SAFETY OF LIFE AT SEA C137 



which a radiotelegraph alarm signal of the minimum strength 

 indicated in (i) is produced. A means shall also be provided for 

 attaching headphones for the purpose of listening to signals 

 received on the radiotelegraph auto alarm. 



(viii) The radiotelegraph auto alarm shall be capable of withstanding 

 vibration, humidity and changes of temperature, equivalent to 

 ^ severe conditions experienced on board ships at sea, and shall 



^ continue to operate under such conditions. 



{b) Before a new type of radiotelegraph auto alarm is approved, the 

 Administration concerned shall be satisfied, by practical tests made under 

 operating conditions equivalent to those obtaining in practice, that the 

 apparatus complies with paragraph (a) of this Regulation. 



(c) In ships fitted with a radiotelegraph auto alarm, its efl&ciency shall be 

 tested by a radio ofl&cer at least once every 24 hours while at sea. If it is 

 not in working order, the radio officer shall report that fact to the master 

 or officer on watch on the bridge. 



(d) A radio officer shall periodically check the proper functioning of the 

 radiotelegraph auto alarm receiver, with its normal aerial connected, by 

 listening to signals and by comparing them with similar signals received 

 on the radiotelegraph distress frequency on the main installation. 



(e) As far as practicable, the radiotelegraph auto alarm, when connected 

 to an aerial, shall not affect the accuracy of the direction-finder. 



(/) Radiotelegraph auto alarms which do not comply with the require- 

 ments of paragraph (a) of this Regulation shall be replaced by radiotelegraph 

 auto alarms which do so comply within four years from the date of coming 

 into force of the present Convention. 



Regulation 11 



Direction-finders 



(a) The direction-finding apparatus required by Regulation 12 of 

 Chapter V shall be efficient and capable of receiving signals with the 

 minimum of receiver noise and of taking bearings from which the true 

 bearing and direction may be determined. 



(b) It shall be capable of receiving signals on the radiotelegraph 

 frequencies assigned by the Radio Regulations for the purposes of distress 

 and direction-finding and for maritime radio beacons. 



(c) In the absence of interference the direction-finding apparatus shall 

 have a sensitivity sufficient to permit accurate bearings being taken on a 

 signal having a field strength as low as 50 microvolts per metre. 



Ch. 4 



