§  90.213   Frequency stability.

   (a) Unless noted elsewhere, transmitters used in the services governed
   by this part must have a minimum frequency stability as specified in
   the following table.

   Table 1 to § 90.213(a)—Minimum Frequency Stability

   [Parts per million (ppm)]
   Frequency range (MHz) Fixed and base stations Mobile stations
   Over 2 watts output power 2 watts or less output power
   Below 25 ^1 2 3100 100 200
   25-50 20 20 50
   72-76 5 50
   150-174 ^5 115 ^65 ^4 650
   216-220 1.0 1.0
   220-222^12 0.1 1.5 1.5
   421-512 ^7 11 142.5 ^85 ^85
   806-809 ^141.0 1.5 1.5
   809-824 ^141.5 2.5 2.5
   851-854 1.0 1.5 1.5
   854-869 1.5 2.5 2.5
   896-901 ^140.1 1.5 1.5
   902-928 2.5 2.5 2.5
   902-928^13 2.5 2.5 2.5
   929-930 1.5
   935-940 0.1 1.5 1.5
   1427-1435 ^9300 300 300
   Above 2450^10

   ^1Fixed and base stations with over 200 watts transmitter power must
   have a frequency stability of 50 ppm except for equipment used in the
   Public Safety Pool where the frequency stability is 100 ppm.

   ^2For single sideband operations below 25 MHz, the carrier frequency
   must be maintained within 50 Hz of the authorized carrier frequency.

   ^3Travelers information station transmitters operating from 530-1700
   kHz and transmitters exceeding 200 watts peak envelope power used for
   disaster communications and long distance circuit operations pursuant
   to § § 90.242 and 90.264 must maintain the carrier frequency to within 20
   Hz of the authorized frequency.

   ^4Stations operating in the 154.45 to 154.49 MHz or the 173.2 to 173.4
   MHz bands must have a frequency stability of 5 ppm.

   ^5In the 150-174 MHz band, fixed and base stations with a 12.5 kHz
   channel bandwidth must have a frequency stability of 2.5 ppm. Fixed and
   base stations with a 6.25 kHz channel bandwidth must have a frequency
   stability of 1.0 ppm.

   ^6In the 150-174 MHz band, mobile stations designed to operate with a
   12.5 kHz channel bandwidth or designed to operate on a frequency
   specifically designated for itinerant use or designed for low-power
   operation of two watts or less, must have a frequency stability of 5.0
   ppm. Mobile stations designed to operate with a 6.25 kHz channel
   bandwidth must have a frequency stability of 2.0 ppm.

   ^7In the 421-512 MHz band, fixed and base stations with a 12.5 kHz
   channel bandwidth must have a frequency stability of 1.5 ppm. Fixed and
   base stations with a 6.25 kHz channel bandwidth must have a frequency
   stability of 0.5 ppm.

   ^8In the 421-512 MHz band, mobile stations designed to operate with a
   12.5 kHz channel bandwidth must have a frequency stability of 2.5 ppm.
   Mobile stations designed to operate with a 6.25 kHz channel bandwidth
   must have a frequency stability of 1.0 ppm.

   ^9Fixed stations with output powers above 120 watts and necessary
   bandwidth less than 3 kHz must operate with a frequency stability of
   100 ppm. Fixed stations with output powers less than 120 watts and
   using time-division multiplex, must operate with a frequency stability
   of 500 ppm.

   ^10Frequency stability for DSRCS equipment in the 5895-5925 MHz band is
   specified in subpart M of this part. For all other equipment, frequency
   stability is to be specified in the station authorization.

   ^11Paging transmitters operating on paging-only frequencies must
   operate with frequency stability of 5 ppm in the 150-174 MHz band and
   2.5 ppm in the 421-512 MHz band.

   ^12Mobile units may utilize synchronizing signals from associated base
   stations to achieve the specified carrier stability.

   ^13Fixed non-multilateration transmitters with an authorized bandwidth
   that is more than 40 kHz from the band edge, intermittently operated
   hand-held readers, and mobile transponders are not subject to frequency
   tolerance restrictions.

   ^14Control stations may operate with the frequency tolerance specified
   for associated mobile frequencies.

   (b) For the purpose of determining the frequency stability limits, the
   power of a transmitter is considered to be the maximum rated output
   power as specified by the manufacturer.

   [ 60 FR 37266 , July 19, 1995, as amended at  61 FR 4235 , Feb. 5, 1996;  61 FR 18986 , Apr. 30, 1996;  61 FR 38403 , July 24, 1996;  62 FR 2040 , Jan.
   15, 1997;  62 FR 18927 , Apr. 17, 1997;  67 FR 41860 , June 20, 2002;  69 FR 46443 , Aug. 3, 2004;  69 FR 67838 , Nov. 22, 2004;  85 FR 43139 , July 15,
   2020;  86 FR 23297 , May 3, 2021]

   Editorial Note: At  85 FR 43139 , July 16, 2020, § 90.613 was amended in
   the table by adding entries in numerical order for “896-901” and
   “935-940”, however due to an inaccurate amendatory instruction, this
   amendment could not be incorporated.