Spread spectrum communications system for networks
First Claim
Patent Images
1. A communication system comprising:
- a plurality of transmitters each generating a plurality of signals, each signal being a chirp and being generated at a plurality of frequencies over a time interval;
a communications channel for carrying the signals;
each said transmitter including means for sensing a presence on the communications channel of a carrier signal prior to initiating a generation of signals, said carrier signal including a sequence of at least one chirp, and having timing which is asynchronous relative to that of at least one other of the plurality of transmitters; and
means for receiving the signals from the communications channel, wherein the means for receiving includes means for self synchronizing on each signal of the plurality of signals.
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Accused Products
Abstract
Spread spectrum chirps (i.e., wideband frequency packets) are propagated on a local area network in a hostile communications environment, such as a powerline or a crowded radio frequency band. Chirps are self-synchronizing, data bit (or subdata bit) in length and detectable by all network nodes, to allow the contention resolution and collision detection needed to support carrier-sense based network protcols. A matched filter of the same time length and encoding sequence as the transmitted chirp provides the self-synchronized chirp reception at each receiver.
290 Citations
37 Claims
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1. A communication system comprising:
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a plurality of transmitters each generating a plurality of signals, each signal being a chirp and being generated at a plurality of frequencies over a time interval; a communications channel for carrying the signals; each said transmitter including means for sensing a presence on the communications channel of a carrier signal prior to initiating a generation of signals, said carrier signal including a sequence of at least one chirp, and having timing which is asynchronous relative to that of at least one other of the plurality of transmitters; and means for receiving the signals from the communications channel, wherein the means for receiving includes means for self synchronizing on each signal of the plurality of signals. - 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 of transmitting data on a communications channel to a receiver comprising the steps of:
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generating a plurality of signals at a transmitter, each signal being a chirp and being generated at a plurality of frequencies over a time interval; providing the signals to a carrier-sense based communications channel; sensing a presence on the communications channel of a carrier signal prior to initiating a generation of signals, said carrier signal including a sequence of at least one chirp, and having a timing which is asynchronous relative to that of at least one other transmitter associated with communications channel; receiving the signals at the receiver from the communications channel; and determining a synchronization for each signal solely from the signal. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. A receiver for a network comprising:
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means connected to the network for receiving an analog signal including a stream of chirps including a plurality of frequencies from the communications channel and converting the analog signal to a digital signal; means for receiving the digital signal and storing the digital signal; means for comparing the stored digital signal to a predetermined value and providing an output signal in response thereto; and means for self synchronizing and locking into the stream of chirps at a predetermined rate, wherein the receiver synchronizes itself independent of a transmitter of the analog signal. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35)
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36. A communication system comprising:
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a plurality of transmitters each generating a plurality of signals, each signal being a chirp and being generated at a plurality of frequencies over a time interval, wherein the chirps are transmitted at a predetermined rate for emulation of a carrier signal; a communications channel for carrying the signals; means for sensing a presence of the carrier signal on the communications channel and thereby inhibiting a generation of signals by at least one transmitter, wherein each transmitter generates signals asynchronously to signals generated by at least one other transmitter; and means for receiving the signals from the communications channel, wherein the means for receiving includes means for self synchronizing on each signal of the plurality of signals.
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37. A method of transmitting data on a communications channel to a receiver comprising the steps of:
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generating a plurality of signals, each signal being a chirp and being generated at a plurality of frequencies over a time interval, wherein chirps are transmitted at a predetermined rate for carrier emulation; providing the signals to a carrier-sense based communications channel; receiving the signals at the receiver from the communications channel; and determining a synchronization for each signal solely from the signal thereby synchronizing independently of a source of the plurality of signals.
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Specification