[Code of Federal Regulations]
[Title 47, Volume 4]
[Revised as of October 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR73.44]

[Page 19-20]
                       TITLE 47--TELECOMMUNICATION
                     Subpart A_AM Broadcast Stations
Sec.  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.

[[Page 20]]

    (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 Sec.  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]