FLEXIBLE REPEATER DESIGN 



99 



and output impedances match the cable. As in regular repeaters a crys- 

 tal and gas tube are provided for maintenance testing. The crystals give 

 approximately 25 db increase in gain and are placed between 173.5 and 

 174.1 kc so as not to duplicate any frequencies used in the line repeaters. 

 The crystal frequency spacing is 100 cycles. 



Wherever possible the same components and mechanical details are 

 used in the repair repeaters as in the line repeaters. When changes in 

 design were necessary, these were modifications in the existing designs 

 rather than new types. Capacitors are like those of line repeaters. Ex- 

 cept for the length of the container, the enclosure is identical to the line 

 repeater. 



Noise and overload considerations restrict the location of a repair 

 repeater to the middle third of a repeater section. 



UNDERSEA EQUALIZERS 



Even though the insertion gain of the line repeater matches the nor- 

 mal loss characteristic of the cable rather closely, uncertainties in the 

 knowledge of the attenuation of the laid cable can lead to misalignment 

 which, if uncorrected, would seriously affect the performance of the 

 system. Misalignment which has cable loss shape can be corrected by 

 shortening or lengthening the cable between repeaters at intervals as the 

 cable is laid. Other shapes, however, require the addition of networks or 

 equalizers in the line. 



With these factors in mind a series of undersea equalizers were de- 

 signed. The loss shapes were chosen on the basis of a power series analy- 

 sis of expected misalignments. The designs were restricted to series im- 



p- -^ 



^V\A/ 1 



^^wr- 



(a) 



^/vV 





4'- -^ 



(b) 



Fig, 22 — (a) Schematic of Type IV equalizer, (b) Schematic of Tj-pe V equalizer 



