CABLE DESIGN AND MANUFACTURE 



213 



40 60 80 100 120 140 



FREQUENCY IN KILOCYCLES PER SECOND 



180 



Fig. 12 — Design characteristic of cable attentuation as a function of fre- 

 quency for 37°F and atmospheric pressure. 



teristic and the changes in attenuation owing to temperature were de- 

 rived from factory measurements of attenuation made on the Florida- 

 Puerto Rico cable. 



By comparing the running average and spread of these deviations with 

 the design requirements, it was possible to assess the performance of the 

 cable and, if required, to make any necessary adjustments in parameters 

 for subsequent sections. In addition, these deviations were used to 

 determine the length adjustment required for each repeater section to 

 keep the sum of the deviations at each frequency in any one ocean block 

 to a minimum. Typical average attenuation deviation characteristics 

 are shown in Fig. 13. 



TEMPERATURE AND PRESSURE COEFFICIENTS 



Measurements of primary constants were made on 20-foot lengths of 

 cable and core placed in a temperature and pressure controlled tank. 

 These measurements were used to compute the temperature coefficients 

 of attenuation in order to check the values derived from measurements 

 made on the Florida-Puerto Rico cable section. Additional attenuation 

 measiu'ements were made on several repeater section lengths of cable 

 over a range of temperature from approximately 40° to 70°F, to estab- 

 lish further the magnitude of the changes in attenuation with tempera- 



