Telephonic communications – Having light wave or ultrasonic link for speech or paging... – Including fiber optic link within telephone network
Patent
1988-05-17
1990-07-03
Ng, Jin F.
Telephonic communications
Having light wave or ultrasonic link for speech or paging...
Including fiber optic link within telephone network
379100, 358 85, 358434, 358438, H04M 1100, H04N 714
Patent
active
049397672
ABSTRACT:
A system for transmitting image data on a telephone network or equivalent, which typically includes video or visual telephones as apparatus of sending part and receiving part. In the video telephone of sending part, when an image data sending key is operated, a DTMF signal generator included in a modem is started to operated and a specified DTMF signal, for example, DTMF-A signal or DTMF-B signal is sent as a signal DTMF-DTA to a telephone circuit through a network control unit for approximate 300 milliseconds. Succeedingly, in spite of presence or absence of a responsive signal from the video telephone of receiving part, a non-signal state is formed for approximate 75 milliseconds, immediately thereafter, the image data is sent from the video telephone of sending part at a transmission speed of 4,800 bps or 2,400 bps. In the video telephone of receiving part, when the signal DTMF-DTA, that is, the above described DTMF-A signal or DTMF-B signal is continuously received for approximate 250 milliseconds, a modem thereof is started at 4,800 bps or 2,400 bps, and the image data being sent from the video telephone of sending part is received.
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Hayasaki Hiroyuki
Matsuyama Hisashi
Nakashima Hisaharu
Saito Yoshinori
Chan Wing F.
Ng Jin F.
Sanyo Electric Co,. Ltd.
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