§  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.

   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.

   ^10Except for DSRCS equipment in the 5850–5925 MHz band, frequency
   stability is to be specified in the station authorization. Frequency
   stability for DSRCS equipment in the 5850–5925 MHz band is specified in
   subpart M of this part.

   ^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]