Goto Section: 74.534 | 74.536 | Table of Contents
FCC 74.535
Revised as of October 1, 2011
Goto Year:2010 |
2012
§ 74.535 Emission and bandwidth.
(a) The mean power of emissions shall be attenuated below the mean
transmitter power (P[MEAN]) in accordance with the following schedule:
(1) When using frequency modulation:
(i) On any frequency removed from the assigned (center) frequency by
more than 50% up to and including 100% of the authorized bandwidth: At
least 25 dB in any 100 kHz reference bandwidth (B[REF]);
(ii) On any frequency removed from the assigned (center) frequency by
more than 100% up to and including 250% of the authorized bandwidth: At
least 35 dB in any 100 kHz reference bandwidth;
(iii) On any frequency removed from the assigned (center) frequency by
more than 250% of the authorized bandwidth: At least 43+10
log[10](P[MEAN]in watts) dB, or 80 dB, whichever is the lesser
attenuation, in any 100 kHz reference bandwidth.
(2) When using transmissions employing digital modulation techniques:
(i) For operating frequencies below 15 GHz, in any 4 kHz reference
bandwidth (B[REF]), the center frequency of which is removed from the
assigned frequency by more than 50 percent up to and including 250
percent of the authorized bandwidth: As specified by the following
equation but in no event less than 50 decibels:
A = 35 + 0.8(G - 50) + 10 Log[10]B.
(Attenuation greater than 80 decibels is not required.)
Where:
A = Attenuation (in decibels) below the mean output power level.
G = Percent removed from the carrier frequency.
B = Authorized bandwidth in megahertz.
(ii) For operating frequencies above 15 GHz, in any 1 MHz reference
bandwidth (B[REF]), the center frequency of which is removed from the
assigned frequency by more than 50 percent up to and including 250
percent of the authorized bandwidth: As specified by the following
equation but in no event less than 11 decibels:
A = 11 + 0.4(G - 50) + 10 Log[10]B.
(Attenuation greater than 56 decibels is not required.)
(iii) In any 4 kHz reference bandwidth (B[REF]), the center frequency
of which is removed from the assigned frequency by more than 250
percent of the authorized bandwidth: At least 43 +10 Log[10](P[MEAN]in
watts) decibels, or 80 decibels, whichever is the lesser attenuation.
(b) For all emissions not covered in paragraph (a) of this section, the
peak power of emissions shall be attenuated below the peak envelope
transmitter power (P[PEAK]) in accordance with the following schedule:
(1) On any frequency 500 Hz inside the channel edge up to and including
2500 Hz outside the same edge, the following formula will apply:
A = 29 Log[10][(25/11)[(D + 2.5 - (W/2)]^2 ] dB
(Attenuation greater than 50 decibels is not required.)
Where:
A = Attenuation (in dB) below the peak envelope transmitter power.
D = the displacement frequency (kHz) from the center of the authorized
bandwidth.
W = the channel bandwidth (kHz).
(2) On any frequency removed from the channel edge by more than 2500
Hz: At least 43+10 Log[10](P[PEAK]in watts) dB.
(c) In the event a station's emissions outside its authorized channel
cause harmful interference, the Commission may require the licensee to
take such further steps as may be necessary to eliminate the
interference.
(d) For purposes of compliance with the emission limitation
requirements of this section:
(1) If the transmitter modulates a single carrier, digital modulation
techniques are considered as being employed when digital modulation
occupies 50 percent or more of the total peak frequency deviation of a
transmitted radio frequency carrier. The total peak frequency deviation
will be determined by adding the deviation produced by the digital
modulation signal and the deviation produced by any frequency division
multiplex (FDM) modulation used. The deviation (D) produced by the FDM
signal must be determined in accordance with § 2.202(f) of this
chapter.
(2) If the transmitter modulates two or more carriers, with at least
one using digital modulation and one using frequency or other analog
modulation, digital modulation techniques are considered as being
employed when the necessary bandwidth of the digital signal(s) is 50
percent or more of the aggregate bandwidth of the system, comprising
the digital necessary bandwidth(s), the analog necessary bandwidth(s),
and any bandwidth(s) between the digital and analog necessary
bandwidths. In this case, the aggregate bandwidth shall be used for the
authorized bandwidth (B) in paragraph (a) of this section, and for
purposes of compliance with the bandwidth limitations in § 74.502 of
this subpart; and the sum of the powers of the analog and digital
signals shall be used for mean transmitter power (P[MEAN]) in paragraph
(a) or the peak envelope transmitter power (P[PEAK]) in paragraph (b)
of this section, and for purposes of compliance with the power
limitations in § 74.534 of this subpart.
(3) For demonstrating compliance with the attenuation requirements for
frequency modulation and digital modulation in paragraph (a) of this
section, the resolution bandwidth (B[RES]) of the measuring equipment
used for measurements removed from the center frequency by more than
250 percent of the authorized bandwidth shall be 100 kHz for operating
frequencies below 1 GHz, and 1 MHz for operating frequencies above 1
GHz. The resolution bandwidth for frequencies removed from the center
frequency by less than 250 percent of the authorized bandwidth shall be
the reference bandwidth (B[REF]) specified in the individual emission
limitations, but may be reduced to not less than one percent of the
authorized bandwidth (B), adjusted upward to the nearest greater
resolution bandwidth available on the measuring equipment. In all
cases, if B[RES]and B[REF]are not equal, then the attenuation
requirement must be increased (or decreased) as determined by a factor
of 10 log[10][(B[REF]in megahertz)/(B[RES]in megahertz)] decibels,
where a positive factor indicates an increase in the attenuation
requirement and a negative factor indicates a decrease in the
attenuation requirement.
(4) Stations licensed pursuant to an application filed before March 17,
2005, using equipment not conforming with the emission limitations
specified above, may continue to operate indefinitely in accordance
with the terms of their current authorizations, subject to periodic
renewal. Existing equipment and equipment of product lines in
production before April 16, 2003, authorized via certification or
verification before March 17, 2005, for equipment not conforming to the
emission limitations requirements specified above, may continue to be
manufactured and/or marketed, but may not be authorized for use under a
station license except at stations licensed pursuant to an application
filed before March 17, 2005. Any non-conforming equipment authorized
under a station license, and replaced on or after March 17, 2005, must
be replaced by conforming equipment.
(e) The following limitations apply to the operation of aural broadcast
microwave booster stations:
(1) The booster station must receive and amplify the signals of the
originating station and retransmit them on the same frequency without
significantly altering them in any way. The characteristics of the
booster transmitter output signal shall meet the requirements
applicable to the signal of the originating station.
(2) The licensee is responsible for correcting any condition of
interference that results from the radiation of radio frequency energy
outside the assigned channel. Upon notice by the FCC to the station
licensee that interference is being caused, operation of the apparatus
must be immediately suspended and may not be resumed until the
interference has been eliminated or it can be demonstrated that the
interference is not due to spurious emissions. However, short term test
transmissions may be made during the period of suspended operation to
determine the efficacy of remedial measures.
(3) In each instance where suspension of operation is required, the
licensee must submit a full report to the FCC after operation is
resumed. The report must contain details of the nature of the
interference, the source of interfering signals, and the remedial steps
taken to eliminate the interference.
[ 28 FR 13716 , Dec. 14, 1963, as amended at 48 FR 50332 , Nov. 1, 1983;
49 FR 7130 , Feb. 27, 1984; 49 FR 37777 , Sept. 26, 1984; 50 FR 48599 ,
Nov. 26, 1985; 68 FR 12766 , March 17, 2003.]
Goto Section: 74.534 | 74.536
Goto Year: 2010 |
2012
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