. The Bell System technical journal . en, to calculate b fora large number of lengths from zeroto the maximum length of cable to beencountered. These values of h areused to calculate &2/&1 for differenttotal lengths of line / and differentfault locations/i: that is, h \s calcu-lated for different lengths up to onehundred miles; then a set of ratios ofbijbi and hlh can be determined usingthe b of one hundred miles as b^ and bfor all the shorter lengths as bi. Simi-larly, a set of ratios can be calculatedfor 95, 90, 85, 80, 75, etc., miles astotal lengths. Since the interpolationof hyperbolic fu
. The Bell System technical journal . en, to calculate b fora large number of lengths from zeroto the maximum length of cable to beencountered. These values of h areused to calculate &2/&1 for differenttotal lengths of line / and differentfault locations/i: that is, h \s calcu-lated for different lengths up to onehundred miles; then a set of ratios ofbijbi and hlh can be determined usingthe b of one hundred miles as b^ and bfor all the shorter lengths as bi. Simi-larly, a set of ratios can be calculatedfor 95, 90, 85, 80, 75, etc., miles astotal lengths. Since the interpolationof hyperbolic functions is at best atedious calculation, even values of hyperbolics can be used in formula(1) and the corresponding odd lengths in miles calculated. The ratio bojbi is then subtracted from the ratio hlh, in each instancethis procedure resulting in a family of correction curves expressed inpercentage such as that shown in Fig. 3. In this figure the correctionis plotted against apparent rather than actual percentage distance in. Fig. 2—Diagram showing the con-struction of a correction curve. Ab-scissas represent true linear distance;ordinates of upper curve representmeasured capacitance; ordinates oflower curve represent errors of com-puted location. LOCATION OF OPENS IN TOLL TELEPHONE CABLES 33 order to facilitate the use of the curves in locating actual cases oftrouble. Where the length of line being measured does not correspondto one of the curve indices, the curves can be interpolated and thedesired curve drawn in. Apparent Percentage Dista nee 0 ) 1 ) 2 ] 3 3 4 D 5 0 6 050 73 8 0 • 9 ) i( ,1 3 1 1 ■^ :::::; = =; ~ : — 1 P 2 < fi,\ .}45,6,7,8,9 Q ^ ■ ^ — Jz L- ^/> <. / V \i N \ ^ ~~~- --. m ^ ) \ R \ s ^ ^, 85 ^ y // \, \ N \ / s \, s s. ^ <■ k X / 1 * Fotal Lern th 0 fCa ble n K s liles \, \ ^i 5 / / \ \ r ^- — — / 1 k ^oc / / 2 ^p~- ■— y 1 Fig. 3—Corrections to be used in finding true position of a fault from the app
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
