------

    (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 Sec. 73.333 [F(50,50) curves] of this chapter.
    (2) The distances to the interference contours are computed using 
Figure 1a of Sec. 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 Sec. 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.

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    (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 the predicted 1 mV/m field strength 
contour of the FM translator station will overlap a populated area 
already receiving a regularly used, off-the-air signal of any authorized 
co-channel, first, second or third adjacent channel broadcast station, 
including Class D (secondary) noncommercial educational FM stations and 
grant of the authorization will result in interference to the reception 
of such signal.
    (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 Sec. 73.207 of this chapter. For 
purposes of determining compliance with Sec. 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 Secs. 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 Sec. 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 Sec. 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 Sec. 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]