Transponder Modulation Timing for RFID Signal Reliability
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Solution Overview
Problem
Existing wireless data transmission methods between base stations and transponders face reliability issues due to interference from synchronization marker generation, leading to misreading of backscattered signals, particularly in passive RFID systems, which complicates signal evaluation and requires complex implementation in base stations.
Innovation Solution
Implementing a time delay in the modulation state change of the transponder relative to synchronization markers, allowing the transponder to change its modulation state after interference from synchronization marker generation has ceased, along with using double sideband modulation with a suppressed carrier and NRZ or NRZI coding, to improve transmission reliability and range without complex envelope curve monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronization markers are generated by amplitude modulation of the carrier signal, then the transponder can detect synchronization markers, but the signal evaluation becomes more difficult due to interference with low-power backscattered signals
Solution Approach 1:
The invention extracts the synchronization marker detection function from the main data transmission signal by using a separate detection signal with a distinct frequency. The detection unit in the transponder is specifically designed to detect this separate detection signal, thereby separating the synchronization detection process from the backscattered data signal evaluation, reducing interference and improving signal evaluation difficulty.
2Quantity of substance
If the carrier signal is completely blanked during modulation, then bandwidth utilization is reduced, but transmission range is limited
Solution Approach 1:
The invention changes the modulation index parameter from complete blanking (modulation index = 1) to partial blanking (modulation index < 1). This parameter change allows the carrier signal to maintain a non-zero amplitude during modulation, preserving energy for backscattering while still enabling synchronization marker detection, thereby extending transmission range without completely sacrificing bandwidth utilization.
3Quantity of substance
If double sideband modulation with suppressed carrier is used, then bandwidth utilization is improved, but the carrier signal must be completely suppressed which limits energy availability
Solution Approach 1:
The invention applies partial blanking instead of complete carrier suppression. By using a modulation index less than one, the carrier signal is partially suppressed during modulation, which improves bandwidth utilization compared to no suppression, while still leaving sufficient carrier energy available for the transponder to perform backscattering and maintain operation.
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 enhances the reliability and range of wireless data transmission with reduced circuit complexity, allowing for flexible adaptation to transmission conditions and simplified implementation in both base stations and transponders, while avoiding misreading of backscattered signals.
Implementation Method 1
the base station emits electromagnetic carrier waves, which the transmitting and receiving device in the transponder modulates and reflects appropriately for data to be transmitted to the base station
Implementation Method 2
so-called backscatter coupling is used to transmit data from a transponder to the base station using UHF or microwaves in the far field of the base station
Implementation Method 3
the carrier signal is amplitude-modulated and/or phase-modulated with a modulating signal by the base station in such a manner that a detection unit within the transponder, which is basically designed for amplitude modulation of the carrier signal, can detect the synchronization marker
Data Source
AI summary
A method and device for wireless data transmission between a base station and one or more transponders, in which electromagnetic carrier waves are emitted by the base station and symbols are transmitted from a given transponder to the base station by modulation and backscattering of the electromagnetic carrier waves, wherein a change in a modulation state takes place synchronously with synchronization markers transmitted by the base station. A change in the modulation state is carried out by a transponder with a specifiable time delay that is relative to the synchronization markers.