RFID Interrogator Synchronization via Periodic Frame Pulses

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Solution Overview

Problem

In RFID systems, multiple interrogators in the same theatre of operation often interfere with each other's broadcasts due to unsynchronized transmissions, leading to incorrect data interpretation or failure to receive signals from RFID tags.

Innovation Solution

Implementing a synchronization mechanism where interrogators can be wired or wirelessly synchronized using a synchronization master, with the ability for one interrogator to take over as master in case of failure, and adjusting frame synchronization pulses to avoid interference, allowing for coordinated transmission timing to prevent overlap with RFID tag response periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If multiple RFID interrogators operate independently without synchronization, then each interrogator can function autonomously and maintain simple operation, but their transmissions interfere with each other causing incorrect data interpretation and signal reception failures

Engineering Contradiction:

Improveautonomous operationVSAvoiddata reception accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements periodic frame synchronization pulses that are transmitted at regular intervals to coordinate the operation of multiple RFID interrogators. Each interrogator transmits synchronization frames at predetermined time intervals, creating a periodic action pattern that ensures all interrogators operate in synchronized cycles, preventing transmission interference while maintaining autonomous functionality.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent employs a feedback mechanism where each RFID interrogator monitors for the presence of synchronization frames from other interrogators and adjusts its transmission timing accordingly. This feedback loop ensures that interrogators can detect and respond to synchronization signals, automatically correcting timing deviations and maintaining coordinated operation without centralized control.

Inventive Principle:

Principle #23Feedback

2Reliability

If a synchronization master is implemented to coordinate interrogator transmissions, then transmission interference is prevented and data reception accuracy improves, but system complexity increases and the system becomes vulnerable to master failure

Engineering Contradiction:

Improvetransmission coordinationVSAvoidsynchronization system structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the synchronization master functionality into each individual RFID interrogator unit. Each interrogator is equipped with both master and slave capabilities, allowing them to function as synchronization sources when needed and as followers when another interrogator is providing synchronization. This merging eliminates the need for a separate dedicated master device, reducing system complexity while maintaining coordination.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements dynamic role assignment where RFID interrogators can switch between master and slave roles based on real-time conditions. When a synchronization master fails or when operating conditions change, any interrogator can transition to master status and begin transmitting synchronization frames. This dynamic adaptability ensures continuous synchronization coordination without requiring a fixed hierarchical structure, reducing vulnerability to single-point failures.

Inventive Principle:

Principle #15Dynamics

3Reliability

If wired synchronization connections are used between interrogators, then synchronization reliability is ensured, but system adaptability to mobile applications is reduced

Engineering Contradiction:

Improvesynchronization stabilityVSAvoidmobile application compatibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical wired synchronization connection system with an electromagnetic field-based wireless synchronization system. Instead of using physical cables to transmit synchronization signals between RFID interrogators, the system utilizes radio frequency electromagnetic fields to transmit synchronization frames wirelessly. This substitution maintains synchronization reliability through structured signal transmission while enabling mobility and adaptability to various deployment scenarios including mobile applications.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10235545B2Systems and methods for synchronizing a plurality of RFID interrogators in a theatre of operation

Publication Date: 2019.03.19 SMARTRAC TECHNOLOGY FLETCHER INC

AI summary

RFID tags are used for many purpose including tracking. RFID interrogators are used to retrieve information from tags. In many applications, a plurality of RFID interrogators are required. Synchronization between interrogators in the same theater of operation is critical to ensure that their broadcasts do not interfere with each other. In fixed RFID interrogator applications, RFID interrogators can be wired together allowing a channel to synchronize the transmissions of the RFID interrogators. Methods described herein can ensure that synchronization is maintained in the event of the failure of a synchronizing master. Furthermore, additional methods for synchronizing RFID interrogators in wireless applications are described allowing synchronization in the absence of wired connections between interrogators.