Power line data transmission system
First Claim
1. A method of transmitting data over a line carrying alternating current power, comprising the steps of:
- varying the phase angle between the voltage and the current of the line between a first and a second predetermined value in response to a data signal to be transmitted, said first phase angle value representing a first signal condition, said second phase angle value representing a second signal condition;
detecting the phase angle between the voltage and the current on said line; and
providing a first signal in response to detecting said first predetermined value of phase angle and a second signal in response to detecting said second predetermined value of phase angle.
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Abstract
A power line data transmission system is disclosed in which data is transmitted over a line carrying alternating current power by varying or modulating the power factor of the line or the phase angle of the power on the line in accordance with a signal to be transmitted. A series connected reactance and switch are connected across the line. The switch is turned on and off in response to the data signal to be transmitted over the line. The phase angle of the voltage and current on the line is detected at the receiving location. The phase relation between the voltage and the current is detected or compared to produce a binary digital signal corresponding to the data sent over the line. The detection of the voltage and current being out of phase by a predetermined amount may be used to generate a signal indicating a digital one. The detection of the voltage and current being in phase may be used to generate a signal corresponding to a digital zero.
61 Citations
13 Claims
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1. A method of transmitting data over a line carrying alternating current power, comprising the steps of:
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varying the phase angle between the voltage and the current of the line between a first and a second predetermined value in response to a data signal to be transmitted, said first phase angle value representing a first signal condition, said second phase angle value representing a second signal condition; detecting the phase angle between the voltage and the current on said line; and providing a first signal in response to detecting said first predetermined value of phase angle and a second signal in response to detecting said second predetermined value of phase angle. - View Dependent Claims (2, 3, 4)
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5. Apparatus for transmitting data over a line carrying alternating current power, comprising:
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means for varying the phase angle between the voltage and current of the line between a first and a second predetermined value in response to a data signal to be transmitted, said first phase angle value representing a first signal condition, said second phase angle value representing a second signal condition; means for detecting the phase angle of the voltage and the current on said line; and means for providing a first signal in response to detecting a first predetermined value of phase angle between the voltage and current of the line and a second signal in response to detecting a second predetermined value of phase angle between the voltage and current of the line. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification