SAFETY OF LIFE AT SEA ^133 



Minimum normal range in miles 



Main , Reserve 



transmitter transmitter 



All passenger ships, and cargo ships of 1,600 ! j 



tons gross tonnage and upwards ... ! 150 I 100 



Cargo ships below 1 ,600 tons gross tonnage ... I 1 00 I 75 



\ I 



(h) (i) The main and reserve receivers shall be capable of receiving the 

 radiotelegraph distress frequency and the class of emission assigned by the 

 Radio Regulations for that frequency. 



(ii) In addition, the main receiver shall permit the reception of such 

 of the frequencies and classes of emission used for the transmission of time 

 signals, meteorological messages and such other communications relating to 

 safety of navigation as may be considered necessary by the Administration. 



(iii) For a period not exceeding five years from the date of coming 

 into force of the present Convention, the radiotelegraph auto alarm receiver 

 may be used as the reserve receiver if capable of effectively producing signals 

 in headphones or a loud-speaker with which it is connected for this purpose. 

 When so used, it shall be connected to the reserve source of energy. 



(/) The main receiver shall have sufficient sensitivity to produce signals in 

 headphones or by means of a loud-speaker when the receiver input is as low 

 as 50 microvolts. The reserve receiver shall, except in cases where a radio- 

 telegraph auto alarm receiver is used for this purpose, have sufficient sensitivity 

 to produce such signals when the receiver input is as low as 100 microvolts. 



0) There shall be available at all times, while the ship is at sea, a supply 

 of electrical energy sufficient to operate the main installation over the normal 

 range required by paragraph {g) of this Regulation as well as for the purpose 

 of charging any batteries forming part of the radiotelegraph station. The 

 voltage of the supply for the main installation shall, in the case of new ships, 

 be maintained within ±10 per cent, of the rated voltage. In the case of 



The values given in the second column of the table correspond to an average value of 

 the ratio 



effective aerial height _ 

 maximum aerial neighi 

 This ratio varies with local conditions of the aerial and may vary between about 0-3 

 and 0-7 



I The values given in the third column of the table correspond to an average value of 

 the ratio 



radiated aerial power _ .. 



— r .— i = U • UO 



total aerial power 

 This ratio varies considerably according to the values of effective aerial height and aerial 

 resistance. 



Ch. 4 



