. The Bell System technical journal . nown null special method employing three winding transformers and ampli-fiers widely used to determine impedance balance conditions betweenlines and networks is also described. Several methods which involvesimply current and voltage measurements have lieen mentioned in 46 SYSTEM JOIKXAL this paper l>iil tlu-st- art- Kt^nirally will known am! tlicrefore requireno tietaiied description. 1. Measirkmknts of Crosstalk In the circuit shown in Kig. 11. if a-c. power is supplied to a circuitknown as the disturhinn circuit and unli
. The Bell System technical journal . nown null special method employing three winding transformers and ampli-fiers widely used to determine impedance balance conditions betweenlines and networks is also described. Several methods which involvesimply current and voltage measurements have lieen mentioned in 46 SYSTEM JOIKXAL this paper l>iil tlu-st- art- Kt^nirally will known am! tlicrefore requireno tietaiied description. 1. Measirkmknts of Crosstalk In the circuit shown in Kig. 11. if a-c. power is supplied to a circuitknown as the disturhinn circuit and unlialances exist between thiscircuit and a second known as the disturbed circuit, power will betransferred from one circuit to the other causing crosstalk in thesecond. A dehnite jwiwer transmission loss therefore takes placebetween the two circuits which can be measured by a loop trans-mission test similar to the elTicicncy tests described in the main bodyof the pajKr. An adjustable shunt called a crosstalk meter cali- Coit Talk Uuijtr. MeMv-em«flU of C/ots TalkFig. 11 — DiaKraiii SliowiiiK IrincipKs of (riisstalk Measurements lirated in either 77 or in irossialk units is subs(iluuinion of the obser\er, the annoyance produced li\ thetone in the recei\er is judged to be equal for the two reading of the shimt if there was no dist<jrtion of the line cross-talk currents Wduld then give the \-olume of crosstalk which couldbe e\|)ressed in Tl^ as 10 login Pr P, similar to loop transmissiontesting. However, this relation only holds approximateK in practisesince the line measured is produced by various currentshaving different phase relations and a certain amoimt of distortiontherefore occurs. The commercial form of crosstalk set now used isequipiKil lo gi\e the a
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
