Sec. 73.1540  Carrier frequency measurements.

    (a) The carrier frequency of each AM and FM station and the visual 
carrier frequency and the difference between the visual carrier and the 
aural carrier or center frequency of each TV station shall be measured 
or determined as often as necessary to ensure that they are maintained 
within the prescribed tolerances.
    (b) In measuring the carrier frequency, the licensee may use any

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method or procedure that has sufficient precision to establish that the 
carrier frequency is within the prescribed departure limits.
    (c) The primary standard of frequency for radio frequency 
measurements is the standard frequency maintained by the National Bureau 
of Standards or the standard signals of Stations WWV, WWVB, and WWVH of 
the National Bureau of Standards.

[ 43 FR 32783 , July 28, 1978, as amended at  48 FR 44805 , Sept. 30, 1983]