Sec. 21.908  Television transmitting equipment.

    (a) Except as otherwise provided in this section, the requirements 
of paragraphs (a), (b), (c), (d), and (e) of Sec. 73.687 of this chapter 
shall apply to stations in this service transmitting standard television 
signals.
    (b) On or after November 1, 1991, the maximum out-of-band power of a 
transmitter operating in the frequency bands 2150-2162 MHz, 2596-2644 
MHz, 2650-2656 MHz, 2662-2668 MHz, and 2674-2680 MHz shall be attenuated 
38 dB relative to the peak visual carrier at the channel edges and 
constant slope attenuation from this level to 60 dB relative to the peak 
visual carrier at 1 MHz below the lower band edge and 0.5 MHz above the 
upper band edge. All out-of-band emissions extending beyond these 
frequencies shall be attenuated at least 60 dB below the peak visual 
carrier power. However, should harmful interference occur as a result of 
emissions outside the assigned channel, additional attenuation may be 
required. A transmitter licensed prior to November 1, 1991, that remains 
at the station site initially licensed, and does not comply with this 
paragraph, may continue to be used for its life if it does not cause 
harmful interference to the operation of any other licensee. Any non-
conforming transmitter replaced after November 1, 1991, must be replaced 
by a transmitter meeting the requirements of this paragraph.
    (c) The requirements of Sec. 73.687(c)(2) of this chapter will be 
considered to be satisfied insofar as measurements of operating power 
are concerned if the transmitter station is equipped with instruments 
for determining the combined visual and aural operating power. However, 
licensees must maintain the operating powers within the limits specified 
in Sec. 21.904 of this part. Measurements of the separate visual and 
aural operating powers must be made at sufficiently frequent intervals 
to insure compliance with the rules, and in no event less than once a 
month.
    (d) Television transmitting equipment designed for stations whose 
authorized bandwidth in 4 MHz or less for the visual and accompanying 
aural signal is subject to the provisions of Sec. 21.101 of this part 
with respect to the frequency tolerance of the visual and aural 
carriers. Such equipment is also subject to paragraphs (a) and (b) of 
this section, except that the provisions of Sec. 73.687 (a), (b), and 
(c)(1) of this chapter shall not apply.
    (e) As a further exception to the other requirements of this 
section, transmitting equipment characteristics may vary from these 
requirements to the extent necessary to insure that transmitted 
information is not likely to be received in intelligible form by 
unauthorized subscribers or licensees, provided such variations permit 
recovery of the transmitted information without perceptible degradation 
as compared to the same information transmitted without such variations.
[ 55 FR 46011 , Oct. 31, 1990, as amended at  56 FR 57818 , Nov. 14, 1991]