§  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 § 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]