35 results about "Immittance" patented technology

An apparatus and method amplify a signal for use in a wireless network. The apparatus includes a power amplifier, an envelope modulator, a tunable matching network (TMN), and a controller. The power amplifier outputs the signal at an output power. The envelope modulator controls a bias setting for the power amplifier. The TMN includes a plurality of immittance elements. The controller is operably connected the envelope modulator and the TMN. The controller identifies a desired value for the output power of the power amplifier, controls the output power of the power amplifier by modifying the bias setting of the power amplifier, and sets a number of the plurality of immittance elements based on the bias setting of the power amplifier.

Techniques are provided for detecting heart failure or other medical conditions within a patient using an implantable medical device, such as pacemaker or implantable cardioverter / defibrillator, or external system. In one example, physiological signals, such as immittance-based signals, are sensed within the patient along a plurality of different vectors, and the amount of independent informational content among the physiological signals of the different vectors is determined. Heart failure is then detected by the implantable device based on a significant increase in the amount of independent informational content among the physiological signals. In response, therapy may be controlled, diagnostic information stored, and / or warning signals generated. In other examples, at least some of these functions are performed by an external system.

A power converter including a resonant circuit is controlled by pulse width modulation (PWM) of a switching circuit to control current in the resonant circuit near the frequency of the resonant circuit (a null-immittance criterion) in order to control current and voltage at the output of the resonant circuit. Further control of voltage can be performed by PWM of a switching circuit at the output of the resonant circuit such that centers of the duty cycles of respective switches for the output of the resonant circuit are substantially synchronized and substantially symmetrical about centers of said duty cycles of respective switches at the input of the resonant circuit. Thus, operation of the converter is substantially simplified by using only PWM, a wide range of input and output voltages can be achieved and the converter circuit can be configured for bi-directional power transfer.

A testing device contains measuring circuitry adapted to apply time-varying electrical excitation to a cell or battery, to sense a time-varying electrical response, and to thus determine components of complex immittance at n+m discrete frequencies, where n is an integer equal to or greater than two and m is an integer equal to or greater than one. Computation circuitry utilizes measured complex immittance components at the n discrete frequencies to evaluate the elements of a 2n-element equivalent circuit model. It then calculates the complex immittance of this model at the m discrete frequencies and mathematically compares components of the calculated immittances with components of the measured immittances at the m discrete frequencies. The results of this comparison establish the degree of cell deterioration without regard to the battery's manufacturer, group size, or its electrical ratings.

The invention relates to sweat activity measurement, e.g. for determining a physiological state of a subject, embodied by a method as well as a kit with an immittance measuring circuit and electrodes with contact electrolyte. Sweat activity is considered a transport phenomenon and can be defined as a flux, e.g. gram water per skin area per second. Prior art methods determining water absorbed per gram dry stratum corneum measures skin moisture and do not truly reflect sweat activity. A periodic signal with frequency of 60 Hz or lower is applied to reduce contribution from complex admittance of the skin, and skin conductance is measured as a degree of sweat activity. The contact electrolyte allows filling of sweat ducts with sweat from sweat glands, this may be characterized in that it does not substantially fill the sweat ducts when being positioned on the skin and / or in that it has a re-absorption time constant from the sweat ducts into the Epidermis of less than 15 min.

An apparatus and method manage impedance values in a radio in a wireless network. The apparatus includes a tunable matching network (TMN) positioned on a path between a transceiver and an antenna. The TMN includes a plurality of immittance elements. A voltage standing wave ratio (VSWR) detector is configured to detect a ratio of a signal passing the VSWR detector and a signal reflected from the TMN. A control circuit is configured to identify an operating setting for the radio, set a number of the immittance elements based on the operating setting, monitor the ratio detected by the VSWR detector, and modify a setting of at least one of the immittance elements based on the ratio detected.

Proposed is a method and apparatus for determining a weighting function for quantizing a linear predictive coding (LPC) coefficient and having a low complexity. The weighting function determination apparatus may convert an LPC coefficient of a mid-subframe of an input signal to one of a immitance spectral frequency (ISF) coefficient and a line spectral frequency (LSF) coefficient, and may determine a weighting function associated with an importance of the ISF coefficient or the LSF coefficient based on the converted ISF coefficient or LSF coefficient.

An apparatus and method for encoding / decoding a speech signal which determines a variable bit rate based on reserved bits obtained from a target bit rate, is provided. The variable bit rate is determined based on a source feature of the speech signal and the reserved bits is obtained based on the target bit rate. The apparatus for encoding the speech signal may include a linear predictive (LP) analysis unit / quantization unit to determine an immittance spectral frequencies (ISF) index, a closed loop pitch search unit, a fixed codebook search unit, a gain vector quantization (VQ) unit to determine a gain vector quantization (VQ) index, and a bit rate control unit to control at least two indexes of the ISF index, the pitch index, the code index, and the gain VQ index to be encoded to be variable bit rates based on a source feature of a speech signal and the reserved bits.

An immittance conversion circuit includes a first terminal and a second terminal, and includes: a conversion target circuit configured to amplify or attenuate a signal with desired frequency and gain characteristics, and output the resultant signal; a difference signal detection circuit configured to supply the input terminal of the conversion target circuit with a signal of a difference between signals generated at the first and second terminals; an immittance conversion drive circuit configured to perform differential output processing to generate a voltage of a difference between a correction voltage and the signal outputted from the conversion target circuit, and output feedback signals to an immittance conversion generation circuit; and the immittance conversion generation circuit having an immittance conversion generation action to generate, at each of the first and second terminals, a signal of currents or voltages of the corresponding inputted feedback signal and the signal inputted to the first or second terminal. A signal of a difference between the signals generated at the first and second terminals is inputted to the immittance conversion drive circuit as the correction voltage.

The invention discloses a method for analyzing the acoustic conductance of the middle ear by using input electrical impedance parameters. The method calculates the acoustic conductance of the middle ear by measuring the electrical impedance of a receiver. The method includes: within a predetermined ear canal pressure range , put pressure on the subject's ear canal; send a sound pressure signal with a certain frequency range and amplitude to the subject's ear canal through the receiver; measure the input electrical impedance of the receiver based on the pre-built receiver detection circuit; according to the input electrical impedance of the receiver , based on the pre-established acoustic immittance calculation model, obtain the middle ear acoustic impedance under the pressure value; traverse the ear canal pressure range, repeat the above steps, and output the set of pressure values ​​applied to the subject's ear canal and the corresponding middle ear Otoacoustic Immittance collection. The invention uses the electrical impedance parameters of the receiver to calculate and measure the middle ear acoustic conductance, so that the middle ear acoustic conductance measurement and analysis device no longer depends on the built-in microphone in the ear canal, and is more convenient.