Nec Corporation

Clarion Co

Nippon Electric Co., Ltd.

Nec Home Electronics, Inc.

Nec Corporation and Clarion Co., Ltd.

Takeshi Kuwajima

Kiyoshi Amazawa

Kouichi Tanaka

Masami Miura

Kunio Iwaibana

A method of controlling communications in response to a communication frame in a simultaneous broadcasting mode transmitted from a third communication control apparatus (CCA). The method includes a step of transmitting from a first CCA to a second CCA a communication frame for releasing the exclusive communication mode. The method also includes a step of receiving at the second CCA the communication frame in the simultaneous broadcasting mode after the second CCA has received the communication frame for releasing the exclusive communication mode. The method further includes a step of starting to transmit a communication frame of a communication message from the first CCA to the second CCA after the first CCA has detected the ending of the communication frame in the simultaneous broadcasting mode. The method lastly includes a step of receiving at the second CCA the communication frame of the communication message transmitted from the first CCA in the exclusive communication mode.

Simultaneous broadcasting method and apparatus for interrupting

A communication control method in which a communication control unit A.sub.2 in an exclusive communication mode with a communication control unit A.sub.1 receives a requesting frame of an exclusive communication mode or broadcast communication frames from another communication control unit B. Unit B sends a communication frame for announcing an exclusive communication mode after receiving a NAK response from unit A.sub.2, sends message frames after the elapse of a predetermined time T.sub.1, and then sends a frame releasing the exclusive communication mode between Unit B and Unit A.sub.2 after sending the message frames. After receiving the announcing frame from unit B, unit A.sub.2 communicates with unit A.sub.1 to release the exclusive mode between them within the time T.sub.1, enters an exclusive mode with unit B, and then receives communication frames from unit B until it receives the frame of releasing the exclusive mode with unit B. When simultaneous broadcasting frames from unit B are detected, communication control unit A.sub.1, which is in the exclusive communication mode and transmitting message frames to unit A.sub.2, transmits a communication frame for temporarily releasing the exclusive communication mode to unit A.sub.2. The exclusive communication mode between units A.sub.1 and A.sub.2 is revived after unit A.sub.2 receives the casting frames from unit B.

Method and apparatus for interrupting communication control units in an

A digital video tape recorder. A clock is extracted from the horizontal sync signal within the luminance signal, and used in processing the luminance portion of the video signal. A clock is also extracted from a color burst within the chrominance signal and is used for processing the chrominance portion. The chrominance portion of the video signal to be recorded is converted to a low frequency band before recording. During playback, the reverse of this operation is performed, thereby producing a signal with the original color frequency.

Magnetic recording and reproducing apparatus obtaining separate clock

A video signal processing circuit for a VTR system is disclosed. In a special playback mode such as 'STILL', 'SLOW' and 'QUICK' modes, a pseudo vertical synchronizing signal is supplied which has a train of pulses at a predetermined cycle proportional to one horizontal cycle. There are provided a detection circuit for detecting the pseudo vertical synchronizing signal to produce a detection signal and a pulse separator separating the train of pulses from the pseudo vertical synchronizing signal. When the detection signal is produced, a reproduced video signal is supplied to a clamping circuit which clamps each synchronizing signal contained in the reproduced video signal at a predetermined level. When the detection signal is not produced, on the other hand, the separated pulses are transferred to the clamping circuit, and the clamping circuit is controlled to be made inoperative during the production period of each pulse.

Video signal processing circuit for VTR system

In a demodulator comprising an indicator (31) for indicating either stereo reception or monaural reception, an indicator circuit (30) is used to cancel a pilot signal included in a stereophonic signal and to produce a drive signal for driving the indicator. The indicator circuit comprises a negative feedback loop formed by an adder circuit (41), a phase detector (43), and a cancellation circuit (45). The cancellation circuit supplies the indicator and the adder circuit with the drive signal and a cancelling signal synchronized with and approximate to the pilot signal, respectively. The adder circuit substracts the cancelling signal from the pilot signal to deliver an intermediate signal to a multiplex decoder and to the cancellation circuit through the phase detector. The cancellation circuit comprises a wave generator for generating a pair of currents proportional to an amplitude of the pilot signal and a level adjusting circuit for converting one of the currents into the cancelling signal. The other current is converted into the drive signal.

Demodulator comprising an indicator circuit for use in common to

In a circuit arrangement comprising a differential transistor circuit which has a threshold level and is operable in response to an input signal level and a reference signal level for producing an output signal, a resistor circuit is provided for changing the reference level. The resistor circuit comprises a resistor (30) for supplying the differential transistor circuit with the reference level and a modifying circuit coupled to the resistor for modifying the reference level by changing a current flowing through the resistor. Consequently, the threshold level can be voluntarily adjusted.

Circuit arrangement capable of adjusting a threshold level of a

A control circuit is configured to detect by an active filter white noise levels in detection outputs from an intermediate frequency amplifier in an FM stereo demodulation circuit so as to control the separation of outputs from the stereo demodulation circuit into left and right stereo channels, responsively to the white noise level, and is characterized in provision of a current detection circuit which is actuated by the output from the active filter and responsive to a current flowing into a resistor connected between the feedback terminal of the active filter and a reference potential point to control a blend control circuit so as to change the point whereat the separation ratio begins to vary.

Control circuit

A full-wave rectifier having a limited number of circuit elements comprises an amplifier, such as an operational amplifier, having an inverting input held at a reference potential, a non-inverting input receiving an input signal through a first resistor and an output, a transistor having its base connected to the output of the amplifier and its collector connected to the non-inverting input of the amplifier through a second resistor and optionally an output circuit for producing an output signal from the connection point between the collector of the transistor and the second resistor.

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Tokyo, Japan

Takeshi Kuwajima