RFID Tag DAC Reference Signal Comparison

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

RFID systems face inefficiencies in identifying specific tags among many due to the need for interrogators to query each tag individually, leading to substantial processing time in environments with numerous tags, such as dock doors or warehouses, where speed of identification is desirable.

Innovation Solution

Incorporating a Digital to Analog Converter (DAC) in RFID tags to generate a reference signal based on stored digital comparison criteria, allowing the tag to selectively respond to interrogator signals only if the signal strength meets the criteria, thereby reducing unnecessary responses and improving processing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If RFID tags respond to every interrogator signal, then all tags can be identified, but processing time increases substantially when many tags are present

Engineering Contradiction:

Improvetag identification accuracyVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The tag performs preliminary comparison of the incoming signal strength against a stored reference signal before deciding to respond. This preliminary action filters out tags that should not respond, reducing the number of tags that actually respond to the interrogator and thereby reducing processing time while maintaining identification accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of signal strength comparison by storing a reference signal strength value in the tag's memory and comparing incoming signal strength against this stored value. This parameter-based filtering allows tags to selectively respond based on whether the incoming signal exceeds the stored reference, efficiently reducing the number of responding tags.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If RFID tags selectively respond based on signal strength, then processing speed improves, but device complexity increases due to DAC and comparison circuitry

Engineering Contradiction:

Improveprocessing speedVSAvoidtag circuit complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Instead of implementing complex real-time signal processing circuitry in each tag, the system copies the reference signal strength value into the tag's memory during a calibration phase. The tag then uses this copied reference value for comparison, avoiding the need for complex DAC and comparison circuitry in each tag while still achieving selective response based on signal strength.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The reference signal strength is determined and stored in the tag's memory in advance, before actual operation. This preliminary calibration action eliminates the need for complex real-time processing circuitry, as the tag only needs to compare incoming signal strength against the pre-stored reference value, thereby reducing device complexity while maintaining processing speed.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8098159B2RF device comparing DAC output to incoming signal for selectively performing an action

Publication Date: 2012.01.17 ZEST LABS INC

AI summary

A Radio Frequency (RF) device such as a Radio Frequency Identification (RFID) tag according to one embodiment includes a Digital to Analog Converter (DAC) for generating a reference signal based on a stored digital comparison criteria value, and a mechanism for comparing an incoming signal to the reference signal. The device performs an action such as backscattering based on the comparison. Additional systems and methods are also disclosed.