Hospital digital data transfer system
First Claim
1. A digital data transfer system comprising:
- (a) a DC voltage source;
(b) a load;
(c) a direct current path between the DC voltage source and the load comprising;
(i) a coaxial cable having a central conductor which includes first and second ends;
(ii) a first end conductive path for connecting the DC voltage source to the first end of the central conductor; and
(iii) a second end conductive path for connecting the load to the second end of the central conductor;
(d) first end switch means in the first end conductive path having an open state in which the flow of DC current from the DC voltage source to the load is interrupted and a closed state in which the flow of DC current is uninterrupted;
(e) first end bit receiving means for receiving a digital bit from a first source of such bits external to the digital data transfer system and for switching the first end switch means into its open state for a period of time corresponding to the duration of the bit;
(f) second end switch means in the second end conductive path having an open state in which the flow of DC current from the DC voltage source to the load is interrupted and a closed state in which the flow of DC current is uninterrupted;
(g) second end bit receiving means for receiving a digital bit from a second source of such bits external to the digital data transfer system and for switching the second end switch means into its open state for a period of time corresponding to the duration of the bit;
(h) first end bit generating means for sensing an interruption in the flow of DC current through the first end conductive path produced by the second end switch means and generating a digital bit in response thereto; and
(i) second end bit generating means for sensing an interruption in the flow of DC current through the second end conductive path produced by the first end switch means and generating a digital bit in response thereto.
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Accused Products
Abstract
A digital data transfer system for transferring baseband digital data between a central location and a patient'"'"'s room is provided. The system employs the existing coaxial cable network found in hospitals and other institutions. The coaxial cable carries power from a DC power source to the patient'"'"'s television receiver or other device. Digital data is addressed and transmitted from the central location to the individual patient'"'"'s room on the coaxial cable by temporarily disconnecting the DC power source from the coaxial cable for each bit which is to be transferred (source switching) and detecting, in the patient'"'"'s room, the interruption in the flow of DC current through the cable. Digital data is transmitted from the patient'"'"'s room back to the central location on the same single coaxial cable by temporarily disconnecting the load, e.g., the patient'"'"'s television receiver or other device, from the coaxial cable for each bit which is to be transferred back (load switching) and detecting, at the central location, the interruption in the flow of DC current through the cable. A storage capacitor is placed in parallel with the load to provide power for the load while the flow of DC current is interrupted. The system can readily achieve transmission rates on the order of 38 kilobaud and above.
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Citations
21 Claims
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1. A digital data transfer system comprising:
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(a) a DC voltage source; (b) a load; (c) a direct current path between the DC voltage source and the load comprising; (i) a coaxial cable having a central conductor which includes first and second ends; (ii) a first end conductive path for connecting the DC voltage source to the first end of the central conductor; and (iii) a second end conductive path for connecting the load to the second end of the central conductor; (d) first end switch means in the first end conductive path having an open state in which the flow of DC current from the DC voltage source to the load is interrupted and a closed state in which the flow of DC current is uninterrupted; (e) first end bit receiving means for receiving a digital bit from a first source of such bits external to the digital data transfer system and for switching the first end switch means into its open state for a period of time corresponding to the duration of the bit; (f) second end switch means in the second end conductive path having an open state in which the flow of DC current from the DC voltage source to the load is interrupted and a closed state in which the flow of DC current is uninterrupted; (g) second end bit receiving means for receiving a digital bit from a second source of such bits external to the digital data transfer system and for switching the second end switch means into its open state for a period of time corresponding to the duration of the bit; (h) first end bit generating means for sensing an interruption in the flow of DC current through the first end conductive path produced by the second end switch means and generating a digital bit in response thereto; and (i) second end bit generating means for sensing an interruption in the flow of DC current through the second end conductive path produced by the first end switch means and generating a digital bit in response thereto. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for the bi-directional, serial transfer of baseband digital data on a single coaxial cable which provides DC power to the power input of a television receiver and RF signal to an RF tuner associated with the television receiver, comprising the steps of:
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(a) connecting a DC voltage source and a RF signal source to a first end of the cable; (b) connecting a second end of the cable to (i) a television receiver'"'"'s power input, (ii) said television receiver'"'"'s RF tuner, and (iii) a DC storage capacitor; (c) for each digital bit which is to be sent from the first end to the second end; (i) temporarily disconnecting the DC voltage source from the first end of the cable so as to temporarily interrupt the flow of DC current, but not RF signals, down the cable, said interruption in the flow of DC current down the cable comprising the digital bit; and (ii) sensing the interruption in the flow of DC current down the cable at the second end; and (d) for each digital bit which is to be sent from the second end to the first end; (i) temporarily disconnecting the second end of the cable from the power input to the television receiver and the DC storage capacitor, but not from the RF tuner, so as to temporarily interrupt the flow of DC current down the cable, said interruption in the flow of DC current down the cable comprising the digital bit; and (ii) sensing the interruption in the flow of DC current down the cable at the first end.
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Specification