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

[[Page 151]]

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)...  0.5 mV/m (54 dBu).
400 kHz.........................  10 mV/m (80 dBu)..  1 mV/m (60 dBu).  
                                  1 mV/m (60 dBu)...  10 mV/m (80 dBu). 
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]