225 results about "Crest factor" patented technology

A method for crest factor reduction of a multi-carrier signal is disclosed. The method comprises determining a plurality of signal values of a plurality of single-carrier signals prior to combining the plurality of single-carrier signals to form the multi-carrier signal. The method further comprises performing a joint potential peak detection on the plurality of signal values, producing a temporal position of a possible peak in the multi-carrier signal, generating a plurality of cancellation pulses, and injecting the plurality of cancellation pulses to the plurality of single-carrier signals at temporal injection positions which correspond to the temporal position of the possible peak in the multi-carrier signal. The single-carrier signals are then combined to form a crest factor reduced multi-carrier signal. A corresponding circuit and corresponding computer program product useable during manufacture and operation are also disclosed.

An electrosurgical generator is disclosed capable of controlling the output crest factor, as well as the output power of the electrosurgical generator across a range of tissue impedances during electrosurgery. The control occurs automatically, in real time and continuously during the duration of electrosurgical activation of the electrosurgical generator by varying both the output crest factor and output power based on the changing impedance of the tissue. The electrosurgical generator also includes controls for allowing a surgeon to manually select the appropriate crest factor value and power output value for a particular surgical procedure. By automatically adjusting the output crest factor and by giving the surgeon the ability to manually “tailor” the output crest factor across a range of tissue impedance, the electrosurgical generator enhances the ultimate surgical effect and desirable surgical results.

An electronic ballast for driving a gas discharge lamp includes a rectifier, a valley-fill circuit, an inverter having first and second series-connected controllably conductive switches having complementary duty cycles, a control circuit for controlling the controllably conductive switches, and an independent cat ear power supply to provide power to the ballast control circuits. The result is a ballast having substantially improved power factor, THD, and current crest factor. In a preferred embodiment, the valley-fill circuit includes an energy storage device that stores energy in response to a controllably conductive switch. In an especially preferred embodiment, the controllably conductive switch of the valley-fill circuit is also one of the switches of the inverter.

A method for conducting electrosurgery using increased crest factors employs an electrosurgical instrument having at least one conductive element that is surrounded by an insulation layer except at a conductor edge portion of the conductive element. The conductor edge portion and insulation layer each having unique geometric shapes and composition of the parts concentrate the electrosurgical power, reduce or eliminate the production of smoke and eschar and reduce tissue damage. The outer profile of the insulation layer and conductive element are configured to facilitate the flow of electrosurgical decomposition products away from the conductor edge where they are formed. The combined effects of the electrosurgical instrument configurations enable safe use of crest factors of 5 or greater in electrosurgical procedures.

The present invention discloses a method for increasing the power amplifying efficiency and the digital predistortion broadband communicator thereof. The digital predistortion broadband communicator comprises a digital signal processing module, an envelope signal channel, a forward signal channel, a feedback signal channel and a radio frequency power amplifier. The digital signal processing module is used for receiving the base band IQ complex signal and generating envelope signal, forward signal and feedback signal with carrier frequency after deplexing. The envelope signal channel executes A/D converting and filtering to the envelope signal and comprises a broadband envelop electric power modulator which is used for generating the voltage varying real-time according to the real-time variation of the envelope signal and supplying the voltage to the radio frequency power amplifier as the drain electric voltage offset. As the method of the invention and the digital predistortion broadband communicator adopt a base band crest factor reducing technique, a digital predistortion technique, an envelop tracing technique, a broadband envelop electric power modulating technique and the like, the power amplifying efficiency is greatly increased and the application of the envelop tracing technique in the wideband signal system field is promoted.

Apparatus and methods configure digital predistortion linearizers for power amplification of bandlimited signals using non-linear amplifiers. The predistorter is configured to achieve both crest factor reduction (CFR) and predistortion for linearization. One embodiment advantageously reduces processing requirements conventionally associated with CFR by considering only the in-band component, that is, the information bearing component, of the desired signal to be reproduced for those cases in which the mitigation of in-band error vector magnitude (EVM) is preferred over the reduction of spurious out-of-band emissions.

A power conversion circuit improves lamp operating life and lamp efficiency by driving a fluorescent lamp with a square wave signal. The square wave signal is an alternating current signal with relatively fast transition times. The square wave signal advantageously reduces lamp current crest factor for more efficient operation of the fluorescent lamp.

A device for generating a crest factor reduced signal is disclosed. The device comprises an interface for receiving an input signal; a peak identifier for identifying one or more peak regions of the input signal; a squelch level determiner for determining a reduction of the input signal near the one or more peak regions; a squelcher for reducing the one or more peak regions of the input signal as indicated by the squelch level determiner; and an interface for outputting a crest factor reduced signal. The crest factor reduced signal has a reduced dynamic range due to the reduction of the one or more peak regions of the input signal. The crest factor reduced signal also has been filtered to reduce undesired frequency components by: calculating a difference between a squelched signal from the squelcher and the input signal, band-pass filtering the difference to generate a result, and summing the result with the input signal that has been delayed.

A system and method for crest factor reduction of OFDM transmission systems using selective sub-carrier degradation, is disclosed. A modulated communications signal comprising a series of symbols is converted into parallel format in groups of plural symbols in the frequency domain. Crest factor reduction reduces a primary peak of the groups of plural symbols by selective sub-carrier degradation, to generate peak reduction symbols. The groups of plural symbols are converted into time domain symbols, and combined with the peak reduction symbols to provide peak reduced symbols in time domain.

A method and apparatus for a radio base station (200) generates a multicarrier communication signal having a reduced crest factor by processing a block of samples (231) with a peak search window (271) to identify and suppress signal peaks exceeding a power threshold value.

An RF detector configured to provide two outputs, one being a function of the true RMS power level of an RF input signal, and the other being a function of the instantaneous/peak power of the RF input signal, normalized to the average power level. The RF detector includes a variable gain detection subsystem including a single detector or detector array that provides a representation of the power level of the RF input signal. The detector or detector array is common to both the RMS power detection channel and the instantaneous/peak power detection channel of the RF detector. A method of RF detection includes providing representations of the RF input signal at different gain levels, selecting one or more of the representations, and averaging the selected signals. The gain levels of the selected representations is adjusted to provide information about the average power level of the RF input signal.

A method for crest factor reduction of a multi-carrier signal is disclosed. The multi-carrier signal comprises a plurality of single-carrier signals, each single-carrier signal having signal-specific spectral properties. The method comprises identifying a peak in the multi-carrier signal and a time of occurrence of the peak and generating a plurality of cancellation pulses depending on the time of occurrence of the peak. A particular cancellation pulse of the plurality of cancellation pulses is associated with a particular single-carrier signal and cancellation pulse-specific spectral properties of the particular cancellation pulse substantially match the signal-specific spectral properties of the associated particular single-carrier signal. The method further comprises combining the plurality of cancellation pulses to form a combined cancellation pulse and applying the combined cancellation pulse to the multi-carrier signal to reduce the peak. A corresponding circuit and corresponding computer program products useable during manufacture and operation are also disclosed.

An apparatus and a method for processing reduced bandwidth Envelope Tracking (ET) and Digital Pre-Distortion (DPD) are provided. The apparatus includes a Crest Factor Reduction (CFR) unit, a resealing Digital Pre-Distortion (DPD) unit, an envelope converter, a Supply Modulator (SM), and a Power Amplifier (PA). The CFR unit suppresses an increase of a side lobe occurring when a Peak to Average Power Ratio (PAPR) decreases with respect to a signal generated in a baseband according to a standard and passes through a transmit (Tx) filter. The resealing DPD unit receives an original envelope amplitude and a reduced bandwidth envelope amplitude of an In-phase/Quadrature-phase (I/Q) signal output from the CFR unit to perform a pre-distortion process. The envelope converter converts an envelope signal to a reduced bandwidth envelope signal based on the I/Q signal output from the CFR unit.

The invention discloses a power control device and method. The method comprises the following steps: performing TAGC (transmission automatic gain control) treatment on a pre-stored training sequence; performing CAGC (carrier automatic gain control) treatment on a signal on each carrier before multi-carrier superimposition, and performing interpolation filtration on the signal after the CAGC treatment to finish spectrum formation; performing spectrum shift on the signal after the spectrum formation; performing CFR (crest factor reduction) treatment on the signal after the multi-carrier superimposition; performing high-speed pre-distortion treatment on the signal after the CFR treatment according to the calculated DPD (digital pre-distortion) coefficient; performing digital automatic control gain treatment on the signal after the high-speed pre-distortion treatment; performing digital-to-analogue conversion on the signal after the digital automatic control gain treatment; performing PGC (programmable gain control) treatment on the signal after the digital-to-analogue conversion, wherein the signal enters a power amplifier and then is output; performing gain control on the signal coupled back by the power amplifier; and controlling the gain fed back to a DPD module. Meanwhile, the power adjustment of the feedback digital signal is finished by comparing the feedback digital signal power with the digital signal power after the pre-distortion.

An electronic control system especially for non-linear loads, such as high pressure sodium (HPS) lamps, includes an active power factor correction circuit (APFC). The system provides a power factor correction of above 0.95; total harmonic distortion (THD) below 5%; lamp crest factor (LCF) close to unity; efficient power consumption and reliable open circuit voltage (OCV) under all power line conditions. A ballast would include integrated circuits (ICs) and a four-arm transistor bridge which is directly driven by integrated circuits. The bridge generates reversal of polarity to the load. An approximate average current feedback is derived from a load current. A resistor divider in parallel with the load provides voltage feedback. The average current feedback and voltage feedback are added together to provide an approximation of power consumed by the load, without the complex circuitry required for a true power feedback of current multiplied by voltage. That composite feedback signal is transmitted to the integrated circuit (IC) which compares it with an internal reference voltage and which adjusts the IC output to minimize the error.

A method for sensing touch inputs to a digital equipment is provided, comprising the steps of sensing a sound/vibration signal generated by a touch, digitally processing the sensed sound/vibration signal, and determining the type of touch means that has generated the touch and the intensity of the touch based on the properties of the processed sound/vibration signal, wherein the properties include at least one of the following properties of the sound/vibration signal in time domain: maximum amplitude, average amplitude, average frequency, mean, standard deviation, standard deviation normalized by overall amplitude, variance, skewness, kurtosis, sum, absolute sum, root mean square (RMS), crest factor, dispersion, entropy, power sum, center of mass, coefficients of variation, cross correlation, zero-crossings, seasonality, DC bias, or the above properties computed for the first, second, third or higher order of derivatives of the sound/vibration signal; and the following properties of the sound/vibration signal in frequency domain: spectral centroid, spectral density, spherical harmonics, total average spectral energy, band energy ratios for every octave, log spectral band ratios, linear prediction-based cepstral coefficients (LPCCs), perceptual linear prediction (PLP) cepstral coefficients, mel-frequency cepstral coefficients, frequency topology, or the above properties computed for the first, second, third or higher order of derivatives of a frequency domain representation of the sound/vibration signal. There is also provided a device for sensing touch inputs.

A method and device for reducing Peak-to-Average Power Ratio (PAPR) of a transmitted signal in a wireless telecommunication system utilizing CFR technique, the method including performing peak-windowed clipping of a transmitted signal using at least two cascaded clipping stages and individually configuring parameters for each clipping stage before performing the peak-windowed clipping.

The present disclosure relates to an electrosurgical generator which includes a controller configured to generate a first pulse train having at least one first control pulse and at least one first reset pulse. The controller also includes a second pulse train having at least one second control pulse and at least one second reset pulse. The first control pulse(s) and the second control pulse(s) are asynchronous and the reset pulse(s) are synchronous. The electrosurgical generator also includes an RF output stage which includes a first switching element and a second switching element. The control pulses are configured to activate the first switching element and second switching elements, respectively, in an asynchronous fashion to generate a non-continuous RF waveform.

Orthogonal frequency division multiplexing (OFDM) is a spectrally efficient multicarrier modulation technique for high speed data transmission over multipath fading channels, but has low power efficiency. OFDM signals have large crest factors, or peak-to-average power ratios (PARs) which lead to power inefficiency in the RF portion of the transmitter. Selected mapping can be used to reduce the PAR of an OFDM signal and is distortionless. A technique is disclosed that links the index of a phase rotation sequence used in selected mapping to the location of pilot tones that are used to estimate the channel. Each pilot tone location—phase sequence selection produces a different PAR value for the time-domain OFDM signal, and the signal with the lowest PAR value is transmitted. The technique is “blind” in that the optimum pilot tone location—phase sequence index is not transmitted as side information. A technique to blindly detect the optimum index at the receiver is also disclosed.

A method is provided for minimizing the peak power level in a combination of orthogonal frequency division multiplexed (OFDM) tones. The method is particularly effective when the information to be communicated is digital data consisting of long patterns of “1”s or “0”s. The digital data of the message is combined with a scrambling vector before the data is modulated. The randomization of data patterns, in turn, leads to a more random combination of OFDM tone amplitude being transmitted. The message is recovered at the receiver by removing the scrambling vector. A table of scrambling vectors is maintained at the transmitters and receivers. The table pointer to select the scrambling vector is selected in response to the position of the message in the communication structure. An OFDM communication system using the above-described method is also provided.