192 results about "Nominal frequency" patented technology

A resonant converter is provided which may be used for supplying power to the primary conductive path of an inductively coupled power transfer (ICPT) system. The converter includes a variable reactive element in the resonant circuit which may be controlled to vary the effective inductance or capacitance of the reactive element. The frequency of the converter is stabilised to a nominal value by sensing the frequency of the converter resonant circuit, comparing the sensed frequency with a nominal frequency and varying the effective inductance or capacitance of the variable reactive element to adjust the converter frequency toward the nominal frequency.

A method for autonomous dynamic voltage (v) and frequency (f) scaling (DVFS) of a microprocessor, wherein autonomous detection of phases of high microprocessor workload and prediction of their duration is performed (PID). The microprocessor frequency (f) will be temporarily increased (LUT) to an appropriate safe value (even beyond its nominal frequency) consistent with technological and ambient constraints in order to improve performance when the computer system comprising the microprocessor benefits most, while during phases of low microprocessor workload its frequency (f) and voltage (v) will be decreased to save energy. This technique exploits hidden performance capabilities and improves the total performance of a computer system without compromising operational stability. No additional hardware such as service processors is needed for contemporary computer systems supporting performance counters and DFVS already. The invention allows significantly increasing the total computer system performance with only minimal impact on power (P_MAX, P_ACTUAL) consumption.

A fully synchronous longitudinal position (LPOS) detection system is provided for improving the reliability of servo channels in tape systems. The system is based on the interpolation of the servo channel output signal, which is sampled by an analog-to-digital converter (ADC) at a fixed sampling rate, using a clock at a nominal frequency, so that interpolated signal samples are obtained at a predetermined fixed rate, independent of tape velocity. This predetermined fixed rate is defined in terms of samples per unit of length, as opposed to samples per unit of time, which is the measure of the ADC sampling rate. The resolution with which the servo channel signal is obtained at the interpolator output is thus determined by the step interpolation distance.

Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f₀ of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.

A method for displaying scanned ultrasound images of tissue employs an apparatus including an ultrasound probe mounted to a mechanical head. A three-dimensional positioning system mounts the head for positioning the probe in proximate orthogonal relation to the tissue. A computer controls the three-dimensional positioning system thereby moving the probe during a scan. The probe transmits high frequency ultrasound waves whose nominal frequency is included within the range from 30 to 100 MHz and with a large pass band, adapted to frequencies reflected by the tissue. The beams of ultrasound transmission are focused in a given zone of the tissue over a vertical penetration distance of between 20 and 30 mm. Reflected signals are acquired and processed for display.

A system and method are provided for correction of parameters used in determination of stator turn faults of an induction motor. An embodiment may include determining a residual impedance and/or a residual voltage of the motor, and correcting a normalized cross-coupled impedance based on the residual impedance and residual voltage. Additional embodiments may include measuring an operating temperature of the motor and determining a negative sequence impedance of the motor based on the temperature. Another embodiment may include measuring voltages and currents of the motor and determining phasors for the voltages and currents using compensation for variations from a nominal frequency of the motor.

A method for controlling a cluster of wind turbines connected to a utility grid includes the steps of determining the frequency of the utility grid, detecting a frequency deviation in the utility grid, and disconnecting the wind turbines at different predefined frequency values above the nominal frequency value. A method for planning the strategy of a utility grid including a wind turbine cluster connected to the grid and a wind turbine cluster is also contemplated.

A system and method is provided that searches for the frequency and phase of a CDMA transmission in an iterative manner. With its automatic frequency control (AFC) disabled, the receiving system performs a coarse search for the transmitter's CDMA phase at a nominal receiving frequency. When the coarse phase is obtained, the AFC is invoked with a large-range pull-in, to obtain an initial, coarse frequency that is likely to be closer to the transmitter's frequency than the initial nominal frequency. At this coarse frequency, the receiving system repeats its search for the transmitter's CDMA phase, starting at the previously determined coarse phase. Because this second phase determination is conducted in the presence of less frequency error, it provides for a more accurate phase determination. The AFC is again invoked, but with a small-range pull-in, to obtain a finer frequency determination. Because the finer frequency determination is conducted in the presence of less phase error, a substantial improvement in the accuracy and precision of the frequency determination can be achieved. To achieve this more accurate phase and frequency determination within the same time duration as a conventional acquisition process, the initial coarse phase determination is conducted using a rapid, albeit less accurate, process than the conventional phase determination.

The invention relates to an aided Global Positioning System (GPS) subsystem within a wireless device. The wireless device includes a wireless processing section capable of receiving signals from a wireless network and a GPS subsystem having a radio frequency (RF) front-end capable of receiving a GPS satellite signal. The wireless processing section of the wireless device receives an external clock and determines the offset between the clock in the wireless processing section and that of the external clock. The GPS subsystem then receives the offset information from the wireless processing section, information related to the nominal frequency of the wireless processing section clock and the wireless processing section clock. Using this information and the GPS clock in the GPS subsystem, the GPS subsystem determines an acquiring signal, which is related to a frequency offset between the GPS clock and the network clock. The GPS subsystem then acquires GPS satellite signals in an acquiring unit though the use of the acquiring signal.

The present invention relates to a ground fault detection arrangement for a synchronous three-phase electrical machine, and an electrical system comprising a ground fault detection arrangement and a synchronous three-phase electrical machine. The ground fault detection arrangement injects an off-nominal frequency voltage between a neutral point of the synchronous three-phase electrical machine and ground and measure resultant currents to detect a ground fault.

The present disclosure is concerned with a power supply system for railway traction applications including a multilevel AC/DC converter. The converter comprises a plurality of series-connected single-stage cycloconverters or direct AC frequency converters connected between an AC supply line and a traction transformer. The transformer is operable at a transformer nominal frequency below 3 kHz and above the AC line frequency. On the secondary side of the transformer, more than one parallel-connected secondary converter are provided and connected to a DC link. In case of failure of one of the secondary converters, the multilevel AC/DC converter may continue to operate with reduced power delivered by the remaining operating levels.

A method of tracking a pilot channel to discipline an oscillator includes: downconverting the RF signal to a low frequency that is of the order of, but greater than the chip rate; converting the signal into digital format; computing complex correlations between the received digital signal and local replicas of the PN codes; and establishing from the correlation values what is the nominal frequency error of the local oscillator. Correlation values between the digital signal {s(n)} and at least one locally generated version of I-channel and Q-channel PN signals {I_PN(n)} and {Q_PN(n)} are averaged over multiple periods of the PN signals. Pilot signal tracking accuracy is improved, computational load is reduced without degradation in performance, and the technique is simple enough to be incorporated in an off-the-shelf FPGA.

A test circuit receives a reference signal having a reference frequency and generates a synchronizer input signal having a synchronizer input frequency for inputting into a synchronizer circuit. A frequency generator is configured to offset the synchronizer input frequency at selectable frequencies from a nominal frequency value. An offset measurement circuit is configured to compare the frequency offset for the synchronizer input frequency with the frequency offset of a synchronizer output signal.

A method of measuring instantaneous signal-dependent nonlinear distortion in a system under test in response to a test signal having a varying frequency sinusoidal component, such as a swept frequency signal or a multi-burst signal, uses a time window to locate a frequency of interest in the corresponding varying frequency component of a signal output from the system under test. Once the location of the frequency of interest is located in the output signal, a spectrum of the portion of the output signal within the time window is generated and the magnitudes of the spectral peaks, including the spectral peak for the frequency of interest or nominal frequency and all isolated peaks representing distortion frequencies, are measured. The amount of distortion is calculated as a ratio of the square-root of the sum of the magnitudes of the distortion frequencies to the magnitude of the nominal frequency.

Systems and methods are provided for testing an individual's hearing and correcting audio signals to compensate for the significant variance in each listener's sensitivity to various frequencies of the audible spectrum. An auditory calibration procedure includes identifying a first volume level as a minimum volume level at which nominal frequency tones are audible, a minimum frequency at which said first volume level is audible, a maximum frequency at which said first volume level is audible, and a minimum volume level at which a number of intervening sample frequencies are audible. A substantially parabolic correction curve is generated based on the minimum volume levels at the various sample frequencies. The correction curve is applied to modify real time audio signals generated upon execution of an audio file functionally linked to the processor, wherein the modified real time audio signals are provided to an audio output device.

A mobile communication device (202) and peer mobile communication devices (204, 206) are capable of direct voice and data communication. The mobile communication device has a reference oscillator (104) which is used for generating operating frequencies, and is subject to frequency errors resulting from manufacturing tolerances, heat, and other error sources. The mobile communication device receives a frequency correction message (506) from a peer mobile communication device that has calibrated its reference oscillator. The frequency correction message contain offset information which is used by the mobile communication device to determine its offset (316) from a nominal frequency (302).

The invention discloses a clock source device based on GPS second pulse and a control method thereof. A closed loop negative feedback control principle is adopted, and the output power of a voltage control x-tal crystal oscillator (VCXCO) is controlled at the nominal frequency thereof so as to satisfy the condition that multiple measuring systems can be used synchronously. Experiment results show that after the VCXCO is subjected to closed loop control, the cumulative errors can be controlled within a plurality of pulses.

The invention provides a coherent simulation method for a radar echo Doppler frequency based on real-time frequency measurement. The specific process comprises the steps that step one, a simulator performs envelop extraction on transmitting signal pulses of a radar, and the simulator performs clock counting N3 by using a local clock in N2 radar transmitting pulse periods; step two, a corrected Doppler frequency simulation variable f'd is calculated, wherein f'd=fd*(N1N2/N3)*(1/[alpha]), fd represents the Doppler frequency corresponding to a simulated target, alpha represents a nominal frequency ratio of working clocks of the radar and the simulator, and N1N2/N3 is a frequency correction coefficient; and step three, coherent simulation for the radar echo Doppler frequency is realized by using the Doppler frequency simulation variable f'd. Coherent simulation for the radar echo Doppler frequency can be realized quickly according to the method.

A sensor structure and a method for operating a vibrating sensor of angular velocity comprising a rotor mass and two linearly moving masses is disclosed. The sensor structure and method comprises a rotor mass, two linearly moving masses, and two T-shaped levers each coupled with the two linearly moving masses and to the rotor mass. The T-shaped levers enable the rotor mass and the two linearly moving masses to be excited into an anti-phase primary mode, where the direction of angular momentum of the rotor mass is opposite to the direction of angular momenta of the linearly moving masses. Angular momenta of the rotor mass and the linearly moving masses cancel each other to a high extent, so that the total sum of angular momentum of the structure is very small. Nominal frequency of the anti-phase primary mode is distinctively low as compared to nominal frequencies of other possible primary modes, such as a parallel phase primary mode.