Sec.  73.701   Definitions.

   The following definitions apply to terminology employed in this subpart:

   (a) International broadcast stations. A broadcasting station employing
   frequencies allocated to the broadcasting service between 5900 and 26100
   kHz, the transmissions of which are intended to be received directly by the
   general public in foreign countries. (A station may be authorized more than
   one transmitter.) There are both Federal and non-Federal Government
   international broadcast stations; only the latter are licensed by the
   Commission and are subject to the rules of this subpart.

   (b) Transmitter-hour. One frequency used on one transmitter for one hour.

   (c) Frequency-hour. One frequency used for one hour regardless of the number
   of transmitters over which it is simultaneously broadcast by a station
   during that hour.

   (d) Multiple operation. Broadcasting by a station on one frequency over two
   or more transmitters simultaneously. If a station uses the same frequency
   simultaneously on each of two (three, etc.) transmitters for an hour, it
   uses one frequency-hour and two (three, etc.) transmitter-hours.

   (e) Coordinated Universal Time (UTC). Time scale, based on the second (SI),
   as defined in Recommendation ITU–R TF.460–6. For most practical purposes
   associated with the ITU Radio Regulations, UTC is equivalent to mean solar
   time at the prime meridian (0 ° longitude), formerly expressed in GMT. (RR)

   (f) Sunspot number. The 12–month running average of the number of sunspots
   for any month as indicated in the U.S. Department of Commerce
   Telecommunications Research and Engineering Report No. 13—available from the
   Superintendent of Documents, Washington, DC 20402. The sunspot number varies
   in an approximate 11–year cycle.

   (g) Day. Any twenty-four hour period beginning 0100 UTC and ending 0100 UTC.

   (h) Schedule A. That portion of any year commencing at 0100 UTC on the last
   Sunday in March and ending at 0100 UTC on the last Sunday in October.

   (i) Schedule B. That portion of any year commencing at 0100 UTC on the last
   Sunday in October and ending at 0100 UTC on the last Sunday in March.

   (j) [Reserved]

   (k) Seasonal schedule. An assignment, for a season, of a frequency or
   frequencies, and other technical parameters, to be used by a station for
   transmission to particular zones or areas of reception during specified
   hours.

   (l) Reference month. That month of a season which is used for determining
   predicted propagation characteristics for the season. The reference month
   for Schedule A is July and the reference month for Schedule B is December.

   (m) Maximum usable frequency (MUF). The highest frequency which is returned
   by ionospheric radio propagation to the surface of the earth for a
   particular path and time of day for 50 percent of the days of the reference
   month.

   (n) Optimum working frequency (FOT). The highest frequency which is returned
   by ionospheric radio propagation to the surface of the earth for a
   particular path and time of day for 90 percent of the days of the reference
   month.

   Note: The international abbreviation for optimum working frequency, FOT, is
   formed with the initial letters of the French words for “optimum working
   frequency” which are “frequence optimum de travail.”

   (o) Zone of reception. Any geographic zone indicated in  Sec. 73.703 in which the
   reception of particular programs is specifically intended and in which
   broadcast coverage is contemplated.

   (p) Area of reception. Any geographic area smaller than a zone of reception
   in which the reception of particular programs is specifically intended and
   in which broadcast coverage is contemplated, such areas being indicated by
   countries or parts of countries.

   (q) Delivered median field strength, or field strength. The field strength
   incident upon the zone or area of reception expressed in microvolts per
   meter, or decibels above one microvolt per meter, which is exceeded by the
   hourly median value for 50 percent of the days of the reference month.

   (r) Carrier power. The average power supplied to the antenna transmission
   line by a transmitter during one radio frequency cycle under conditions of
   no modulation.

   [ 38 FR 18892 , July 16, 1973, as amended at  68 FR 25538 , May 13, 2003;  70 FR 46676 , Aug. 10, 2005]