Trolley Carrier Phone Mine Communications. Adaptive Volume Control and Use of a Dedicated Wire or a Low Impedance Line for Improved Carrier Phone Communications in Mines.
Lagace RL; Jeffreys DC; Spencer RH; Williams J
NTIS: PB/82-246034 :146 pages
This report presents the results of a program that was initiated to study, implement, and test the operation of an adaptive volume control circuit for the loudspeaker of a mine trolley carrier phone. The design goal was for the control to sense the ambient noise conditions and to operate the communications equipment such that the sound output would be loud under noisy conditions, and quieter under quiet conditions, thereby resulting in an understandable and nonstartling volume level under all normal operation conditions.
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