Time independent data transmission system having capability for accessing a plurality of data devices
First Claim
1. An apparatus coupling a plurality of data devices and a telephone instrument at a first location to a telephone transmission line so as to enable the communication of data between a selected one of the data devices at the first location and a second location without interfering with normal use of the telephone instrument, comprising:
- first means coupled to each of said data devices for selecting one of said data devices in response to a code signal transmitted over said telephone transmission line;
second means, coupled to said telephone transmission line, said telephone instrument and said first means and normally connecting said first means to said telephone transmission line, for disconnecting said first means from said telephone transmission line connecting said telephone instrument to said telephone transmission line in response to any of selected ones of a plurality of first electrical signals transmitted on said telephone transmission line, said first signals each being indicative of a call from a caller on said telephone transmission line, said second means preventing disconnection of said first means in response to a selected one of said first signals;
third means, coupled to said telephone transmission line and said first means, for detecting any of said first electrical signals transmitted on said telephone transmission line without answering the call and for generating a second electrical signal when any of the first electrical signals on said telephone transmission line has terminated, indicating that the caller has hung up;
said selected data device being adapted to communicate data via said first means and said second means in response to the generation of said second electrical signal after said selected one of said first electrical signals has terminated.
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Accused Products
Abstract
A time independent data transmission system which allows a computer to access a selected one of a plurality of data devices at a location remote from the computer at any time via a non-dedicated telephone line is disclosed. The system is coupled to a telephone instrument, the plurality of data devices and the telephone transmission line and normally connects a data set coupled to the data devices to the telephone transmission line. The telephone instrument is normally disconnected. A counting circuit senses the number of ring bursts in a ringing signal from a caller and a central computer is programmed to transmit a ringing signal having only one ring burst. When only one ring burst is sensed, the data set remains connected to the telephone transmission line and the data set dials up the central computer when the ringing signal terminates. The data set comprises a decoder circuit which receives a coded signal from the central computer designating which of the data devices is to be accessed. The decoder controls a switch to select one of the data devices. If more than one ring burst occurs, a non-computer call is being sensed and the data set is disconnected and the telephone connected to the telephone transmission line so that normal telephone usage is allowed. Communication between the computer and the data set via the telephone line occurs without ringing the telephone instrument and without otherwise interfering with normal telephone usage.
31 Citations
22 Claims
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1. An apparatus coupling a plurality of data devices and a telephone instrument at a first location to a telephone transmission line so as to enable the communication of data between a selected one of the data devices at the first location and a second location without interfering with normal use of the telephone instrument, comprising:
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first means coupled to each of said data devices for selecting one of said data devices in response to a code signal transmitted over said telephone transmission line; second means, coupled to said telephone transmission line, said telephone instrument and said first means and normally connecting said first means to said telephone transmission line, for disconnecting said first means from said telephone transmission line connecting said telephone instrument to said telephone transmission line in response to any of selected ones of a plurality of first electrical signals transmitted on said telephone transmission line, said first signals each being indicative of a call from a caller on said telephone transmission line, said second means preventing disconnection of said first means in response to a selected one of said first signals; third means, coupled to said telephone transmission line and said first means, for detecting any of said first electrical signals transmitted on said telephone transmission line without answering the call and for generating a second electrical signal when any of the first electrical signals on said telephone transmission line has terminated, indicating that the caller has hung up; said selected data device being adapted to communicate data via said first means and said second means in response to the generation of said second electrical signal after said selected one of said first electrical signals has terminated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of providing communication of data between a data set at a first location and a second location over a telephone transmission line without interfering with normal use of a telephone instrument coupled to the line, comprising the steps of:
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disconnecting said data set from said telephone transmission line and connecting said telephone instrument to said telephone transmission line in response to any of selected ones of a plurality of first electrical signals transmitted on said telephone transmission line, said first signals each being indicative of a call from a caller on said telephone transmission line; preventing disconnection of said data set in response to a selected one of said first signals; detecting any of said first electrical signals transmitted on said telephone transmission line without answering the call and generating a second electrical signal when any of the first electrical signals on said telephone transmission line has terminated, indicating that the caller has hung up; said data set communicating data in response to the generation of said second electrical signal after said selected one of said first electrical signals has terminated. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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Specification