Simulated Preamble Signal for RFID Noise Immunity

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Solution Overview

Problem

RFID devices without a battery or active power source face challenges in accurately decoding data streams without a preamble signal, making them susceptible to noise and errors due to low power levels and the need for cost-effective, disposable designs.

Innovation Solution

An interrogation unit generates a power-up signal and a constant power transmission signal for the RFID device, and internally simulates a preamble signal to be combined with the received data stream, allowing accurate decoding without requiring the RFID device to transmit a preamble.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a preamble signal is transmitted by the RFID device, then data decoding accuracy is improved, but power consumption increases and interrogation cycle time increases

Engineering Contradiction:

Improvedata decoding accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The interrogation unit generates and transmits a simulated preamble signal before the RFID device transmits its data. This preliminary action prepares the reception circuitry in advance, allowing the RFID device to skip its own preamble transmission while still achieving accurate data decoding. The simulated preamble is averaged with the received data stream to enhance signal quality.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If a preamble signal is transmitted by the RFID device, then data decoding accuracy is improved, but interrogation cycle time increases

Engineering Contradiction:

Improvedata decoding accuracyVSAvoidinterrogation cycle time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The interrogation unit performs the preamble generation and transmission as a preliminary action before the RFID device needs to send its data. By initiating this preparation in advance, the system eliminates the time the RFID device would otherwise spend transmitting its own preamble, thereby reducing the total interrogation cycle time while maintaining decoding accuracy through the averaging process.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If the RFID device uses low power level for transmission, then manufacturing cost is reduced and device simplicity is improved, but noise susceptibility increases

Engineering Contradiction:

Improvedevice simplicityVSAvoidnoise susceptibility

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The simulated preamble signal acts as an intermediary that bridges the gap between the low-power transmitted data and the reception circuitry. By introducing this intermediary signal that is averaged with the received data stream, the system compensates for the low power level and reduces noise susceptibility without requiring the RFID device to transmit at higher power or include its own preamble.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Use of energy by moving object

If preamble transmission is eliminated, then power usage is reduced and interrogation cycle time is reduced, but data reliability deteriorates

Engineering Contradiction:

Improvepower usageVSAvoiddata reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Instead of having the RFID device transmit its own preamble, the interrogation unit creates a copy of the expected preamble signal (the simulated preamble) and transmits it separately. This copy is then averaged with the received data stream, allowing the system to maintain data reliability without the RFID device consuming additional power for its own preamble transmission.

Inventive Principle:

Principle #26Copying

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach reduces power usage and time for interrogation cycles while enhancing data accuracy and reliability by averaging the simulated preamble with the received data, reducing noise susceptibility and enabling accurate decoding of Manchester-coded data streams.

Implementation Method 1

the transponder unit may simply comprise a capacitor that collects and stores RF energy transmitted from the interrogation unit

Methodology Applied

Scientific EffectElectromagnetic energy collection: Electromagnetic Induction

Data Source

PatentUS7346003B2Method of increasing noise immunity with a simulated preamble

Publication Date: 2008.03.18 TEXAS INSTRUMENTS INC

AI summary

Circuitry and method for receiving and decoding a data stream without a preamble transmitted from the transmitting device. The invention includes circuitry in the receiver or interrogation unit for generating a simulated preamble signal that is provided to the input of an averaging circuit and a comparator. The averaging circuitry then averages the simulated preamble signal and the actual received data signal to avoid loss of messages and information data at the front end of the received signal from a transponder.