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FCC 2.1049
Revised as of October 2, 2015
Goto Year:2014 | 2016
§ 2.1049   Measurements required: Occupied bandwidth.

   The occupied bandwidth, that is the frequency bandwidth such that, below its
   lower and above its upper frequency limits, the mean powers radiated are
   each  equal to 0.5 percent of the total mean power radiated by a given
   emission shall be measured under the following conditions as applicable:

   (a) Radiotelegraph transmitters for manual operation when keyed at 16 dots
   per second.

   (b) Other keyed transmitters—when keyed at the maximum machine speed.

   (c) Radiotelephone transmitters equipped with a device to limit modulation
   or peak envelope power shall be modulated as follows. For single sideband
   and independent sideband transmitters, the input level of the modulating
   signal shall be 10 dB greater than that necessary to produce rated peak
   envelope power.

   (1) Other than single sideband or independent sideband transmitters—when
   modulated  by a 2500 Hz tone at an input level 16 dB greater than that
   necessary  to  produce 50 percent modulation. The input level shall be
   established at the frequency of maximum response of the audio modulating
   circuit.

   (2) Single sideband transmitters in A3A or A3J emission modes—when modulated
   by two tones at frequencies of 400 Hz and 1800 Hz (for 3.0 kHz authorized
   bandwidth), or 500 Hz and 2100 Hz (for 3.5 kHz authorized bandwidth), or 500
   Hz and 2400 Hz (for 4.0 kHz authorized bandwidth), applied simultaneously.
   The input levels of the tones shall be so adjusted that the two principal
   frequency components of the radio frequency signal produced are equal in
   magnitude.

   (3) Single sideband transmitters in the A3H emission mode—when modulated by
   one tone at a frequency of 1500 Hz (for 3.0 kHz authorized bandwidth), or
   1700  Hz  (for  3.5 kHz authorized bandwidth), or 1900 Hz (for 4.0 kHz
   authorized bandwidth), the level of which is adjusted to produce a radio
   frequency  signal component equal in magnitude to the magnitude of the
   carrier in this mode.

   (4) As an alternative to paragraphs (c) (2) and (3) of this section, other
   tones besides those specified may be used as modulating frequencies, upon a
   sufficient  showing  of need. However, any tones so chosen must not be
   harmonically related, the third and fifth order intermodulation products
   which occur must fall within the −25 dB step of the emission bandwidth
   limitation curve, the seventh and ninth order products must fall within the
   −35 dB step of the referenced curve and the eleventh and all higher order
   products must fall beyond the −35 dB step of the referenced curve.

   (5) Independent sideband transmitters having two channels—when modulated by
   1700 Hz tones applied simultaneously to both channels. The input levels of
   the tones shall be so adjusted that the two principal frequency components
   of the radio frequency signal produced are equal in magnitude.

   (d) Radiotelephone transmitters without a device to limit modulation or peak
   envelope  power shall be modulated as follows. For single sideband and
   independent sideband transmitters, the input level of the modulating signal
   should be that necessary to produce rated peak envelope power.

   (1) Other than single sideband or independent sideband transmitters—when
   modulated by a 2500 Hz tone of sufficient level to produce at least 85
   percent modulation. If 85 percent modulation is unattainable, the highest
   percentage modulation shall be used.

   (2) Single sideband transmitters in A3A or A3J emission modes—when modulated
   by two tones at frequencies of 400 Hz and 1800 Hz (for 3.0 kHz authorized
   bandwidth), or 500 Hz and 2100 Hz (for 3.5 kHz authorized bandwidth), or 500
   Hz and 2400 Hz (for 4.0 kHz authorized bandwidth), applied simultaneously.
   The input levels of the tones shall be so adjusted that the two principal
   frequency components of the radio frequency signal produced are equal in
   magnitude.

   (3) Single sideband transmitters in the A3H emission mode—when modulated by
   one tone at a frequency of 1500 Hz (for 3.0 kHz authorized bandwidth), or
   1700  Hz  (for  3.5 kHz authorized bandwidth), or 1900 Hz (for 4.0 kHz
   authorized bandwidth), the level of which is adjusted to produce a radio
   frequency  signal component equal in magnitude to the magnitude of the
   carrier in this mode.

   (4) As an alternative to paragraphs (d) (2) and (3) of this section, other
   tones besides those specified may be used as modulating frequencies, upon a
   sufficient  showing  of  need. However any tones so chosen must not be
   harmonically related, the third and fifth order intermodulation products
   which occur must fall within the −25 dB step of the emission bandwidth
   limitation curve, the seventh and ninth order products must fall within the
   −35 dB step of the referenced curve and the eleventh and all higher order
   products must fall beyond the −35 dB step of the referenced curve.

   (5) Independent sideband transmitters having two channels—when modulated by
   1700 Hz tones applied simultaneously to both channels. The input levels of
   the tones shall be so adjusted that the two principal frequency components
   of the radio frequency signal produced are equal in magnitude.

   (e) Transmitters for use in the Radio Broadcast Services:

   (1)  AM  broadcast  transmitters for monaural operation—when amplitude
   modulated 85% by a 7,500 Hz input signal.

   (2) AM broadcast stereophonic operation—when the transmitter operated under
   any stereophonic modulation condition not exceeding 100% on negative peaks
   and tested under the conditions specified in § 73.128 in part 73 of the FCC
   rules for AM broadcast stations.

   (3) FM broadcast transmitter not used for multiplex operation—when modulated
   85 percent by a 15 kHz input signal.

   (4) FM broadcast transmitters for multiplex operation under Subsidiary
   Communication Authorization (SCA)—when carrier is modulated 70 percent by a
   15 kHz main channel input signal, and modulated an additional 15 percent
   simultaneously by a 67 kHz subcarrier (unmodulated).

   (5) FM broadcast transmitter for stereophonic operation—when modulated by a
   15  kHz input signal to the main channel, a 15 kHz input signal to the
   stereophonic subchannel, and the pilot subcarrier simultaneously. The input
   signals to the main channel and stereophonic subchannel each shall produce
   38 percent modulation of the carrier. The pilot subcarrier should produce 9
   percent modulation of the carrier.

   (6) Television broadcast monaural transmitters—when modulated 85% by a 15
   kHz input signal.

   (7)  Television  broadcast  stereophonic  sound  transmitters—when the
   transmitter is modulated with a 15 kHz input signal to the main channel and
   the stereophonic subchannel, any pilot subcarrier(s) and any unmodulated
   auxiliary subcarrier(s) which may be provided. The signals to the main
   channel and the stereophonic subchannel must be representative of the system
   being  tested  and when combined with any pilot subcarrier(s) or other
   auxiliary subcarriers shall result in 85% deviation of the maximum specified
   aural carrier deviation.

   (f) Transmitters for which peak frequency deviation (D) is determined in
   accordance with § 2.202(f), and in which the modulating baseband comprises
   more than 3 independent speech channels—when modulated by a test signal
   determined in accordance with the following:

   (1) A modulation reference level is established for the characteristic
   baseband frequency. (Modulation reference level is defined as the average
   power level of a sinusoidal test signal delivered to the modulator input
   which provides the specified value of per-channel deviation.)

   (2) Modulation reference level being established, the total rms deviation of
   the transmitter is measured when a test signal consisting of a band of
   random noise extending from below 20 kHz to the highest frequency in the
   baseband, is applied to the modulator input through any preemphasis networks
   used in normal service. The average power level of the test signal shall
   exceed the modulation reference level by the number of decibels determined
   using the appropriate formula in the following table:
   Number of message circuits that modulate the transmitter Number of dB by
   which the average power (Pavg) level test signal shall exceed the modulation
   reference level Limits of Pavg (dBm0)
   More than 3, but less than 12 To be specified by the equipment manufacturer
   subject to FCC approval
   At least 12, but less than 60 X + 2 log10 Nc X: −2 to + 2.6
   At least 60, but less than 240 X + 4 log10 Nc X: −5.6 to −1.0
   240 or more X + 10 log10 Nc X: −19.6 to −15.0

   Where X represents the average power in a message circuit in dBm0; Nc is the
   number of circuits in the multiplexed message load. Pavg shall be selected
   by  the  transmitter manufacturer and included with the technical data
   submitted with the application for type acceptance. (See § 2.202(e) in this
   chapter.)

   (g) Transmitters in which the modulating baseband comprises not more than
   three independent channels—when modulated by the full complement of signals
   for which the transmitter is rated. The level of modulation for each channel
   should be set to that prescribed in rule parts applicable to the services
   for which the transmitter is intended. If specific modulation levels are not
   set forth in the rules, the tests should provide the manufacturer's maximum
   rated condition.

   (h) Transmitters employing digital modulation techniques—when modulated by
   an  input signal such that its amplitude and symbol rate represent the
   maximum rated conditions under which the equipment will be operated. The
   signal  shall  be  applied  through any filter networks, pseudo-random
   generators or other devices required in normal service. Additionally, the
   occupied bandwidth shall be shown for operation with any devices used for
   modifying the spectrum when such devices are optional at the discretion of
   the user.

   (i) Transmitters designed for other types of modulation—when modulated by an
   appropriate signal of sufficient amplitude to be representative of the type
   of  service in which used. A description of the input signal should be
   supplied.

   (Secs. 4, 303, 307, 48 Stat., as amended, 1066, 1082, 1083; 47 U.S.C. 154,
   303, 307)

   [ 39 FR 5919 , Feb. 15, 1974, as amended at  39 FR 35664 , Oct. 3, 1974;  47 FR 13164 , Mar. 29, 1982;  48 FR 16493 , Apr. 18, 1983;  49 FR 18105 , Apr. 27,
   1984. Redesignated at  63 FR 36599 , July 7, 1998]

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