RFID Carrier Phase Modulation for Stable Power and Clock Recovery
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Solution Overview
Problem
Current phase modulation techniques in contactless RFID systems face challenges such as parasitic amplitude modulations, clock loss, and non-compliance with European radio emission standards due to significant phase jumps, which affect remote power supply and data transmission rates.
Innovation Solution
A method and device for phase modulation that limits phase jumps between symbols to π/4, spreading the phase jump over the first part of the symbol time and maintaining constant cycle periods during the second part, ensuring the maximum total phase jump is less than π, thereby minimizing unwanted effects and adhering to emission standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase modulation with significant phase jumps is used to increase data rates, then productivity is improved, but reliability deteriorates due to clock loss and remote power supply failure
Solution Approach 1:
The patent segments the phase modulation process into distinct phases: a first part where phase jump is applied to carry data information, and a second part where no phase jump occurs to maintain stable clock and power supply. This segmentation allows the system to achieve high data rates during the first part while ensuring reliability during the second part, thus resolving the contradiction between productivity and reliability.
2Productivity
If phase modulation techniques are used to extend transmission speed beyond Mb/s, then productivity is improved, but object-generated harmful factors worsen due to non-compliance with European radio emission standards
Solution Approach 1:
The patent divides the symbol duration into two parts: the first part allows phase jumps necessary for high-speed data transmission, while the second part maintains constant phase to ensure compliance with European radio emission standards (ERC-70-03 and ETS 300-330). This segmentation enables the system to achieve transmission speeds beyond Mb/s while generating acceptable electromagnetic emissions.
3Productivity
If the quality coefficient of the transmitting antenna is reduced to widen channel bandwidth, then productivity is improved, but use of energy by stationary object deteriorates due to reduced remote power supply capability
Solution Approach 1:
The patent segments the symbol time into a first part for data transmission with phase jumps and a second part for stable power supply without phase jumps. This allows the system to utilize wider channel bandwidth for high-speed data transmission during the first part while maintaining sufficient power supply capability during the second part, thus resolving the contradiction between productivity and energy usage.
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 optimizes data rates while maintaining remote power supply and clock recovery, ensuring compatibility with existing standards and reducing communication failures.
Implementation Method 1
The reader, considered a base station, generates a carrier wave (short-range alternating magnetic field) which is used to power contactless cards near the reader antenna.
Implementation Method 2
This antenna can be electrically modeled in the form of a resonant circuit of type R, L, C characterized by a central frequency f c, a quality coefficient Q and having a limited bandwidth BP.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a method for the phase modulation of a carrier signal transmitted from a transmitter to a contactless transponder, and to a device for implementing same. According to said method, data is encoded in the form of consecutive symbols (Sn-1, Sn), each of which correspond to a predefined number of carrier cycles, and have a symbol time (Ts) that is greater than or equal to two cycles of the carrier signal. Then, at the transmitter, a phase hop is applied to one symbol with respect to a previous symbol over a first portion (11) of the symbol time, the establishment of the phase hop being completed during the first portion (11) of the symbol time, and the periods of the cycles being constant during the second portion of the symbol time.