1. (a) The mean power of emissions must be attenuated below the mean output power of the transmitter in accordance with the following schedule:

   1. (1) When using transmissions other than those employing digital modulation techniques:

      1. (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;
      2. (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;
      3. (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. (2) When using transmissions employing digital modulation techniques (see § 101.141(b)) in situations not covered in this section:

      1. (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 or to an absolute power of less than −13 dBm/1MHz is not required.) where:

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

      2. (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 or to an absolute power of less than −13 dBm/1MHz is not required.)

      3. (iii) In any 1 MHz 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 (the mean output power in watts) decibels, or 80 decibels, whichever is the lesser attenuation. The authorized bandwidth includes the nominal radio frequency bandwidth of an individual transmitter/modulator in block-assigned bands. Equipment licensed prior to April 1, 2005 shall only be required to meet this standard in any 4 kHz band.
      4. (iv) The emission mask for LMDS and the 24 GHz Service shall use the equation in paragraph (a)(2)(ii) of this section and apply it only to the band edge of each block of spectrum, but not to subchannels established by licensees. The value of P in the equation is the percentage removed from the carrier frequency and assumes that the carrier frequency is the center of the actual bandwidth used. The emission mask can be satisfied by locating a carrier of the subchannel sufficiently far from the channel edges so that the emission levels of the mask are satisfied. The LMDS or 24 GHz emission mask shall use a value B (bandwidth) of 40 MHz, for all cases even in the case where a narrower subchannel is used (for instance the actual bandwidth is 10 MHz) and the mean output power used in the calculation is the sum of the output power of a fully populated channel. For block assigned channels, the out-of-band emission limits apply only outside the assigned band of operation and not within the band.
      5. (v) The emission mask for the 71-76 GHz, 81-86 GHz, 92-94 GHz, and 94.1-95 GHz bands used in the equation in paragraph (a)(2)(ii) of this section applies only to the edge of each channel, but not to sub-channels established by licensees. The value of P in the equation is for the percentage removed from the carrier frequency and assumes that the carrier frequency is the center of the actual bandwidth used. The value of B will always be 500 MHz. In the case where a narrower sub-channel is used within the assigned bandwidth, such sub-carrier will be located sufficiently far from the channel edges to satisfy the emission levels of the mask. The mean output power used in the calculation is the sum of the output power of a fully populated channel.

      6. (vi)

         1. (A) In order to protect Federal Earth Exploration-Satellite Service (passive), aeronautical and maritime endpoints in motion operating in the 70 and 80 GHz bands must comply with the following limits:

            (1) Ground-to-air transmissions shall not exceed an unwanted emission level of -38.5 dBW per 100 MHz in any portion of the 86-92 GHz passive band;

            (2) Air-to-air, ship-to-shore, and aerostat-to-shore transmissions shall not exceed an unwanted emission level of −29.7 dBW per 100 MHz in any portion of the 86-92 GHz passive band.

         2. (B) Any changes to system specifications, operations, or deployment scenarios for aeronautical or maritime end points in motion shall be pre-coordinated with NTIA and affected Federal agencies, and licensees of aeronautical or maritime end points in motion must cooperate fully with any updates to the required unwanted emission limits that may result from these modifications.

   3. (3) For Digital Termination System channels used in the Digital Electronic Message Service (DEMS) operating in the 10,550-10,680 MHz band:

      1. (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.

      2. (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

      3. (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. (4) For DEMS channels in the 17,700-19,700 MHz band:

      1. (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.

      2. (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

      3. (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. (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:

      1. (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;
      2. (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;
      3. (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
      4. (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. (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:

      1. (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;
      2. (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
      3. (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 decibels, whichever is the lesser attenuation.
2. (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.
3. (c) The emission of an unmodulated carrier is prohibited except for test purposes as required for proper station and system maintenance.

4. (d) Interference to passive sensors. These limitations are necessary to minimize the probability of harmful interference to reception in the 10.6-10.68 GHz and 31-31.3 GHz bands onboard space stations in the Earth exploration-satellite service (passive).

   1. (1) 10.6-10.68 GHz.

      1. (i) Fixed stations are restricted to point-to-point operations, with each station supplying not more than −3 dBW of transmitter power to the antenna, producing not more than 40 dBW of EIRP, and radiating at an antenna main beam elevation angle of 20° or less. Licensees holding a valid authorization on August 6, 2015 to operate in this band may continue to operate as authorized, subject to proper license renewal. Licensees are urged to:

         1. (A) Limit the maximum transmitter power supplied to the antenna to −15 dBW; and
         2. (B) Employ automatic transmitter power control (ATPC).
      2. (ii) The maximum transmitter power supplied to the antenna of stations using ATPC may be increased by a value corresponding to the ATPC range, up to a maximum of −3 dBW.
   2. (2) 31-31.3 GHz. For fixed stations authorized after August 6, 2018, the unwanted emissions power in any 100 MHz of the 31.3-31.5 GHz band shall be limited to −38 dBW (−38 dBW/100 MHz), as measured at the input to the antenna.

Note: MVDDS operations in the 12.2-12.7 GHz band shall use 24 megahertz for the value of B in the emission mask equation set forth in this section. The emission mask limitation shall only apply at the 12.2-12.7 GHz band edges and does not restrict MVDDS channelization bandwidth within the band.

[61 FR 26677, May 28, 1996, as amended at 62 FR 24582, May 6, 1997; 65 FR 59358, Oct. 5, 2000; 67 FR 43038, June 26, 2002; 68 FR 4957, Jan. 31, 2003; 69 FR 3266, Jan. 23, 2004; 69 FR 31746, June 7, 2004; 80 FR 38912, July 7, 2015; 89 FR 33259, Apr. 29, 2024]