§ 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.

   return arrow Back to Top