APPLYING CARRIER TELEPHONE SYSTEMS 569 



Terminal Office Equipment 



The various major items of equipment which are provided at a 

 terminal office are shown schematically by Fig. 9. Two bays of 

 sealed test terminals — one input and one output — are associated with 

 the pair of cables which bring the carrier pairs into the office and are 

 equipped initially to terminate 40 pairs. The input high-frequency 

 jacks are mounted in high-frequency patching bays adjacent to the in- 

 put sealed test terminal bays and the output jacks in bays adjacent to 

 the output sealed test terminal bays. At points where more than 50 

 terminals are expected to be required at some future date plans have 

 been made for one input and two output high-frequency patching bays. 

 The input and output high-frequency patching and sealed test terminal 

 bays for two cable routes, together with a high-frequency transmission 

 measuring bay, are grouped so as to form a desirable arrangement for 

 testing and maintenance purposes. This group of bays serves some- 

 what the same purpose as a primary testboard on voice frequency 

 facilities. The arrangement of these bays as installed at New York is 

 shown in Figs. 10- A and 10-B. 



A portable transmission measuring set has been provided and may be 

 placed on a writing shelf mounted in the high-frequency transmission 

 measuring bay. This set may be connected to the various circuits by 

 means of patching cords. 



Line and twist amplifiers with associated flat and twist gain master 

 controller equipment and crosstalk balancing bays also are installed at 

 each terminal office. The arrangement of the amplifier equipment and 

 controllers as installed at New York is shown in Fig. 11. 



The terminal equipment for one system consists of six channel modem 

 (modulator plus demodulator) panels, each of which mounts the send- 

 ing and receiving apparatus for two channels.' Channel modem 

 equipment for three systems is mounted in two adjacent bays with the 

 first two systems occupying separate bays. One bay of carrier supply 

 equipment for each ten systems provides both regular and emergency 

 units for generating carrier frequencies for the operation of the channel 

 and group modem units and pilot channel equipment. The group 

 modem units, one of which is required for each system, are mounted 

 nine in one bay. Figures 12 and 13, respectively, show the method in 

 which these bays are installed at New York. 



The d-c power supply for the carrier equipment at terminal and main 

 repeater offices is obtained from the existing 24-volt and 130-volt office 

 power plants. Two sets of main distributing leads have been provided 

 for each filament and plate power supply. Odd numbered circuits are 



