Transponder Data Allocation via IQ Demodulation
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Solution Overview
Problem
Existing systems for communicating with multiple transponders are inefficient due to the potential for signal collisions when transponders respond during the same time slot, leading to a time-consuming process of discarding and re-sending commands to receive unambiguous signals.
Innovation Solution
A method involving in-phase and in-quadrature demodulation of received signals to generate orthogonal signals, allowing for the allocation of digital data from multiple transponders using a constellation diagram, which separates and identifies data clusters associated with each transponder based on amplitude and phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If transponders randomly select time slots for transmitting reply signals, then the system structure remains simple, but signal collisions occur when multiple transponders transmit simultaneously, reducing communication efficiency
Solution Approach 1:
The patent applies parameter changes by transitioning from time-division multiplexing to frequency-division multiplexing. Multiple transponders transmit simultaneously on different frequencies (carrier frequencies), eliminating collisions while maintaining simple system structure. Each transponder modulates its data on a unique carrier frequency, allowing the reader to receive and separate multiple signals concurrently through frequency discrimination.
2Reliability
If the reader discards colliding reply signals and re-sends inventory commands, then signal reliability is maintained, but communication time increases significantly
Solution Approach 1:
The patent applies preliminary action by pre-assigning unique carrier frequencies to different transponders before communication begins. This prevents collisions from occurring in the first place, eliminating the need for retransmission and significantly reducing communication time while maintaining signal reliability through frequency separation.
3Speed
If multiple transponders transmit reply signals simultaneously, then communication speed improves, but signal separation and allocation to specific transponders becomes difficult
Solution Approach 1:
The patent uses carrier frequency as an intermediary to enable simultaneous transmission. Each transponder's signal is modulated on a unique carrier frequency, which acts as a mediator that allows the reader to separate and identify individual transponder signals through frequency discrimination, making simultaneous multi-transponder communication feasible without complex signal processing.
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
Enables simultaneous allocation of digital data from multiple transponders, reducing the time required for communication and preventing signal collisions by clearly distinguishing data clusters through IQ-demodulation and constellation diagram analysis.
Implementation Method 1
generating second and third signals by subjecting the first signal to an in-phase and to an in-quadrature demodulation
Data Source
AI summary
In a method of allocating digital data (55a, 55b) coming from transponders, a reader (1) receives a first signal (13) that comprises a first signal component (7) coming from a first transponder (2) and a second signal component (8) coming from a second transponder (3). The digital data (55a) coming from the first transponder (2) are encoded in the first signal component (7) and digital data (55b) coming from the second transponder (3) are encoded in the second signal component (8). Second and third signals (10, 11) are generated by subjecting the first signal (13) to an in-phase and to an in-quadrature demodulation. The digital data (55a, 55b) of the first and second transponders (2, 3) are encoded in the second and third signals (10, 11). Clusters (51-54) of the digital data (55a, 55b) associated with a constellation diagram, which is related to the second and third signals (10, 11), are allocated to the first and second transponder (2, 3).