Abstract: The present invention enables tomography data in the sea to be collected and transmitted via an artificial satellite to a ground station. Accordingly, data on the Doppler phenomenon and shift of a sound wave is also obtainable based on the temperature and density of sea water and an ocean current. This makes it possible to obtain information about a wide sea area, such as the relationship between the KUROSHIO and the El nino which is now attracting attention in relation to fishery, agriculture and abnormal weather. Hence, the present invention will be of wide application.

Abstract: A self-contained, expendable sea-state measuring device which deeply submed submarines can launch in order to determine sea surface conditions prior to a missle launch. The device comprises a multi-chambered, buoyant cylindrical metal shell which houses a sea-state measuring instrumentation package, a moment correcting counterwieght, a long data downlink with spooling means and a bouyant lifting body which "flies" the data wire away from the launch platform. The buoy is launched from the submarine via the aft signal ejector, buoyantly ascends to the surface, and then transmits sea surface information back to the submarine via the data link.

Abstract: A cable driver and method for an underwater telemetry transmitter puts a signal on a single insulated wire forming part of a cable pack in which the wire is coiled and which is connected to a surface transmitting unit. The underwater transmitter includes an amplifier having an input, directly, time division multiplexed or digitally encoded from one or more hydrophones and an output into the primary winding of a toroidal transformer having a center hole through which the cable passes as it is deployed from the cable pack. The cable also passes through a similar toroidal transformer whose winding is connected to provide a feedback signal to the input of the amplifier. Since the insulated wire may be of greatly varying length and the cable pack may have greatly varying numbers of turns, the load impedance and resulting noise also vary and the above described arrangement makes the signal on the wire substantially independent of the variable load.

Abstract: High sensitivity interferential electro-optical modulator. The invention concerns an interferential electro-optical modulator. This modulator contains a Mach-Zehnder integrated interferometer in which each interferometer arm (24, 26) is overlapped by an electrode (40, 42), itself surrounded by two lateral electrodes (44, 46, 48, 50) to uniformize the electrical field crossing through each arm perpendicular to the face of the electro-optical crystall on which it is formed. Application to the detection of accoustic waves and low voltage measurement.

Abstract: The transmission of prelaunch weapon communication in a submarine is accoished without the use of an umbilical cord. Acoustic transducers transmit and receive acoustic data through water in place of the umbilical cord. The data transmitted through the water from the launch tube wall to the weapon is in serial format having been converted from parallel data by multiplexing.

Abstract: An underwater communication system of the present invention comprises a transmitter including message inputting means having keys, each being assigned to each word, code converting means for converting a key input entered through the inputting means to a code assigned to the key input, modulator means responsive to the code for performing modulation, and transmit transducer means for converting an output of the modulator means to an acoustic wave, and a receiver including a receiver transducer means for reconverting the incoming acoustic wave from the transmitter to an electric signal, demodulator means for demodulating the electric signal to generate the code, speech synthesis means responsive to the demodulated code for producing a word corresponding to the code as a speech, and speaker means for outputting the synthesized speech.

Abstract: A portable, self-contained underwater signalling device adapted to be worn by a diver. A waterproof housing has contained therein an acoustic sound generator, a power source and a three-position switch and circuit board connected in circuit between the power source and sound generator. The three-position switch provides an off or open position, a momentary on position and a full on position. The circuit board may vary the frequency of the signal output of the sound generator when the switch is in the constant on position to generate a pulsed frequency or a constant frequency.

Abstract: An electronic diving apparatus detects pressure by means of a bellows transducer (12). A variable frequency oscillator (10) produces a variable frequency output in proportion to the pressure applied to the transducer (12). A local oscillator (16) produces a fixed frequency signal which is mixed with the variable frequency signal in a mixer-demodulator (14) to produce an audio depth signal. The audio depth signal is provided to up/down counters (30). A time base and synchronizer circuit (24) sequences the counters (30) for an up frequency count and a down frequency count of the audio depth signal. When the difference count exceeds a preset limit, a maximum rate of depth change circuit (34) produces an alarm signal which is transmitted through a beep timer circuit (36) to activate an audio driver and output circuit (28) which produces alarm signal at an audio disk (38). This gives a warning of too rapid of an ascent or descent by the diver.

Abstract: Apparatus which provides both range and bearing information between a transponder and a transponder interrogator. The interrogator transmits an acoustic interrogating pulse which is received by the transponder and in response thereto transmits back a first signal of a certain frequency f1. Two spaced apart hydrophones on the transponder provide their respective output signals to a phase meter, the output signal of which is indicative of the direction, that is, bearing, from which the interrogating pulse impinged. The phase meter output is converted to a corresponding time delay after which a second signal of a frequency f2 is transmitted. A counter in the interrogator starts counting upon transmission of the interrogating pulse and stops upon reception of the first signal of frequency f1. A second counter of the interrogator starts its count when the first counter turns off and terminates its count when the second signal f2 is received.

Abstract: An underwater communicator device (10) is disclosed which permits acoustic communication with another diver by use of a voice synthesizer (42) cooperating with an acoustic transducer (40). A display (34A) is also provided to visually communicate the message. The keyboard (18) of the device (10) permits the diver to communicate stored messages by activating a single key 54 or to enter a complete arbitrary message by keying in the actual message. In other forms, the device (10) can include an air pressure transducer (60) for monitoring air tank pressure with a warning of low pressure. A depth pressure transducer (64) can be incorporated into the device (10) to monitor the depth of the device and diver. A bottom timer can be incorporated within the device for measuring the time of the depth. These functions can be continuously displayed to the diver on display screen 34B.

Abstract: Acoustic transponders are attached to sections of a submarine cable for use in accurately locating the cable during deployment or retrieval. An acoustic signal at one frequency, transmitted from the surface or elsewhere, stimulates one of the transponders to generate a first reply signal at a different frequency. The acoustic reply signal generated by each transponder is used to determine the location of that transponder and thus the location of its associated section of the cable. In order to measure cable tension during deployment or retrieval, a strain gauge at each transponder senses the tension of the cable at the location of its associated transponder. After each transponder transmits its first reply signal, it transmits a second reply signal delayed from the first reply signal by a time interval which is controlled by the output of its associated strain gauge.

Abstract: A modulation/signal processing technique for acoustic communication in show water. Digital information is transmitted in a time expended version of frequency shift keying where a tone burst at a first frequency represents a logical zero and a tone burst at a second frequency represents a logical one. There is a long quiet time between bits to allow multipath interference to decay. A relative energy detector with a fast attack/slow decay circuit for Doppler compensation is used to receive the transmitted tone bursts and reproduce a digital data train equivalent to the transmitted pulse train. A single communication channel employs two frequencies to transmit an identity code as a signal validating and identification method and two frequencies to simultaneously transmit telemetry data.

Abstract: An acoustic ocean measuring system is disclosed which uses measurements of sound intensity to locate and measure ocean anomalies. Several free-floating sound pulse emitting floats are placed in the ocean area to be measured; the position of the floats can be determined by well-known ranging techniques. Several hydrophones are positioned either in the immediate area or at distant locations to receive the sound pulses. A fixed number of received sound signals are electronically processed to obtain peak intensity signals. A fixed set of peak signals received from the floats over a fixed period of time are used to generate a trend line which can be used to predict the peak intensity received from the position data. The actual received intensity measurements are compared to the predicted measurements; substantial deviations from the predicted values are used to locate and measure parameters of ocean anomalies.

Abstract: An undersea communications system provides for improved data transmission pabilities. Two separate sources of information respectively modulate the upper and the lower sidebands of an acoustic carrier. The discretely modulated sidebands are simultaneously transmitted without the acoustic carrier or the acoustic carrier can be added to allow asynchronous or synchronous demodulation and use of the two modulating informations. Separation of the information in the two discretely modulated sidebands is assured by shifting the modulating information to ultrasonic regions and filtering out upper and lower sidebands of modulating information. Next, the shifted sidebands are modulated by an acoustic carrier which, optionally, is transmitted along with the discretely modulated upper and lower sidebands. A phase locked loop in the receiver portion assures synchronous demodulation or a crystal oscillator allows asynchronous demodulation of the discretely modulated upper and lower sidebands.

Abstract: An acoustic telemetry system and technique are disclosed for remotely meaing the underwater depth and descent rate of a hydrographic package. Analog signals indicative of hydrostatic pressure exerted on the package and related to its underwater depth are periodically sampled and converted to an N-bit digital word representative of the value of pressure. Each bit of the digital word operates one of a plurality of tone generators of different acoustic frequencies in a narrow band, and the outputs of the tone generators are combined with a reference tone continuously generated to permit resolution of Doppler shifts. Acoustically projected through the water to a remote hydrophone, a composite signal representative of the combined tones is corrected for Doppler shifts by translating the frequency of the signal in accordance with shifts detected in the reference tone.

Abstract: Apparatus for monitoring cable tension during submarine laying operations is housed in a separable case suitable for nondestructive attachment around the circumference of a cable at any desired location prior to laying. A strain gauge within the housing is positioned in a saddle across which the cable is placed in a bowed state. The electrical output from the strain gauge, which is proportional to tension in the cable, is translated into an acoustical signal transmissible through a submarine environment. The underwater sound can be picked up by the laying vessel or an assist vessel and displayed in real time. A plurality of tension monitors can be interrogated in sequence or at random under the control of transponder signals from the vessel. The monitor is self-powered and requires no metallic electrical connection to the cable or to the laying vessel.

Abstract: An apparatus and technique reduces the data transmission rate required to ansmit acoustic signals from undersea sensors to remote monitoring locations without degrading the surveillance information content of the signals. The signals are digitized and fed to an adaptive line enhancer (Wiener filter) which processes them so that a fast Fourier transform (Karhunen-Loeve approximation) coefficient generator can feed representative signals to a programmable quantizer and a signal averager. When significant shifts are detected in the fast Fourier transform coefficient variances, responsive signals are generated by the programmable quantizer for adaptive bit allocation. An interconnected multiplexer transmits multiplexed signals to the remote monitoring station where the inverse of the foregoing allows an analysis of the acoustic signals being monitored.

Abstract: The underwater signalling and identification device comprises an emitter (5) having four submerged transducers (10 to 13) arranged to form a square and fitted in a water-tight case (25) placed above an opening (7) formed in the hull of a ship, and also comprises a transducer-control circuit designed to emit an identification signal specific to the vessel and made up of a series of figures or letters in Morse code, the signal being emitted at at least one frequency selected as a function of the sound spectrum of the vessel and falling within the range of 4 to 6 kHz, the strength of emission of the signal being in accordance with the relationshipLI.sub.sl .gtoreq.LI.sub.bl +.DELTA.(dB),wherein LI.sub.sl is the level of acoustic intensity converted to the unit of distance of the identification signal of mean frequency f.sub.s.

Abstract: An inertial measurement underwater tracking system which determines range sition onboard an underwater vehicle using inertial navigation techniques. The system uses acoustic telemetry to relay the range position from the vehicle to an operations site. The position data is also recorded onboard the vehicle for post-run analysis. An onboard computer receives the inertial measurements from an inertial measurement unit and computes vehicle position with respect to an initialized reference. An acoustic transmitter receives the measurements, formats the data and transmits it by acoustic telemetry. An underwater hydrophone receives the acoustic telemetry and inputs the data to an acoustic processor to reconstruct the original position data. A range computer processes in real-time the data, and displays and records the time history of vehicle location on the range. After recovery the onboard recorded data is played back into the range computer to provide a maximum accuracy, continuous vehicle-run history.

Abstract: Acoustic beacon for use at sea and having a pipe-shaped housing in the one nd of which is space for a battery which drives a transmitter disposed coaxially around the housing at the other end where there is arranged a pressure switch covered by a membrane. The transmitter is switched on by the pressure switch when the pressure on the outside of the membrane exceeds a certain limit when the beacon falls in water.

Abstract: A system, which automatically or manually signals and senses the event of a person falling overboard from a vessel (12) into water (14), comprises a portable transmitter (16) coupled to a sound-producing transducer carried by the person (10) for transmitting ultrasonic and/or audible sound waves (18) through the water to a receiver (20) carried by the vessel. The receiver thereby permits rescue operations of the person to be initiated.

Abstract: An acoustic transmission system for a gaseous or liquid transmission medium, in which the transmitting apparatus double-sideband amplitude modulates a carrier with the signal to be transmitted, the double-sideband amplitude modulated carrier is radiated acoustically over the transmission medium, and the receiving apparatus receives the modulated carrier plus noise introduced in the medium, rejects the superimposed noise by sampling and reconstruction means, and delivers the modulated carrier substantially free from superimposed noise.

Abstract: An acoustic data link using the I-beam frame of a structure. The use of sl or aluminum framing permits a structure such as a ship to suffer damage in one section without loss of communication between sections. A universal asynchronous receive and transmit circuit converts data to be sent into a binary code which is inputted to the frame by a transducer. At a different location, a similar transducer receives the signal which is then converted back into an electrical signal.

Abstract: 1.

Abstract: 2. A method by which a submarine while deeply submerged in the sea may receive a message from a remote station without disclosing to others the position of the submarine, which comprises transmitting from said remote station into the atmosphere message information modulated on electromagnetic radiant energy, intercepting said radiant energy at a plurality of separated and widely dispersed relay stations on the surface of the sea, extracting the message information from the electromagnetic energy and transmitting acoustic wave energy modulated by said message information from each of said relay stations into the sea, locating said submerged submarine in message receiving range of one of said relay stations and detecting the acoustic wave energy modulated by the message information aboard said submarine.

Abstract: A secure sonar communication system for transmitting and receiving intellnce signals within an aqueous medium comprising in combination means for generating an electrical pseudo random noise signal within a predetermined bandwidth, means connected to said pseudo random noise generating means for selectively driving same at one of a plurality of predetermined frequencies, keying oscillator means adapted to selectively produce an output of one of a plurality of predetermined frequency signals, a balanced modulator means coupled to said pseudo random noise signal generating means and said keying oscillator means for mixing the output signals therefrom, bandpass filter means connected to the output of said balanced modulator means for passing the upper sideband thereof, means for receiving an electrical pseudo random noise signal, transducer means, said transducer means being capable of broadcasting acoustical energy upon excitation by the upper sideband from the aforesaid bandpass filter means and in proportion

Abstract: A system for deploying a vertical linear sensor array from a transiting vessel comprising a tubular deployment case closed at the bottom by a descent weight that is connected to a plurality of sensors packed in the case and connected in sequence by a cable of signal wires to a unit for creating drag in the descent of the deployment case and sensors, such as a collapsed parasol-type drogue or a buoyant body. Stacked over the telemetering unit is a cable dispenser open at the bottom and closed at the top by a nose weight. A substantial length of signal cable is coiled in the cable dispenser to pay out from the center with one end connected to the nose weight and the other connected to transmit sensor signals. A toroid core around the signal cable where it is being payed out inductively couples sensor signals to a signal line connected to an inner conductor of an armored cable.

Abstract: A phase shift keyed (PSK) pulse synthesizer which is part of an acoustic transmitter located in an underwater vehicle to provide identification and tracking of the vehicle as well as telemetry data when used on an instrumented underwater tracking range. The synthesizer is synchronized with the range time standard and generates phase coded pulses in a format suitable for input to an amplifier. A timing circuit divides a high frequency clock to produce square wave outputs at the desired frequency. A programmed read only memory (PROM) contains the identification code and is addressed from the timing circuit. A phase shift modulator combines the desired frequency with signals from the PROM and from a telemetry data generator to provide the amplifier with a digital analog of the desired acoustic message to be transmitted.