Transmission system for still-picture tv telephone

Claim 2

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.

Claim 3

A still-picture TV telephone system according to claim 1, wherein the baud rate frequencies of said phase/amplitude modulation means is set to 1/n of the carrier signal frequencies, where n stands for an integer.

Claim 4

A still-picture TV telephone system according to claim 2, wherein the baud frequencies of said phase/amplitude modulation means is set to 1/3 of the carrier signal frequency.

Claim 5

A still-picture TV telephone system according to claim 1, wherein said low-pass filter means is a filter having a roll-off characteristic.

Claim 6

A still-picture TV telephone system according to claim 1, wherein said voice band filter means has a filter characteristic so as to leave both low and high frequency ranges of the voice signal.

Claim 7

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; and (e) a receiver circuit for receiving a transmitted voice-and-picture composite signal and for separating the composite signal in band.

Claim 8

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; and (e) a receiver circuit for receiving a transmitted voice-and-picture composite signal and for separating the composite signal in band.

Claim 9

A still-picture TV telephone system according to claim 6, wherein said receiver circuit includes a voice separating band-pass filter having a filter characteristic similar to that of said voice band filter means.

Claim 10

A still-picture TV telephone system according to claim 6, wherein said receiver circuit includes a demodulator circuit composed of a multiplier circuit for mixing the received signal and the carrier signal, and a low-pass filter for eliminating the high frequency components of output of said multiplier circuit, said low-pass filter having a filter characteristic similar to that of said low-pass filter means.

Claim 11

A still-picture TV telephone system according to claim 8, further comprising a carrier reproduction circuit for separating the carrier signal from the received signal to obtain a carrier signal to be mixed in said demodulator circuit.

Claim 12

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 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.

Claim 13

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 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.

Claim 14

A still-picture TV telephone system according to claim 10, wherein the baud rate frequency of said phase/amplitude modulation means is set to 1/n of the carrier signal frequencies, where n stands for an integer.

Claim 15

A still-picture TV telephone system according to claim 11, wherein the baud rate frequency of said phase/amplitude modulation means is set to 1/3 of the carrier signal frequencies.

Claim 16

A still-picture TV telephone system according to claim 10, wherein said low-pass filter means is a filter having a-roll-off characteristic.

Claim 17

A still-picture TV telephone system according to claim 10, wherein said voice band filter means has a filter characteristic so as to leave both low and high frequency ranges of the voice signal.