[Code of Federal Regulations]

[Title 47, Volume 2]

[Revised as of October 1, 2004]

From the U.S. Government Printing Office via GPO Access

[CITE: 47CFR21.106]



[Page 52]

 

                       TITLE 47--TELECOMMUNICATION

 

                    CHAPTER I--FEDERAL COMMUNICATIONS

                         COMMISSION (CONTINUED)

 

PART 21_DOMESTIC PUBLIC FIXED RADIO SERVICES--Table of Contents

 

                      Subpart C_Technical Standards

 

Sec. 21.106  Emission limitations.



    (a) The mean power of emissions shall 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 Log\10\ 

(mean output power in watts) decibels, or 80 decibels, whichever is the 

lesser attenuation.

    (2) When using transmissions employing digital modulation techniques 

(see Sec. 21.122(b)) in situations other than those covered by subpart 

K of this part:

    (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;minus;50)+10 Log\10\ 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) 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 Log\10\ (mean output power in watts) decibels, 

or 80 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.



[44 FR 60534, Oct. 19, 1979, as amended at 46 FR 23450, Apr. 27, 1981; 

52 FR 23550, June 23, 1987; 61 FR 26675, May 28, 1996; 65 FR 46617, July 

31, 2000]