(a) 



REF 



SWITCH POS 1 



LINE TEST 



A SET 1 



DETECTOR 





Tfmt-'- 



(b) 



SWITCH POS 2 



SET3 E2A 



(c) 



Et3 OR E23 

 SWITCH POS 3 



fd) 



E31 OR E32 

 SWITCH POS 4 



(e) 



E3 

 SWITCH POS 5 



Fig. 26 — Sequence of transmission measurements. 

 1088 



