Hitachi Denshi Kabushiki Kaisha

Hitachi, Ltd.

Hitachi-kokusai Electric Inc.

Nobuo Murata

Yoshizumi Eto

Kazuhiro Tanabe

Hiroyuki Nisikawa

Nobukazu Doi

Kazuhiro Sato

Seiichi Mita

Morishi Izumita

Nobuo Tsukamoto

Kenji Takahashi

Shusaku Nagahara

Masuo Umemoto

Atsushi Miyashita

Hiroto Yamauchi

Nobuo Hirose

Takashi Asahina

Yasuo Yoshimura

Yasutoshi Tada

Shigeaki Fujino

Suguru Hirono

Hiroyuki Hisatomi

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

A registration correction apparatus having interpolation circuits. The interpolation circuits receives digital sampled pixel signals from at least one channel of a plurality of color signal channels. The digital sampled pixel signals have been obtained by sampling consecutive pixel signals. Each of the interpolation circuits generates a digital pixel signal in a desired position between adjacent two of the digital sampled pixel signals by interpolation processing. The desired position between the two adjacent digital sampled pixel signals is set in accordance with a registration discrepancy among the plurality of color signal channels by a control circuit.

Apparatus and method of registration correction for video signal processor and a television camera having registration correcting function

A bidirectional digital signal transmission system includes a transmission line, and video instruments respectively connected to both ends of the transmission line. In each of the video instruments, a digitized signal is multiplexed on a time division basis and compressed in a time base, thereby generating a transmission signal constituted by repetition of a signal period and a quiescent period. The transmission signal generated by one of the video instruments is transmitted during the quiescent period of the transmission signal generated by another one of the video instruments, thereby realizing bidirectional digital signal transmission. The system further includes a repeater circuit inserted in the transmission line at an intermediate location thereof to compensate for deterioration of the signal occurring during transmission over the transmission line. The repeater circuit includes a switch device for preventing a transmission signal feedback loop from being formed in the repeater circuit.

Bidirectional digital signal transmission system and repeater for the same

A digital transmission network comprises a plurality of transmission terminals and receiving terminals, which are all connected with each other by a transmission line of a metal cable or optical fiber cable in the form of loop. Signals are transmitted by timeshare multiplexing in one direction. An individual time slot which is defined for each transmission terminal by time sharing multiplexing is allocated to each of all transmitted signals. A timing device is inserted into the loop for retransmitting a signal so that the delay time is corrected to the delay time of one frame including the delay time caused by the transmission line, cable and the like so that the consecutive frames are continuous. The transmission line is in single or dual loop. In case of the single loop, the transmission terminal includes a bypass circuit for bypassing a signal input to the transmission line if necessary. In case where the transmission line is in a dual loop comprising optical fiber cables of a working line and backup line, a control signal of loop-back is transmitted to all receiving terminals from a receiving terminal which serves as a central unit to bring all receiving terminals into a state enabling signals to be input from the optical fiber cable of the backup line. A control signal is transmitted which returns the receiving terminals into a state enabling signals to be input from the working line in order of proximity to the central unit for confirming that the receiving terminals are normally operating in order of proximity to the central unit.

Digital transmission network

A camera head unit generates a digital video signal, a transmission unit transmits the digital video signal from the camera head unit, and a camera control unit processes the digital video signal transmitted from the camera head unit through the transmission unit. The camera head unit includes a replacing unit for replacing the least significant bit data of the digital video signal to be transmitted from the camera head unit to the camera control unit with another signal data to thereby produce a replacement video signal which is transmitted to the transmission unit. The camera control unit includes an extraction unit for extracting the least significant bit data from the replacement video signal transmitted from the camera head unit through the transmission unit to thereby produce the above-mentioned another signal data.

Digital television camera apparatus provided with camera head unit and camera control unit, independently

In each of two video appliances mutually connected by means of a transmission line, video, voice and other signals are converted to digital signals, subjected to time-division multiplexing and time-base compressing operations to generate a transmission signal having a repetition of signal presence and absence periods, and then the transmission signal is transmitted to the transmission line. While the transmission signal of the signal absence period is transmitted from one of the video appliances to the transmission line, the transmission signal of the signal presence period is transmitted from the other video appliance to the transmission line; whereas, while the transmission signal of the signal presence period is transmitted from one video appliance to the transmission line, the transmission signal of the signal absence period is transmitted from the other video appliance to the transmission line. In each of the video appliances, there is stopped at least one of the operation of a reception circuit of the video appliance during transmission of the transmission signal of the signal presence period from a transmission circuit to the transmission line and the operation of the transmission circuit of the video appliance during reception of the transmission signal of the signal presence period transmitted from the reception circuit through the transmission line.

Digital video signal multiplex transmission system

In a video signal transmission method and system wherein a signal containing a video signal is bidirectionally transmitted and received in a substantially real time in video appliances coupled via a transmission path to each other, a digital signal containing a digital video signal is time-compressed, and a transmission operation is controlled in such a manner that a transmission period and a no transmission period are alternately produced in a preselected period. Then, the time-compressed digital signal is transmitted to the transmission path during the transmission period, whereas another digital signal transmitted via the transmission path from the video appliance on the counter side is received during the no transmission period. Then, the received digital signal is time-expanded to reproduce the original signal.

Method for bidirectionally transmitting digital video signal and digital

A digital video signal processing device for clipping a digital video signal to keep the signal at a predetermined level, includes an interpolation data signal generating unit for predicting video signal levels between adjacent sampling points for generating an interpolation data signal, clipping units for clipping the sampled video signal and the interpolation data signal at their levels, and a synthesizing unit for performing a predictive coding operation with respect to at least any one of the clipped video signal and the interpolation data signal and synthesizing these signals with each other.

Digital video signal processing device and TV camera device arranged to

A demodulation circuit for demodulating a modulated digital including a unit for detecting a specific pattern contained in a series of data before modulation, a unit for judging the phase relation between the specific pattern and a clock pulse used for demodulation, a unit for performing a counting operation on the basis of the result of said judgment, and a unit for controlling the phase of said clock pulse for demodulation on the basis of the count.

Demodulation circuit for digital modulated signal

Disclosed is a solid state television camera with solid state image sensor for converting an optical image into electrical signals, which is comprised of a pulse generator for generating a train of pulses with a frequency equal to the horizontal scanning frequency of a television system, a frequency divider for frequency-dividing the pulse train into a signal with a frequency substantially equal to the vertical scanning frequency alternately in two modes of l/n and l/n+l (where n is a positive integer), and a selective circuitry for forming a train of pulses with a desired vertical scanning frequency on the basis of the pulse trains derived from the pulse generator and the frequency divider.

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Musashino, Japan

Nobuo Murata