Sec.  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:


------------------------------------------------------------------------
                                      Contour of       Contour of other
      Frequency separation         proposed station         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 mV/m (60 dBu)1..  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:


------------------------------------------------------------------------
                                      Contour of        Contour of any
      Frequency separation         proposed station      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  Sec. 73.333 [F(50,50) curves] of this part.

   (2) The distance to the other contours are to be computed using Figure 1a of
    Sec. 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]