§  73.44   AM transmission system emission limitations.

   (a) The emissions of stations in the AM service shall be attenuated in
   accordance with the requirements specified in paragraph (b) of this
   section. Emissions shall be measured using a properly operated and
   suitable swept-frequency RF spectrum analyzer using a peak hold
   duration of 10 minutes, no video filtering, and a 300 Hz resolution
   bandwidth, except that a wider resolution bandwidth may be employed
   above 11.5 kHz to detect transient emissions. Alternatively, other
   specialized receivers or monitors with appropriate characteristics may
   be used to determine compliance with the provisions of this section,
   provided that any disputes over measurement accuracy are resolved in
   favor of measurements obtained by using a calibrated spectrum analyzer
   adjusted as set forth above.

   (b) Emissions 10.2 kHz to 20 kHz removed from the carrier must be
   attenuated at least 25 dB below the unmodulated carrier level,
   emissions 20 kHz to 30 kHz removed from the carrier must be attenuated
   at least 35 dB below the unmodulated carrier level, emissions 30 kHz to
   60 kHz removed from the carrier must be attenuated at least [5 + 1
   dB/kHz] below the unmodulated carrier level, and emissions between 60
   kHz and 75 kHz of the carrier frequency must be attenuated at least 65
   dB below the unmodulated carrier level. Emissions removed by more than
   75 kHz must be attenuated at least 43 + 10 Log (Power in watts) or 80
   dB below the unmodulated carrier level, whichever is the lesser
   attenuation, except for transmitters having power less than 158 watts,
   where the attenuation must be at least 65 dB below carrier level.

   (c) Should harmful interference be caused to the reception of other
   broadcast or non-broadcast stations by out of band emissions, the
   licensee may be directed to achieve a greater degree of attentuation
   than specified in paragraphs (a) and (b) of this section.

   (d) Measurements to determine compliance with this section for
   transmitter type acceptance are to be made using signals sampled at the
   output terminals of the transmitter when operating into an artificial
   antenna of substantially zero reactance. Measurements made of the
   emissions of an operating station are to be made at ground level
   approximately 1 kilometer from the center of the antenna system. When a
   directional antenna is used, the carrier frequency reference field
   strength to be used in order of preference shall be:

   (1) The measure non-directional field strength.

   (2) The RMS field strength determined from the measured directional
   radiation pattern.

   (3) The calculated expected field strength that would be radiated by a
   non-directional antenna at the station authorized power.

   (e) Licensees of stations complying with the ANSI/EIA-549-1988, NRSC-1
   AM Preemphasis/Deemphasis and Broadcast Transmission Bandwidth
   Specifications (NRSC-1), prior to June 30, 1990 or from the original
   commencement of operation will, until June 30, 1994, be considered to
   comply with paragraphs (a) and (b) of this section, absent any reason
   for the Commission to believe otherwise. Such stations are waived from
   having to make the periodic measurements required in § 73.1590(a)(6)
   until June 30, 1994. However, licensees must make measurements to
   determine compliance with paragraphs (a) and (b) of this section upon
   receipt of an Official Notice of Violation or a Notice of Apparent
   Liability alleging noncompliance with those provisions, or upon
   specific request by the Commission.

   [ 47 FR 8588 , Mar. 1, 1982, as amended at  49 FR 3999 , Feb. 1, 1984]