§ 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]

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