THE N-1 CARRIER SYSTEM 



11 



in passing through the N repeater. Thus, the highest frequency channel in 

 one line section becomes the lowest frequency channel in the succeeding 

 line section. So nearly constant are the sums of the losses in two line sections 

 for all channels for the frequency range chosen, that equalization is provided 

 without resort to any major slope correction in the repeaters. The small 

 amount of slope and bulge remaining are easily taken care of in the repeater 

 through use of a few shaping elements in the feedback circuit. 



TYPE K 



E-W 



CABLE A 



— {> 



HIGH GROUP 



7H> 



fHD>T 



LOW GROUP 



W-E 



i^-- 



^^-- 



— <^ 

 — ^ 



LOW GROUP 



8 MILES 



TYPE N 



HIGH GROUP 



E-W 



SMILES 



-•1 



Fig. 4— Cable frogging and frequency frogging. 



In Fig. 5(a) the sum of the line losses is shown for two successive 7.5 

 mile cable sections. The residual slope of only 3.7 db is in contrast to about 

 34 db of slope in two successive low-group sections in an unfrogged system. 

 The flat line loss of about 90 db is accompanied by only about 0.4 db of 

 bulge. Also shown in Fig. 5(a) is the summation of LH and HL repeater 

 gains. The difference in slope between line and repeater amounts to about 

 1.5 db and is taken care of by a small range slope control in the repeater. 



The remaining difference between line and repeater is nearly flat with 

 frequency and is compensated for either through use of flat pads in the line 

 (span pads) or through use of the repeater flat gain regulators. At about 

 each tenth repeater enough frequency distortion has accumulated through 

 lack of match between repeater and line to require use of a deviation equal- 



