18 results about "Crest factor" patented technology

Methods and apparatus for performing crest factor reduction (CFR) to adjust the output power of a digital-to-analog converter (DAC) are described. An example method includes applying CFR to a digital input signal to generate a crest factor reduced signal. Applying CFR includes: (a) adjusting an amplitude of a real component of the digital input signal based on a first threshold while maintaining a phase of the digital input signal; and (b) adjusting the amplitude of the imaginary component of the digital input signal based on a second threshold while maintaining the phase of the digital input signal. The crest factor reduced signal is converted to an analog signal via a DAC.

A method for compensating for nonlinear distortion of a signal, a model, and a communication system are disclosed. Based on a preset nonlinear compensation fusion model, digital pre-distortion (DPD), crest factor reduction (CFR) and error compensation are separately performed on an initial orthogonal frequency division multiplexing (OFDM) signal, and an initial OFDM signal after nonlinear distortion compensation is obtained accordingly. The nonlinear compensation fusion model may include a band limited-digital pre-distortion (BL-DPD) module, a band limited-crest factor reduction (BL-CFR) module and an error compensation module.

The invention discloses an overload protection method for an audio power amplifier, and relates to the field of audio power amplifiers. According to the invention, the instantaneous output amplitude signal of the power amplifier is divided by the preset overload threshold impedance to obtain the reference current dynamically changing along with the signal, and the actual output current is compared with the reference current in real time, so that the protection criterion is converted from a fixed current threshold to an adaptive impedance threshold; therefore, real-time identification and turn-off of a low-impedance abnormal load are realized, and normal output of a high-peak-factor audio signal is compatible.

The invention relates to a crest factor reduction method and device based on a peak value type, and relates to the technical field of signal processing, and the method comprises the steps: calculating a modulus value of an in-phase orthogonal signal based on an in-phase component and an orthogonal component of the in-phase orthogonal signal; determining a peak value based on the modulus value of the in-phase orthogonal signal and a preset first peak clipping threshold; determining the type of the peak value based on the peak value and the first peak clipping threshold; determining a base pulse based on the type of the peak value; calculating a pulse coefficient based on the first peak clipping threshold, the in-phase orthogonal signal and the modulus value of the in-phase orthogonal signal; calculating a peak clipping pulse based on the basic pulse and the pulse coefficient; subtracting the peak clipping pulse from the in-phase orthogonal signal to obtain a signal after peak cancellation; determining a module value of the signal after peak cancellation; and based on the signal after peak cancellation, the module value of the signal after peak cancellation and a preset second peak clipping threshold, determining a signal after hard peak clipping.

Techniques are disclosed for the use of Crest Factor Reduction (CFR) technique that utilizes a cancellation pulse signal having a reduced length. The CFR technique may be applied to a signal to be transmitted, which may comprise a composite signal having one or more carrier signals. Each carrier signal of the composite signal may be filtered via a respective channel filter and then recombined to form the signal to be transmitted, on which the CFR operations are then applied. The length of the cancellation pulse signal is less than the number of taps of the channel filter with the largest number of taps. This reduction in cancellation pulse signal length significantly reduces the processing power required to perform the CFR operations while maintaining regulatory emissions compliance.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may perform a crest factor reduction on a radio frequency (RF) waveform in multiple passes, wherein the multiple passes each include: a clipping operation to reduce a peak-to-average power ratio (PAPR) associated with the RF waveform according to a threshold; and a filtering operation to remove at least a portion of out-of-band emission from the clipped RF waveform. The UE may transmit the RF waveform over a wireless channel, wherein the RF waveform transmitted over the wireless channel satisfies a spectral mask. Numerous other aspects are described.

A method of synthesizing an audio signal for use by a horn apparatus for a vehicle to produce an audible warning sound, wherein the audio signal contains a fundamental frequency and harmonics corresponding to the fundamental frequency. The method includes: selecting weights for each of a plurality of harmonics corresponding to a fundamental frequency; using the selected weights to synthesize a precursor audio signal from only the fundamental frequency and the plurality of harmonics; compressing the precursor audio signal one or more times to provide an audio signal which has a crest factor that is below a predetermined threshold.

A system includes a receiver (RX) configured to receive an RX output signal in an RX band, where the RX output signal has a first passive intermodulation (PIM) source in the RX band and a second PIM source in the RX band; and a processing device configured to: receive the RX output signal from the receiver on an RX path, receive a crest factor reduction (CFR) output signal from a CFR on a transmit (TX) path, identify the first PIM source and the second PIM source based on the RX output signal and the CFR output signal, calibrate the CFR output signal based on the first and second PIM sources in the RX output signal to generate a non-linear actuation (NA) input signal, and generate an intermodulation distortion signal by using an NA function on the NA input signal.

The embodiments described herein relate to the execution of combined input signals x / x m The peak factor reduction is used to determine the output signal y / y for transmission to multiple wireless devices. m Methods and apparatus, wherein a combined input signal is derived from a plurality of individual input signals, wherein each individual input signal includes data intended for use with one of a plurality of wireless devices. One method includes: generating a high-amplitude portion x of the combined input signal by applying an amplitude threshold to the combined input signal. high / x m high Wherein, the amplitude threshold is derived from the highest allowed clipping distortion level on a single input signal; for one or more of a plurality of single input signals: by utilizing the corresponding factor α derived from the corresponding allowed clipping distortion level for the corresponding single input signal. q The corresponding compensation signal is generated based on the individual input signal; and the output signal is determined by adding the combined input signal to the corresponding compensation signal and subtracting the high amplitude portion of the input signal.

The present application relates to a kind of frequency division multiplexing biological impedance multi-frequency measurement system and method.The method is aimed at the frequency range of biological tissue impedance change, the problem that excitation signal and response signal are difficult to sample in whole cycle in actual measurement is solved, and the accuracy of biological tissue impedance measurement is improved.Using the OFDM frequency division multiplexing idea minimizes crest factor, uses grouping search algorithm to optimize the phase at each excitation frequency, reduces peak factor, and improves signal-to-noise ratio;And an adaptive dynamic synchronous sampling rate adjustment method combined with window function optimization is proposed, which realizes whole cycle sampling and makes the optimal scheme of Fourier change spectrum resolution to fall in the measurement frequency range, and improves the measurement accuracy.

Methods and systems for performance assessment of a multichannel signal generator including a plurality of transmit channels. Configuration information is sent to the multichannel signal generator. An amplitude and phase is determined for a plurality of tones, and the tones are distributed over the transmit channels. Each transmit channel generates a periodic modulated signal comprising its respective tone. The generated periodic modulated signals are combined in a combined signal. The amplitudes and phases are determined so that the combined signal has a crest factor below a given threshold level. The combined signal is measured, based on the configuration information, and aligned relative to a reference combined signal. Individual tones are extracted from the aligned combined signal, and a relative delay and / or a phase offset is determined for at least two transmit channels by comparing the extracted individual tones with corresponding individual tones extracted from the reference combined signal.

A method for compensating for nonlinear distortion of a signal, a model, and a communication system are disclosed. Based on a preset nonlinear compensation fusion model, digital pre-distortion (DPD), crest factor reduction (CFR) and error compensation are separately performed on an initial orthogonal frequency division multiplexing (OFDM) signal, and an initial OFDM signal after nonlinear distortion compensation is obtained accordingly. The nonlinear compensation fusion model may include a band limited-digital pre-distortion (BL-DPD) module, a band limited-crest factor reduction (BL-CFR) module and an error compensation module.

Methods, systems, and devices for wireless communications are described. A transmitting device may determine channel quality, and may shape frequency domain noise (e.g., crest factor reduction (CFR) related noise) to locations in which channel quality is poor. For example, by shaping channel noise to frequency resources with poor channel quality (e.g., instead of uniformly distributing such channel noise), transmissions may be more reliable, and quality on other frequency resources may be improved (e.g., without negatively impacting the quality of communications via frequency resources that already have a low channel quality), resulting in improved dynamic range of the signal (e.g., peak to average power ratio (PAPR)), which means that power efficiency is improved.

The invention relates to the technical field of data processing, and discloses a peak offset crest factor reduction implementation method and device based on a multi-phase structure, and the method comprises the steps: a time delay processing module obtains a time delay signal, an interpolation filter module obtains a fractional time delay copy, a peak detection module obtains a peak detection signal, and a peak offset crest factor reduction module obtains a peak offset crest factor; the resource distributor module updates a resource control signal, the multi-phase CPG coefficient module obtains a CPG coefficient signal, the CPG resource module determines a peak value offset coefficient, the peak value scaling module calculates a peak value scaling factor, and the calculation module determines an output signal corresponding to an input signal according to a peak value offset waveform and a time delay signal. Therefore, by integrating the multi-phase structure, high-precision peak detection, phase compensation and efficient multi-phase CPG coefficient generation, the problem of subsequent peak regeneration caused by peak false detection and missing detection at a low oversampling rate is solved, the peak offset effect is improved, and the multi-carrier signal PAPR suppression performance is improved.

A processor of this inspection device executes processing including: acquiring a sound signal of a percussion instrument sound in a first time; calculating a power density corresponding to the time and frequency in the first time; dividing the maximum value of the power density on the high frequency side greater than or equal to a preset frequency threshold by the effective value of the power density in the first time on the high frequency side to calculate a crest factor on the high frequency side; dividing the maximum value of the power density on the low frequency side less than the frequency threshold by the effective value of the power density in the first time on the low frequency side to calculate a crest factor on the low frequency side; and determining whether the result of connector fitting work is good or bad on the basis of the crest factor on the high frequency side and the crest factor on the low frequency side.

The present disclosure provides a system and a method for crest factor reduction (CFR) with a restricted peak regrowth. The system receives a complex signal from a physical layer (PHY) of a base station equipped with orthogonal frequency division multiplexing (OFDM). The system uses a coordinate rotation digital computer (CORDIC) to convert the complex signal into a polar form. Further, the system utilizes an advanced interpolation processing (AIP) technique to minimize the peak regrowth that can happen in an x4 (digital up-conversion (DUC) in the later stage of a downlink chain. Hence, a teething problem of peak growth due to DUC process is restricted to a limited regrowth in the proposed CFR design. Further, the CFR design can operate multiple multiple-input multiple-output (MIMO) channels by multiplexing in time domain which further reduces resource utilization.

A system includes a receiver (RX) configured to receive an RX output signal in an RX band, where the RX output signal has a first passive intermodulation (PIM) source in the RX band and a second PIM source in the RX band; and a processing device configured to: receive the RX output signal from the receiver on an RX path, receive a crest factor reduction (CFR) output signal from a CFR on a transmit (TX) path, identify the first PIM source and the second PIM source based on the RX output signal and the CFR output signal, calibrate the CFR output signal based on the first and second PIM sources in the RX output signal to generate a non-linear actuation (NA) input signal, and generate an intermodulation distortion signal by using an NA function on the NA input signal.

The present disclosure provides a system and a method for crest factor reduction (CFR) with a restricted peak regrowth. The system receives a complex signal from a physical layer (PHY) of a base station equipped with orthogonal frequency division multiplexing (OFDM). The system uses a coordinate rotation digital computer (CORDIC) to convert the complex signal into a polar form. Further, the system utilizes an advanced interpolation processing (AIP) technique to minimize the peak regrowth that can happen in an x4 (digital up- conversion (DUC) in the later stage of a downlink chain. Hence, a teething problem of peak growth due to DUC process is restricted to a limited regrowth in the proposed CFR design. Further, the CFR design can operate multiple multiple-input multiple-output (MIMO) channels by multiplexing in time domain which further reduces resource utilization.