This function uses the FCC's CURVES program to make calculations of the F(50,50) FM and NTSC (analog) TV service curves, the F(50,10) interfering signal curves, and the F(50,90) digital TV service curves. Printable copies of these propagation curves are available at FM and TV Propagation Curves Graphs.
Antenna Height Above Average Terrain (HAAT) values for a particular FM or TV station can be obtained from the FM Query or the TV Query, or use the HAAT Calculator. The class of an FM station may be retrieved from the FM Query.
FM Broadcast RadioF(50,50) protected service contours for FM stations are defined as follows:
- 54 dBu contour for commercial Class B stations
- 57 dBu contour for commercial Class B1 stations
- 60 dBu (1 mV/m) contour for commercial Class A, C3, C2, C1, and C stations
- 60 dBu for all classes of noncommercial educational stations in the reserved band (88.1 to 91.9 MHz)
- 60 dBu service contour for LPFM stations
City coverage for commercial FM stations is defined by the F(50,50) 70 dBu contour, per Section 73.315. For noncommercial educational stations (except LPFM), coverage over the community of license is defined by the 60 dBu contour (see Section 73.515).
For the appropriate FM interfering contour, please consult Section 73.509 for noncommercial educational stations (88.1 MHz to 91.9 MHz) or Section 73.215 for commercial FM stations (92.1 MHz to 107.9 MHz).
If you already know the FM station class and the HAAT, use FMpower to compute the effective radiated power (ERP) needed to achieve coverage equivalent to the reference (maximum) facilities for the station class.
Digital Television (DTV)For DTV TV stations, service is defined to exist where the received signal strength exceeds the limit shown in the following table, using the F(50,90) propagation curves. These field strength values are defined in Section 73.622 and Section 73.625).
|Channels||DTV Noise-Limited Service||Minimum Field Strength over Community of License|
|Channels 2 through 6||28 dBu||35 dBu|
|Channels 7 through 13||36 dBu||43 dBu|
|Channels 14 through 69||41 dBu||48 dBu|
Note: Using ERP and HAAT to define the F(50,90) contour may not give identical results to the
more complex methods of noise-limited coverage prediction used for DTV allocations work.
NTSC (analog) TelevisionFor NTSC (analog) TV stations, the service contours are as follows (from Section 73.683 and Section 73.685):
|Channels 2 through 6||47 dBu||68 dBu||74 dBu|
|Channels 7 through 13||56 dBu||71 dBu||77 dBu|
|Channels 14 through 69||64 dBu||74 dBu||80 dBu|
Updated: February 24, 2014