. The Bell System technical journal . e characteristic effective during thebrief interval in the switching process when both branches of the circuit areconnected. Its similarity to the other two characteristics is a measure ofthe effectiveness of the phase simulation over most of the message channelspectrum. Its departure from the other characteristics in the channel 5 176 BELL SYSTEM TECUMCAL JOURNAL and channel 9 allocations marks the encl of the region in which the phase ofthe blocking tilter can be successfully simulated. Outside of this region,in parts of channels 5 and 9, the switching o
. The Bell System technical journal . e characteristic effective during thebrief interval in the switching process when both branches of the circuit areconnected. Its similarity to the other two characteristics is a measure ofthe effectiveness of the phase simulation over most of the message channelspectrum. Its departure from the other characteristics in the channel 5 176 BELL SYSTEM TECUMCAL JOURNAL and channel 9 allocations marks the encl of the region in which the phase ofthe blocking tilter can be successfully simulated. Outside of this region,in parts of channels 5 and 9, the switching operation shifts both phase andamplitude of the transmission and i)recludes the use of these channels forvoice-frequency telegraph or telephoto services. Equipment As previously stated a carrier program terminal consists of a modemunit, a demodulator-amplifier panel, and a reversing panel. As shown in CHAN- 12 3^ NELs Cir-^t^crr^C:^-.! 9 10 II 12 80 1 O V. ^1 FILTERIN 11 BOTH FILTER ANDNETWORK IN DURING50-MILLISECONDSWITCHING INTERVAL. 32 36 40KILOCYCLES 44 48 52 56PER SECOND 20 24 28FREQUENCY II Fig. 6—Transmission characteristics of blocking and by-passing circuit under normalconditions and during switching. Fig. 7 two such terminals, together with fuse panels for 24 and 130-voltbattery supply for several bays, are mounted in one standard cable ducttype bay 19 wide and 116 high. The equipment is mounted on the bayin a group, from top down, in the order mentioned. The front or wiringside of the equipment is provided with three separate covers which furnishthe necessary electrical shielding as well as physical protection. Connec-tions to carrier systems are made through carrier program high-frequencypatching jacks on a 4-\vire basis and to the program circuits through audiofrequency testing jacks on a 2-wire basis from which point the carrierprogram channel is lined up for program service at the proper transmissionlevels for both directions of transmission. A through branching
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
