FCC 73.317 Revised as of December 4, 2012
Goto Year:2011 |
§ 73.317 FM transmission system requirements.
(a) FM broadcast stations employing transmitters authorized after
January 1, 1960, must maintain the bandwidth occupied by their
emissions in accordance with the specification detailed below. FM
broadcast stations employing transmitters installed or type accepted
before January 1, 1960, must achieve the highest degree of compliance
with these specifications practicable with their existing equipment. In
either case, should harmful interference to other authorized stations
occur, the licensee shall correct the problem promptly or cease
(b) Any emission appearing on a frequency removed from the carrier by
between 120 kHz and 240 kHz inclusive must be attenuated at least 25 dB
below the level of the unmodulated carrier. Compliance with this
requirement will be deemed to show the occupied bandwidth to be 240 kHz
(c) Any emission appearing on a frequency removed from the carrier by
more than 240 kHz and up to and including 600 kHz must be attenuated at
least 35 dB below the level of the unmodulated carrier.
(d) Any emission appearing on a frequency removed from the carrier by
more than 600 kHz must be attenuated at least 43 + 10 Log10 (Power, in
watts) dB below the level of the unmodulated carrier, or 80 dB,
whichever is the lesser attenuation.
(e) Preemphasis shall not be greater than the impedance-frequency
characteristics of a series inductance resistance network having a time
constant of 75 microseconds. (See upper curve of Figure 2 of § 73.333.)
[ 51 FR 17028 , May 8, 1986]
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