Jamming detection in a wireless security system
First Claim
1. A method of detecting RF jamming signals at a receiver in a system having a plurality of RF transmitters, comprising:
- determining a short-term noise value;
determining a long-term noise value;
determining an expected received RF signal strength value;
generating a signal indicating the presence of a jamming condition if the short-term noise value exceeds the sum of the long-term noise value and a jamming threshold, and further exceeds the expected received RF signal strength minus a detection threshold.
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Accused Products
Abstract
In a wireless security system having a plurality of RF sensor/transmitters and a system controller, jamming signals are detected by comparing a near-term noise value with the expected signal strength of transmissions from the RF sensor/transmitters minus a detection threshold, and with the sum of a long-term noise value and a jamming threshold. In addition, the trend of the long-term noise value is analyzed to determine whether a jamming signal is being intentionally and gradually introduced into the security system environment. The system controller may include a plurality of antennas. Jamming may be detected for each antenna or for all of the antennas, collectively.
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Citations
35 Claims
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1. A method of detecting RF jamming signals at a receiver in a system having a plurality of RF transmitters, comprising:
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determining a short-term noise value; determining a long-term noise value; determining an expected received RF signal strength value; generating a signal indicating the presence of a jamming condition if the short-term noise value exceeds the sum of the long-term noise value and a jamming threshold, and further exceeds the expected received RF signal strength minus a detection threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of detecting RF jamming signals at a receiver in a system having a plurality of RF transmitters, comprising:
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determining a short-term noise value; determining a long-term noise value; determining an expected received RF signal strength value; analyzing the long-term noise value to determine if its trend is increasing by a predetermined amount; and generating a signal indicating the presence of a jamming condition if the short-term noise value exceeds the expected received RF signal strength minus a detection threshold, and further if the trend of the long-term noise value is increasing by the predetermined amount. - View Dependent Claims (14, 15, 16)
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17. A method of detecting RF jamming signals at a receiver in a system having a plurality of RF transmitters, comprising:
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determining a short-term noise value; determining a long-term noise value; determining an expected received RF signal strength value; analyzing the long-term noise value to determine if its trend is increasing by a predetermined amount; and generating a signal indicating the presence of a jamming condition if; the short-term noise value exceeds the sum of the long-term noise value and a jamming threshold, and further exceeds the expected received RF signal strength minus a detection threshold;
orthe short-term noise value exceeds the expected received RF signal strength minus a detection threshold, and further if the trend of the long-term noise value is increasing by the predetermined amount. - View Dependent Claims (18, 19, 20, 21)
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22. A wireless security system comprising:
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a plurality of RF transmitters; a system controller comprising a receiving unit adapted to receive RF transmissions from the RF transmitters, a signal-strength circuit adapted to measure a noise level when RF signals are not being received, and a processor adapted to determine a long-term noise value and a short-term noise value, wherein the processor is further adapted to indicate the presence of a jamming condition if the short-term noise value exceeds the sum of the long-term noise value and a jamming threshold, and further exceeds an expected received RF signal strength minus a detection threshold; and an indicator adapted to notify users of the presence of the jamming condition. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A system controller for use with a wireless security system comprising a plurality of RF transmitters, the system controller comprising:
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a receiving unit adapted to receive RF transmissions from the RF transmitters; a signal-strength circuit adapted to measure a noise level when RF signals are not being received; and a processor adapted to determine a long-term noise value and a short-term noise value, wherein the processor is further adapted to indicate the presence of a jamming condition if the short-term noise value exceeds the sum of the long-term noise value and a jamming threshold, and further exceeds an expected received RF signal strength minus a detection threshold. - View Dependent Claims (30, 31, 32, 33, 34, 35)
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Specification