Sec.  22.359   Emission masks.

   

   Link to an amendment published at  70 FR 19308 , Apr. 13, 2005.

   Unless otherwise indicated in the rules governing a specific radio
   service, all transmitters intended for use in the Public Mobile
   Services must be designed to comply with the emission masks outlined
   in this section. If an emission outside of the authorized bandwidth
   causes harmful interference, the FCC may, at its discretion, require
   greater attenuation than specified in this section.

   (a) Analog modulation. For transmitters other than those employing
   digital modulation techniques, the mean or peak envelope power of
   adjacent channel emissions must be attenuated below the output mean or
   peak envelope power of the total emission (P, in Watts) in accordance
   with the following schedule:

   (1) On any frequency removed from the center frequency of the assigned
   channel by more than 50 percent up to and including 100 percent of the
   authorized bandwidth:

   at least 25 dB:

   (2) On any frequency removed from the center frequency of the assigned
   channel by more than 100 percent up to and including 250 percent of
   the authorized bandwidth:

   at least 35 dB:

   (3) On any frequency removed from the center frequency of the assigned
   channel by more than 250 percent of the authorized bandwidth:

   at least 43 + 10 log P dB, or 80 dB, whichever is the lesser
   attenuation.

   (b) Digital modulation. For transmitters not equipped with an audio
   low pass filter and for transmitters employing digital modulation
   techniques, the mean or peak envelope power of sideband emissions must
   be attenuated below the mean or peak envelope power of the total
   emission (P, in Watts) in accordance with the following schedule:

   (1) For transmitters that operate in the frequency ranges 35 to 44
   MHz, 72 to 73 MHz, 75.4 to 76.0 MHz and 152 to 159 MHz,

   (i) On any frequency removed from the center frequency of the assigned
   channel by a displacement frequency f[d] (in kHz) of more than 5 kHz
   but not more than 10 kHz:

   at least 83 log (f[d]÷5) dB;

   (ii) On any frequency removed from the center frequency of the
   assigned channel by a displacement frequency f[d] (in kHz) of more
   than 10 kHz but not more than 250 percent of the authorized bandwidth:

   at least 29 log f[d]2÷11) dB or 50 dB, whichever is the lesser
   attenuation;

   (iii) On any frequency removed from the center frequency of the
   assigned channel by more than 250 percent of the authorized bandwidth:

   at least 43 + 10 log P dB, or 80 dB, whichever is the lesser
   attenuation.

   (2) For transmitters that operate in the frequency ranges 450 to 512
   MHz and 929 to 932 MHz,

   (i) On any frequency removed from the center frequency of the assigned
   channel by a displacement frequency f[d] (in kHz) of more than 5 kHz
   but not more than 10 kHz:

   at least 83 log (f[d]÷5) dB;

   (ii) On any frequency removed from the center frequency of the
   assigned channel by a displacement frequency f[d] (in kHz) of more
   than 10 kHz but not more than 250 percent of the authorized bandwidth:

   at least 116 log (f[d]÷6.1) dB, or 50 + 10 log P dB, or 70 dB,
   whichever is the lesser attenuation;

   (iii) On any frequency removed from the center frequency of the
   assigned channel by more than 250 percent of the authorized bandwidth:

   at least 43 + 10 log P dB, or 80 dB, whichever is the lesser
   attenuation.

   (c) Measurement procedure. Either peak or average power may be used,
   provided that the same technique is used for both the adjacent channel
   or sideband emissions and the total emission. The resolution bandwidth
   of the measuring instrument must be set to 300 Hz for measurements on
   any frequency removed from the center frequency of the assigned
   channel by no more than 250 percent of the authorized bandwidth and 30
   kHz for measurements on any frequency removed from the center
   frequency of the assigned channel by more than 250 percent of the
   authorized bandwidth.