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)]
------------------------------------------------------------------------
                                                        Mobile stations
                                                     -------------------
                                          Fixed and    Over 2    2 watts
         Frequency range (MHz)              base        watts    or less
                                          stations     output    output
                                                        power     power
------------------------------------------------------------------------
Below 25..............................  \1,2,3\ 100      100       200
25-50                                           20        20        50
72-76.................................           5    ........      50
150-174...............................    \5,11\ 5     \6\ 5    \4,6\ 50
216-220...............................           1.0  ........       1.0
220-222 \12\..........................           0.1       1.5       1.5
421-512...............................   \7,11,14\     \8\ 5     \8\ 5
                                                 2.5
806-809...............................      \14\ 1.0       1.5       1.5
809-824...............................      \14\ 1.5       2.5       2.5
851-854...............................           1.0       1.5       1.5
854-869...............................           1.5       2.5       2.5
896-901...............................      \14\ 0.1       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.............................     \9\ 300       300       300
Above 2450 \10\.......................  ............  ........  ........
------------------------------------------------------------------------
\1\ Fixed 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.
\2\ For single sideband operations below 25 MHz, the carrier frequency
  must be maintained within 50 Hz of the authorized carrier frequency.
\3\ Travelers 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.
\4\ Stations 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.
\5\ In 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.
\6\ In 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.
\7\ In 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.
\8\ In 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.
\9\ Fixed 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.
\10\ Except 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.
\11\ Paging 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.
\12\ Mobile units may utilize synchronizing signals from associated base
  stations to achieve the specified carrier stability.
\13\ Fixed 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.
\14\ Control 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]