Sec. 101.107  Frequency tolerance.

    (a) The carrier frequency of each transmitter authorized in these 
services must be maintained within the following percentage of the 
reference frequency except as otherwise provided in paragraph (b) of 
this section or in the applicable subpart of this part (unless otherwise 
specified in the instrument of station authorization the reference 
frequency will be deemed to be the assigned frequency):

------------------------------------------------------------------------
                                         Frequency Tolerance (percent)  
                                     -----------------------------------
                                                    Mobile      Mobile  
           Frequency (MHz)             All fixed   stations   stations 3
                                       and base     over 3     watts or 
                                       stations      watts       less   
------------------------------------------------------------------------
928 to 929 2, 5.....................     0.0005   ..........  ..........
932 to 932.5 \2\....................     0.00015  ..........  ..........
932.5 to 935 \2\....................     0.00025  ..........  ..........
941 to 941.5........................     0.00015  ..........  ..........
941.5 to 944........................     0.00025  ..........  ..........
952 to 960 \7\......................  ..........  ..........  ..........
944.0 to 1,000......................     0.0005       0.0005      0.0005
1,850 to 1,990......................     0.002    ..........  ..........
2,110 to 2,200......................     0.001    ..........  ..........
2,200 to 12,200 1, 3................     0.005        0.005       0.005 
2,450 to 2,500......................     0.001    ..........  ..........
3,700 to 4,200......................     0.005    ..........  ..........
5,925 to 6,875......................     0.005    ..........  ..........
10,550 to 11,700....................     0.005    ..........  ..........
12,200 to 13,250 \6\................     0.005    ..........  ..........
12,200 to 17,700....................     0.03         0.03        0.03  
17,700 to 18,820 4, 5...............     0.003    ..........  ..........
18,820 to 18,920 4, 5...............     0.001    ..........  ..........
18,920 to 19,700 4, 5...............     0.003    ..........  ..........
19,700 to 27,500 \6\................     0.03     ..........  ..........
27,500 to 28,350....................     0.001    ..........  ..........

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29,100 to 29,250....................     0.001    ..........  ..........
31,000 to 31,075 \8\................     0.001    ..........  ..........
31,075 to 31,225 \8\................     0.001    ..........  ..........
31,225 to 31,300 \8\................     0.001    ..........  ..........
31,300 to 40,000 \6\................     0.03     ..........  ..........
------------------------------------------------------------------------
\1\ Applicable only to common carrier LTTS stations. Beginning Aug. 9,  
  1975, this tolerance will govern the marketing of LTTS equipment and  
  the issuance of all such authorizations for new radio equipment. Until
  that date new equipment may be authorized with a frequency tolerance  
  of .03 percent in the frequency range 2,200 to 10,500 MHz and .05     
  percent in the range 10,500 MHz to 12,200 MHz, and equipment so       
  authorized may continue to be used for its life provided that it does 
  not cause interference to the operation of any other licensee.        
\2\ Equipment authorized to be operated on frequencies between 890 and  
  940 MHz as of Oct. 15, 1956, must maintain a frequency tolerance      
  within 0.03 percent subject to the condition that no harmful          
  interference is caused to any other radio station.                    
\3\ See subpart G of this part for the stability requirements for       
  transmitters used in the Digital Electronic Message Service.          
\4\ Existing type accepted equipment with a frequency tolerance of 0.03% may be marketed until December 1, 1988. Equipment         
  installed and operated prior to December 1, 1988 may continue to      
  operate after that date with a minimum frequency tolerance of 0.03%. However, the replacement of equipment requires that the  
  &177;0.003% tolerance be met.                                  
\5\ For remote stations with 12.5 KHz bandwidth, the tolerance is 0.00015%.                                                       
\6\ Applicable to private operational fixed point-to-point microwave    
  only. For exceptions see Sec.  101.147.                               
\7\ For private operational fixed point-to-point microwave systems, with
  a channel greater than or equal to 50 KHz bandwidth, 0.0005%; for multiple address master stations, regardless of    
  bandwidth, &177;0.00015%; for multiple address remote stations 
  with 12.5 KHz bandwidths, &177;0.00015%; for multiple address  
  remote stations with channels greater than 12.5 KHz bandwidth, 0.0005%.                                                        
\8\ For stations authorized prior to March 11, 1997, transmitter        
  frequency tolerance shall not exceed 0.03 percent.                    

    (b) Heterodyne microwave radio systems may be authorized at a 
somewhat less restrictive frequency tolerance (up to .01 percent) to 
compensate for frequency shift caused by numerous repeaters between base 
band signal insertion. Where such relaxation is sought, applicant must 
provide all calculations and indicate the desired tolerance over each 
path. In such instances the radio transmitters and receivers used must 
individually be capable of complying with the tolerance specified in 
paragraph (a) of this section. Heterodyne operation is restricted to 
channel bandwidth of 10 MHz or greater.
    (c) As an additional requirement in any band where the Commission 
makes assignments according to a specified channel plan, provisions must 
be made to prevent the emission included within the occupied bandwidth 
from radiating outside the assigned channel at a level greater than that 
specified in Sec. 101.111.
[61 1997 FR 26677 , May 28, 1996, as amended at  62 FR 23167 , Apr. 29, 1997]