from sensitive instrument circuits is re- 

 quired to isolate electromagnetic fields. 

 Sources of radiated interference include 

 transformers, inductors and cables operating 

 at frequencies from zero to the radio commu- 

 nication spectrum. Other sources are invert- 

 ers, converters (DC to DC), and fluorescent 

 lighting. Protection includes encasing low 

 level cables in solid drawn steel conduits, as 

 well as conventional shielding. An example 

 of one source of coupled intereference is 

 shown in Figure 7.42 wherein the close prox- 

 imity of cables seems to make such interfer- 

 ence inevitable. Further problems with such 

 a layout is that of identifying various cables 

 and protecting them from physical destruc- 

 tion. 



b) Line Effects: 



These encompass unexpected tuning ef- 

 fects of cables and associated equipment 

 which cannot be completely anticipated in 

 the design stage and arise during installa- 

 tion and the effects of grounding upon inter- 

 ference suppression. Haigh separates these 

 into feedback and ground loops and suggests 

 various remedies, e.g., filters and grounding, 

 to ameliorate their effects. 



c) Electrostatic Interference: 

 Electrostatic interference arises chiefly 



from the movement of cables or machinery 

 rubbing against cable sheaths. Should the 

 submersible be concerned with towing a low 

 level sensor, or derive its power from a sur- 

 face umbilical, then the action of the cable 



Fig 7 42 ALUMINAUTs internal |unction boxes (NAVOCEANIO) 



365 



