SOME APPLICATIONS OF TYPE "J" CARRIER SYSTEM 353 



office. This alarm has been arranged to operate by direct current over 

 one conductor between offices without interfering with existing tele- 

 phone circuits but at the expense of one DC telegraph path. For fuse 

 failure, rectifier failure, power off, power restored, high-low voltage, 

 high-low temperature, fire, burglary, pilot channel failure, and end of 

 pilot channel control, alarms are sent and identified. A questionable 

 alarm may be rechecked from the attended office. 



P\ CABLE TO 

 OFFICE 



SP. 4 CABLE 



TO OFFICE 



NORTH - 



TERMINAL 



POLE 



legend: 

 sr 4 'spiral four 



P.I. « FttPER INSULATED 



Fig. 9 — Cable arrangement at Austin. 



Special Problems 



Some of the problems encouRtered in connection with the other two 

 systems may be of interest. At Corsicana, a repeater point on the 

 Dallas-Houston system, a filter hut was used on only one side of the 

 repeater station. The situation which led to this arrangement is that 

 an intermediate cable in the Dallas-Houston line extends 0.2 mile 

 north and 0.5 mile south from the local central office. As it is 

 necessary that the J system operate through this entrance cable and 

 since space was available in the local central office building, repeater 

 equipment similar to that installed in unattended buildings was placed 

 in one room in the office. 



The section of cable north of the central office terminates on a corner 

 in a business district with all adjacent property occupied by buildings, 

 making it more economical to use loaded spiral-four cable to this 

 location than to extend the existing cable to an available site and 

 provide the necessary filter hut and equipment. For the longer cable, 

 it was more economical to provide the filter equipment in a hut in 

 order to use existing facilities. Although this cable terminates in a 

 fully developed residential area, a site for a filter hut was obtained 

 adjacent to an alley in the rear of one of the residences facing the 

 street on which the terminal pole is located. 



