SAW Sensor Coding With PN Switching for ON-OFF State Detection
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Solution Overview
Problem
Existing surface acoustic wave (SAW) devices face challenges in identifying and transmitting both sensor identification and sensed information simultaneously in multi-sensor environments, particularly in distinguishing between ON and OFF states using the same orthogonal frequency code.
Innovation Solution
The implementation of passive wireless surface acoustic wave devices that utilize the same orthogonal frequency code for both ON and OFF states, incorporating additional pseudo noise (PN) sequences and external switches for multi-level coding and distinguishing between states, along with the use of thin film ferromagnetic materials to alter delay, loss, or frequency, ensuring a wireless communication link is established.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the same orthogonal frequency code is used for both ON and OFF states, then code diversity is enhanced and device complexity is reduced, but the ability to distinguish between states deteriorates
Solution Approach 1:
The patent segments the state information into two parts: the orthogonal frequency code (same for both states) and the pseudo-noise sequence (different for ON/OFF states). This segmentation allows the system to maintain code diversity through the frequency code while distinguishing states through the PN sequence modulation.
Solution Approach 2:
The patent transitions from single-dimension frequency coding to multi-dimensional coding by adding the pseudo-noise sequence dimension. The same orthogonal frequency code is modulated with different PN sequences for ON and OFF states, creating state distinction in a new dimension while maintaining frequency code reuse.
2Measurement precision
If additional pseudo noise sequences and external switches are incorporated, then state distinction capability is improved, but device complexity increases
Solution Approach 1:
The patent employs external switches that respond to environmental stimuli (magnetic fields, temperature, etc.) to automatically modulate the pseudo-noise sequence based on the sensor state. This self-service mechanism reduces the need for complex control circuitry while maintaining state distinction capability.
Solution Approach 2:
The external switches serve multiple functions: they act as state indicators, signal modulators, and environmental response elements simultaneously. This multi-functionality reduces overall device complexity by consolidating multiple roles into single components.
3Measurement precision
If thin film ferromagnetic materials are used to alter delay, loss, or frequency, then sensing capability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes thin film ferromagnetic materials to dynamically change the physical parameters (delay, loss, frequency) of the SAW device in response to environmental stimuli. These parameter changes enhance sensing capability while the thin film nature keeps the manufacturing process relatively simple compared to bulk material modifications.
Solution Approach 2:
The patent employs composite structures combining standard SAW device materials with thin film ferromagnetic materials. This composite approach allows integration of enhanced sensing capability into existing manufacturing processes, minimizing the increase in manufacturing complexity.
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 enhances code diversity, allows for efficient identification and data transmission in multi-sensor systems, ensuring reliable wireless communication by maintaining the same orthogonal frequency code for both states and verifying signal presence through external closure detection.
Implementation Method 1
The surface acoustic wave (SAW) sensor offers advantages in that it is wireless, passive, small and has varying embodiments for different sensor applications.
Implementation Method 2
use of thin film ferromagnetic materials to alter delay, loss, or frequency
Data Source
AI summary
Methods and systems for passive wireless surface acoustic wave devices for orthogonal frequency coded devices to implement ON-OFF sensors reusing orthogonal frequency code and distinguishing between ON and OFF states using additional PN sequence and on/off switches producing multi-level coding as well as external stimuli for switching and identification of a closure system. An embodiment adds a level of diversity by adding a dibit to each surface acoustic wave devices, thus providing four different possible coding states. The PN on-off coding can be with the dibit for coding in a multi-tag system.