148 results about "Frequency periods" patented technology

A system and method for aligning a local timebase to a remote timebase given a timebase error value from a higher-level protocol, and using the aligned timebases to generate and distribute synchronized events and synchronized adjustable frequency periodic signals across a domain using the aligned timebases. Slightly speeding up or slowing down a periodic signal used to count time, a local timebase may be aligned to a remote timebase when given an error value from a higher-level protocol. A device may be configured to begin generating a periodic waveform at an agreed upon time in the future, once the timebases are aligned, where the time may be synchronized to remote devices via a synchronization protocol and an alignment mechanism. Remote periodic signals may remain synchronized to each other as long as the higher-level protocol and timebase alignment algorithm keep the timebases aligned. A common reference periodic signal may be shared between all devices, and the reference periodic signal or a conditioned version of the reference periodic signal may be specified as the periodic signal to control the operation of the timebase circuitry. The common reference periodic signal may improve synchronization performance beyond the capabilities of the higher-level protocol, and may in addition provide means for synchronization fault tolerance.

A communications cable is provided that reduces the additive distortion of intended information encoded as electromagnetic energy that propagates longitudinally along the cable by varying the propagation velocity along its length. The additive distortion is reduced by varying the propagation periodically at a frequency that is lower than the highest frequency at which said electromagnetic energy propagates along said cable.

The invention discloses a life evaluation method for a modular multilevel converter (MMC). The life evaluation method comprises the following steps: reading year-round temperature data of a running natural environment of the MMC and power data input into the MMC; performing analytic calculation on the average value and the effective value of the current of sub-modules IGBT and Diode of the MMC; calculating the average loss power Ploss,T and Ploss,D of the sub-modules IGBT and Diode of the MMC within the fundamental frequency period; calculating the average temperature rise Tja of a semiconductor device within the working frequency period by use of a Forster network model to obtain the average junction temperature value Tj of IGBT modules (IGBT modules, IGBTs, including IGBT and Diode); modifying fitting calculation of loss of the IGBTs according to the average junction temperature of the IGBTs; calculating the extreme values of the function temperature within the working frequency and counting the year-round fundamental frequency junction temperature cycle; counting fluctuation information of the year-round low-frequency junction temperature; and calculating the failure number Nf of the fundamental frequency and the low frequency of the semi-conductor device by use of a Bayerer life model, and obtaining the life of the MMC in combination with operation conditions. The life evaluation method can reliably forecast the life of the MMC, can effectively improve the forecasting calculation speed through obtaining an analytical expression of both current and the junction temperature, and has the characteristics of project operational capability and the like.

The invention dislcoses a single-phase earth fault line selection method based on transient state high-frequency component correlation analysis. The method comprises the steps that whether or not a single-phase earth fault happens is judged according to the magnitude of a busbar zero-mode voltage instantaneous value, db10 wavelets are adopted for performing five-layer wavelet packet decompositionon zero-mode current of two work frequency periods after each feeder line fault, after the minimum frequency band is removed, node wavelet packet deposition coeffiences are reconstructed and summeredto obtain a fault transient high-frequency capacitance-current component, and a correlation coeefient matrix M between every two feeder lines is obtained; Si is set as a correlation accumulation coefficient for the ith feeder line fault transient high-freuqency capacitance-current component, when rho ij is larger than rho set, Si is equal to 1, 1 is subtracted from Si, and a correlation accumulation coefficient matrix S can be obtained; if Si is larger than 0 constantly, the busbar breaks down; if Si of only one feeder line is smaller than 0, the circuit is a fault circuit; if Si is smaller than 0 constantly, the circuit with the maximum high-frequency-band wavelet packet energy sum is determined as the fault circuit. According to RTDS simulation experimental verification, the method has the good accuracy, adaptability and the like.

A method of generating a MPWM signal for a portable device such as a cellular telephone. For a first duty cycle that includes a MPWM frequency having N magnitude levels, the method generates a first waveform comprising a first and a second On pulse during a first MPWM frequency period. The first and second On pulses are separated by an Off period.

Magnetometer systems, and associated methods, are provided including a first magnetometer adapted to generate an external magnetic field having a characteristic that is varied over time, and a second magnetometer adapted to receive the magnetic field and generate at least one magnetometer signal representing a change in the magnetic field. In one embodiment, the magnetic field characteristic includes the frequency of the generated magnetic field. In another embodiment, the magnetic field characteristic includes the frequency period of the magnetic field.

The invention provides an oscillator circuit with the characteristic of frequency jitter, comprising a reference current modulating circuit and an oscillator main body circuit; wherein, the reference current modulating circuit mainly comprises a fixed resistor, a variable resistance network, a compensation capacitor and a negative feedback control loop consisting of four NMOS transistors. The oscillator main body circuit comprises two transmission gates, two capacitors, a comparator, a D trigger, two current mirror, five NMOS control transistors and two inverters. By adjusting the equivalent resistance value of the variable resistance network in a control loop periodically, the reference current is modulated into current which changes periodically and is used as charging current of the oscillator, thus generating oscillating impulse, the frequency of which changes periodically. The invention has simple implementing structure and can save the area of a chip.

The invention discloses a control method for a dual-bucking full-bridge grid-connected inverter, belonging to an inverter control method. In the invention, the grid current of the grid-connected inverter is sampled by a current sensor; the network voltage is sampled by a voltage sensor; the grid current given having the same frequency and the same phase with the network voltage is output by a phase locking ring; a grid current ring receives the grid current given and the grid current feedback signal and outputs the voltage given 1. A PWM (pulse-width modulation) generating circuit receives the voltage given 1 and outputs logic control signals PWM1 and PWM2. A power switch tube drives the logic circuit to receive the logic control signals PWM1 and the PWM 2 as well as the network voltage feedback signal, and outputs the high and low level driving signals of all power switch tubes. In the invention, single-polarity frequency-doubling control is realized, the volume and the weight of a filter are reduced, the problem of zero crossing point distortion occurring to the traditional single-polarity modulation network current does not exist, only two power switch tube high-frequency switches are used in every half working frequency period, and the conversion efficiency is improved.

The present invention relates to an electrical test field of high voltage direct current transmission converter valve, and especially relates to a synthesizing method of operation test of high voltage direct current transmission converter valve. The method comprises the following steps: firstly starting the operation of a voltage source, extracting energy by each high-level board on a sampled converter valve and the auxiliary valve of current source, and then activating the current source for synthesizing the operation test. Preferably the current source is activated when the voltage source operates for 3-5 industrial frequency periods.

A device and method for controlling the changing operation of an on-load tap changer (LTC) that interrupts current surely passing the current zero point of a commercial frequency and prevents a serious accident such as short-circuiting between taps caused by an interruption failure in any operation environment with any kinds of consumer loads and either in a single or parallel arrangement are provided. The device includes a current zero point detecting unit that detects a zero point in the waveform of current passed through an LTC, a current zero point cycle measuring unit that measures the cycle of the current zero point detected by the current zero point detecting unit, a commercial frequency determining unit that generates an output signal when the cycle of the current zero point measured by the current zero point cycle measuring unit corresponds to a commercial frequency, and an actuation signal output unit that outputs an actuation signal used to have the LTC carry out tap changing operation in response to the output signal of the commercial frequency cycle determining unit.

The present invention relates to a method for reducing the radio frequency interference in the double module mobile terminal, the GSM outputs an effective control signal when the GSM is working at the frequency period between 1800M to 1900M, otherwise, the control signal is ineffective; if the control signal is effective and the CDMA is working at the frequency of 1900M, the transmission power of the CDMA signal will be weaken; the invention also relates to a device for reducing the radio frequency interference in the double module mobile terminal, which includes a global mobile communication system GSM module and a code division multiple access CDMA module, and the device also includes an analogue switch, and the control end of the analogue switch leads out the control signal a from the front end of the GSM radio frequency or the GSM base band circuit, the access signals b1 and b2 of the CDMA base band circuit are inputted as the two inputs of the analogue switch, and the control signal inputs the strobe alternative access signal to the CDMA radio frequency transmitting circuit.

The invention relates to a clock pulse signal generation method, which is performed on a display. Specifically, the clock pulse signal generation method comprises the steps of: providing at least one initial clock pulse signal, which includes an initial high potential in a duty cycle within a frequency cycle; and performing potential shifting operation on the initial clock pulse signal so that the initial high potential of the initial clock pulse signal is respectively shifted to a first high potential and a second high potential in a first time period and a second time period within the duty cycle, thereby resulting in at least one new clock pulse signal which is used by a grid drive circuit of the display to generate a grid drive signal, wherein the first time period is earlier than the second time period, and the first high potential is larger than the second high potential.

The invention discloses a phase-multiplexing-based full-range sweep frequency OCT (Optical Coherence Tomography) imaging method and system. An electrooptical modulator is arranged in a reference arm of the sweep frequency OCT system so as to realize high-speed phase modulation of an interference spectrum. Preset phase change can be kept between adjacent sampling points of the collected interference spectrum through trigger synchronization between a data collecting card and the electrooptical modulator so as to realize collection on phase multiplexing of the interference spectrum in a single sweep frequency period, the data sampling points of the collected interference spectrum are grouped according to corresponding additional phases, the grouped sampling points are respectively mapped in a wave number space with sampling points at equal intervals so as to form phase shift interference spectrum data subsets of the wave number space. Interference spectrum data can be constructed by utilizing the phase shift interference spectrum subsets so as to reconstruct full-range sweep frequency OCT images. On the basis of phase modulation and multiplexing of the interference spectrum in the single sweep frequency period of the electrooptical modulation, the phase shift is fast in speed and high in precision, the image rejection rate is high, and high-sensitivity imaging in an interesting depth area can be realized.

The invention discloses an OFDM power-frequency synchronous power carrier communication and physical layer coded modulation method. The communication method comprises that P OFDM symbols are sent within 1/2 AC power-frequency period, and P represents a positive integer; the SNR of each subcarrier and the corresponding OFDM symbol is measured repeatedly; and according to a measured SNR sequence, a bit loading table is generated via a time domain and frequency domain 2D ToneMap and sent to achieve the channel adaptability and improve the reliability and communication speed of the whole communication system. The method of the invention has the advantages that the sparsity of period static characteristic and noises in the time and frequency domains of power line noises is utilized fully, the utilization rate (speed) of a PLC channel is improved, the transmission reliability and the system throughput are improved, and coding efficiency is high. The method can support an OFDM power-frequency synchronous continuous sending mode as well as a discontinuous sending mode.

The invention discloses a ship speed detection method based on visible light remote-sensing images. According to the method, the speed of a ship is detected through the visible light remote-sensing images. The method includes the implementation steps of (1) acquiring the visible light remote-sensing images, (2) preprocessing the images, (3) acquiring a gray value matrix of the wake of the ship, (4) acquiring the frequency period of the wake of the ship, (5) detecting the speed of the ship, and (6) outputting the speed of the ship by a computer. By utilizing the corresponding relation between the frequency period of the wake of the ship and the speed of the ship, the speed of the ship is acquired with the method of combining the ship wake gray value matrix extraction and minimization calculation. The ship speed detection method based on the visible light remote-sensing images can be used for monitoring speed of ships in the marine monitoring field, and can improve the detection accuracy of speed of ships, lower system complexity and promote real time performance.

A thin film capacitor includes a pair of electrodes and a dielectric layer having piezoelectricity sandwiched therebetween. The phase characteristic of an impedance resulting from application of a voltage to the pair of electrodes peaks periodically according to a frequency of a signal to be inputted or outputted. The frequency of the signal is adjusted to fall in between the values representing the adjacent peaks. Since there are periodic peak values that depend upon the frequency of the inputted or outputted signal, in fabricating a band-pass filter, a higher attenuation can be attained by ensuring that the peak value stands at a low-frequency level. Thus, a higher attenuation can be attained at low frequencies without sacrificing the band-pass characteristic, whereby making it possible to produce a band-pass filter that is excellent in band-pass characteristic.

A method and apparatus is described for contact-free 3 dimensional-measuring of a moving object with periodic motion. The method and apparatus makes use of the projection of a defined intensity pattern onto the moving object and the recording and analysis of a reflected pattern from the object wherein the intensity pattern projection is synchronized to a characteristic periodic frequency period or sub-period of the moving object.

The invention discloses a phase angle tracking method for a power grid. The phase angle tracking method includes steps of 1), acquiring three-phase voltage of the power grid to obtain three-phase voltage instantaneous values; 2), obtaining components U alpha and U beta of the voltage of the power grid in a two-phase static coordinate system according to 3/2 conversion; 3), calculating instantaneous phase angles of the power grid by the aid of arc tangent transformation; 4), calculating an instantaneous step value according to an equation of delta theta=theta i-theta i-1; 5), calculating phase step within a working frequency period when an absolute delta theta is larger than 4Xpi /3 according to an equation of theta s=T/K; 6), determining upper and lower envelope curves according to equation of LH(i)=theta sXi+theta s/3 and LL(i)=theta sXi-theta s/3; and 7), setting theta(i) as a true value if LH (i) is larger than or equal to theta (i) and theta (i) is larger than or equal to LL (i), setting LH (i) as a true value if theta (i) is larger than LH (i), and setting LL (i) as a true value if theta (i) is smaller than LL (i). By the aid of the phase angle tracking method, phase angles and frequencies of the power grid can be precisely calculated.

A method for limiting debit card transactions includes establishing a limited debit card account linked to a financial funding account. A frequency period for funding the limited debit account and a maximum holding amount for the limited debit account are established by an individual. A debit card linked to the limited debit account is issued to the individual for making withdrawals and purchases. Based on a predetermined method and time period interest is paid by the entity maintaining the limited debit account, to the individual. Also, upon expiration of the frequency period funds are transferred from the financial funding account to the limited debit account to return the limited debit account to the designated maximum holding amount.