Hitachi, Ltd.

Hitachi Denshi Kabushiki Kaisha

Nippon Telegraph and Telephone Public Corporation

Nippon Hoso' Kyokai

Hitachi Electronics, Ltd.

Hitachi Electronics Co., Ltd.

Yoshizumi Eto

Masuo Umemoto

Seiichi Mita

Morishi Izumita

Hidehiro Kanada

Nobukazu Doi

Toshiyuki Akiyama

Naoki Ozawa

Itaru Mimura

Akio Kumada

Nobuo Murata

Morito Rokuda

Hiroshi Takano

Masao Hibi

Kazuhiro Sato

Kenji Takahashi

Yasuhiro Hirano

Kazuhiro Tanabe

Kazuyuki Takeshita

Yuichi Michikawa

Takahiro Matsumoto

Hitoshi Katayama

Hiroyuki Nisikawa

Shinichi Miyazaki

Hidehiko Sawamura

Takashi Nakamura

Shigeru Nakamura

Koji Kudo

Hideaki Yamamoto

Toshihisa Tsukada

Takayuki Tanaka

Yoshito Tsunoda

Tadaaki Hirai

Eiichi Maruyama

Hiroyuki Tsuchinaga

Taizo Kinoshita

Hirotake Ishii

Masuo Kasai

Makoto Matsui

Takahiko Fukinuki

Shizuka Ishibashi

Yuuichi Oonami

Fumio Hara

Ryu Watanabe

Takashi Asahina

Hiroyuki Hanyu

Sinich Miyazaki

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 spread spectrum communication method includes the steps of measuring a parameter indicative of a C/N value of a received signal at one station during a communication between stations remote from each other in accordance with a spread spectrum communications scheme, and changing the data rate of a signal to be transmitted from another station when the C/N value changes by a predetermined value or more.

Spread spectrum communication method and system wherein data rate of data to be transmitted is changed in accordance with transmission quality

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 method and an apparatus for digital signal recording and/or reproduction are disclosed in which tracks are formed sequentially on a recording medium by use of a head unit mounted on a rotary cylinder, an input digital data is recorded in the recording medium, and the digital data thus recorded is reproduced. The input digital data is modulated into a code word having at least d (d: an integer of at least two) successive bits of high- and low-level data in a signal waveform recorded in the recording medium. The timebase of the code word is compressed. The compressed code word is recorded in the tracks of the recording medium by use of the head unit. The code word recorded and compressed in the recording medium is reproduced. The timebase of the reproduced code word is expanded, and the input digital data is reproduced from the expanded code word.

Method and apparatus for digital signal recording and/or reproduction

A picture signal encoding multiplexing method and apparatus in which encoded data of a plurality of picture signals, which are respectively output from a plurality of picture signal encoding processing units, is multiplexed in a channel multiplexing unit. The method includes the steps of: generating a transmission rate control signal corresponding to information related to the encoded distortion supplied from each of picture signal encoding processing units in a channel multiplexing unit, and supplying the transmission rate control signal to each of the picture signal encoding processing units; and outputting the encoded data of the picture signal from each of the picture signal encoding processing units in accordance with the transmission rate control signal. The apparatus includes a unit provided in channel multiplexing unit for generating a transmission rate control signal corresponding to information relating to encoded distortion supplied from each picture signal encoding processing unit and for supplying the transmission rate control signal to each of the picture signal encoding processing units; and a unit for outputting, from each of the picture signal encoding processing units, the encoded data of the associated picture signal in accordance with the transmission rate control signal.

Method of encoding and multiplexing picture signals and apparatus

An image pickup apparatus for a television and a depth-of-field control apparatus used in the same. Image signals corresponding to a plurality of picture images different in focal point or length position are obtained by a mechanism for changing a focal point or length position to produce a new image signal by composing these image signals through a composition circuit, and motion information of an object is obtained by a circuit for detecting a moving portion in the object to control the image composition by the motion information. The focal point or length position is moved in synchronism with an integer multiple of a vertical scanning period of the television. The image signals corresponding to the plurality of picture images different in focal point or length position are obtained within one vertical scanning period determined by the system of the television. The amount of movement of the focal point or length position is controlled in conjunction with a value of a lens aperture of the camera lens. The image composition is controlled by a composition control circuit made up of a circuit for detecting individual powers of image signals corresponding to a plurality of different picture images, a circuit for comparing the detected powers with each other, and a circuit for detecting the position of an edge included in one of the image signals, wherein a control signal for the image composition produced by the power comparison circuit is compensated by the edge position information obtained by the edge detection circuit.

Depth-of-field control apparatus and image pickup apparatus having the

A replay equalization circuit for reproducing digital image information recorded on a recording medium includes a transducer for reading the digital image information, an equalization circuit connected to the transducer for equalizing an output of the transducer based on a speed information input, a clock recovery circuit connected to the equalization circuit for extracting a clock signal from an output of the equalization circuit for latching the output of the equalization circuit in response to the clock signal.

Replay equalization circuit in digital image recorder

A video signal transmitting method comprising: a sending method including the steps of: dividing an analog video signal in a unit corresponding to integer times of a number of bits composing an information field of one packet in packet transmission and converting into a digital video signal, forming a digitalized video signal into a plurality of packets, forming a plurality of packets into a first packet block in M lines.times.N columns, adding an error correction code which corrects a longitudinal error of data in a first packet block as a second packet block in P lines.times.N columns in an (M+1)th line and thereafter, and sending a packet; and a receiving method including the steps of: recomposing the same packet block as that composed on a sending side from plurality of received packets, recovering a video signal with packet loss information from an exchange and an error correction code formed into a packet, and regenerating an analog video signal from a digital video signal after recovery.

Video signal transmitting method and equipment of the same

An image pickup apparatus comprising: a two-dimensional filter for interpolating the registration discrepancy due to the chromatic aberrations of the lens used; and a two-dimensional filter for correcting the fixing discrepancy of an image pickup element. The registration discrepancy may be corrected by guiding video signals from the image pickup element through the two-dimensional filters.

Solid state image pickup apparatus for correcting discrepancy of

An adaptive transform encoder can keep a recording rate of a digital signal at a constant level. It comprises a unit for orthogonal-transforming one block of digital input signal, a unit for calculating an activity index of the orthogonal-transformed block, a unit for comparing the activity index of the block with a predetermined reference, a unit for classifying the block to a standard bit class having a predetermined number of bits when the activity index of the block is equal to the reference, classifying the block to a low bit class having a smaller number of bits than the predetermined number of bits of the standard bit class when the activity index of the block is smaller than the reference, and classifying the block to a high bit class having a larger number of bits than the predetermined number of bits of the standard bit class when the activity index is larger than the reference, a quantization unit for quantizing the input signal of the block with the number of bits designated by the bit class, a unit for selecting the block of the low bit class from the quantized blocks, an allocation unit for adding to the selected block of the low bit class the data having more bits than the number of bits of the standard bit class of the block of the quantized high bit class, and an encoder unit for encoding the quantized block signal.

Adaptive transform encoder for digital image signal in

An original digital signal is converted into either a Miller-squared code signal or a Miller code signal, and undergoes serial-to-parallel conversion to produce n-phase signals (where n is desired to be a positive even number). N-phase virtual demodulated signals are simultaneously generated at clock timing having a period equivalent to 1/n times the period of the transmission clock. Out of the n-phase virtual demodulated signals, n/2 phases are selected to undergo parallel-to-serial conversion, the original digital signal being thus obtained.

Demodulation apparatus

An optical tape apparatus having improved focus and tracking control. An optical head records, reproduces, or rewrites data on an optical tape by helically scanning the tape with a laser beam. A guide plate is disposed between the optical head and the tape to prevent the beam from becoming unfocused due to fluctuation of the tape cuased by an air film between the optical head and the tape. The optical head contains a semiconductor laser and an optical system exhibiting chromatic aberration for directing the laser beam onto the tape. The optical system includes a condenser lens for focusing the beam onto the tape. Fine focus control is achieved by changing the wavelength of the laser beam by directing part of the beam reflected from the tape back to the laser, thereby changing the focal point of the beam by virtue of the chromatic aberration of the optical system. Coarse focus control is achieved by mounting the condenser lens on a piezoelectric actuator which moves the consenser lens to focus the beam onto the tape. A recording head for recording timing marks and tracking signals on the tape is disposed in advance of the optical head. A reading head reads the timing marks and the optical head reads the tracking signals. The timing marks and tracking signals are used to control the operation of the apparatus such that the tape is transported with a constant speed and data on diagonal signal tracks on the tape is accurately recorded, reproduced, or rewritten.

Optical tape apparatus with a tracking control mechanism and/or a

An apparatus for recording an reproducing a digital video signal is disclosed which includes n sampling circuits each for performing a sub-Nyquist sampling operation for the digital video signal in such a manner that the amount of data is reduced to one-n-th of an original amount (where n is a positive integer) and a pixel sampled by the sub-Nyquist sampling operation is not sampled by the remaining sampling circuits, recording/reproducing means for recording and reproducing information at all or part of pixels which are sampled by the n sampling circuits and a device for reconstructing the digital video signal from reproduced information at pixels with the aid of a synthesizing technique or interpolation technique.

Apparatus for recording/reproducing digital video signals in both a

Solid-state televison camera with storage time controller

Growing community of inventors

Sagamihara, Japan

Yoshizumi Eto