EAS System Interference Trimming via Reference Pattern Matching

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Solution Overview

Problem

Electronic Article Surveillance (EAS) systems experience interference from adjacent transmitters, leading to reduced detection sensitivity, false alarms, and increased service calls due to unsynchronized operations, especially when unsynchronized systems with random pulse transmission are in close proximity.

Innovation Solution

The system determines the transmit pattern and energy levels of adjacent EAS systems and trims received signals during transmission windows, using reference patterns to ignore interfering signals and prevent false alarms, thereby reducing interference without the need for synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If EAS transmitters operate simultaneously in close proximity without synchronization, then system deployment flexibility and ease of operation are improved, but interference between systems increases causing reduced detection sensitivity and false alarms

Engineering Contradiction:

Improvedeployment flexibilityVSAvoiddetection sensitivity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary detection of transmit patterns from adjacent EAS systems before making detection decisions. By identifying and storing reference patterns of interfering transmissions in advance, the system can pre-determine which received signals should be trimmed or ignored, thereby eliminating interference issues before they affect detection sensitivity or cause false alarms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors received signals to detect transmit patterns from adjacent systems, compares them against stored reference patterns, and dynamically adjusts which signals to trim or ignore. This feedback mechanism allows the system to adapt to changing interference conditions while maintaining deployment flexibility without synchronization

Inventive Principle:

Principle #23Feedback

2Reliability

If EAS transmitters are synchronized to avoid interference, then detection sensitivity and system reliability are improved, but system complexity and difficulty of installation increase

Engineering Contradiction:

Improvedetection sensitivityVSAvoidsynchronization complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Each EAS system independently detects and identifies transmit patterns from adjacent systems on its own, without requiring coordination or synchronization with those systems. The system autonomously stores reference patterns and determines which received signals to trim or ignore, thereby achieving interference mitigation through self-service rather than complex inter-system synchronization

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system changes the approach from synchronizing transmitter timing parameters to instead modifying the signal processing parameters - specifically, which received signals are trimmed or ignored based on detected transmit patterns. This parameter change eliminates the need for complex synchronization while maintaining detection sensitivity

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If unsynchronized EAS systems with random pulse transmission are deployed, then ease of installation and adaptability are improved, but interference and false alarms increase significantly

Engineering Contradiction:

Improveinstallation adaptabilityVSAvoidinterference level

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection and storage of random transmit patterns from unsynchronized adjacent systems. By building a library of reference patterns in advance through continuous monitoring, the system prepares to identify and trim interfering signals before they cause false alarms or affect detection sensitivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors for transmit patterns from unsynchronized adjacent systems, compares received signals against stored reference patterns, and dynamically determines which signals to trim or ignore. This feedback loop enables the system to adapt to random pulse transmissions from diverse unsynchronized systems while maintaining installation adaptability and reducing interference

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8106777B2Method and system to negate interference from adjacent transmitters in an electronic article surveillance system

Publication Date: 2012.01.31 SENSORMATIC ELECTRONICS CORP

AI summary

A method and electronic article surveillance (“EAS”) system reduce interference. The EAS system includes a detection zone. At least one reference pattern of transmission windows for an interfering EAS system is provided. The reference pattern indicates a sequence of time slots for which the interfering EAS system is transmitting. A sample pattern of signals is received. Each signal has a corresponding amplitude. The received sample pattern is compared to the at least one reference pattern. Responsive to determining that the received sample pattern matches the at least one reference pattern, the at least one reference pattern is used to trim samples received during receive windows corresponding to the time slots for which the interfering EAS system is transmitting.