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GB304930A
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Improvements in or relating to sub-aqueous depth and distance measuring and signalling by sound waves
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US1735460A
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Method and arrangement of directional wave reception and emission
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US1698864A
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Train-control apparatus
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DE476449C
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Device for the timely delivery of signals
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DE463646C
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Electric train protection device
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GB238250A
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Improvements in sound apparatus for producing and receiving sound waves
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US1655267A
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Sound apparatus for producing and receiving sound waves
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US1618982A
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Device for the production of mechanical vibrations by means of a continuous stream of fluid
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DE431976C
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Arrangement for utilizing the direct current surge in microphone circuits when mechanical vibrations or impulses occur
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DE426596C
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Solder with detonator to generate a bang signal
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DE425973C
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Device for determining distance by means of reflected pulses
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DE430461C
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Method for determining distance by means of reflected mechanical pulses
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DE447597C
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Device for generating sound signals
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US1651414A
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Switching device
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DE424418C
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Sink bodies for depth determination
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DE425403C
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Device for determining the direction of wave-like processes, especially sound waves
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DE594045C
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Device for transmitting sound signals in which the natural characteristics of the transmitting or receiving membranes are used
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DE431974C
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Device for sending and receiving sound waves within a large frequency range with three or more oscillating structures coupled to one another
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US1616185A
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Sound producer comprising a vibratory system coupled with a resonator
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DE433399C
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Vibrating apparatus driven by a flowing resource
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