Mitsubishi Denki Kabushiki Kaisha

Luma Telecom Incorporated

Yutaka Ueno

Takayoshi Semasa

Fumitaka Ono

Lawrence D Emmons

Yoshifumi Imanaka

Hiroshi Ohtsuka

Koji Kaneko

James S Mackley

Shuzi Iwata

Syuzi Iwata

Ryoichi Ohnishi

A still-picture TV telephone system for transmitting and receiving, via a telephone circuit, a still picture taken by a camera; a picture signal stored in a memory is modulated in phase and amplitude digitally and is offered or supplied to the telephone circuit during talking in voice. To superposing the talk in voice also during offering of the picture signal, the voice and picture signals are divided by frequency band. The frequency band of the voice signal is partially restricted, and the picture signal is inserted in the omitted band, during which time the picture signal is restricted in band by setting the band rate frequency to be lower than the carrier signal frequency when modulating the phase and amplitude. The picture signal is further restricted in band by a low-pass filter so that the voice and picture signals are separated by band so as not to overlap each other at the same frequency band.

Transmission system for still-picture TV telephone

A still picture picturephone communication system for transmitting and receiving a still picture over a telephone circuit including a handshaking process wherein prior to still picture transmission, identification code data indicating a function of the picturephone set is transmitted and received, and a decision is made as to whether the still picture is being transmitted or not. A designation code of a desired response waiting time within an identification code data used at the time of handshaking is formed, and the response is delayed by a period of time corresponding to the response waiting time. A still picture data is directly transmitted and received without handshaking. In addition character data including character information and the like can be transmitted and received, and by manipulating the picturephone set of one party the picturephone set of the other party can be made to transmit picture data therefrom. Furthermore, the picture sent from the called party can be transferred to a third party.

Still picture picturephone communications system

The present invention provides a QAM modulation scheme compatible with a single channel demodulator. The inphase (I) channel is provided with luminance information encoded on a series of sine wave symbols. The quadrature (Q) channel is used for color difference values with a sine or cosine symbol being used for each color difference value. Alternate ones of these color difference symbols are inverted so that, on the average, their effect on the I channel zero-crossings simply cancels out. Thus, when sent to a single channel demodulator which expects a black and white picture, the quadrature channel will be filtered out; leaving luminance information which will be decoded as a black and white picture. The color information does not disturb the zero crossings of the luminance signal on an averaged basis, allowing the carrier recovery phase lock loop to maintain synchronization for demodulation purposes. When received by a QAM demodulator, the color difference values are recovered on the Q channel, to give a color picture. In one embodiment, the cosine symbols on the channel are offset with a positive or negative DC value, depending on whether the symbol is inverted, to shift the Q channel zero-crossings so they are aligned with the I channel zero-crossings.

Quadrature amplitude modulation preserving one channel zero crossing for

A redundancy reduction coding method of a multi-tone picture element comprises the steps of selecting reference picture elements from picture elements already scanned and transmitted, selecting a single reference picture element as a base reference element and then evaluating a plurality of first tone level differences between the base reference picture element and the reference picture elements other than the base reference picture element and a second tone level difference between the base reference picture element and an objective picture element to be transmitted. Then, if and when all of the tone level differences are within a predetermined region, the second tone level difference is converted into a predictive order in which a second tone level difference appears for a particular combination of the plurality of first tone level differences, the predictive order being produced in advance based on statistics of a standard picture. Thereafter, the predictive order is converted into a predetermined assigned code. The code is a variable length code in which a shorter code is assigned to a higher rank of the predictive order.

Redundancy reduction coding method of multi-tone picture signal and

Binary signals from picture elements arranged in rows and columns of the subject copy are successively applied to a group of shift registers and suitably time-delayed under the control of clock pulses so that the signals from reference picture elements for each object picture element simultaneously enter two logic circuits provided for a high and low scanning resolution. The logic circuits calculate predicted values for each object element following respective prediction functions. That circuit for the scanning resolution used delivers the predicted value to an exclusive OR gate also supplied with the actual signal from the same object element. Each time the gate determines a discord with the prediction, a coder delivers coded serial signals having predetermined variable lengths dependent upon the number of pulses counted up to that time by the coder. Also by referring to a picture element or elements farther distant from the object element, generized prediction functions are disclosed.

Facsimile communication system

Binary 0's and 1's from picture elements in each line are counted with respect to each mode determined by adjacent picture elements to form symbol patterns determined by both the counts and the information content of a memory. Each pattern is encoded into a code word to be transmitted having a bit number determined by the arrangement of binary symbols included in it. Also the code words can be transmitted on the basis of address numbers of picture elements, starting with the output from a coder associated with a mode having the two-valued signal with the least address number.

Growing community of inventors

Kanagawa, Japan

Yutaka Ueno