Methods and devices may be used to perform underwater communication using one or more electronic devices. The one or more electronic devices include a first wireless transceiver configured to transmit first wireless signals through an air medium with the first wireless signals not being conducive for transmission through a water medium. The one or more electronic devices also include a second wireless transceiver configured to transmit second wireless signals through water. The electronic devices detect whether at least one electronic device has been submerged, and in response to submersion, transmits at least some communication types from the second wireless transceiver rather than the second wireless transceiver.

Methods and devices may be used to perform underwater communication using one or more electronic devices. The one or more electronic devices include a first wireless transceiver configured to transmit first wireless signals through an air medium with the first wireless signals not being conducive for transmission through a water medium. The one or more electronic devices also include a second wireless transceiver configured to transmit second wireless signals through water. The electronic devices detect whether at least one electronic device has been submerged, and in response to submersion, transmits at least some communication types from the second wireless transceiver rather than the second wireless transceiver.

Embodiments described herein relate to generating an image of an acoustic field associated with an underwater region. A plurality of submersible sensing devices (SSDs) are disposed so as to be substantially separate from each other in an underwater region, wherein each respective SSD is configured to execute a sink/float mission. During at least a portion of the sink/float mission, within each SSD, an environmental sensor measures at least one environmental parameter, a position sensor detects position information, an acoustic detection sensor detects at least one underwater signal, and a data recording system records mission data. After the sink/float mission, a processor receives mission data from the SSDs and generates an acoustic field image. Advantageously, during the sink/float mission some SSDs can transmit an orthogonal high time-bandwidth signal to help prevent interference between SSD during acoustic detection.

Disclosed herein is a system including an underwater housing having an underwater wireless module communicating with a camera, an above-water wireless module configured in a floating above-water housing, the underwater wireless module communicating with the above-water wireless module via a tether and a tether extension and retraction device that extends and retracts the tether. The above-water wireless module can be configured on a boat or a separate floating housing. The underwater module receives a first wireless signal from the media capture device capturing images to yield a first signal. The underwater module in the extended system transmits the first signal via the tether to the above-water module and the above-water module in the extended system transmits the first signal to yield a second wireless signal, wherein a mobile device can receive the second wireless signal and display the images or video captured from the camera.

Disclosed herein is a system including an underwater housing having an underwater wireless module communicating with a camera, an above-water wireless module configured in a floating above-water housing, the underwater wireless module communicating with the above-water wireless module via a tether and a tether extension and retraction device that extends and retracts the tether. The above-water wireless module can be configured on a boat or a separate floating housing. The underwater module receives a first wireless signal from the media capture device capturing images to yield a first signal. The underwater module in the extended system transmits the first signal via the tether to the above-water module and the above-water module in the extended system transmits the first signal to yield a second wireless signal, wherein a mobile device can receive the second wireless signal and display the images or video captured from the camera.

A communication device includes a channel estimation unit configured to estimate an impulse response based on signals of sound waves received by each of a plurality of hydrophones, a long delay removal unit configured to remove a long-delay impulse response from the impulse response to generate a post-removal impulse response, a weighting factor calculation unit configured to calculate a weighting factor based on the post-removal impulse response, and a synthesizing unit configured to synthesize the signals received by each of the plurality of hydrophones based on the weighting factor.

A communication device includes a channel estimation unit configured to estimate an impulse response based on signals of sound waves received by each of a plurality of hydrophones, a long delay removal unit configured to remove a long-delay impulse response from the impulse response to generate a post-removal impulse response, a weighting factor calculation unit configured to calculate a weighting factor based on the post-removal impulse response, and a synthesizing unit configured to synthesize the signals received by each of the plurality of hydrophones based on the weighting factor.

An electromagnetic (EM) telemetry method comprises encoding downhole data into a single data stream; separating the single data stream into a plurality of separate data streams; converting each separate data stream into a corresponding separate waveform using a selected digital modulation technique wherein at least one of the frequency and phase of each waveform is assigned a unique value or unique non-overlapping range of values; combining each separate waveform into a combined waveform; and transmitting from a downhole location, an electromagnetic (EM) telemetry carrier wave comprising the combined waveform.

An electromagnetic (EM) telemetry method comprises encoding downhole data into a single data stream; separating the single data stream into a plurality of separate data streams; converting each separate data stream into a corresponding separate waveform using a selected digital modulation technique wherein at least one of the frequency and phase of each waveform is assigned a unique value or unique non-overlapping range of values; combining each separate waveform into a combined waveform; and transmitting from a downhole location, an electromagnetic (EM) telemetry carrier wave comprising the combined waveform.

An underwater observation apparatus includes an observation apparatus body, a weight structure, a coupling device, and a fusion cutting device. The observation apparatus body is configured to house at least a power source, a communication circuit for a communication device, and a signal processing device. The coupling device couples the observation apparatus body with the weight structure via a remote-controlled release structure capable of releasing the observation apparatus body from the weight structure. The underwater observation apparatus also includes a power feeding coil located inside of a glass sphere to generate magnetic flux, and a power receiving coil located outside of the glass sphere. The power receiving coil generates an induced voltage when interlinked by the magnetic flux generated by the power feeding coil. The power receiving coil is configured to supply drive power to the fusion cutting device.