47 CFR §80.221

1. (a)Each device for automatically generating the radiotelephone alarm signal must be capable of being disabled to permit the immediate transmission of a distress call and message.
2. (b)The device must comply with the following requirements:
   1. (1)The frequency tolerance of each tone must be ±1.5 percent;
   2. (2)The duration tolerance of each tone must be ±50 milliseconds;
   3. (3)The interval between successive tones must not exceed 50 milliseconds; and
   4. (4)The amplitude ratio of the tones must be flat within 1.6 dB.
3. (c)Devices installed on or after January 1, 1983, must comply with the following requirements:
   1. (1)The frequency tolerance of each tone must be ±1.5 percent;
   2. (2)The duration tolerance of each tone must be ±10 milliseconds;
   3. (3)The interval between successive tones must not exceed 4 milliseconds;
   4. (4)The amplitude ratio of the tones must be flat within 1.6 dB;
   5. (5)The output of the device must be sufficient to modulate the associated transmitter for H2B emission to at least 70 percent, and for J2B emission to within 3 dB of the rated peak envelope power;
   6. (6)Light from the device must not interfere with the safe navigation of the ship;
   7. (7)After activation the device must automatically generate the radiotelephone alarm signal for not less than 30 seconds and not more than 60 seconds unless manually interrupted;
   8. (8)After generating the radiotelephone alarm signal or after manual interruption the device must be immediately ready to repeat the signal;
   9. (9)The transmitter must be automatically switched from the stand-by condition to the transmit condition at the start and return to the stand-by condition at the conclusion of the radiotelephone alarm signal.
4. (d)Any device used by a station to automatically generate the radiotelephone alarm signal must be certificated by the Commission.