290 results about "Modulation index" patented technology

Binary and Quadrature Feher's Modulation (F-Modulation, or FMOD) Transmitter-Receiver systems and circuits exhibit reduced envelope fluctuation and peak radiation, and increased efficiency. A subclass of these systems has a constant envelope. They advantageously provide lower power operation with improved performance including robust BER performance, and compatibility with both linearly and nonlinearly amplified narrow spectrum, and without disadvantages of conventional BPSK, DBPSK QPSK and pi/4-QPSK. Feher's BPSK (FBPSK) is an improved efficiency transmitter which is compatible with conventional BPSK receivers. FBPSK modems are based on using quadrature structure where Q-channel data is inserted in quadrature with I-channel data for certain applications. The Q-channel data may be “offset” from the I-channel data by an amount selectable between zero and a specified time. Further improvement in the spectrum is attained using correlation between I and Q channels. FBPSK modem is shown to meet the IEEE 802.11 specified spectral direct sequence spread spectrum mask (−30 dB point) for wireless LAN, and leads to an output power gain of 6.5 dB over conventional BPSK modems. The cross-coupled quadrature FMOD structure is also suitable for continuous mode and for burst operated TDMA, FDMA, CDMA, WCDMA and CSMA Frequency Modulation Quadrature AM (QAM), QPSK and offset QPSK, as well as pi/4-shifted QPSK modems/processors. Reduced modulation index Gaussian FSK (GFSK), multilevel FM and cross-coupled Quadrature Amplitude Modulated (QAM) transmitters and combinations of these modulations and corresponding coherent demodulators are disclosed. Controlled rise and fall time descriptions of burst operated systems are included.

A method of controlling a current command by comparing voltage with a set value needs to vary the set value depending on voltage fluctuation, which involves taking a complicated control. A vector controller for a permanent-magnet synchronous electric motor, according to the present invention, can realize with a simplified configuration a field-weakening operation in a one-pulse mode in a high speed range by providing a current command compensator that corrects a current command by a corrected current command calculated based on a modulation index.

A phase-difference sensor measures the spatially resolved difference in phase between orthogonally polarized reference and test wavefronts. The sensor is constructed as a pixelated phase-mask aligned to and imaged on a pixelated detector array. Each adjacent pixel of the phase-mask measures a predetermined relative phase shift between the orthogonally polarized reference and test beams. Thus, multiple phase-shifted interferograms can be synthesized at the same time by combining pixels with identical phase-shifts. The multiple phase-shifted interferograms can be combined to calculate standard parameters such as modulation index or average phase step. Any configuration of interferometer that produces orthogonally polarized reference and object beams may be combined with the phase-difference sensor of the invention to provide, single-shot, simultaneous phase-shifting measurements.

An external transmitter circuit drives an implantable neural stimulator having an implanted coil from a primary coil driven by a power amplifier. For efficient power consumption, the transmitter output circuit (which includes the primary coil driven by the power amplifier inductively coupled with the implanted coil) operates as a tuned resonant circuit. When operating as a tuned resonant circuit, it is difficult to modulate the carrier signal with data having sharp rise and fall times without using a high power modulation amplifier. Sharp rise and fall times are needed in order to ensure reliable data transmission. To overcome this difficulty, the present invention includes an output switch that selectively inserts a resistor in the transmitter output coil circuit in order to de-tune the resonant circuit only during those times when data modulation is needed. Such de-tuning allows sharp rise and fall times in the data modulation without the need for using a high power modulation amplifier. Because data modulation is typically needed for only a small percent of the time that a carrier signal is present, it is thus possible using the present invention to achieve reliable data modulation, transmission and reception without having to use a high power modulation amplifier in the transmitter.

A head up display include an image source, and a waveguide. The waveguide has a first diffraction grating and a first end and a second diffraction grating at a second end. The waveguide is positioned as a combiner and allows viewing of an outside scene and information from the image source. The first and second diffraction gratings are surface relief gratings having a high index of modulation.

A DC matrix converter having six forward current conducting power switches and six reverse current conducting power switches has the on time duration of each power switch within each pulse width modulation period controlled by relationships between d, q components of a modulation index determined by the ratio of a voltage command to the instantaneous voltage of the AC mains expressed in stationary d, q coordinates, the selection of which is made based on inequalities between the AC mains voltage components expressed in dq coordinates, and relationships of the AC main voltage components expressed in d, q coordinates. Zero vectors are related to the one AC main having lower line-to-neutral voltage than the other AC mains, using relationships between the instantaneous AC mains voltage in d, q coordinates.

A method for measuring current in each phase of a three-phase inverter driven motor is based on the three-phase inverter being controlled in a PWM mode by three PWM signals including the use of a common DC-link current sensing resistor. The current on the sensing resistor is intermittently sampled. The method includes determining a modulation index for the voltage demand set by a motor controller. Based on specific mutual duty cycle conditions of the three PWM phase driving signals, sampling windows of sufficient duration are created for allowing distinct sampling of two of the phase currents.

A coupling arrangement for allowing multiple wavelengths to be coupled into and out of a relatively thin silicon optical waveguide layer utilizes a diffractive optical element, in the form of a volume phase grating, in combination with a prism coupling structure. The diffractive optical element is formed to comprise a predetermined modulation index sufficient to diffract the various wavelengths through angles associated with improving the coupling efficiency of each wavelength into the silicon waveguide. The diffractive optical element may be formed as a separate element, or formed as an integral part of the coupling facet of the prism coupler.

Methods and systems for controlling a power inverter in an electric drive system of an automobile are provided. A signal controlling the power inverter is modified utilizing a first voltage distortion compensation method if a modulation index of the signal is less than a first modulation index value. The signal is modified utilizing a second voltage distortion compensation method if the modulation index is at least equal to the first modulation index value.

A variable modulation index for a transponder (102, 200, 400) capable of measuring one or more parameters (e.g., temperature, pressure) in an object (e.g., a tire, (104)) and transmitting a data stream (FIGS. 3C, 4B) to an external reader/interrogator (106). The transponder typically operates in a passive mode, deriving its power (Vxx, Vcc, Vdd) from an RF interrogation signal received by an antenna system (210, 410, 710), but can also operate in a battery-powered active mode. The transponder includes memory (238, 438) for storing measurements, calibration data, programmable trim settings (436b), transponder ID and the like. Data stream transmission is preferably accomplished by PSK modulation (700) of the received RF signal, wherein the magnitude of modulation (index) is programmably varied in binary steps according to the programmed trim settings, and dynamically varied according to the level of input power in order to optimize the transmission. The transmitted signal is cleaned of noise by synchronizing a clock signal with the data stream signal.

A method of detecting a phase winding fault in a multi-phase electric machine is executable via a motor controller, and includes measuring feedback signals of the machine, including each phase current, and generating reference phase voltages for each phase. The method includes calculating a predetermined voltage value using the feedback signals and reference phase voltages, and comparing the voltage value to a corresponding threshold to determine the fault. A control action is executed when the voltage value exceeds the corresponding threshold. The voltage value is one or more of: a ratio of a normalized negative sequence voltage to a modulation index, an RMS voltage for each phase, and total harmonic distortion of each phase current. An apparatus detects the fault, and includes a motor controller and an algorithm as set forth above. The apparatus may include a voltage inverter for generating a multi-phase alternating current output for powering the machine.

A cryptographic key distribution method, in which coherent light being suitable for optical fiber communication network is used and high security is secured, is provided. A sending end encodes random numbers so that symmetry probability distributions can be obtained at a receiving end, and also sets light intensity and a modulation index of signal light radiating from the sending end so that the SNR of an eavesdropper is less than 2 dB even when said eavesdropper uses a most suitable receiving equipment at the sending end, and also so that the SNR of the receiving end is more than −10 dB, and transmits signals. The receiving end calculates probability distributions of obtained signals and sets a discrimination threshold value after a set of random numbers was transmitted from the sending end. When the probability distributions have some abnormal states, it is judged that the eavesdropper exists, and distributing the cryptographic key is stopped and a fresh cryptographic key is distributed again.

The present invention relates to a listening device for a hearing impaired person. The present invention furthermore relates to a corresponding operating method of operating a listening device and to a corresponding computer program. In particular, the present invention relates to a listening device that comprises a signal processing unit that is controlled by a controller configured to implement a combined feed-forward and feed-back control in order to ensure that both an electric input signal and a processed electric output signal have at least almost identical modulation index values. Thereby, speech intelligibility is increased, in particular for a hearing impaired person being capable of perceiving sound pressure levels in a substantially decreased dynamic range.

Methods and systems for driving an automobile are provided. The system includes a prime mover power source and a two-mode, compound-split, electromechanical transmission, including first and second motors, coupled to the prime mover power source, a power inverter coupled to the first and second motors, and a processor coupled to the first and second motors and the power inverter. The processor is configured to modify a signal controlling the power inverter utilizing a first voltage distortion compensation method if a modulation index of the signal is less than a first modulation index value and modify the signal utilizing a second voltage distortion compensation method if the modulation index is at least equal to the first modulation index value.

The system and method for radar calibration using antenna leakage is a simplified means of calibrating the channels in amplitude and phase using natural signal leakage between antennas. It utilizes as calibration signal a wideband sinusoidal Frequency Modulated Continuous Wave (FMCW) waveform with a modulation index and modulation frequency chosen to generate spectral components (or discrete signal frequencies) that fall within the receiver Doppler passband of the radar. The calibration signal is radiated out of the transmitting antenna and enters the radar receiver front-end through the transmit-to-receive antenna leakage which occurs naturally. This technique provides a low-complexity (simpler hardware realization) means for achieving a wideband calibration rapidly and is a practical alternative to the conventional calibration approach that relies on generating offset Doppler signals that are coupled into the radar receiver front-end through the use of couplers and cabling within the radar.

Programmable trimming for a transponder (102, 200, 400) capable of measuring one or more parameters (e.g., temperature, pressure) in an object (e.g., a tire, 104) and transmitting a data stream (FIGS. 3C, 4B) to an external reader/interrogator (106). The transponder typically operates in a passive mode, deriving its power (Vxx, Vcc, Vdd) from an RF interrogation signal received by an antenna system (210, 410), but can also operate in a battery-powered active mode. The transponder includes memory (238, 438) for storing measurements, calibration data, programmable trim settings (436), transponder II) and the like. The trim settings can be programmed in each transponder's EEPROM memory (436), and can be used to control operating characteristics of the transponder, such as modulation index, active/passive mode, current scaling for temperature, and current scaling for pressure. The programmable trim settings feature direct and continuous access (496) to the EEPROM cells containing the trim settings, with a dedicated line (485, 485.n) for each trimming bit, having a sensing circuit (498) powered independently of the EEPROM circuitry.

A method and apparatus are provided for correcting burn-in in a flat screen display. The method includes the steps of determining a maximum cumulative luminance of each pixel (15) within the display (14) based upon a usage of the pixel, providing a modulation map (40) of the display (14) from the maximum cumulative luminance of each pixel (15) within the display (14), transforming the modulation map (40) based upon the maximum cumulative luminance of groups of adjacent pixels to provide a modulation index for each pixel location of the map (40), comparing the modulation indexes with a set of threshold values and adjusting a luminosity of associated pixels (15) of the display (40) when the modulation index exceeds the threshold.

The control apparatus controls a controlled variable of the electric rotating machine by manipulating an output voltage of a power converter circuit including switching elements operated at a set modulation index to connect positive and negative terminals of a DC power source to corresponding terminals of the electric rotating machine. The control apparatus includes a prediction section configured to predict the controlled variable for each of a plurality of cases where the power converter circuit is set in a corresponding one of a plurality of predetermined operating states, a manipulation section configured to determine one of the predetermined operating states depending on a result of evaluation by an evaluation function, and set the converter circuit to the determined operating state, and a feedback control section configured to feedback-control the output voltage of the power converter circuit at a target value by manipulating the input parameters of the evaluation function.

A information modulating and demodulating method used on digital communication includes realizing modulation by utilizing binary information code element to directly vary abrupt phase of sine carrier wave, utilizing lock phase ring to realize demodulation, making modulated signal g0(t) corresponding to number zero be sine wave of N carrier wave period and making g1(t) corresponding to number one be in sine wave of N carrier wave period with frequency of fc, applying phase jump off angle theta and parameter tau as modulation index for varying signal bandwidth and transmission code rate as well as demodulation property.

The present invention relates to a system for generating a two-way light phase modulation millimeter wave and providing remote local oscillator in a millimeter wave optical fiber transmission system and a method thereof. The system comprises a center station and a base station. The center station is composed of a laser, two polarization controllers, a double-electrode Mach-Zehnder modulator, a microwave difference power amplifier, a light intensity modulator, an optical fiber amplifier and the like. The base station is composed of a photodetector, a front low-noise amplifier, a power divider,two band-pass filters, two millimeter wave amplifier and a millimeter wave transmitting antennae. In the method, a single mode laser is divided into two routes at the center station. Two opposite-phase 5GHz cosine microwave signals are used for phase modulating with large modulation index to the two routes of optical wave. The two routes of optical waves are overlapped. The phase variation of theoptical wave is switched to a strength variation through a FM-IM effect. The strength variation comprises a microwave signal and a high order component thereof. The millimeter wave signal is obtainedby extracting the high order harmonic. Then the optical fiber is executed with a strength modulation with a 2GHz BPSK signal and a mode of regulated subcarrier through a light intensity modulator. A 40GHz millimeter wave remote reference local oscillator and a 38GHz BPSK signal are obtained at the base station. The number of optical frequency doubling gets to 8, and the speed of baseband data transmission gets to 200Mbps.