DESIGN OF SYSTEM — NORTH ATLANTIC LINK 



49 



Cable Length Equalizer — In planning the system, an estimate was 

 made of how far the last repeater (receiving end) would be from the 

 shore. Considerations of interference and level dictated a maximum dis- 

 tance not exceeding approximately 32 miles. For protection against wave 

 action, trawlers and similar hazards, the repeater should be no closer 

 than about five miles. To take care of this variation, a cable length equal- 

 izer was designed that is capable of simulating the loss of 10 miles of 

 cable, adjustable in 0.5 db steps at the top of the frequency band. Two 

 of these could be used if needed. Once the system is laid, this equalizer 

 should require no further adjustment unless it is used to take care of 

 cable aging or a cable repair near shore. 



Receiving Fixed Equalizer — This is the mop-up equalizer for the sys- 

 tem. A final receiving equalizer, Fig. 9, has been constructed for the first 

 crossing. Another, tailored to the No. 2 cable, will be designed on the 

 basis of data taken after completion. 



RECEIVING 



FIXED 

 EQUALIZER 



RECEIVING 



AMPLIFIER 



NO. 2 



Fig. 8 — Receiving equalizers — block schematic. 



Receiving Temperature Equalizer — The receiving temperature equal- 

 izer is identical with the transmitting temperature unit. 



OPERATIONAL DESIGN 



General 



The operational design of a transmission system considers the supple- 

 mentary facilities which are needed for operation of the main transmis- 

 sion facility, for its supervision and for its maintenance. In the present 

 instance, these facilities include the cable station power plants for driving 

 the carrier terminals and high frequency line, the carrier terminals them- 

 selves and their associated carrier supply bays, the telephone and tele- 

 graph (speaker and printer) equipments needed for maintenance, super- 

 vision and administration of the overall facility, the pilots, protection 

 devices and alarms and the maintenance and fault locating equipment. 



Power Supplies 



With the exception of the plants for cable current supply, the power 

 plants at Clarenville and Oban are relatively conventional, and follow 

 telephone office techniques which are standard for the telephone adminis- 



