§ 80.317   Radiotelegraph and radiotelephone alarm signals.

   (a) The international radiotelegraph alarm signal consists of a series
   of twelve dashes sent in one minute, the duration of each dash being
   four seconds and the duration of the interval between consecutive
   dashes one second. The purpose of this special signal is the actuation
   of automatic devices giving the alarm to attract the attention of the
   operator when there is no listening watch on the distress frequency.

   (b) The international radiotelephone alarm signal consists of two
   substantially sinusoidal audio frequency tones transmitted alternately.
   One tone must have a frequency of 2200 Hertz and the other a frequency
   of 1300 Hertz, the duration of each tone being 250 milliseconds. When
   generated by automatic means, the radiotelephone alarm signal must be
   transmitted continuously for a period of at least 30 seconds, but not
   exceeding one minute; when generated by other means, the signal must be
   transmitted as continuously as practicable over a period of
   approximately one minute. The purpose of this special signal is to
   attract the attention of the person on watch or to actuate automatic
   devices giving the alarm.

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