TYPE-O CARRIER SYSTEM 



711 



2000 



2400 



4800 



2800 3200 

 FREQUENCY 



Fig. 21 — Typical receiving low pass and signaling filter characteristics. 



3600 4000 4400 



CYCLES PER SECOND 



ments. Similar characteristics apply to the Ab + Bb auxiliary filter 

 (53 lA). The A and B characteristics are used in the group receiving 

 filters Ab + Db , (531B) and Bb + Db , (531C). The D filter is a band- 

 pass filter with relatively gradual cutoff to pass the 180-196 band for 

 the channel filters, and has peaks at the group carrier frequencies of 

 236 kc and 256 kc. These filter characteristics are not shown. 



PHYSICAL ARRANGEMENTS 



A four-channel carrier terminal is shown on Fig. 24. This terminal 

 includes four channel units shown in detail on Figs. 25, 26, 27 and 28. 

 In Fig. 28 the unit is separated into the three sub-assemblies, of which 

 as noted above, the two voice frequency sub-assemblies are substantially 

 the same as for N carrier. The carrier sub-assembly with its plug-in 

 channel band filters is shown on Fig. 29. 



The interior arrangement of the plug-in unit containing the trans- 

 mitting and receiving band filters is shown on Fig. 30. This assembly 

 contains an adjustable ferrite inductance, a miniaturized transformer, 



