RFID Phase Jitter Demodulation for Low-Noise High Data Rates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RFID data transmission systems face challenges with high data rates due to pulse position modulation (PPM) causing high sideband levels, which restrict excitation field strength and result in amplitude compression, reducing operating range and increasing noise interference.
Innovation Solution
Implementing a Phase Jitter Modulation (PJM) signal with a delay line in the demodulation circuit to provide a stable reference, reducing noise and InterSymbol Interference (ISI), and using a differential phase detector with a Low Pass Filter to reconstruct the data signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Pulse Position Modulation (PPM) is used to achieve high data rates, then data transmission rate is improved, but sideband levels increase causing amplitude compression and reduced operating range
Solution Approach 1:
The patent changes the modulation parameter from PPM to Phase Shift Keying (PSK), fundamentally altering how data is encoded. PSK modulates phase rather than position, which reduces sideband levels while maintaining high data rates, thereby resolving the contradiction between productivity and harmful emissions
Solution Approach 2:
The patent uses a delayed copy of the received signal as a reference for demodulation. By creating a time-delayed version of the signal and using it as a reference in the phase detector, the system achieves coherent detection without requiring a separate local oscillator, thus maintaining high data rate capability while reducing complexity
2Power
If excitation field strength is increased to compensate for less efficient antenna in passive tags, then signal strength is improved, but amplitude compression increases reducing operating range
Solution Approach 1:
The patent replaces amplitude-based detection with phase-based detection. Instead of relying on amplitude variations that suffer from compression effects, the system detects phase differences between the received signal and a delayed reference signal, thereby eliminating amplitude compression as a limiting factor
Solution Approach 2:
The patent introduces a delayed version of the received signal as an intermediary reference. This delayed signal serves as a mediator that allows phase comparison without requiring direct amplitude measurement, thus bypassing the amplitude compression problem while maintaining sensitivity to weak signals
3Object-generated harmful factors
If modulation depth is reduced to decrease sideband levels, then emission compliance is improved, but tag voltage regulation circuits cause amplitude compression
Solution Approach 1:
The patent inverts the conventional approach by not trying to mitigate amplitude compression through reduced modulation depth, but rather by completely changing to phase modulation where amplitude variations are irrelevant. This inversion of the modulation strategy eliminates the conflict between emission compliance and signal detection reliability
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The present invention relates to the field of receiving data and/or demodulating a data transmission signal. The present invention provides a method of and/or device for determining a data signal imposed on a phase jitter modulation signal. In one form, the invention relates to the field of Radio Frequency Identification (RFID), and the transmission of data between a tag and an interrogator.