Contactless Receiver Phase Demodulation Null Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing contactless communication systems face challenges in maintaining reliable data transmission due to nulls caused by varying distances between antennas, which cannot be entirely avoided through antenna adjustment or tuning frequency adjustments alone.
Innovation Solution
A receiving apparatus that includes an amplitude demodulation section, a phase information extraction section, and a selection section to demodulate and select between amplitude and phase information outputs, enabling data reception even when amplitude changes are undetectable, by utilizing phase information to decode data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antenna adjustment and tuning frequency adjustment are performed, then communication reliability is improved under certain conditions, but nulls cannot be avoided for all possible combinations of PCDs and PICCs
Solution Approach 1:
The patent changes the detection parameter from amplitude-only to include both amplitude and phase information. By extracting phase information from the carrier wave and comparing it with a reference phase, the system can detect load changes even when amplitude changes are undetectable due to nulls. This parameter change enables universal adaptability across all PCD-PICC combinations regardless of distance.
2Productivity
If amplitude demodulation is used to detect load changes, then data transmission is achieved, but nulls occur at certain distances where amplitude change becomes zero
Solution Approach 1:
The patent introduces phase information as an intermediary detection mechanism. Instead of relying solely on amplitude changes, the system uses phase changes of the carrier wave as an alternative indicator of load changes. When amplitude demodulation fails at certain distances, phase demodulation serves as the intermediary that enables continued data transmission.
3Stability of the object's composition
If load switch is turned on to reduce distance dependence of carrier wave amplitude, then amplitude stability is improved, but information transmission capability is reduced when amplitude change becomes zero
Solution Approach 1:
The patent makes the receiving apparatus universal by implementing both amplitude demodulation and phase demodulation capabilities. The selection section automatically chooses the appropriate demodulation method based on which one provides detectable changes. This multi-functionality ensures that information transmission can occur regardless of whether amplitude or phase changes are more prominent, eliminating the trade-off between stability and transmission capability.
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
Ensures reliable data transmission by selecting the appropriate demodulation output based on amplitude and phase information, effectively overcoming nulls caused by antenna distance variations and ensuring consistent data reception.
Implementation Method 1
an electromagnetic induction method may be adopted, where an AC voltage can be induced in the antenna coil of the PICC by bringing the PICC into an AC magnetic field which is generated by electric current supplied to an antenna coil of a PCD
Implementation Method 2
by changing load connected to a resonance circuit including the antenna coil of the PICC, for example, electric current that flows to antenna coils can be changed in the PCD side in which antenna coils are electromagnetically-coupled to each other
Data Source
AI summary
In contactless communication in which a carrier wave transmitted from a first antenna of a host is received via a second antenna of a terminal and the carrier wave is amplitude-modulated on the terminal to transmit data to the host, a carrier wave detected from the first antenna is amplitude-demodulated to obtain a first demodulated output, and phase information included in the carrier wave detected from the first antenna is extracted and the extracted phase information is decoded to obtain a second demodulated output. Then, either of the first and second demodulated outputs is selected and output. Even when a null is caused by an antenna distance between a PCD and a PICC, demodulated data is reliably obtained by utilizing demodulation processing that uses phase information.