Hitachi, Ltd.

Nihon Dempa Kogyo Co., Ltd.

Hitachi Denshi Kabushiki Kaisha

Hitachi-kokusai Electric Inc.

Kokusai Electric Co., Ltd.

Dsp Technology Associates, Inc.

Other

Nippon Telegraph and Telephone Public Corporation

Nippon Hoso' Kyokai

Nobuo Tsukamoto

Toshiyuki Akiyama

Atsushi Miyashita

Seiichi Sano

Kazuo Akaike

Tsukasa Kobata

Hiroyuki Takesue

Tatuhiro Nakada

Hiroshi Kuwahara

Kumiko Takikawa

Naoki Onishi

Hiroshi Noguchi

Kazuo Yamakido

Tatsuhiro Nakada

Kaoru Kobayashi

Arata Nakagoshi

Tsuyoshi Shiobara

Yoshiro Kokuryo

Hiroki Kimura

Masahiro Koya

Yasuo Kitayama

Nobuo Hirose

Tetsuomi Ikeda

Yuji Sakamoto

Atushi Hoshi

Isao Ishikawa

Satoshi Sakata

Kozo Ono

Isao Ikuta

Teiji Okamoto

Yasuhiro Kita

Hisashi Andoh

Shirou Tanabe

Masaichi Nagai

Yoshihito Maeda

Jiroh Sakaguchi

Nobuo Murata

Narimichi Maeda

Minoru Fukuda

Tsutomu Yamakawa

Kenichi Tsuchida

Yoshimi Kato

Shigeru Takegishi

Yukiji Yamauchi

Shigeki Moriyama

Seiei Ohkoshi

Isamu Mitomo

Kunihiko Kondo

Satoshi Okabe

Hiroyuki Hamazumi

Itsuo Ishida

Hisao Koda

Kenji Terada

Atsushi Mizuno

Makoto Okamoto

Masato Horaguchi

Yasutoshi Tada

Fumihito Tomaru

There is provided a frequency synthesizer capable of improving phase noise. A sinusoidal signal with a frequency set by a frequency setting part is output as a digital signal from a set signal output part, and the digital signal is D/A-converted. A difference between a sinusoidal signal with a frequency corresponding to an output frequency of a voltage controlled oscillating part and a sinusoidal signal output from a D/A converting part is amplified by a differential amplifier, and an amplified signal is input via an A/D converting part to a means for extracting a phase difference between the aforesaid sinusoidal signals. A voltage corresponding to a signal being the result of integration of the phase difference is input as a control voltage to the voltage controlled oscillating part. Then, a gain of the differential amplifier is set larger than a maximum value of phase noise degradation of the A/D converting part, whereby the phase noise degradation of the A/D converting part is cancelled.

Frequency synthesizer

There is provided a signal processing device and a wireless apparatus capable of not erroneously determining polarity, appropriately performing a spread modulation process, a carrier modulation process, and reception data demodulation process, improving reception accuracy, and miniaturizing a circuit, even when IF carrier frequency shift occurs. The signal processing device and the wireless apparatus includes a spread modulation unit which includes a first differential encoding process section for performing a differential encoding process on a reception data, a differential encoding process section for performing a second differential encoding process on the output, and a spread modulation process section for performing a spread modulation process on the output using a spread code; a carrier modulation unit which quadrature-modulates a transmission data spread modulation signal and a continuous wave; and a reception data decoding unit which performs a correlation process twice and a delay detection process twice.

Signal processing device and wireless apparatus

Provided is a high frequency radio apparatus for correcting a frequency of a carrier of the own apparatus in accordance with a frequency of a reception carrier when performing spread spectrum communication using very weak power. A carrier demodulating part demodulates a spread code received from a communication counterpart radio apparatus by using default carrier data, and sends the demodulated spread code to a synchronization timing detecting part. When the synchronization timing detecting part detects the spread code from the carrier demodulated data, a carrier frequency deviation detecting part performs a frequency analysis of the spread code to detect a deviation amount of the carrier frequency. A carrier data generating part generates corrected carrier data based on the detected deviation amount. A DBPSK modulating part uses the corrected carrier data to perform data transmission to the communication counterpart radio apparatus.

Spectrum spread communication method and system using very weak power, and high frequency radio apparatus

An object of the present invention is to provide a sensing instrument capable to detect a substance existing in a very small quantity, such as environmental pollutants, instantly with a high degree of precision. As a specific means for solving the problem, a frequency signal from a crystal oscillator is sampled using a frequency signal from a reference clock generating part, the sampling value is outputted in a digital signal, quadrature detection is conducted with the digital signal for a frequency signal corresponding to the output signal, the rotational vector rotating at a frequency corresponding to the difference between the frequency of the frequency signal and the frequency of a sinusoidal wave used for the quadrature detection is taken out, and the variation of the frequency is detected by detecting the velocity of the rotational vector based on the respective sampling values. In addition to that, the measurement range of the variation of frequency can be widened by multiplying the above-described rotational vector by the reversely rotational vector corresponding to the velocity of the rotational vector.

Sensing apparatus

A VCO driving circuit and a frequency synthesizer wherein the impedance viewed from a VCO control terminal is reduced to prevent the VCO phase noise characteristic from degrading. A VCO driving circuit and a frequency synthesizer having the VCO driving circuit, which comprises a coarse adjustment DAC that receives a digital data, which has a coarse adjustment frequency, to output an analog signal; a fine adjustment DAC that receives a digital data, which has a fine adjustment frequency, to output an analog signal; a low response speed LPFthat removes noise from the output signal from the coarse adjustment DAC and then provides the resultant signal as an input to a VCO control terminal; a high response speed LPFthat converts the output signal from the fine adjustment DAC to a voltage, thereby smoothing the signal; a resistor that connects an input stage of the LPFto that of the LPF; and a capacitor used for providing a capacitive coupling such that the output of the LPFis added to that of the LPF

VCO driving circuit and frequency synthesizer

An object of the present invention provides a frequency synthesizer having a broad frequency entraining range which can finely set a frequency over a broad band by a novel principle. As a specific solving means, a sinusoidal signal of an output frequency of a voltage-controlled oscillator is subjected to orthogonal detection, a vector rotating at the differential frequency (speed) between the output frequency and the frequency of the frequency signal used for the detection is created, and the frequency of a vector when the output frequency of the voltage-controlled oscillator is equal to a set value is calculated in advance. The voltage signal corresponding to the difference between the frequency of the vector and the calculated frequency is fed back to the voltage-controlled oscillator when the voltage-controlled oscillator is driven, and PLL is formed so that the difference is equal to zero. Accordingly, the output frequency of the voltage-controlled oscillator is adjusted to the set frequency when PLL is locked. After the difference between both the frequencies is increased after PLL is locked, the set value is integrated by the integrating circuit portion and added to the control voltage.

An object of the present invention provides a frequency synthesizer having a broad frequency entraining range which can finely set a frequency over a broad band by a novel principle. As s specific solving means, a sinusoidal signal of an output frequency of a voltage-controlled oscillator is subjected to orthogonal detection, a vector rotating at the differential frequency (speed) between the output frequency and the frequency of the frequency signal used for the detection is created, and the frequency of a vector when the output frequency of the voltage-controlled oscillator is equal to a set value is calculated in advance. The voltage signal corresponding to the difference between the frequency of the vector and the calculated frequency is fed back to the voltage-controlled oscillator when the voltage-controlled oscillator is driven, and PLL is formed so that the difference is equal to zero. Accordingly, the output frequency of the voltage-controlled oscillator is adjusted to the set frequency when PLL is locked. After the difference between both the frequencies is increased after PLL is locked, the set value is integrated by the integrating circuit portion and added to the control voltage.

A high-frequency wireless communication device is provided that is capable of enlarging the range of communication by enhancing reception sensitivity while avoiding mutual interference. The device comprises an antenna filter and a direct detection type reception mechanism connected to the antenna filter. A crystal filter is used as the antenna filter. A crystal chip constituting the crystal filter and an IC chip into which the reception mechanism is integrated are housed in a single modular container to configure a high-frequency wireless module.

High-frequency radio apparatus

A TMCC carrier is demodulated from a received OFDM signal having a TMCC carrier. A relative carrier position of the demodulated TMCC carrier is detected. A carrier shift amount is detected from the detected relative carrier position of the TMCC carrier and a normal TMCC carrier position. The received OFDM signal is corrected for the carrier frequency shift based on the detected carrier shift amount.

Method and detecting carrier shift amount in digital transmission signal, method of correcting carrier shift amount, and receiver employing these methods

Difference between a received signal which is an OFDM modulated signal having a guard interval and a delayed signal acquired by delaying the received signal by time equivalent to a data interval is calculated, a reference signal of an FFT calculation window is generated based upon the acquired result of the calculation of the difference and a predetermined threshold and a boundary between symbols is detected. As a result, the boundary between symbols can be stably detected, compared with a method of detecting a boundary between symbols based upon the result of the correlation calculation of the guard interval and the demodulation of received data is also stably enabled in multipath phasing and ghost.

Signal transmission system for transmitting a signal with a guard interval and a demodulation method thereof

A distortion compensating circuit for a power amplifier attains raised compensating accuracy with shorter convergence time by accurately and quickly generating a distortion compensation signal for pre-distortion. An error signal representing the difference between the input and output signals of the power amplifier is generated. From the error signal and the input signal, the coefficients of the third-order intermodulation distortion, fifth-order intermodulation distortion and seventh-order intermodulation distortion are calculated. According to these coefficients, a distortion compensating signal which is characteristically opposite in phase and gain to the intermodulation distortions is generated.

Distortion compensation circuit, power amplifier using distortion compensation circuit, and distortion compensation signal generating method

Distortion compensation circuit, distortion compensation signal generating method, and power amplifier

A transmission apparatus of orthogonal frequency division multiplexing for multiplexing a plurality of carriers orthogonal to one another to transmit a modulated signal. The transmission apparatus includes a first modulator for outputting a code modulated in accordance a modulation scheme which can be applied with a synchronous detection for demodulation, a second modulator for outputting a code modulated in accordance with a modulation scheme different from the modulation scheme associated with the first modulator, and a distributing circuit for distributing the codes modulated by the first and second modulators to a plurality of carriers. The distributing circuit distributes the code modulated by the second modulator to all or some of carriers existing within a predetermined number of columns from at least one of both end regions of a signal transmission frequency band, and the code modulated by the first modulator to the remaining carriers.

Signal transmission/reception system of orthogonal frequency division multiplexing

Growing community of inventors

Akishima, Japan

Nobuo Tsukamoto