17502 results about "Ultrasound attenuation" patented technology

A low attenuation surface wave transmission line system for launching surface waves on a bare and unconditioned conductor, such as are found in abundance in the power transmission lines of the existing power grids. The conductors within the power grid typically lack dielectric and special conditioning. Accordingly, the present invention includes a first launcher, preferably including a mode converter and an adapter, for receiving an incident wave of electromagnetic energy and propagating a surface wave longitudinally on the power lines. The system includes at least one other launcher, and more likely a number of other launchers, spaced apart from one another along the constellation of transmission lines. The system and associated electric fields along any given conductor are radially and longitudinally symmetrical.

A secondary-emitter sensor position indicator has primary emitters that transmit light having primary wavelengths and at least one secondary emitter that transmits light having at least one secondary wavelength. A detector outputs a sensor signal in response to received light. An attachment assembly, in a sensor-on condition, positions the emitters and detector relative to a tissue site so that the sensor signal is substantially responsive to the primary wavelength light after attenuation by pulsatile blood flow within the tissue site and is negligibly responsive to the secondary wavelength light. The attachment assembly, in a sensor out-of-position condition, positions the secondary emitter relative to the tissue site so that the sensor signal is at least partially responsive to the secondary wavelength.

A congenital heart disease monitor utilizes a sensor capable of emitting multiple wavelengths of optical radiation into a tissue site and detecting the optical radiation after attenuation by pulsatile blood flowing within the tissue site. A patient monitor is capable of receiving a sensor signal corresponding to the detected optical radiation and calculating at least one physiological parameter in response. The physiological parameter is measured at a baseline site and a comparison site and a difference in these measurements is calculated. A potential congenital heart disease condition in indicated according to the measured physiological parameter at each of the sites or the calculated difference in the measured physiological parameter between the sites or both.

An ear sensor provides a sensor body having a base, legs extending from the base and an optical housing disposed at ends of the legs opposite the base. An optical assembly is disposed in the housing. The sensor body is flexed so as to position the housing over a concha site. The sensor body is unflexed so as to attach the housing to the concha site and position the optical assembly to illuminate the concha site. The optical assembly is configured to transmit optical radiation into concha site tissue and receive the optical radiation after attenuation by pulsatile blood flow within the tissue.

A disposable active pulse sensor has an emitter that generates optical radiation having a plurality of wavelengths, a detector that is responsive to the optical radiation and an unbalanced electrical motor that vibrates when energized. A tape assembly removably attaches the emitter, the detector and the unbalanced electrical motor to a tissue site. The tape assembly also physically mounts the emitter, the detector and the unbalanced electrical motor in a spatial arrangement so that vibration from the unbalanced electrical motor induces pulsatile blood flow within the tissue site, the emitter transmits the optical radiation into the tissue site and the detector generates a sensor signal responsive to the intensity of the optical radiation after attenuation by the pulsatile blood flow within the tissue site.

A cellular communications system comprising a space based system comprising a first set of cells, and a ground based system comprising a second set of cells. The space and ground systems can optionally function substantially autonomously, with each using spectrum from at least one predetermined frequency band.

An efficient, low-loss, low sidelobe, high dynamic range phased-array radar antenna system is disclosed that uses metamaterials, which are manmade composite materials having a negative index of refraction, to create a biconcave lens architecture (instead of the aforementioned biconvex lens) for focusing the microwaves transmitted by the antenna. Accordingly, the sidelobes of the antenna are reduced. Attenuation across microstrip transmission lines may be reduced by using low loss transmission lines that are suspended above a ground plane a predetermined distance in a way such they are not in contact with a solid substrate. By suspending the microstrip transmission lines in this manner, dielectric signal loss is reduced significantly, thus resulting in a less-attenuated signal at its destination.

A data-modulated ultra wideband transmitter that modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and / or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and / or modulated UWB or wideband signals. In a special case where the oscillator has zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, a low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

An aircraft phased array antenna system has transmit and receive antenna structures externally mounted on the aircraft fuselage. Each antenna comprises a plurality of phased array elements and antenna power and support equipment. Aerodynamically shaping antenna structure to enclose an antenna element grid provides additional antenna structure volume, which is efficiently utilized by locating antenna support equipment within the antenna structure. To control signal attenuation a receive antenna internal converter converts receive frequency signals to L-band frequency signals for aircraft use, and a similar transmit antenna converter converts L-band frequency signals to transmit frequency signals, thus unconstraining antenna to internal aircraft equipment spacing. To reduce power loss and cabling weight, antenna operating power is first generated in the 28 to 270 volts DC range within the aircraft, and locally converted in each antenna to the 3 to 6 volt DC power to operate each antenna's phased array elements.

A method for equalizing audio and a video apparatus using the audio equalizing method are provided. The method for equalizing audio includes detecting the distance between a speaker mounted in a video apparatus and a reflective surface, and equalizing an audio signal to be output from the speaker based on the detected distance. Accordingly, attenuation of audio output is reduced, so audio output is optimized.