Nec Corporation

Kiyohiko Takahashi

Toshiki Takeuchi

Naoto Ishii

Kazuaki Kunihiro

Taichi Ohtsuji

Kaoru Kishimoto

A signal detection unit detects, from a baseband signal of a received radio wave, two types of fixed signal sections that have different communication information and are present in sufficiently shorter time than a time period in which influence of fading fluctuates, and designate the detected two types of fixed signal sections as an information-1 section and an information-2 section. An information-1 section signal processing unit clips the information-1 section from the baseband signal, and performs Fourier transform on the clipped information-1 section. An information-2 section signal processing unit clips the information-2 section from the baseband signal, and performs Fourier transform on the clipped information-2 section. A feature value computation unit computes a feature value, based on an output of the information-1 section signal processing unit and an output of the information-2 section signal processing unit.

Radio wave feature value computation apparatus, radio wave emission source identification apparatus, and method therefor

A modulation format estimation deviceincludes: a frequency shift correction unitconfigured to estimate the amount of a frequency shift using a baseband signal acquired from a received signal and correct the baseband signal based on an estimation result; a frequency error generation unitconfigured to generate a plurality of frequency errors from a range set based on an error occurring in the estimation of the frequency shift amount; a frequency error introduction unitconfigured to acquire learning baseband signals in which each of a plurality of source signals modulated by different modulation formats is frequency-shifted by each frequency error; and a modulation format estimation unitconfigured to input a corrected baseband signal to a first machine learning model created by machine learning using learning data including the plurality of learning baseband signals and a label, and estimate a modulation format of the received signal.

Modulation format estimation device, and modulation format estimation method

A power supply circuit () includes: a linear amplifier () for generating a linear amplification signal based on an input signal; a first switching amplifier () for generating a first switching amplification signal of a first frequency band based on the linear amplification signal; a second switching amplifier () for generating a second switching amplification signal of a second frequency band based on the first switching amplification signal; and a power supply unit () for supplying a combined signal in which the linear amplification signal and the first and second switching amplification signals are combined to an external circuit as a power supply. It is therefore possible to improve the power efficiency.

Power supply circuit, high-frequency power amplification circuit, and power supply control method

A power supply circuit includes a first power amplifier that amplifies an input signal; a high pass filter that removes frequency components that are lower than a predetermined first cutoff frequency from an output signal of the first power amplifier; a current detector that detects a current value of the output signal of the first power amplifier; a composite signal generation circuit that combines the input signal and an output signal of the current detector; a second power amplifier that amplifies an output signal of the composite signal generation circuit; a low pass filter that removes frequency components that are higher than a predetermined second cutoff frequency from an output signal of the second power amplifier; and a signal output terminal that combines a current of an output signal of the high pass filter and a current of an output signal of the low pass filter and then outputs the resultant signal.

Power supply circuits

The present invention allows amplification with low distortion and high efficiency. A power amplifier of the present invention comprises signal conversion means which generates a digital signal and an analog signal from an input signal that is an amplification target based on a signal generation parameter, a switching amplifier which amplifies the digital signal, a linear amplifier which amplifies the analog signal, and DC level detection means which detect a DC level of at least one of the signal amplified by the linear amplifier and the amplified signal and output a detection result to the signal conversion means, wherein the signal conversion means adjust the signal generation parameter so that the DC level inputted by the DC level detection means is virtually equal to zero.

Power amplifier, radio-frequency power amplification device, and amplification control method

In a power supply circuit which uses a switching amplifier in combination with a linear amplifier, in order to be capable of correcting errors of operation of the switching amplifier and the linear amplifier, that is to say, in order to cause the switching amplifier and the linear amplifier to operate in coordination in a near-ideal state, the power supply circuit is provided with first amplification unit for delaying an input signal by a predetermined set time and amplifying the input signal, current detection unit for detecting a current value of an output signal of the first amplification unit, predicted signal generation unit for generating a pulse signal on a basis of an output signal of the current detection unit and the input signal, second amplification unit for amplifying the pulse signal and signal output unit for combining current of the output signal of the first amplification unit and current of the output signal of the second amplification unit to output the combined current, wherein the set time is time for reducing an effect of delay times generated at the current detection unit, the predicted signal generation unit and the second amplification unit.

Power supply circuit and power supply control method

A power amplifier () comprises: an A/D converter () for converting, to a time discrete signal, an envelope signal included in a high-frequency modulated signal and including only an amplitude modulated component of the high-frequency modulated signal; a switching amplifier () for amplifying the output signal of the A/D converter (); a low-pass filter () for removing high frequency noise from the output signal of the switching amplifier (); a plurality of high-frequency power amplifiers (-to-) for receiving the output signal of the low-pass filter () as a power supply and for amplifying a carrier signal included in the high-frequency modulated signal; and a power controller () for adjusting the average power of the output signal of the power amplifier () by controlling the total gains of the plurality of high-frequency power amplifiers (-to-).

Power amplifier and radio wave transmitter having the same

A power amplifier is provided with an AD converter pulse modulating an envelope signal extracted from a high frequency modulation signal; a switching amplifier amplifying an output signal from the AD converter; a low-pass filter removing high frequency noise from an output signal from the switching amplifier; a voltage control device controlling a power supply voltage of the switching amplifier; and a high frequency amplifier amplifying a phase-modulated signal having a constant envelope and having output from the low-pass filter as a power supply. The average power of the envelope signal to be inputted to the AD converter is permitted to be constant so that an input dynamic range of the AD converter can be most efficiently used. In addition the average power of the output signal from the power amplifier is adjusted by a power supply voltage to be supplied to the switching amplifier.

Power amplifier

A pulse modulator generates a pulse-modulated signal by pulse-modulating and amplifying the amplitude component of an input signal. A low-pass filter filters the pulse-modulated signal from the pulse modulator, and generates an amplified amplitude signal which is obtained by amplifying the amplitude component. An error corrector generates a corrected amplitude signal by correcting an error of the amplified amplitude signal from the low-pass filter by using the amplitude component of the input signal. A mixing unit generates the output signal by mixing the corrected amplitude signal from the error corrector and the phase component of the input signal.

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Tokyo, Japan

Kiyohiko Takahashi