Sec.  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  Sec.  Sec. 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]