Sec. 90.210  Emission masks.

    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 (m) 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 in the 
frequency bands governed under this part.


                        Applicable Emission Masks                       
------------------------------------------------------------------------
                                  Mask for equipment  Mask for equipment
      Frequency band (MHz)       with audio low pass   without audio low
                                        filter            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\....................  B, D, or E.........  C, D, or E        
450 Paging-only................  B..................  G                 
806-821/851-866 \3\............  B..................  G                 
821-824/866-869................  B..................  H                 
896-901/935-940................  I..................  J                 
902-928........................  K..................  K                 
929-930........................  B..................  G                 
Above 940......................  B..................  C                 

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All other bands................  B..................  C                 
------------------------------------------------------------------------
\1\ Equipment 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.         
\2\ Equipment 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.                                                   
\3\ Equipment used in this band licensed to EA or non-EA systems shall  
  comply with the emission mask provisions of Sec.  90.691.             

    (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 pursuant to Sec. 90.211(a), the power of any 
emission must be 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 pursuant to Sec. 90.211(b), 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 (fd\2\/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.
    (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 to three times the channel bandwidth) to capture the true 
peak emission of the equipment under test. In order to show compliance 
with the emissions 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

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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 
(m) 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, then 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 to three times the channel bandwidth) to capture the true 
peak emission of the equipment under test. In order to show compliance 
with the emissions 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 (m) 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, then 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 pursuant to Sec. 90.211(b), 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 5 kHz, but no 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 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;
    (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.
    (h) Emission Mask H. For transmitters that are not equipped with an 
audio low-pass filter pursuant to Sec. 90.211(b), 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

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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 + log (P) dB.
    (i) Emission Mask I. For transmitters that are equipped with an 
audio low pass filter pursuant to Sec. 90.211(a), 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 pursuant to Sec. 90.211(b), 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, the peak power of any emission shall be attenuated below the 
power of the highest emission contained within the authorized channel 
bandwidth in accordance with the following schedule:

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    (i) On any frequency within the authorized bandwidth: Zero dB;
    (ii) On any frequency outside of the authorized bandwidth: 
55+10log(P) dB where (P) is the highest emission (watts) of the 
transmitter inside the authorized bandwidth.
    (4) 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 within 1 MHz of 
the edge of the authorized subband. If a video filter is used, its 
bandwidth shall not be less than the resolution bandwidth.
    (5) Emission power shall be measured in peak values.
    (l) 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.
    (m) Instrumentation. The reference level for showing compliance with 
the emission mask shall be established, except as indicated in 
Secs. 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 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 10 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, as amended at  61 FR 4235 , Feb. 5, 1996;  61 FR 6155 , Feb. 16, 1996;  61 FR 18986 , Apr. 30, 1996;  62 FR 41214 , July 
31, 1997]