US3150345A - Sonic communication system - Google Patents

Sonic communication system Download PDF

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US3150345A
US3150345A US71143758A US3150345A US 3150345 A US3150345 A US 3150345A US 71143758 A US71143758 A US 71143758A US 3150345 A US3150345 A US 3150345A
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connected
transducer
plate
via
audio
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Jeff E Freeman
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Jeff E Freeman
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B11/00Transmission systems employing sonic, ultrasonic or infrasonic waves
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/72Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves

Description

Sept. 22, 1964 J. E. FREEMAN some COMMUNICATION SYSTEM Filed Jan. 27 195 8 2 Sheets-Sheet l /\2 l2 l3 ///O94 8 7 1 INVENTOR JEFF E. FREEMAN ATTORNEY Sept. 22, 1964 E. FREEMAN some COMMUNICATION SYSTEM Filed Jan. 27, 1958 2 Sheets-Sheet 2 w Q. i J 1 INVENTOR JEFF E FREEMAN ATTORNEY United States Patent 3,1 9, SONIC QQMMUNICATION SYSTEM .leil E. Freeman, 2727 Weaver St, Fort Worth, Tex. Filed Jan. 27, 1958, Ser. No. 711,437

4 (Ilaims. (Cl. 346-6) This invention relates to electrical sound systems and more particularly to systems for producing or responding to underwater sound. While not limited thereto, the invention is particularly applicable to sound systems for use in connection with swimming pools.

A general object of the invention is to devise an improved electrical system -for selectively producing sound under water or detecting underwater sound and reproducingthe same above water. In this regard, the invention is useful for producing underwater oral instructions for swimmers, for producing musical accompaniments for water ballets, and for like purposes, the device also being capable of response to underwater sound, as for warning purposes, or of reproducing underwater sounds.

Another object is to provide a novel, selectively operable, multi-purpose sound system for swimming pools and like applications.

A further object is to provide an electrical circuit incorporating an underwater transducer which detects and determines when there has been an increase and when there has been a decrease in pressure at the transducer thus providing a means to maintain the water in a swimming pool or tank at a .constant level or to maintain a submarine at a predetermined depth.

A further object is to provide an improved underwater transducer for such systems.

In order that the manner in which these and other objects are achieved in accordance with the invention can he understood in detail, reference is had to the accompany drawings, which form a part of this specification, and wherein FIG. 1 is a sectional view, Withsome parts shown in elevation and with windings shown schematically for clarity, of an underwater transducer constructed in accordance with the invention;

FIG. 2 is a schematic diagram illustrating one embodi ment of the invention, and

FIG. 3 is a schematic diagram illustratinga second embodiment. a i

Referring now to FIG. 1, it will be seen that the invention includes a transducer indicated generally at 1 and cOmprising a solid body 2 in which is partially embedded a U-shaped permeable core 3. The body 2 is provided at one face with a recess 2 the ends .of the legs of core 3 extending out of the-body into the recess. 'Onone leg of the core 2 is wound a coil 4 embedded completely in body 2. Disposed betweenthelegs of core 3 and extending parallel thereto is a permanent magnet 5, to the tip of which is secured a permeable cored on which is wound a second coil 7.

Disposed within recess 2 and extending thereacross is a plate 3 of permeable material such as mild steel or soft iron. Provided with a flea joint 9 adjacentits periphery,

the plate 8 is secured in place by means comprising an into gasket 11, which force clamps the periphery of perme- 3,l5,3i5 Patented Sept. 22, 1964 its? able plate 8 between the gaskets. The combination of plate 8, gaskets 10, l1 and clamping plate 12 serves to seal the interior of recess 2 It will be noted that permeable plate 8 is spaced outwardly from the tips of the legs of core 3.

When the transducer is placed below the surface of a body of water the pressure existing at the transducer, due to the water above the transducer, will tend to move the plate 8 to a position which is closer to the tips of core 3. The combination of flex joint 9 and resilient gaskets ill, 11 permit the pressure present at the transducer to be efifective to so move plate 8.

At the face of the body 2 opposite permeable plate 8, there is partially embedded in the body a coupling or adaptor 14 via which insulated conductors are led to coils 4 and 7. Thus, conductors i5, 16 are connected to the terminals of coil 4, While conductors l7, 18 are connected to the terminals of coil 7.

Body 2., with the elements 3-6 and 14 embedded or partially embedded therein, is advantageously formed by conventional casting procedures from a suitable plastic material, such as wax or synthetic resin composition.

It is of the utmost importance that the acoustic impedance of the moving system of the transducer 1 be accurateiy matched to that of the water. in this regard, the thickness of permeable plate 8, the flexibility of joint 9 and the compliance of gaskets ill, it must be carefully selected to accomplish acoustic impedance matching.

To employ transducer 1 for producing underwater sound, an audio frequency voltage is applied to coil 7, via conductors i7, 18, so changing the magnetic flux density at the tip of core 6 in accordance with the audio frequency of the voltage, resulting in a corresponding vibration of permeable plate 8.

The transducer 1 can be employed as a detector 6f underwater acoustic energy. The device is then employed as a microphone using the voltage induced in coil 7 by the movement of the permeable plate 8 caused by underwater acoustic energy.

One mode of employing the transducer 1 in accordance with the invention is illustrated in the system embodiment shown in PEG. 2. Here, the invention employs electrical circuit components indicated generally at F and connected to transducer ii, the transducer being submerged in a swimming pool. The system comprises four ganged rotary selector switches i 22 provided with movable contacts 2346, respectively. Each selector switch has four fixed contacts AD. The switches are so ganged that all four rotary contacts engage like fixed contacts, that is, when one is in the A position, all are in A position. The A, C and D contacts of switch 19 are connected to ground through coil 27 of speaker 28. Contact B of switch 1% is connected to ground through resistor 29 and coil 27. The pivotal end of contact arm 23 is connected to the output of audio amplifier 3%. Switch 19 thus provides a means for connecting'the output of the amplifier. to speaker 23 for each position of movable con tact 23. The output of amplifier 3b is also connected to contact B of switch 21. The outputs of microphone 31, radio frequency detector 32 and phonograph pick-up 33 are connected to the fixed contacts of a switch 34. The movable contact of selector switchfid is connected via resistor .35 to the A and contacts of switch 269. The movable contact of switch 2% is 3 connected to ground via the resistance 36 of potentiometer 37. The adjustable contact 38 of the potentiometer is connected to the input of audio amplifier St). The potentiometer 37 provides a means for varying the level of input to the audio amplifier.

The lead 17 of coil '7 of the electromagnetic transducer 1 is connected to contact C of switch 20 and is also connected to the movable contact of switch 21. Lead 18 of coil 7 of the transducer is connected to ground.

Contact D of switch 21 is connected to ground via the primary winding 39 of transformer at). One end of the secondary winding 41 is connected to ground and the other end is connected through the grid current limiting resistor 42, to the grid of triode vacuum tube 43. The cathode of tube 43 is connected to ground through the grid biasing resistor 44. The plate of the triode is connected to ground via coupling capacitor 45 and grid resistance 46. The plate is also connected via load resistance 47 to contact D of switch 22.

The grid of a second triode vacuum tube 43 is connected, via grid current limiting resistance 49, to the conductor which connects capacitor 45 and resistance 46. The cathode of tube 48 is connected to ground through the grid biasing resistor 51). The plate of this tube is connected to ground via coupling capacitor 51 and grid resistance 52, and is also connected via load resistance 53 to contact D of switch 22.

The grid of a gas discharge tube 54, which in this embodiment is a thyratron, is connected via grid limiting resistance 55 to the conductor which joins capacitor 51 and resistance 52. The plate of thyratron 54 is connected to contact D of switch 22. The thyratron cathode is connected to one end of resistance 56. The other end of resistance 56 is connected to ground via capacitor 57. A gas discharge tube 58, which in this embodiment is a neon tube, is connected in parallel with capacitor 57, the anode of the neon tube being connected to the conductor which connects resistance 56 to capacitor 57. The cathode of the neon tube is connected to ground. The anode of neon tube 58 is also connected, via series-connected capacitor 5% and resistance 60 to contact D of switch 29.

The cathode of thyratron 54 is also connected, via resistor 61, to the movable contact 62 of potentiometer 63. The resistance 64 of the potentiometer 63 is connected between the D contact of switch 22 and ground. The potentiometer 63 is used to adjust the bias of the thyratron 54.

The B+ or plate supply voltage for tubes 43, 48 and 54 is connected to the movable contact 26 of switch 22.

Operation of the system of FIG. 2 is as follows: First consider the system when the respective movable contacts of switches 19-22 are in their A positions. Switch 34- can be positioned to select any one of the three audio frequency sources 31-253. The audio signal so selected is applied to the input of audio amplifier 30, with fixed resistor 35 and potentiometer 37 controlling the magnitude of the input signal. The output of the amplifier is supplied, via movable contact 23 and the contact A of switch 19, to speaker 23. Thus, the system provides a loudspeaker operation for audio frequency signals obtainable from either a radio frequency detector, microphone or phonograph pick-up.

When the movable contacts 23-26 are in their B positions, the system is eifectively connected as just described and, in addition, the output of amplifier 30 is applied to the coil 7 of transducer 1 via contact 25. Application of the audio frequency signal to coil 7 causes the plate 8 to vibrate correspondingly, resulting in audible transmission of the amplifier output to the medium surrounding the transducer.

Transducer 1 requires a greater operating voltage than does speaker 23. Accordingly, to maintain the speaker volume at a desired level, the signal is now supplied to the speaker via resistor 29.

A third function of the system is provided when the movable contacts 23-26 are in their C positions. The system now utilizes transducer 1 as a microphone with the signal amplified and supplied to speaker 28. In this case the lead 17 of coil 7 is connected to the input of audio amplifier 30 via movable contact 24 and input adjusting potentiometer 37. The amplifier output is connected to the coil 27 of speaker 28 via movable contact 23.

The fourth, or D positions of selector switches 19-22 provide a sound warning system which is initiated by a disturbance of the water surrounding the transducer, which functions now as a pick-up. The voltage induced in coil 7 by vibration of plate 8 is applied, via movable contact 25, to the primary winding 39 of transformer 40. The output of transformer 40 appears across the secondary winding 41 and is applied to the first stage of the two-stage resistance-coupled audio amplifier indicated generally at E and hereinbefore described in detail. The B+ supply for the amplifier tubes is derived via movable contact 26.

The audio output of the second stage of amplifier E is applied across grid resistor 52. The thyratron 54 is biased via the potentiometer 63, which is connected between ground and the B+ supply present at the D contact of switch 22. The audio output of the second stage of the amplifier E is then used to overcome the grid bias on the thyratron, causing the thyratron to conduct. This, in effect, connects the B+ supply voltage to capacitor 57 which then charges at a rate determined by the size of resistance 56 and capacitor 57. The voltage variation appearing across capacitor 57 is applied as an input voltage for the audio amplifier 30 via capacitor 59 and resistance 60. This voltage variation is amplified to the coil 27 of speaker 28 where it is then emitted as a warning sound. The voltage across the capacitor 5'7 continues to increase until it is high enough to cause the neon tube 58 to conduct. The discharge of the capacitor 57 through the neon tube is also amplified and emitted as a warning sound via speaker 28. Thyratron 5 continues to conduct, again charging the capacitor 57, so that the cycle of operation just described is repeated for so long as the thyratron remains conductive.

In the embodiment of the invention shown in FIG. 3, the transducer is employed in an electrical circuit which provides a means of detecting and determining whether the pressure at plate 8 of the transducer has increased or whether it has decreased and a means for actuating a warning device, water supply controls or other devices which are to respond according to whether the pressure has increased or decreased.

The circuit comprises an audio oscillator, a two-stage amplifier, a push-pull detection circuit, a push-pull amplifier, two relays, and a B+ or plate voltage supply. One output terminal of the audio oscillator 81 is connected to lead 15 of coil 4 of the transducer. The other output terminal 82 of the oscillator and lead 16 of coil 4 are connected to ground. Lead 18 of coil 7 of the transducer is connected to ground. The lead 17 of coil 7 is connected via series connected resistance 83 and variable resistance 84 to the conductor which connects terminal 80 to lead 15 of coil 4.

The grid of a triode vacuum tube 85 is connected via grid limiting resistor 86 to the conductor connecting resistances 83 and 84. The cathode of tube 85 is connected to ground via grid biasing resistance 87, and the plate is connected to the B+ or plate supply voltage via load resistance 88. The plate is also connected to ground via coupling capacitor 39 and grid resistance 90.

The grid of a triode vacuum tube 91 is connected via grid limiting resistance 92 to the conductor connecting capacitor 89 to resistance 50. The cathode of tube 91 is connected to ground via grid biasing resistance 93, and the plate is connected to the B+ or plate supply voltage via the primary winding 94 of transformer 95.

The secondary winding 96 of transformer 95 has a center tap 97 connected to ground via resistance 98. Center tap 97 is also connected via capacitor 99 to the plate of the output tube of the audio oscillator 81. One lead of the secondary winding is connected to the plate of diode 100. The other lead of the secondary winding is connected to the plate ofdiode 101. The resistance 102 of a potentiometer 103 is connected between the cathode of diode 1'00 and the cathode of diode 101. The movable contact 104 of potentiometer 103 is connected to ground. The cathode of diode 100 is also connected via grid current limiting resistance 105 to the grid of a triode vacuum tube 106. Similarly, the cathode of diode 101 is connected via grid current limiting resistance 107 to the grid of a triode vacuum tube 108.

The cathodes of tubes 106 and 108 are connected together via resistance 109 of a potentiometer 110. The movable contact 111 of the potentiometer is connected to ground. The plate of tube 106 is connected to B+ or plate supply voltage via winding 112 of relay 113. Similarly, the plate of tube 108 is connected to B+ or plate supply voltage via winding 114 of relay 115. The normally-open contacts of relays 113, 115 are each connected in a control or warning system. Thus, one warning system comprises a current source and a bell 116 in series with the contacts of relay 113, while the other warning system comprises a current source and a bell 117 in series with the contacts of relay 115.

Operation of the embodiment of FIG. 3 is as follows: When the transducer is placed below the surface of a body of water, plate 8 is moved closer to the tips of core 3 due to the pressure of the water on plate 8. Placing the transducer at a particular depth establishes a certain degree of magnetic coupling between coil 4 and coil 7 which changes when the transducer is moved to a different depth or when the water level changes. The audio oscillator output is applied to coil 4 of transducer 1 which adds to and subtracts from the flux created by permanent magnet 5 which causes permeable plate 8 to vibrate. When plate 8 vibrates the magnetic coupling between coil 4 and coil 7 is varied in response to the vibrations. A voltage is induced in coil 7 which is a function of the magnetic coupling between coil 4 and coil 7 and the change in current in coil 7;

The voltage induced in coil 7 is approximately 180 out of phase with the voltage which is applied to coil 4 from the audio oscillator 81 via adjustable resistance 84 and resistance 83. By adjusting resistance 84 the voltage across coil 4 and resistance 83 can be set at Zero. After such an adjustment is made, any change in pressure at plate 8 of the transducer due to a change in the water level or movement of the transducer to a diflerent depth results in a change in the voltage induced in coil 7. The change in the voltage induced in coil 7 causes the voltage at summing point X to be either in phase or 180 out of phase with the audio oscillator output, such in phase or 180 out of phase voltage then being applied as the grid signal of tube 85. Whether the increment of pressure change was an increase or decrease in pressure determines the phase relationship of the voltages.

tube will conduct only when the amplifier signal is 180 out of phase with the audio oscillator. The potentiometer 103 is used to equalize the current flow through diodes 100, 101.

When diode 100 conducts, the flow of current will be through that portion of resistance 102 of potentiometer 103 between the cathode of diode 100 and ground thus providing the grid signalvoltage for the grid of tube 106. The grid of tube 108 is similarly provided with a grid signal voltage when diode 101 conducts. The tubes 106, 108 will conduct when a grid signal is applied to their respective grids. Here again, the potentiometer 110 is used to equalize the flow of current through tubes 106, 108.

Since the coil of relay 113 is in the plate circuit of tube 106, relay 113 operates when tube 106 conducts. Closure of the contacts of relay 113 completes the circuit containing bell 116. Similarly relay 114 operates and bell 117 rings when tube 108 conducts. Thus, one relay operates in response to an increase in pressure at the plate of the transducer while the other relay operates in response to a decrease in pressure. Rather than completing a circuit containing a bell as shown in FIG. 3, the relays can be used to control operation of a mechanism designed to correct for the pressure changes.

While specific embodiments of the invention have been employed to illustrate the invention, it will be understood that the invention is not limited to these specific embodiments and that numerous changes can be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In a versatile communication system for underwater and above surface use, the combination comprising a water submersed transducer, an atmospherically immersed loudspeaker, an audio frequency input source for introducing radio signals and voice messages, and a unitarily actuated switching means for selectively connecting said input source to said loudspeaker in a first position and connecting said input source simultaneously to said transducer and said loudspeaker in a second position, whereby the emission of signals originating at the input source may be selectively transmitted as sound waves in the air in said first position and as sound waves both underwater and in the air simultaneously in said second position.

2. The communication system of claim 1, wherein there is a first audio amplifier having an input and an output, said unitarily actuated switching means being connected to the input of said first audio amplifier, the output of said audio amplifier being connected to said loudspeaker in the first position of the switching means and to said loudspeaker and said transducer in the second position of the Tube 85 is in the first stage of a two stage amplifier I indicated generally at G. The voltage across resistance.

83 and coil 7 which-is applied to the grid of tube85 is amplified and appears across secondary winding'fita of transformer 95.

The center tap 97 of the secondary winding is coupled to the plate of the last tube of the audio oscillator 81 via capacitor 99 and is also connected to ground via resistance 98. The voltage at the center tap with respect to ground thus varies in accordance with the voltage present at the plate of the last tube of audio oscillator 81. Dependent on whether the amplified signal was in phase or 180 out of phase with the audio oscillator voltage, one or the other of diodes 100, 101 will conduct. One

switching means.

3. The communication system of claim 2, wherein said unitarily actuated switching means, in a third position connects the transducer to the input of said first audio amplifier, the" output of said first audio amplifier being connected to said speaker whereby the under water vi-, brations may be emitted only as sound waves in the air.

4. The communication system of claim 3, wherein there is visual signalling means, and a second audio amplifier having an input and an output, said unitarily actuated switching means, in a fourth position, connects the transducer to the input of said second audio amplifier, actuating means connecting the output of said second audio amplifier to the visual signalling means to actuate said" visual signaling means upon audio frequency signals from said transducer reaching said second audio amplifier said actuating means connected also to the input of the first audio amplifier to emit a signal from said loudspeaker, whereby the water pressure changes against the submersed transducer cause visible and audible signals.

(References on following page) Refexenees Cited in the file of this patent UNITED STATES PATENTS Fessenden Jan. 23, 1917 Spath June 2, 1925 Cooke May 16, 1933 Colton Dec. 24, 1935 West July 4, 1939 Bennet Sept. 26, 1939 Shaw Oct. 8, 1940 Murphy Apr. 15,1941 Black Nov. 12, 1946 8 Trent Feb. 1, 1949 Tiffany Feb. 20, 1951 Garstang Oct. 30, 1951 Campbell Aug. 12, 1952 Scott Apr. 12, 1955 Geneslay Apr. 3, 1956 Levy July 17, 1956 Kursman July 9, 1957 OTHER REFERENCES Military Specification, MILC-17831A (Ships), Feb. 16, 1956. Fig. 1, Block Diagram (page 21).

Claims (1)

1. IN A VERSATILE COMMUNICATION SYSTEM FOR UNDERWATER AND ABOVE SURFACE USE, THE COMBINATION COMPRISING A WATER SUBMERSED TRANSDUCER, AN ATMOSPHERICALLY IMMERSED LOUDSPEAKER, AN AUDIO FREQUENCY INPUT SOURCE FOR INTRODUCING RADIO SIGNALS AND VOICE MESSAGES, AND A UNITARILY ACTUATED SWITCHING MEANS FOR SELECTIVELY CONNECTING SAID INPUT SOURCE TO SAID LOUDSPEAKER IN A FIRST POSITION AND CONNECTING SAID INPUT SOURCE SIMULTANEOUSLY TO SAID TRANSDUCER AND SAID LOUDSPEAKER IN A SECOND POSITION, WHEREBY THE EMMISSION OF SIGNALS ORIGINATING AT THE INPUT SOURCE MAY BE SELECTIVELY TRANSMITTED AS SOUND WAVES IN THE AIR IN SAID FIRST POSITION AND AS SOUND WAVES BOTH UNDERWATER AND IN THE AIR SIMULTANEOUSLY IN SAID SECOND POSITION.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3317889A (en) * 1963-09-30 1967-05-02 Roy A Bartram Method of and means for repelling sharks
US3573395A (en) * 1968-07-10 1971-04-06 Henry B Whitmore Fireproof electrical isolation speaker
US4276623A (en) * 1979-10-17 1981-06-30 Abbott Frank R Underwater audio intercommunication system
US4875199A (en) * 1986-09-09 1989-10-17 Hutchins Roger W Deep water transient sound generator
US5136555A (en) * 1991-07-05 1992-08-04 Divecomm, Inc. Integrated diver face mask and ultrasound underwater voice communication apparatus

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US1213610A (en) * 1913-01-29 1917-01-23 Submarine Signal Co Dynamo-electric machinery.
US1540093A (en) * 1922-09-09 1925-06-02 Signal Gmbh Electromagnetic vibrator, telephone, or the like
US1909812A (en) * 1931-11-20 1933-05-16 Bell Telephone Labor Inc Monitoring system
US2025041A (en) * 1931-03-09 1935-12-24 Roger B Colton Electromagnetic vibrator
US2164858A (en) * 1936-06-29 1939-07-04 Roger Williams Submarine sound system
US2174456A (en) * 1937-04-16 1939-09-26 Philco Radio & Television Corp Electrical circuit for communication systems
US2217497A (en) * 1938-11-02 1940-10-08 Gen Electric Switching scheme
US2238070A (en) * 1940-05-10 1941-04-15 Bell Telephone Labor Inc Broadcast switching system
US2410805A (en) * 1942-01-16 1946-11-12 Bell Telephone Labor Inc Vibration detector
US2460316A (en) * 1944-07-31 1949-02-01 Horace M Trent Echo ranging and listening gear
US2542594A (en) * 1946-05-13 1951-02-20 Tiffany Carter Supersonic communication system
US2573257A (en) * 1947-02-24 1951-10-30 Cornell Dubilier Electric Combined radio and intercommunicating set
US2606976A (en) * 1948-03-26 1952-08-12 Webster Electric Co Inc Intercommunicating apparatus
US2706285A (en) * 1951-08-21 1955-04-12 Roderic M Scott Dynamic monitor for echo ranging equipment
US2740946A (en) * 1952-12-16 1956-04-03 Geophysique Cie Gle Seismometer
US2755343A (en) * 1951-10-05 1956-07-17 Univ Loudspeakers Inc Blast-proof and submergence-proof sound reproducing device
US2798902A (en) * 1956-06-15 1957-07-09 Kursman Daniel Richard System and method for underwater communication

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1213610A (en) * 1913-01-29 1917-01-23 Submarine Signal Co Dynamo-electric machinery.
US1540093A (en) * 1922-09-09 1925-06-02 Signal Gmbh Electromagnetic vibrator, telephone, or the like
US2025041A (en) * 1931-03-09 1935-12-24 Roger B Colton Electromagnetic vibrator
US1909812A (en) * 1931-11-20 1933-05-16 Bell Telephone Labor Inc Monitoring system
US2164858A (en) * 1936-06-29 1939-07-04 Roger Williams Submarine sound system
US2174456A (en) * 1937-04-16 1939-09-26 Philco Radio & Television Corp Electrical circuit for communication systems
US2217497A (en) * 1938-11-02 1940-10-08 Gen Electric Switching scheme
US2238070A (en) * 1940-05-10 1941-04-15 Bell Telephone Labor Inc Broadcast switching system
US2410805A (en) * 1942-01-16 1946-11-12 Bell Telephone Labor Inc Vibration detector
US2460316A (en) * 1944-07-31 1949-02-01 Horace M Trent Echo ranging and listening gear
US2542594A (en) * 1946-05-13 1951-02-20 Tiffany Carter Supersonic communication system
US2573257A (en) * 1947-02-24 1951-10-30 Cornell Dubilier Electric Combined radio and intercommunicating set
US2606976A (en) * 1948-03-26 1952-08-12 Webster Electric Co Inc Intercommunicating apparatus
US2706285A (en) * 1951-08-21 1955-04-12 Roderic M Scott Dynamic monitor for echo ranging equipment
US2755343A (en) * 1951-10-05 1956-07-17 Univ Loudspeakers Inc Blast-proof and submergence-proof sound reproducing device
US2740946A (en) * 1952-12-16 1956-04-03 Geophysique Cie Gle Seismometer
US2798902A (en) * 1956-06-15 1957-07-09 Kursman Daniel Richard System and method for underwater communication

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3317889A (en) * 1963-09-30 1967-05-02 Roy A Bartram Method of and means for repelling sharks
US3573395A (en) * 1968-07-10 1971-04-06 Henry B Whitmore Fireproof electrical isolation speaker
US4276623A (en) * 1979-10-17 1981-06-30 Abbott Frank R Underwater audio intercommunication system
US4875199A (en) * 1986-09-09 1989-10-17 Hutchins Roger W Deep water transient sound generator
US5136555A (en) * 1991-07-05 1992-08-04 Divecomm, Inc. Integrated diver face mask and ultrasound underwater voice communication apparatus

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