Goto Section: 90.209 | 90.212 | Table of Contents

FCC 90.210
Revised as of December 7, 2018
Goto Year:2018 | 2020
  § 90.210   Emission masks.

   Link to an amendment published at  83 FR 61096 , Nov. 27, 2018.

   Except as indicated elsewhere in this part, transmitters used in the
   radio services governed by this part must comply with the emission
   masks outlined in this section. Unless otherwise stated, per paragraphs
   (d)(4), (e)(4), and (o) of this section, measurements of emission power
   can be expressed in either peak or average values provided that
   emission powers are expressed with the same parameters used to specify
   the unmodulated transmitter carrier power. For transmitters that do not
   produce a full power unmodulated carrier, reference to the unmodulated
   transmitter carrier power refers to the total power contained in the
   channel bandwidth. Unless indicated elsewhere in this part, the table
   in this section specifies the emission masks for equipment operating
   under this part.

   Applicable Emission Masks
   Frequency band (MHz) Mask for equipment
   with audio low
   pass filter Mask for equipment
   without audio low
   pass filter
   Below 25^1 A or B A or C
   25-50 B C
   72-76 B C
   150-174^2 B, D, or E C, D or E
   150 paging only B C
   220-222 F F
   421-512^2 5 B, D, or E C, D, or E
   450 paging only B G
   806-809/851-854^6 B H
   809-824/854-869^3 5 B G
   896-901/935-940 I J
   902-928 K K
   929-930 B G
   4940-4990 MHz L or M L or M
   5850-5925^4
   All other bands B C

   ^1Equipment using single sideband J3E emission must meet the
   requirements of Emission Mask A. Equipment using other emissions must
   meet the requirements of Emission Mask B or C, as applicable.

   ^2Equipment designed to operate with a 25 kHz channel bandwidth must
   meet the requirements of Emission Mask B or C, as applicable. Equipment
   designed to operate with a 12.5 kHz channel bandwidth must meet the
   requirements of Emission Mask D, and equipment designed to operate with
   a 6.25 kHz channel bandwidth must meet the requirements of Emission
   Mask E.

   ^3Equipment used in this licensed to EA or non-EA systems shall comply
   with the emission mask provisions of § 90.691 of this chapter.

   ^4DSRCS Roadside Units equipment in the 5850-5925 MHz band is governed
   under subpart M of this part.

   ^5Equipment may alternatively meet the Adjacent Channel Power limits of
   § 90.221.

   ^6Transmitters utilizing analog emissions that are equipped with an
   audio low-pass filter must meet Emission Mask B. All transmitters
   utilizing digital emissions and those transmitters using analog
   emissions without an audio low-pass filter must meet Emission Mask H.

   (a) Emission Mask A. For transmitters utilizing J3E emission, the
   carrier must be at least 40 dB below the peak envelope power and the
   power of emissions must be reduced below the output power (P in watts)
   of the transmitter as follows:

   (1) On any frequency removed from the assigned frequency by more than
   50 percent, but not more than 150 percent of the authorized bandwidth:
   At least 25 dB.

   (2) On any frequency removed from the assigned frequency by more than
   150 percent, but not more than 250 percent of the authorized bandwidth:
   At least 35 dB.

   (3) On any frequency removed from the assigned frequency by more than
   250 percent of the authorized bandwidth: At least 43 + 10 log P dB.

   (b) Emission Mask B. For transmitters that are equipped with an audio
   low-pass filter, the power of any emission must be attenuated below the
   unmodulated carrier power (P) as follows:

   (1) On any frequency removed from the assigned frequency by more than
   50 percent, but not more than 100 percent of the authorized bandwidth:
   At least 25 dB.

   (2) On any frequency removed from the assigned frequency by more than
   100 percent, but not more than 250 percent of the authorized bandwidth:
   At least 35 dB.

   (3) On any frequency removed from the assigned frequency by more than
   250 percent of the authorized bandwidth: At least 43 + 10 log (P) dB.

   (c) Emission Mask C. For transmitters that are not equipped with an
   audio low-pass filter, the power of any emission must be attenuated
   below the unmodulated carrier output power (P) as follows:

   (1) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 5 kHz,
   but not more than 10 kHz: At least 83 log (fd/5) dB;

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 10 kHz,
   but not more than 250 percent of the authorized bandwidth: At least 29
   log (fd2/11) dB or 50 dB, whichever is the lesser attenuation;

   (3) On any frequency removed from the center of the authorized
   bandwidth by more than 250 percent of the authorized bandwidth: At
   least 43 + 10 log (P) dB.

   (4) In the 1427-1432 MHz band, licensees are encouraged to take all
   reasonable steps to ensure that unwanted emissions power does not
   exceed the following levels in the 1400-1427 MHz band:

   (i) For stations of point-to-point systems in the fixed service: −45
   dBW/27 MHz.

   (ii) For stations in the mobile service: −60 dBW/27 MHz.

   (d) Emission Mask D—12.5 kHz channel bandwidth equipment. For
   transmitters designed to operate with a 12.5 kHz channel bandwidth, any
   emission must be attenuated below the power (P) of the highest emission
   contained within the authorized bandwidth as follows:

   (1) On any frequency from the center of the authorized bandwidth f0 to
   5.625 kHz removed from f0: Zero dB.

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 5.625
   kHz but no more than 12.5 kHz: At least 7.27(fd−2.88 kHz) dB.

   (3) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 12.5
   kHz: At least 50 + 10 log (P) dB or 70 dB, whichever is the lesser
   attenuation.

   (4) The reference level for showing compliance with the emission mask
   shall be established using a resolution bandwidth sufficiently wide
   (usually two or three times the channel bandwidth) to capture the true
   peak emission of the equipment under test. In order to show compliance
   with the emission mask up to and including 50 kHz removed from the edge
   of the authorized bandwidth, adjust the resolution bandwidth to 100 Hz
   with the measuring instrument in a peak hold mode. A sufficient number
   of sweeps must be measured to insure that the emission profile is
   developed. If video filtering is used, its bandwidth must not be less
   than the instrument resolution bandwidth. For emissions beyond 50 kHz
   from the edge of the authorized bandwidth, see paragraph (o) of this
   section. If it can be shown that use of the above instrumentation
   settings do not accurately represent the true interference potential of
   the equipment under test, an alternate procedure may be used provided
   prior Commission approval is obtained.

   (e) Emission Mask E—6.25 kHz or less channel bandwidth equipment. For
   transmitters designed to operate with a 6.25 kHz or less bandwidth, any
   emission must be attenuated below the power (P) of the highest emission
   contained within the authorized bandwidth as follows:

   (1) On any frequency from the center of the authorized bandwidth f0 to
   3.0 kHz removed from f0: Zero dB.

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 3.0 kHz
   but no more than 4.6 kHz: At least 30 + 16.67(fd−3 kHz) or 55 + 10 log
   (P) or 65 dB, whichever is the lesser attenuation.

   (3) On any frequency removed from the center of the authorized
   bandwidth by more than 4.6 kHz: At least 55 + 10 log (P) or 65 dB,
   whichever is the lesser attenuation.

   (4) The reference level for showing compliance with the emission mask
   shall be established using a resolution bandwidth sufficiently wide
   (usually two or three times the channel bandwidth) to capture the true
   peak emission of the equipment under test. In order to show compliance
   with the emission mask up to and including 50 kHz removed from the edge
   of the authorized bandwidth, adjust the resolution bandwidth to 100 Hz
   with the measuring instrument in a peak hold mode. A sufficient number
   of sweeps must be measured to insure that the emission profile is
   developed. If video filtering is used, its bandwidth must not be less
   than the instrument resolution bandwidth. For emissions beyond 50 kHz
   from the edge of the authorized bandwidth, see paragraph (o) of this
   section. If it can be shown that use of the above instrumentation
   settings do not accurately represent the true interference potential of
   the equipment under test, an alternate procedure may be used provided
   prior Commission approval is obtained.

   (f) Emission Mask F. For transmitters operating in the 220-222 MHz
   frequency band, any emission must be attenuated below the power (P) of
   the highest emission contained within the authorized bandwidth as
   follows:

   (1) On any frequency from the center of the authorized bandwidth fo to
   the edge of the authorized bandwidth fe: Zero dB.

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 2 kHz up
   to and including 3.75 kHz: 30 + 20(fd − 2) dB or 55 + 10 log (P), or 65
   dB, whichever is the lesser attenuation.

   (3) On any frequency beyond 3.75 kHz removed from the center of the
   authorized bandwidth fd: At least 55 + 10 log (P) dB.

   (g) Emission Mask G. For transmitters that are not equipped with an
   audio low-pass filter, the power of any emission must be attenuated
   below the unmodulated carrier power (P) as follows:

   (1) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 10 kHz,
   but no more than 250 percent of the authorized bandwidth: At least 116
   log (fd/6.1) dB, or 50 + 10 log (P) dB, or 70 dB, whichever is the
   lesser attenuation;

   (2) On any frequency removed from the center of the authorized
   bandwidth by more than 250 percent of the authorized bandwidth: At
   least 43 + 10 log (P) dB.

   (h) Emission Mask H. For transmitters that are not equipped with an
   audio low-pass filter, the power of any emission must be attenuated
   below the unmodulated carrier power (P) as follows:

   (1) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of 4 kHz or less:
   Zero dB.

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 4 kHz,
   but no more than 8.5 kHz: At least 107 log (fd/4) dB;

   (3) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 8.5 kHz,
   but no more than 15 kHz: At least 40.5 log (fd/1.16) dB;

   (4) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 15 kHz,
   but no more than 25 kHz: At least 116 log (fd/6.1) dB;

   (5) On any frequency removed from the center of the authorized
   bandwidth by more than 25 kHz: At least 43 + 10 log (P) dB.

   (i) Emission Mask I. For transmitters that are equipped with an audio
   low pass filter, the power of any emission must be attenuated below the
   unmodulated carrier power of the transmitter (P) as follows:

   (1) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency of more than 6.8 kHz, but no more
   than 9.0 kHz: At least 25 dB;

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency of more than 9.0 kHz, but no more
   than 15 kHz: At least 35 dB;

   (3) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency of more than 15 kHz: At least 43
   + 10 log (P) dB, or 70 dB, whichever is the lesser attenuation.

   (j) Emission Mask J. For transmitters that are not equipped with an
   audio low-pass filter, the power of any emission must be attenuated
   below the unmodulated carrier power of the transmitter (P) as follows:

   (1) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 2.5 kHz,
   but no more than 6.25 kHz: At least 53 log (fd/2.5) dB;

   (2) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 6.25
   kHz, but no more than 9.5 kHz: At least 103 log (fd/3.9) dB;

   (3) On any frequency removed from the center of the authorized
   bandwidth by a displacement frequency (fd in kHz) of more than 9.5 kHz:
   At least 157 log (fd/5.3) dB, or 50 + 10 log (P) dB or 70 dB, whichever
   is the lesser attenuation.

   (k) Emission Mask K—(1) Wideband multilateration transmitters. For
   transmitters authorized under subpart M to provide forward or reverse
   links in a multilateration system in the subbands 904-909.75 MHz,
   921.75-927.25 MHz and 919.75-921.75 MHz, and which transmit an emission
   occupying more than 50 kHz bandwidth: in any 100 kHz band, the center
   frequency of which is removed from the center of authorized sub-band(s)
   by more than 50 percent of the authorized bandwidth, the power of
   emissions shall be attenuated below the transmitter output power, as
   specified by the following equation, but in no case less than 31 dB:

   A = 16 + 0.4 (D−50) + 10 log B (attenuation greater than 66 dB is not
   required)

   Where:

   A = attenuation (in decibels) below the maximum permitted output power
   level

   D = displacement of the center frequency of the measurement bandwidth
   from the center frequency of the authorized sub-band, expressed as a
   percentage of the authorized bandwidth B

   B = authorized bandwidth in megahertz.

   (2) Narrowband forward link transmitters. For LMS multilateration
   narrowband forward link transmitters operating in the 927.25-928 MHz
   frequency band the power of any emission shall be attenuated below the
   transmitter output power (P) in accordance with following schedule:

   On any frequency outside the authorized sub-band and removed from the
   edge of the authorized sub-band by a displacement frequency (fd in
   kHz): at least 116 log ((fd + 10)/6.1) dB or 50 + 10 log (P) dB or 70
   dB, whichever is the lesser attenuation.

   (3) Other transmitters. For all other transmitters authorized under
   subpart M that operate in the 902-928 MHz band, the peak power of any
   emission shall be attenuated below the power of the highest emission
   contained within the licensee's sub-band in accordance with the
   following schedule:

   (i) On any frequency within the authorized bandwidth: Zero dB.

   (ii) On any frequency outside the licensee's sub-band edges: 55 + 10
   log(P) dB, where (P) is the highest emission (watts) of the transmitter
   inside the licensee's sub-band.

   (4) In the 902-928 MHz band, the resolution bandwidth of the
   instrumentation used to measure the emission power shall be 100 kHz,
   except that, in regard to paragraph (2) of this section, a minimum
   spectrum analyzer resolution bandwidth of 300 Hz shall be used for
   measurement center frequencies with 1 MHz of the edge of the authorized
   subband. The video filter bandwidth shall not be less than the
   resolution bandwidth.

   (5) Emission power shall be measured in peak values.

   (6) The LMS sub-band edges for non-multilateration systems for which
   emissions must be attenuated are 902.00, 904.00, 909.5 and 921.75 MHz.

   (l) Emission Mask L. For low power transmitters (20 dBm or less)
   operating in the 4940-4990 MHz frequency band, the power spectral
   density of the emissions must be attenuated below the output power of
   the transmitter as follows:

   (1) On any frequency removed from the assigned frequency between 0-45%
   of the authorized bandwidth (BW): 0 dB.

   (2) On any frequency removed from the assigned frequency between 45-50%
   of the authorized bandwidth: 219 log (% of (BW)/45) dB.

   (3) On any frequency removed from the assigned frequency between 50-55%
   of the authorized bandwidth: 10 + 242 log (% of (BW)/50) dB.

   (4) On any frequency removed from the assigned frequency between
   55-100% of the authorized bandwidth: 20 + 31 log (% of (BW)/55) dB
   attenuation.

   (5) On any frequency removed from the assigned frequency between
   100-150% of the authorized bandwidth: 28 + 68 log (% of (BW)/100) dB
   attenuation.

   (6) On any frequency removed from the assigned frequency above 150% of
   the authorized bandwidth: 40 dB.

   (7) The zero dB reference is measured relative to the highest average
   power of the fundamental emission measured across the designated
   channel bandwidth using a resolution bandwidth of at least one percent
   of the occupied bandwidth of the fundamental emission and a video
   bandwidth of 30 kHz. The power spectral density is the power measured
   within the resolution bandwidth of the measurement device divided by
   the resolution bandwidth of the measurement device. Emission levels are
   also based on the use of measurement instrumentation employing a
   resolution bandwidth of at least one percent of the occupied bandwidth.

   (m) Emission Mask M. For high power transmitters (greater that 20 dBm)
   operating in the 4940-4990 MHz frequency band, the power spectral
   density of the emissions must be attenuated below the output power of
   the transmitter as follows:

   (1) On any frequency removed from the assigned frequency between 0-45%
   of the authorized bandwidth (BW): 0 dB.

   (2) On any frequency removed from the assigned frequency between 45-50%
   of the authorized bandwidth: 568 log (% of (BW)/45) dB.

   (3) On any frequency removed from the assigned frequency between 50-55%
   of the authorized bandwidth: 26 + 145 log (% of BW/50) dB.

   (4) On any frequency removed from the assigned frequency between
   55-100% of the authorized bandwidth: 32 + 31 log (% of (BW)/55) dB.

   (5) On any frequency removed from the assigned frequency between
   100-150% of the authorized bandwidth: 40 + 57 log (% of (BW)/100) dB.

   (6) On any frequency removed from the assigned frequency between above
   150% of the authorized bandwidth: 50 dB or 55 + 10 log (P) dB,
   whichever is the lesser attenuation.

   (7) The zero dB reference is measured relative to the highest average
   power of the fundamental emission measured across the designated
   channel bandwidth using a resolution bandwidth of at least one percent
   of the occupied bandwidth of the fundamental emission and a video
   bandwidth of 30 kHz. The power spectral density is the power measured
   within the resolution bandwidth of the measurement device divided by
   the resolution bandwidth of the measurement device. Emission levels are
   also based on the use of measurement instrumentation employing a
   resolution bandwidth of at least one percent of the occupied bandwidth.

   Note to paragraph (m): Low power devices may as an option, comply with
   paragraph (m).

   (n) Other frequency bands. Transmitters designed for operation under
   this part on frequencies other than listed in this section must meet
   the emission mask requirements of Emission Mask B. Equipment operating
   under this part on frequencies allocated to but shared with the Federal
   Government, must meet the applicable Federal Government technical
   standards.

   (o) Instrumentation. The reference level for showing compliance with
   the emission mask shall be established, except as indicated in § § 90.210
   (d), (e), and (k), using standard engineering practices for the
   modulation characteristic used by the equipment under test. When
   measuring emissions in the 150-174 MHz and 421-512 MHz bands the
   following procedures will apply. A sufficient number of sweeps must be
   measured to insure that the emission profile is developed. If video
   filtering is used, its bandwidth must not be less than the instrument
   resolution bandwidth. For frequencies more than 50 kHz removed from the
   edge of the authorized bandwidth a resolution of at least 100 kHz must
   be used for frequencies below 1000 MHz. Above 1000 MHz the resolution
   bandwidth of the instrumentation must be at least 1 MHz. If it can be
   shown that use of the above instrumentation settings do not accurately
   represent the true interference potential of the equipment under test,
   then an alternate procedure may be used provided prior Commission
   approval is obtained.

   [ 60 FR 37264 , July 19, 1995]

   Editorial Note: For Federal Register citations affecting § 90.210, see
   the List of CFR Sections Affected, which appears in the Finding Aids
   section of the printed volume and at www.fdsys.gov.

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