Power line communications
First Claim
1. Apparatus for extracting communications signals carried upon RF carriers from power lines, which lines suffer from leakage of signals between them, the apparatus comprising:
- means for receiving an RF signal from each of at least two of the lines, which received signals include at least one component of a wanted communications signal;
means for variably weighting the received signals so as to increase the ratio of wanted signal to interference plus noise S/(1+N), which interference occupies the same frequencies as the RF carriers.
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Accused Products
Abstract
An Apparatus for extracting communications signals from power lines, which lines are arranged such that leakage of signals occurs between them. The apparatus receives a signal from each of at least two of lines (blue, red, yellow) and combines the received signals so as to increase the ratio of wanted signal to interference plus noise S/(1+N). Preferably the combining is achieved by weights WB, WR, WY and a summer. The weights phase shift and scale the received signals in amplitude. The apparatus can also be used for transmitting in the downstream direction.
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Citations
18 Claims
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1. Apparatus for extracting communications signals carried upon RF carriers from power lines, which lines suffer from leakage of signals between them, the apparatus comprising:
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means for receiving an RF signal from each of at least two of the lines, which received signals include at least one component of a wanted communications signal;
means for variably weighting the received signals so as to increase the ratio of wanted signal to interference plus noise S/(1+N), which interference occupies the same frequencies as the RF carriers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
a measuring unit, coupled to the output of the weighting means, which is operable to measure a quantity of the weighted signal which is indicative of the ratio of wanted signal to interference plus noise; and
control means, coupled to the measuring unit, for controlling the weighting means whereby to increase the value of the measured quantity.
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3. Apparatus according to claim 2 wherein the measuring unit measures bit error rate of the weighted signal.
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4. Apparatus according to any one of claim 2 wherein the measuring unit measures at a predetermined period during the weighted signal when the wanted signal is known to be absent.
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5. Apparatus according to any one of claim 2 wherein the measuring unit measures at a predetermined period during the weighted signal when a carrier of the wanted signal is present, but the modulating signal is known to be absent.
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6. Apparatus according to any one of claim 2 wherein the measuring unit measures during a period when a test signal is known to be present in the signal.
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7. Apparatus according to claim 1 wherein the weighting means comprises:
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weights for weighting the received signals in phase; and
a summer which is operable to sum the weighted signals.
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8. Apparatus according to claim 7 wherein the weighting means also scales the received signals in amplitude.
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9. Apparatus according to claim 7 wherein the control means performs an iterative technique in which perturbations are applied to the weighting means.
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10. Apparatus according to any one of the preceding claims wherein the weighting means is operable to weight the received signals in a different manner during each of a plurality of time periods.
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11. Apparatus according to claim 10 wherein each time period corresponds to a time slot on a time-shared carrier frequency.
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12. Apparatus according to claim 10 wherein the weighting means stores settings for use with weighting signals from a particular subscriber who is coupled to the power lines.
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13. Apparatus according to claim 1 wherein the apparatus is also operable to apply a communications signal to each of at least two of the lines.
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14. Apparatus according claim 1 comprising an antenna which couples to the weighting means and which is operable to receive interference.
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15. Apparatus for applying communications signals to power lines, which lines suffer from leakage of signals between them, there being a subscriber terminal coupled to at least one of the power lines, the apparatus comprising:
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a dividing means for dividing a communications signal;
means for applying the divided signals to each of at least two of the power lines;
wherein the dividing means is operable to apply weighting to each of the divided signals whereby to increase the ratio of signal to interference plus noise at a receiver of the subscriber terminal. - View Dependent Claims (16)
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17. A method of extracting communications signals carried upon RF carriers from power lines, which lines suffer from leakage of signals between them, the method comprising:
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receiving an RF signal from each of at least two of the lines, which received signals include at least one component of a wanted communications signal; and
variably weighting the received signals so as to increase the ratio of wanted signal to interference plus noise S/(1+N), which interference occupies the same frequencies as the RF carriers.
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18. A method of applying communications signals to power lines, which lines suffer from leakage of signals between them, there being a subscriber terminal coupled to at least one of the power line, the method comprising:
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dividing a communications signal;
applying the divided signals to each of at least two of the power lines; and
wherein the dividing means is operable to apply weighting to each of the divided signals whereby to increase the ratio of signal to interference plus noise at a receiver of the subscriber terminal.
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Specification