Abstract: A system determines the frequency of grid signals corresponding to an electrical grid in real time. The system includes a transient detector that monitors a grid signal from a voltage meter or a current meter connected to the electrical grid. The system produces, in real time and at a sampling rate, a deviation signal indicative of a periodicity of the monitored grid signal. The system determines, over one or more cycles of the monitored grid signal, a measurement signal corresponding to the deviation signal. The system determines a frequency signal that corresponds a frequency estimation of the monitored signal by applying a frequency estimation when values of the measurement signal are less than a deviation threshold and maintaining the frequency signal at a constant value when values of the measured signal equal or exceeds the deviation threshold.

Abstract: Apparatus and method for determining a phase connection for a power conditioning unit (PCU). In one embodiment, the method comprises determining, by a controller coupled to a multi-phase AC line, a reference phase stamp; determining, by the PCU, a local phase stamp, wherein the PCU is coupled to a subset of phase lines in the multi-phase AC line; determining a difference between the reference phase stamp and the local phase stamp; comparing the difference to one or more of a first range of values or at least a second range of values; and determining the phase connection for the PCU based on whether the difference is within the first range or the at least a second range.

Abstract: The disclosed embodiments relate to components of a memory system that support timing-drift calibration. In specific embodiments, this memory system contains a memory device (or multiple devices) which includes a clock distribution circuit and an oscillator circuit which can generate a frequency, wherein a change in the frequency is indicative of a timing drift of the clock distribution circuit. The memory device also includes a measurement circuit which is configured to measure the frequency of the oscillator circuit. Additionally, the memory system contains a memory controller which can transmit a request to the memory device to trigger the memory device to measure the frequency of the oscillator circuit. The memory controller is also configured to receive the measured frequency from the memory device and uses the measured frequency to determine the timing drift in the memory device.

Abstract: This load connection state detection circuit includes a PNP type transistor whose emitter is connected to a power source terminal, a NPN type transistor where the emitter thereof is connected to the power source terminal, the collector thereof is connected to the base of the PNP type transistor, and the base thereof is connected to the collector of the PNP type transistor, and a diode inserted between the collector of the PNP type transistor and an external antenna load, wherein the diode is configured to perform temperature compensation for the base voltage of the NPN type transistor and prevent currents from flowing from the external antenna load to the PNP type transistor and the NPN type transistor.

Abstract: A flyback converter includes a transformer to convert an input voltage into an output voltage, a control circuit senses a primary current of the transformer to generate a current sense signal, and a sensing circuit is configured to sense a variation of the current sense signal between two time points for extracting the input voltage information therefrom.

Abstract: An apparatus for determining a resonant frequency of a wind turbine tower is provided. The apparatus includes a processing unit configured to receive an acceleration measurement value, the acceleration measurement value representative of the acceleration of the wind turbine tower in the direction parallel to a rotor rotational axis of the wind turbine and/or in the direction perpendicular to both the rotor rotational axis and the tower axis of the wind turbine. The apparatus includes a memory configured to store a series of acceleration measurement values, and the processing unit includes a Fourier transform module configured to calculate a spectral vector based on calculating a convolution-based fast Fourier transform of the series of acceleration measurement values, and includes a resonant frequency calculation module configured to calculate the tower resonant frequency based on the calculated spectral vector.

Abstract: A method for operating a measuring device, in particular, a vectorial network analyzer, which can be connected via at least two ports to a device under test, with excitation units assigned to each port, wherein each excitation unit provides a signal generator, with which the assigned port can be supplied with an excitation signal, provides the following procedural stages: a measurement at measuring positions of the actual phase offset between the excitation signals output at the ports; and a variation of the frequency of at least one of the two signal generators during a correction interval so that a specified set phase offset is achieved at reference positions between the excitation signals output at the ports.

Abstract: Systems and methods that detect a phase loss condition in a three-phase electrical power source are presented. The system includes a detection component that measures and/or monitors a magnitude and frequency of a voltage of a power source, and a controller component that compares measured and/or monitored voltage characteristics to characteristics associated with phase loss.

Abstract: A radio frequency communication device and methods of testing and tuning an antenna attached thereto are disclosed. A radio frequency communication device comprises internal circuitry and an antenna having a plurality of antenna segments associated therewith. Each antenna segment is associated with the antenna in either series or parallel relation through at least one of a fuse and an antifuse. In testing and tuning, a comparison is made to indicate whether the antenna is too short or too long. If the antenna is too short, an antenna segment may be attached to the antenna by initiating an antifuse. If the antenna is too long, an antenna segment may be detached from the antenna by blowing a fuse. If it is indeterminate whether the antenna is too short or too long, an antenna segment may be either attached or detached, the test repeated, and the results of the repeated test compared with the prior test to determine whether the correct action was taken.

Abstract: A method of determining the critical path of a circuit includes first determining the paths, their mean path transit times and their path transit time fluctuations. Paths having similar statistical parameters are combined to form one path group. For each path group, a statistical group figure is, then, calculated and, for the totality of paths considered, a statistical total figure is calculated. Finally, the critical paths of the circuit are determined by taking into consideration the total figure, comparing the group figures at or above a critical path transit time Tc.

Abstract: A power inverter includes a regulator circuit that controls real and reactive power output by the inverter. The regulator measures real and reactive output power by calculating x-phasor components of the inverter's voltage and current output waveforms. Phasor calculation can be adapted for one or more pairs of single-phase voltages and currents. Determining the fundamental in-phase and quadrature components of output voltage and current reduces computational complexity by permitting the regulator to perform its power control processing largely in a dc signal domain, and enables separate real and reactive power control. The power inverter can include islanding detection logic, which exploits the ability to separately control reactive power. Exemplary islanding detection logic is based on determining whether changing the amount of reactive power output by the inverter induces an output frequency shift.

Abstract: A frequency measuring device can measure the frequency of a noisy power system at high speed. The system voltage is measured at timings obtained by equally dividing one reference-wave period. Voltage vectors are calculated which have tip ends, each voltage vector consisting of a real part of a first measured voltage and an imaginary part of another voltage measured at timing 90 degrees before the first measured voltage. The length of a chord connecting tip ends of adjacent voltage vectors is calculated. A voltage root-mean-square value is calculated from voltages measured between two timings spaced from each other by the one reference-wave period. Chord lengths obtained between two timings spaced from each other by the one reference-wave period are summed. Based on the total of the chord lengths and the voltage root-mean-square value, there is calculated a phase angle between two adjacent voltage vectors, from which the system frequency is calculated.

Abstract: Disclosed is a method of measuring the time signal of an electronic device including steps for measuring a true signal and an inverted signal. The measured true path signal and inverted path signal are combined to reduce measurement error and provide an accurate measurement of the time signal of the device under test. Also disclosed is an interface for use between a device-under-test and test equipment. The interface includes means for alternately switching a time signal from the device-under-test to provide a true signal path and an inverted signal path for measurement. A system embodiment of the invention is also disclosed in which an interface and measuring means are used to alternately measure and combine a true signal and an inverted signal to provide an accurate time measurement result.

Abstract: A radio frequency communication device and methods of testing and tuning an antenna attached thereto are disclosed. A radio frequency communication device according to the present invention is disclosed comprising internal circuitry and an antenna having a plurality of antenna segments associated therewith. Each antenna segment is associated with the antenna in either series or parallel relation through at least one of a fuse and an antifuse. In testing and tuning, a comparison is made to indicate whether the antenna is too short or too long. If the antenna is too short, an antenna segment may be attached to the antenna by initiating an antifuse. If the antenna is too long, an antenna segment may be detached from the antenna by blowing a fuse. If it is indeterminate whether the antenna is too short or too long, an antenna segment may be either attached or detached, the test repeated, and the results of the repeated test compared with the prior test to determine whether the correct action was taken.

Abstract: A phase-locked loop with dual-mode phase/frequency detection is provided. The phase-locked loop circuit includes a dual-mode phase/frequency detector, a loop filter, a voltage-controlled oscillator, and a frequency converter. In addition, the dual-mode phase/frequency detector includes a digital phase/frequency detector, an analog phase/frequency detector, a charge pump, and a control unit. When the phase-locked loop circuit starts, the control unit causes a detection output signal from the dual-mode phase/frequency detector to correspond to a digital signal from the digital phase/frequency detector. When the phase-locked loop circuit approaches a lock state, the control unit causes the detection output signal to correspond to an analog signal from the analog phase/frequency detector. The phase-locked loop with dual-mode phase/frequency detection has the advantages of providing linear characteristics, fast switching speed, and high sensitivity.

Abstract: A clock skew measuring apparatus for measuring a clock skew between a plurality of clock signals to be measured in a device under test, includes: a clock signal selecting element for receiving clock signals and outputting them by selecting one of the clock signals one by one; and a clock skew estimator for receiving a reference signal input to the device under test and the clock signals to be measured selected by the clock signal selecting element one by one and for obtaining the clock skew between the clock signals to be measured.