Sec. 101.111  Emission limitations.

    (a) The mean power of emissions must be attenuated below the mean 
output power of the transmitter in accordance with the following 
schedule:
    (1) When using transmissions other than those employing digital 
modulation techniques:
    (i) On any frequency removed from the assigned frequency by more 
than 50 percent up to and including 100 percent of the authorized 
bandwidth: At least 25 decibels;
    (ii) On any frequency removed from the assigned frequency by more 
than 100 percent up to and including 250 percent of the authorized 
bandwidth: At least 35 decibels;
    (iii) On any frequency removed from the assigned frequency by more 
than 250 percent of the authorized bandwidth: At least 43+10 
Log10 (mean output power in watts) decibels, or 80 decibels, 
whichever is the lesser attenuation.
    (2) When using transmissions employing digital modulation techniques 
(see Sec. 101.141(b)) in situations not covered in this section:
    (i) For operating frequencies below 15 GHz, in any 4 KHz band, 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(P - 50) + 10 Log10 B. (Attenuation greater than 
    80 decibels is not required.)

where:

A = Attenuation (in decibels) below the mean output power level.
P = Percent removed from the carrier frequency.
B = Authorized bandwidth in MHz.

    (ii) For operating frequencies above 15 GHz, in any 1 MHz band, 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(P - 50) + 10 Log10 B. (Attenuation greater than 
    56 decibels is not required.)

    (iii) In any 4 KHz band, the center frequency of which is removed 
from the assigned frequency by more than 250 percent of the authorized 
bandwidth: At least 43+10 Log10 (mean output power in watts) 
decibels, or 80 decibels, whichever is the lesser attenuation.
    (3) For Digital Termination System channels used in the Digital 
Electronic Message Service (DEMS) operating in the 10,550-10,680 MHz 
band:
    (i) In any 4 KHz band, the center frequency of which is removed from 
the edge of the DEMS channel by up to and including 1.125 times the DEMS 
subchannel bandwidth: As specified by the following equation may in no 
event be less than 50+10 log10 N decibels:

A = 50 + 0.0333(F - 0.5B) + 10 log10 N decibels

Where:

A = Attenuation (in decibels) below means output power level contained 
within the DEMS channel for a given polarization.
B = Bandwidth of DEMS channel (in KHz).
F = Absolute value of the difference between the center frequency of the 
4 KHz band measured and the center frequency of the DEMS channel (in 
KHz).
N = Number of active subchannels of the given polarization within the 
DEMS channel.


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    (ii) In any 4 KHz band within the authorized DEMS band the center 
frequency of which is removed from the center frequency of the DEMS 
channel by more than the sum of 50% of the DEMS channel bandwidth plus 
1.125 times the subchannel bandwidth: As specified by the following 
equation but in no event less than 80 decibels:

A = 80 + 10 log10 N decibels

    (iii) In any 4 KHz band the center frequency of which is outside the 
authorized DEMS band: At least 43+10 log10 (mean output power 
in watts) decibels.
    (4) For Digital Termination System channels used in the Digital 
Electronic Message Service (DEMS) operating in the 17,700-19,700 and 
24,250-25,250 MHz bands:
    (i) In any 4 KHz band, the center frequency of which is removed from 
the frequency of the center of the DEMS channel by more than 50 percent 
of the DEMS channel bandwidth up to and including 50 percent plus 500 
KHz: As specified by the following equation but in no event be less than 
50+10 log10 N decibels:

A = 50 + 0.06(F -0.5B) + 10 log10 N decibels

Where:
A = Attenuation (in decibels) below means output power level contained 
within the DEMS channel for a given polarization.
B = Bandwidth of DEMS channel (in KHz).
F = Absolute value of the difference between the center frequency of the 
4 KHz band measured and the center frequency of the DEMS channel (in 
KHz).
N = Number of active subchannels of the given polarization within the 
DEMS channel.

    (ii) In any 4 KHz band within the authorized DEMS band, the center 
frequency of which is removed from the center frequency of the DEMS 
channel by more than the sum of 50 percent of the channel bandwidth plus 
500 KHz: As specified by the following equation but in no event less 
than 80 decibels:

A=80+10 log10 N decibels

    (iii) In any 4 KHz band the center frequency of which is outside the 
authorized Digital Message Service band: At least 43+10 log10 
(mean output power in watts) decibels.
    (5) When using transmissions employing digital modulation techniques 
on the 900 MHz multiple address frequencies with a 12.5 KHz bandwidth, 
the power of any emission must be attenuated below the unmodulated 
carrier power of the transmitter (P) in accordance with the following 
schedule:
    (i) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency (fd in KHz) of more than 2.5 KHz 
up to and including 6.25 KHz: At least 53 log10 (fd/2.5) 
decibels;
    (ii) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency (fd in KHz) of more than 6.25 KHz 
up to and including 9.5 KHz: At least 103 log10 (fd/3.9) 
decibels;
    (iii) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency (fd in KHz) of more than 9.5 KHz 
up to and including 15 KHz: At least 157 log10 (fd/5.3) 
decibels; and
    (iv) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency greater than 15 KHz: At least 50 
plus 10 log10(P) or 70 decibels, whichever is the lesser 
attenuation.
    (6) When using transmissions employing digital modulation techniques 
on the 900 MHz multiple address frequencies with a bandwidth greater 
than 12.5 KHz, the power of any emission must be attenuated below the 
unmodulated carrier power of the transmitter (P) in accordance with the 
following schedule:
    (i) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency (fd in KHz) of more than 5 KHz up 
to and including 10 KHz: At least 83 log10 (fd/5) decibels;
    (ii) On any frequency removed from the center of the authorized 
bandwidth by a displacement frequency (fd in KHz) of more than 10 KHz up 
to and including 250 percent of the authorized bandwidth: At least 116 
log10 (fd/6.1) decibels or 50 plus 10 log10 (P) or 
70 decibels, whichever is the lesser attenuation; and
    (iii) On any frequency removed from the center of the authorized 
bandwidth by more that 250 percent of the authorized bandwidth: At least 
43 plus 10 log10 (output power in watts) decibels or 80

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decibels, whichever is the lesser attenuation.
    (b) When an emission outside of the authorized bandwidth causes 
harmful interference, the Commission may, at its discretion, require 
greater attenuation than specified in paragraph (a) of this section.
    (c) The emission of an unmodulated carrier is prohibited except for 
test purposes as required for proper station and system maintenance.
[ 61 FR 26677 , May 28, 1996, as amended at  62 FR 24582 , May 6, 1997]