47 C.F.R. § 73.509
(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 in Table 1 to this paragraph (a):
| 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 in Table 2 to this paragraph (b):
| Frequency separation | Contour ofproposed station | Contour ofany 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) |
| 400/600 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:
(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:
[50 FR 27962, July 9, 1985, as amended at 52 FR 43765, Nov. 16, 1987; 65 FR 79778, Dec. 20, 2000; 87 FR 15343, Mar. 18, 2022]