. The Bell System technical journal . is purpose the readingsat some parts of the scale are not exactly the same as those of the non- RECORDING TRANSMISSION MEASURING SYSTEM 25 recording meters used in the standard volume indicators. Records oftelephone circuit noise, which sometimes fluctuates in magnitude, canalso be recorded. This high recording speed is made possible by mak-ing use of the fact that a record can be made on heat-sensitive paperwithout actual contact between the heat source and the paper and,therefore, without friction between the paper and the moving systemwhich carries the
. The Bell System technical journal . is purpose the readingsat some parts of the scale are not exactly the same as those of the non- RECORDING TRANSMISSION MEASURING SYSTEM 25 recording meters used in the standard volume indicators. Records oftelephone circuit noise, which sometimes fluctuates in magnitude, canalso be recorded. This high recording speed is made possible by mak-ing use of the fact that a record can be made on heat-sensitive paperwithout actual contact between the heat source and the paper and,therefore, without friction between the paper and the moving systemwhich carries the heat source. Of particular importance is the factthat there is no static friction between these parts so that the powerrequired to turn the moving system is only that necessary to overcomeinertia, restoring spring force, damping and pivot friction, as is thecase with an ordinary indicating meter. Figure 3 illustrates the general principles of this recorder. Heat-sensitive paper is drawn over a straight bar which is at right angles to. Fig. 3—Diagram illustrating recording principle. the direction of paper movement, the bar being shaped so that only aline of paper is directly below the pointer of the moving system. A finestraight electrically heated wire is placed on the end of the pointer sothat as the current through the moving system is varied the hot wiretravels at approximately right angles to the line of the exposed paperand only a small spot of the paper is affected by the heat at any this arrangement the plot obtained has rectangular coordinates,which is a very desirable feature. The heat-sensitive paper is a colored paper coated with white waxand before exposure is nearly pure white. The application of heatcauses the wax to melt and be absorbed by the paper, making a distinctcolored trace. The rapidity of action is dependent upon the amountof heat and the rate of movement of the heated wire with respect to 26 BELL SYSTEM TECHNICAL JOURNAL the paper. The t
Size: 1993px × 1254px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
