Transmitting signals over alternating current power networks
First Claim
1. A method of transmitting signals over the lines of an alternating current power distribution network from a transmitter to a receiver, said network having a predetermined signal frequency transmission range, comprising the steps of producing at said transmitter an audio-frequency signal representing intelligence to be transmitted and having a given frequency band-width and time duration, expanding said signal at said transmitter to produce a relatively long time duration, relatively wide-band signal having at least some frequency components within said transmission range, transmitting said expanded signal over said network to said receiver, compressing the received expanded signal at said receiver in at least one of time and frequency, and evaluating said compressed signal to derive said intelligence.
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Abstract
This invention relates to communication systems of the type particularly useful in power line communications. Signals to be transmitted, which can be in the form of short, fixed frequency signals, are expanded in time and/or bandwidth to provide a longer signal with a variable frequency. At the receiver, power line noise, which is typically either short wideband noise or long narrowband noise, is removed and the remaining expanded signal is detected. The expanded signal can then be compressed in time and/or bandwidth to reproduce the original signal.
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20 Claims
- 1. A method of transmitting signals over the lines of an alternating current power distribution network from a transmitter to a receiver, said network having a predetermined signal frequency transmission range, comprising the steps of producing at said transmitter an audio-frequency signal representing intelligence to be transmitted and having a given frequency band-width and time duration, expanding said signal at said transmitter to produce a relatively long time duration, relatively wide-band signal having at least some frequency components within said transmission range, transmitting said expanded signal over said network to said receiver, compressing the received expanded signal at said receiver in at least one of time and frequency, and evaluating said compressed signal to derive said intelligence.
- 8. Apparatus for transmitting signals over the lines of an alternating current power distribution network, said network having a predetermined signal frequency transmission range, the apparatus including a transmitter comprising means for generating an audio-frequency signal representing intelligence to be transmitted and having a given frequency band-width and time duration, means to expand said signal to produce a relatively long time duration, relatively wide-band signal having at least some frequency components within said transmission range, and means to couple said expanded signal to said network, and a receiver comprising coupling means to derive said expanded signal from said network, means to compress the received said expanded signal in at least one of time and frequency, and means to evaluate said compressed signal to derive said intelligence.
Specification