Spread-spectrum receiver with progressive fourier transform
First Claim
1. A communications system comprising:
- a plurality of reporting devices,each reporting device including;
a data collection device that is configured to determine a state of one or more sensors, anda transmitter that is configured to transmit the state of the one or more sensors about a nominal frequency that is common to the plurality of reporting devices using a spreading code that is common to the plurality of reporting devices;
whereina code-phase of the spreading code used at each transmitter is independent of the code-phase used at other transmitters of the plurality of devices,actual transmission frequencies used by the transmitters of the plurality of reporting devices differ pseudo-randomly about the nominal frequency, andeach transmitter is configured to transmit the state of the one or more sensors at a rate and duration that are selected to, provide a low likelihood of collision with transmissions from the other transmitters, thereby facilitating discrimination of receptions of the state of the one or more sensors of the plurality of reporting devices at a receiving system that operates asynchronous to any of the transmitters, based on energy detected at each reception frequency and code-phase corresponding to each non-colliding transmission.
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Accused Products
Abstract
A receiving system dynamically searches the communications band for transmissions of messages having the same nominal communications parameters, including the use of the same spreading code, but having potentially different specific frequencies and code-phases. The receiver, which is independent of the transmitters, samples the communications band at each code-phase of the spreading code over a span of downconverted transmission frequencies. When a message element is detected at a particular code-phase and frequency, it is forwarded to a demodulator that demodulates the message and sends it to its intended destination. In a preferred embodiment, a progressive Fourier Transform is used to incrementally determine the power level at each successive code-phase at a given frequency, thereby substantially reducing the time required to search for transmissions at each discrete code-phase.
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Citations
15 Claims
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1. A communications system comprising:
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a plurality of reporting devices, each reporting device including; a data collection device that is configured to determine a state of one or more sensors, and a transmitter that is configured to transmit the state of the one or more sensors about a nominal frequency that is common to the plurality of reporting devices using a spreading code that is common to the plurality of reporting devices; wherein a code-phase of the spreading code used at each transmitter is independent of the code-phase used at other transmitters of the plurality of devices, actual transmission frequencies used by the transmitters of the plurality of reporting devices differ pseudo-randomly about the nominal frequency, and each transmitter is configured to transmit the state of the one or more sensors at a rate and duration that are selected to, provide a low likelihood of collision with transmissions from the other transmitters, thereby facilitating discrimination of receptions of the state of the one or more sensors of the plurality of reporting devices at a receiving system that operates asynchronous to any of the transmitters, based on energy detected at each reception frequency and code-phase corresponding to each non-colliding transmission. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification