Jamming Detection via Noise Floor Derivative
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Solution Overview
Problem
Current alarm systems do not detect jamming until the system is completely jammed, leading to potential false alarms when threshold levels are set too low and missed detections when set too high, and they fail to identify moving jamming devices before they cause complete disruption.
Innovation Solution
The method involves monitoring the change in noise floor over time using a sliding window to detect a moving jammer by calculating the time derivative of the received signal strength indicator, allowing for early detection of jamming without generating false alarms, and includes a system comprising a radio transceiver unit and processor to determine if a jamming device is closing in based on a predetermined threshold level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold level is used for jamming detection, then the system can detect jamming at a certain level, but it generates false alarms when the threshold is set too low or misses detections when set too high
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed threshold to a dynamic threshold that adapts to changing environmental conditions. The system continuously monitors the noise floor and adjusts the detection threshold accordingly, allowing it to distinguish between normal environmental variations and actual jamming signals. This dynamic adaptation eliminates false alarms caused by static thresholds while maintaining detection sensitivity.
Solution Approach 2:
The patent changes the parameter of the detection threshold from a fixed value to a variable that evolves based on observed signal characteristics. By monitoring the noise floor over time and adjusting the threshold parameter dynamically, the system optimizes its detection accuracy without generating false alarms, resolving the contradiction between detection precision and reliability.
2Reliability
If the system waits for complete jamming before detection, then false alarms are reduced, but the system fails to provide early warning of approaching jamming threats
Solution Approach 1:
The patent applies preliminary action by detecting changes in the noise floor that precede complete jamming. The system monitors for gradual increases in background noise and detects the approach of a jamming device before it fully disrupts communication. This early detection provides advance warning while maintaining reliability by using adaptive thresholds that prevent false alarms from normal environmental variations.
Solution Approach 2:
The system uses feedback by continuously monitoring the noise floor and comparing it against dynamically adjusted thresholds. The feedback loop allows the system to detect trends in noise levels and distinguish between temporary fluctuations and sustained jamming patterns, enabling early detection without increasing false alarm rates.
3Measurement precision
If the system monitors for jamming signals, then it can detect jamming events, but it cannot distinguish between environmental noise and actual jamming threats
Solution Approach 1:
The patent uses dynamics to differentiate between environmental noise and jamming signals by monitoring the temporal characteristics of noise floor changes. Environmental noise typically exhibits random, short-term fluctuations, while jamming signals produce sustained, directional increases in noise. The dynamic threshold adapts to environmental conditions while detecting the distinctive pattern of approaching jamming threats.
Solution Approach 2:
The system applies preliminary action by establishing a baseline of normal environmental noise levels before detecting jamming events. By monitoring deviations from this baseline over time, the system can distinguish between normal environmental variations and the systematic noise increases caused by approaching jamming devices, improving detection precision without false alarms.
Data Source
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Figure 1g
AI summary
A method of detecting a moving jamming device issuing a jamming signal, and closing in on an alarm installation, the method comprising the following steps - providing a first signal representative of instantaneous received radio energy; - creating a second signal representative of the average of the first signal taken over a predetermined window; - creating a third signal representative of the time derivative of the second signal; - indicating whether a jammer is closing in based on the third signal