§  73.509   Prohibited overlap.

   (a) An application for a new or modified NCE-FM station other than a
   Class D (secondary) station will not be accepted if the proposed
   operation would involve overlap of signal strength contours with any
   other station licensed by the Commission and operating in the reserved
   band (Channels 200–220, inclusive) as set forth below:
   Frequency separation Contour of proposed station Contour of other
   station
   Co-channel 0.1mV/m (40 dBu)
   1 mV/m (60 dBu) 1 mV/m (60 dBu)
   0.1 mV/m (40 dBu)
   200 kHz 0.5 mV/m (54 dBu)
   1 mV/m (60 dBu)1 1 mV/m (60 dBu)
   0.5 mV/m (54 dBu)
   400 kHz/600 kHz 100 mV/m (100 dBu)
   1 mV/m (60 dBu) 1 mV/m (60 dBu)
   100 mV/m (100 dBu)

   (b) An application by a Class D (secondary) station, other than an
   application to change class, will not be accepted if the proposed
   operation would involve overlap of signal strength contours with any
   other station as set forth below:
   Frequency separation Contour of proposed station 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 10 mV/m (80 dBu) 1 mV/m (60 dBu).
   600 kHz 100 mV/m (100 dBu) 1 mV/m (60 dBu).

   (c) The following standards must be used to compute the distances to
   the pertinent contours:

   (1) The distance of the 60 dBu (1 mV/m) contours are to be computed
   using Figure 1 of § 73.333 [F(50,50) curves] of this part.

   (2) The distance to the other contours are to be computed using Figure
   1a of § 73.333 [F(50,10) curves]. 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) that is the maximum ERP for any
   elevation plane on any bearing will be used.

   (d) An application for a change (other than a change in channel) in the
   facilities of a NCE-FM broadcast station will be accepted even though
   overlap of signal strength contours, as specified in paragraphs (a) and
   (b) of this section, would occur with another station in an area where
   such overlap does not already exists, 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.

   (e) The provisions of this section concerning prohibited overlap will
   not apply where the area of such overlap lies entirely over water.

   [ 50 FR 27962 , July 9, 1985, as amended at  52 FR 43765 , Nov. 16, 1987;
    65 FR 79778 , Dec. 20, 2000]