Sec. 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.