THE TORONTO-BARRIE TOLL CABLE 589 



with H88-50 loading with open wire or cable feeders, depending on the 

 length and numbers of feeder circuits, indicated the cable plan to be 

 best. In addition to the indicated money savings of the cable plan 

 over the period of the cost studies, other indicated advantages in the 

 toll cable plan were improved service continuity (the southerly section 

 of the territory under study is one of heavy sleet conditions) and re- 

 duced noise from power induction. 



The quadded cable plan, however, had one disadvantage in that it 

 required a repeater station approximately 45 miles north of Toronto, in 

 a territory remote from any town or village with unfavorable living 

 conditions and subject to isolation during winter snow storms. The 

 nearest feasible location to the ideal, at Cookstown, involved such an 

 increase in length of cable and added expenditure that the cost ad- 

 vantage changed to the open-wire plan. Also, the use of B88-50 load- 

 ing with a repeater spacing of 50 miles appeared to offer no advantage 

 in that the additional cost of loading became an important factor. 



These difficulties in the use of the standardized type of toll cable 

 led to a review of the possibility of employing some combination of 

 conductor and loading which would permit a 60-mile repeater spacing, 

 thus eliminating any need for an intermediate repeater station between 

 Toronto and Barrie. If such a cable were to have the same unit at- 

 tenuation as 19-gauge H88-50 cable, then it must have considerably 

 improved crosstalk and return loss characteristics. On the other hand, 

 if a cable could be obtained with crosstalk and return loss characteris- 

 tics about equal to that of 19H88-50 cable, it must have an attentua- 

 tion of about % that of 19H88-50 cable. 



Of the standard types of cable and loading, 19-gauge non-quadded 

 exchange cable having a capacity of about 0.083 mf. per mile with B-135 

 loading appeared to have an attenuation of about the value required 

 to meet the second of the two requirements noted above. It was 

 estimated that such a cable would have the following transmission 

 characteristics : 



1000-cycle attenuation at 68° F 0.26 db per mile 



Passive singing point at repeater exceeded by 72% of 



circuits 25 db 



Maximum crosstalk gain 14 db 



Overall active balance ^ 6.0 db 



Overall circuit loss 8 db (PO-TC) with 4 db pad at PO. 



These assumed limits required a 72 per cent return loss of 26 db or 

 better at the critical frequency which was expected to be about 2600 

 cycles, and a 1 per cent maximum near-end crosstalk of 74.5 db. Based 



1 Computed by summation of the 72 per cent singing points at individual repeaters 

 with a 5 db end path. 



