Hitachi, Ltd.

Other

Hitachi, Ltd. (501)

Toshio Nagashima

Hiroyuki Mizukami

Yutaka Igarashi

Hiroshi Hatashita

Takeshi Saitoh

Akio Yamamoto

Masaki Noda

Susumu Yamamoto

Keiro Shinkawa

Noriharu Sato

Mitsuhisa Shinagawa

Takashi Omata

Shiro Horii

Kenji Katsumata

Isao Nakagawa

Takanori Eda

Shigeo Matsuura

Satoshi Iimuro

Tsutomu Noda

Tomomi Matsumoto

Masatoshi Oga

An easy-to-use remote keyless entry system is provided. To execute 2-way long distance communication at a low output and within a short time, transmission is effected while a data rate of a terminal board is changed. To reduce battery consumption in a system capable of setting an automatic output mode, the operation mode is shifted to the automatic output mode when an automatic output mode button is pushed or when a door lock release button of an operation button, etc, is kept pushed for a predetermined time. To execute a reserved operation at a reserved time, a storage circuit for storing reservation is provided to the terminal board.

Remote keyless entry system

A digital broadcast recorder capable of recording digital television (TV) signals includes a first frequency converter which converts a received digitally modulated TV signal into a first intermediate frequency signal having a frequency lower than that of the digitally modulated TV signal, the first intermediate frequency signal having a frequency in a standard TV band and useable in demodulating standard TV signals, a band-pass filter coupled to the first frequency converter, which selectively passes-through the first intermediate frequency signal, a phase-lock loop (PLL) circuit coupled to the first frequency converter, which controls an oscillation frequency of a local oscillator in the first frequency converter, a second frequency converter coupled to the band-pass filter, which converts the first intermediate frequency signal passed through the band-pass filter into a second intermediate frequency signal lower in frequency than said first intermediate frequency signal a digital demodulator coupled to the second frequency converter, which demodulates the second intermediate frequency signal as converted by the second frequency converter and a writer coupled to the digital demodulator, which records demodulated signal as demodulated by said digital demodulator in a recording medium.

Digital broadcast recorder

A digital broadcast recorder capable of recording a digital television (TV) signals, includes a first frequency converter which converts a received digitally modulated TV signal into a first intermediate frequency signal having a frequency lower than that of the digitally modulated TV signal, the first intermediate frequency signal having a frequency in a standard TV band and useable in demodulating standard TV signals, a band-pass filter coupled to the first frequency converter, which selectively passes-through the first intermediate frequency signal, a phase-lock loop (PLL) circuit coupled to the first frequency converter, which controls an oscillation frequency of a local oscillator in the first frequency converter, a second frequency converter coupled to the band-pass filter, which converts the first intermediate frequency signal passed through the band-pass filter into a second intermediate frequency signal lower in frequency than said first intermediate frequency signal a digital demodulator coupled to the second frequency converter, which demodulates the second intermediate frequency signal as converted by the second frequency converter and a writer coupled to the digital demodulator, which records demodulated signal as demodulated by said digital demodulator in a recording medium.

Digital broadcasting receiver

To make it possible to receive a modulated signal which is obtained by suppressing a carrier signal such as a high definition TV signal which is digitally demodulated such as QAM (quadrature amplitude modulation), a receiver of the double super-heterodyne system having the first and second mixers 9 and 13 is a basic constitution. A band pass filter having a flatness in pass band and a small deviation of group delay which will prevent the demodulation of a high definition TV signal from degradation is used a first intermediate frequency filter 11. An SAW filter is used as a second intermediate frequency filter 16. The third mixer 28 for converting a second intermediate frequency signal to a third intermediate frequency signal in frequency is installed and the frequency of the third intermediate frequency signal to be converted is set to a value lower than the frequency of the second intermediate frequency signal. The demodulator 33 for a high definition TV signal is installed so as to demodulate a high definition TV signal included in the third intermediate frequency signal.

An automatic gain controlling circuit and a high-definition television signal receiving apparatus includes an input terminal for receiving a signal including first and second signal components creating interference, a first automatic gain controlling amplifier for amplifying the received signal and providing an amplified output signal, a filter for selectively passing a signal portion in a predetermined band of the amplified output signal from the first automatic gain controlling amplifier, and a second automatic gain controlling amplifier for amplifying the signal portion passed by said filter and providing amplified output signal portion. There is also provided a switching signal generator responsive to one of the amplified output signal and the amplifier output signal portion for generating a switching signal, a switching circuit at least being responsive to the switching signal for at least controlling supply of a gain control signal to the first and second automatic gain controlling amplifiers in accordance therewith, and an automatic gain control signal detector for detecting the amplified output signal for supplying an output indicative thereof to the switching circuit.

High-definition television signal receiving apparatus and gain control

A digital signal transmission system including a transmitter and a receiver and capable of transmitting highly efficiently compressed/coded digital video signals and receiving the video signals so that the text of emergency information or the like can be displayed together with video images without once expanding/decoding the digital video signals on the transmitter side. In this system, the multiplexer of the transmitter multiplexes digital video signals and digital audio signals with a digital information signal of text which is produced and has N-level priority information added by the information stream generator, and transmits the multiplex signal to the receiver. The receiver determines whether the text of the digital information signal is to be displayed on the basis of the priority information added to the digital information signal, and when it is determined that the text are to be displayed, the receiver can display the text of the digital information signal together with the image of the digital video signal.

Digital signal transmission system with priority information forcing

A wide-band receiving apparatus used in an FM-FDM type optical image distributing system for transmitting multi-wave and multiple TV signals comprises a circuit for receiving a wide-band input signal containing modified RF signals of two or more different frequency bands and separating the RF signals by the bands; respectively, a first circuit for selecting one of the separated RF signals; a local oscillating circuit for generating a first oscillating signal of a fundamental frequency which is determined based on the frequency range of the selected RF signal; a circuit for producing at least one oscillating signal of a frequency having a predetermined ratio to the fundamental frequency; a second selecting circuit for selecting one of the first oscillating signal and at least one second oscillating signal; a circuit for mixing the selected RF signal with the selected oscillating signal thereby producing an intermediate-frequency signal; and a circuit for demodulating the intermediate-frequency signal.

Wide-band receiving apparatus with local oscillating circuit

High definition TV signal receiver

A receiver apparatus having a mixer circuit, an oscillator circuit and a tuner circuit is provided with a trap circuit, interposed between the tuner circuit and the mixer circuit, for removing disturbing mutual modulation waves generated by receiving two or more RF signals. Further, the mixer circuit employs a double balanced mixer structure to offset two or more disturbing mutual modulation waves.

Receiver apparatus

Disclosed is a mixer circuit which employs four FET's in a manner so that a source electrode of a first FET and a source electrode of a second FET are connected to a first terminal, a source electrode of a third FET and a source electrode of a fourth FET are connected to a second terminal, a first impedance circuit is connected between the first terminal and the earth, a second impedance circuit is connected between the second terminal and the earth, a first high frequency input terminal is connected through a first switching circuit to a junction between the first impedance circuit and the first terminal, a second high frequency input terminal is connected through a second switching circuit to a junction between the second impedance circuit and the second terminal, a gate electrode of the first FET and a gate electrode of the fourth FET are connected to a third terminal, a gate electrode of the second FET and a gate electrode of the third FET are connected to a fourth terminal, a drain electrode of the first FET and a drain electrode of the third FET are connected to a fifth terminal, a drain electrode of the second FET and a drain electrode of the fourth FET are connected to a sixth terminal, and an electric source supply circuit is connected to the fifth and sixth terminals. Phase-reversed local oscillation signals are fed to the third and fourth terminals.

Mixer circuit for use in a tuner of a television set or the like

A frequency converter which is capable of rejecting unnecessary signals generated by image signals. The frequency converter has first and second local oscillation circuits which generate local oscillation signals whose frequencies are the same and whose phases are different by 90 degrees from each other. The converter further includes two mixer circuits, and a hybrid coupler. The mixer circuits generate two unnecessary signals whose phases are different by 90 degrees from each other. The hybrid coupler delays one unnecessary signal by a quarter of a wavelength to generate two unnecessary signals whose phases are different by 180 degrees from each other, so that they are cancelled by each other.

Frequency converter used for a receiver which receives signals of a UHF

A double superheterodyne tuner including a first and a second frequency converter and a bandpass filter, constituted of microstrip lines, wherein the substrate in which the bandpass filter is built is disposed back to back with the substrates in which the first and second frequency converters are constructed, with the substrate for the bandpass filter extending over the first and second frequency converters, so that a sufficient high-frequency isolation of circuit elements can be effected by the use of smaller shielding plates, the overall size can be reduced and a uniform grounded condition can be obtained.

Double superheterodyne tuner

In a band pass filter of micro strip line structure, an input conductor, an output conductor, a first open end conductor and a second open end conductor are provided. The first and the second open end conductors are located opposite to the input and the output conductors forming narrow gaps between said open end conductors and said input and output conductors. The mutual inductance between the first and the second open end conductors is adjusted by selecting the width of the gap between the first and the second open end conductors.

Band pass filters

A thick film multilayer substrate using a green ceramic sheet is constructed such that at least three conductor layers and at least two dielectric layers are alternately arranged in turn on the green ceramic sheet substrate, a power supply line being formed in the second conductor layer and thus interposed between the first and third conductor layers in which grounded conductors are formed.

Growing community of inventors

Yokohama, Japan

Toshio Nagashima