32 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1951 



Noise and crosstalk in the over-all system come from many causes. 

 Figure 17 shows relative levels of principal contributions. 



Order Wire and Alarm Circuit 



Two spare pairs in the cable along an N carrier route are provided for 

 testing and maintenance purposes. One pair, either 16- or 19-gauge with 

 B88 or HI 72 loading, is used for order wire. Signaling uses either 1900 cycles 

 or 1000-20 ringing. A cableman's whistle is used at pole repeaters to signal 

 attended points. A second pair of conductors is used to bring alarms to 

 attended points from unattended repeater power points. Tones at 700, 1100, 

 1500 or 1900 cycles are provided for alarming four separate points. Tone is 

 normally on the line and is removed by a relay during a trouble. A 5-second 

 delay in the alarm circuit prevents false operation on line hits. D-C. power 

 is simplexed over the alarm and order wire pairs to pole repeaters as a power 

 source for switching in a spare repeater. Figure 18 shows the order wire and 

 alarm circuit arrangement. 



References 



1. "Improved Three-Channel Carrier Telephone System," J. T. O'Leary, E. C. Blessing 



and J. W. Beyer, Bell Sys. Tech. Jour., Jan. 1939. 



2. "New Single Channel Carrier Telephone System," H. J. Fisher, M. L. Almquist and 



R. H. Mills, A.I.E.E. Trans. 57, 25, (1938); also Bell Sys. Tech. Jour., Jan. 1938. 



3. "Twelve Channel Carrier Telephone System for Open Wire Lines," B. W. Kendall 



and H. A. Affel, AJ.E.E. Trans. 58, 351 (1939); also Bell Sys. Tech. Jour., Jan. 

 1939. 



4. "Some Applications of the Type J. Carrier System," L. C. Starbird and J, D. Mathis, 



AJ.E.E. Trans. 58, 666 (1939); also Bell Sys. Tech. Jour., Apr. 1939. 



5. "Carrier Telephone System for Toll Cables," C. W. Green and E. I. Green, Elec- 



trical Engineering, 57, 227 (1938) ; also Bell Sys. Tech. Jour., Jan. 1938. 



6. "Cable Carrier Telephone Terminals," R. W. Chesnut, L. M. Ilgenfritz and A. Ken- 



ner, Electrical Engineering, 57, 237 (1938); also Bell Sys. Tech. Jour., Jan. 1938. 



7. "Crosstalk and Noise Features of Cable Carrier Telephone Systems," M. A. Weaver, 



R. S. Tucker and P. S. Darnell, Electrical Engineering, 57, 251 (1938); also Bell 

 Sys. Tech. Jour., Jan. 1938. 



8. "Experience in Applying Carrier Telephone Systems to Toll Cables," W. B. Bedell, 



G. B. Ransom and W. A. Stevens, Bell. Sys. Tech. Jour., Oct. 1939. 



9. "An Improved Cable Carrier System," H. S. Black and others, A.I.E.E. Trans., 66, 



741 (1947). 



10. "A Million-cycle Telephone System," M. E. Strieby, Bell Sys. Tech. Jour., Jan. 1937. 



11. "Frequency-Division Techniques for a Coaxial Cable Network," R. E. Crane and 



others, AJ.E.E. Trans., 66, 1451 (1947). 



12. "Progress in Coaxial Telephone and Television Systems," L. G. Abraham, AJ.E.E. 



Trans., 67, 1520 (1984). 



13. "Stability of Tandem Regulators with L-1 Carrier Systems," J. P. Kinzer, AJ.E.E. 



Trans. 6S (pt. 2), 1179 (1949). 



14. "Attenuation and Delay Equalization for Coaxial Lines," W. R. Lundry, AJ.E.E. 



Trans. 68 (pt. 2), 1174 (1949). 



15. "Equalization of Coaxial Lines," K. E. Gould. AJ.E.E. Trans. 68 (pt. 2) 1187 (1949). 



16. "Carrier Telephone System for Rural Service," J. M. Barstow, A J.E.E. Trans. 66, 



501 (1947). 



17. "Application of Rural Carrier Telephone System," E. H. Bartelink and others, 



AJ.E.E. Trans. 66, 511 (1947). 



