Transponder Clock-Stop Frequency Shifting to Avoid Reader False Detection
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Solution Overview
Problem
RFID transponders generate electromagnetic disturbance (EMD) noise due to power consumption variations, leading to unreliable operations across different readers with varying sensitivities, as the noise can be misinterpreted as response signals by readers.
Innovation Solution
Incorporating a clock-stop sensor with a frequency detector and a frequency shifter that monitors and shifts the output frequency and duty cycle to values outside the response detection range of the reader, using programmable parameters stored in a non-volatile memory to ensure reliable communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the transponder uses a clock-stop sensor to gate clock signals for power management, then power consumption is reduced, but electromagnetic disturbance noise is generated that can be misinterpreted as response signals by readers
Solution Approach 1:
The patent detects the harmful EMD noise generated by the clock-stop sensor and converts it into a beneficial signal by using frequency detection to identify when the noise falls within the reader's response detection range, then applying frequency shifting to eliminate the interference while maintaining power management benefits
Solution Approach 2:
The patent changes the frequency parameter of the clock-stop sensor output by introducing a frequency shifter that modifies the output frequency to move it outside the reader's response detection range, thereby eliminating the harmful effect while preserving the power management function
2Device complexity
If the transponder operates at fixed clock frequency, then communication is simple, but reliability varies across different readers due to EMD noise falling within their response detection ranges
Solution Approach 1:
The patent introduces dynamic frequency adjustment by detecting the clock-stop sensor output frequency and shifting it when necessary, transforming the fixed frequency system into a dynamic one that adapts to different reader sensitivities and eliminates EMD noise interference
Solution Approach 2:
The patent implements a feedback mechanism where the frequency detector continuously monitors the clock-stop sensor output and provides feedback to the frequency shifter, which adjusts the frequency accordingly to ensure it remains outside the reader's response detection range, thereby improving reliability
3Object-generated harmful factors
If the transponder adds frequency detection and frequency shifting capabilities, then EMD noise interference is eliminated, but device complexity increases
Solution Approach 1:
The patent introduces intermediary components (frequency detector and frequency shifter) that mediate between the clock-stop sensor and the rest of the transponder system, isolating the EMD noise generation from the communication process while maintaining the power management benefits
Data Source
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Figure 2B
Figure 2C
AI summary
In accordance with a first aspect of the present disclosure, a transponder is provided, comprising: a frequency detector configured to monitor an output frequency of a clock-stop sensor of said transponder, wherein said frequency detector is further configured to determine if said output frequency falls within a response detection frequency range of an external reader; and a frequency shifter configured to shift, in response to the frequency detector determining that the output frequency falls within said response detection frequency range, said output frequency to a value outside said response detection frequency range. In accordance with a second aspect of the present disclosure, a corresponding method of operating a transponder is conceived. In accordance with a third aspect of the present disclosure, a corresponding computer program is provided.