Transmission system for still-picture TV telephone
First Claim
1. A still-picture TV telephone system for transmitting and receiving, via a telephone circuit, a still picture taken by a camera, comprising:
- (a) a voice band filter means for eliminating a special band signal of a voice signal introduced from a transmitting means;
(b) a low-pass filter means for restricting a still picture signal in band, cut-off frequencies of said low-pass filter means being set to less than or equal to 1/2 of the restricted band of said voice band filter means;
(c) a phase/amplitude modulation means for modulating the phase and amplitude of the still picture signal, high frequency components of which have been eliminated, by a carrier signal, frequencies of the carrier signal being set to substantially central frequencies of the signal-free band of said voice band filter means, a baud rate frequency being set substantially to the restricted band width of said voice band filter means; and
(d) a composer means for composing a picture transmission signal of modulated phase and amplitude in the narrow band and a voice transmission signal of the restricted band to divide frequency bands of the picture and voice signals and, at the same time, to transmit the picture and voice signals.
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Accused Products
Abstract
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.
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Citations
14 Claims
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1. A still-picture TV telephone system for transmitting and receiving, via a telephone circuit, a still picture taken by a camera, comprising:
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(a) a voice band filter means for eliminating a special band signal of a voice signal introduced from a transmitting means; (b) a low-pass filter means for restricting a still picture signal in band, cut-off frequencies of said low-pass filter means being set to less than or equal to 1/2 of the restricted band of said voice band filter means; (c) a phase/amplitude modulation means for modulating the phase and amplitude of the still picture signal, high frequency components of which have been eliminated, by a carrier signal, frequencies of the carrier signal being set to substantially central frequencies of the signal-free band of said voice band filter means, a baud rate frequency being set substantially to the restricted band width of said voice band filter means; and (d) a composer means for composing a picture transmission signal of modulated phase and amplitude in the narrow band and a voice transmission signal of the restricted band to divide frequency bands of the picture and voice signals and, at the same time, to transmit the picture and voice signals. - View Dependent Claims (2, 3, 4, 5)
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6. A still-picture TV telephone system for transmitting and receiving, via a telephone circuit, a still picture taken by a camera, comprising:
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(a) a voice band filter means for eliminating a special band signal of a voice signal introduced from a transmitting means; (b) a low-pass filter means for restricting a still picture signal in band, cut-off frequencies of said low-pass filter means being set to less than or equal to 1/2 of the restricted band of said voice band filter means; (c) a phase/amplitude modulation means for modulating the phase and amplitude of the still picture signal, high frequency components of which have been eliminated, by a carrier signal, frequencies of the carrier signal being set to substantially central frequencies of the signal-free band of said voice band filter means, a baud rate frequency being set substantially to the restricted band width of said voice band filter means; and (d) a composer means for composing a picture transmission signal of modulated phase and amplitude in the narrow band and a voice transmission signal of the restricted band to divide frequency bands of the picture and voice signals and, at the same time, to transmit the picture and voice signals; and (e) a receiver circuit for receiving a transmitted voice-and-picture composite signal and for separating the composite signal in band. - View Dependent Claims (7, 8, 9)
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10. A still-picture TV telephone system for transmitting and receiving, via a telephone circuit, a still picture taken by a camera, comprising:
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(a) a voice band filter means for eliminating a special band signal of a voice signal introduced from a transmitting means; (b) a pair of low-pass filter means for restricting a still picture signal in band, cut-off frequencies of said low-pass filter means being set to less than or equal to 1/2 of the restricted band of said voice band filter means; (c) an I phase/amplitude modulation means for modulating the phase and amplitude of the still picture signal, outputted from one of said pair of low-pass filter means, by a carrier signal of 0 degree phase, frequencies of the carrier signal being set to substantially central frequencies of the signal-free band of said voice band filter means, baud rate frequencies being set substantially to the restricted band width of said voice band filter means; (d) a Q phase/amplitude modulation means for modulating the phase and amplitude of the still picture signal, outputted from the other low-pass filter means, by a carrier signal of 90 degree phase, frequencies of the carrier signal being set to substantially central frequencies of the signal-free band of said voice band filter means, a baud rate frequency being set substantially to the restricted band width of said voice band filter means; and (e) an amplitude composer circuit for composing the modulated outputs of both said I and Q phase/amplitude modulation means; and (f) a composer means for composing a picture transmission signal of modulated phase and amplitude in the narrow band and a voice transmission signal of the restricted band to divide frequency bands of the picture and voice signals and, at the same time, to transmit the picture and voice signals. - View Dependent Claims (11, 12, 13, 14)
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Specification