Wireless Sensor Reader Using Discrete Excitation Frequencies
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Solution Overview
Problem
Existing fixed frequency wireless LC resonant tank sensor systems have a limited operational measurement range, requiring narrow bandwidth design that incurs penalties in size, precision, and manufacturability, and are susceptible to signal detection failures at distances away from resonance frequency.
Innovation Solution
A wireless sensor reader that selects a transmit frequency from a plurality of discrete narrowband frequencies before determining the sensor's resonance frequency, using a phase locked loop to lock onto the response signal and obtain multiple samples over a measurement time interval, adjusting the excitation frequency as needed to maintain signal strength within a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single fixed excitation frequency is used, then the device complexity is reduced and manufacturing is simplified, but the operational measurement range is limited and signal detection reliability deteriorates at distances from resonance frequency
Solution Approach 1:
The patent implements a dynamic frequency selection mechanism where the reader can switch between multiple discrete excitation frequencies based on the sensor's resonant frequency detection. This dynamic adaptation allows the system to maintain optimal measurement conditions across a wider operational range without requiring continuous frequency sweeping, thus increasing adaptability while controlling complexity.
Solution Approach 2:
The system changes the excitation frequency parameter from a single fixed value to multiple discrete values. By selecting from a plurality of predefined frequencies, the system can adapt to different sensor resonant frequencies and operational conditions, expanding the measurement range while avoiding the complexity of continuous frequency adjustment mechanisms.
2Adaptability or versatility
If multiple discrete narrowband frequencies are supported, then the operational range is widened, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The frequency spectrum is segmented into multiple discrete narrowband channels rather than requiring a continuous wideband capability. Each frequency can be implemented as a separate, standardized module or circuit block, making the system easier to manufacture through modular design and assembly while achieving wide operational coverage.
Solution Approach 2:
The reader is designed with multi-functionality to support multiple discrete frequencies using common hardware components. By implementing a universal frequency selection mechanism that can operate at any of the predefined frequencies, the system achieves wide operational range without proportionally increasing manufacturing complexity, as the same basic circuitry serves multiple frequency functions.
3Volume of moving object
If narrow bandwidth design is used, then the device size is reduced, but the operational measurement range is limited
Solution Approach 1:
The system dynamically selects from multiple discrete frequencies rather than requiring a continuously tunable wideband design. This dynamic frequency selection allows a compact device with narrow individual bandwidth channels to achieve wide effective operational range by switching between channels, maintaining small device size while expanding measurement capabilities.
Solution Approach 2:
The reader performs periodic frequency sampling or sweeping through the discrete frequency options to identify and lock onto the sensor's resonant frequency. This periodic action enables a compact device to cover a wide measurement range by systematically testing predefined frequency points rather than requiring simultaneous wideband 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
Enables wider operational range for LC resonant tank sensors without compromising size, precision, or manufacturability, ensuring reliable detection of resonance frequency across a broad bandwidth by dynamically adjusting excitation frequency.
Implementation Method 1
transmit an energizing pulse at a selected frequency to excite a resonant circuit within the sensor to resonance
Implementation Method 2
The sensor's inductor receives energy from the EM field to cause the sensor LC tank to resonate
Implementation Method 3
using a phase locked loop to lock onto the response signal and obtain multiple samples
Data Source
AI summary
A wireless sensor reader configured to ascertain the resonance frequency of a sensor may comprise a transmit circuit configured to transmit a wireless energizing pulse at a transmit frequency to the sensor, exciting a resonant circuit within the sensor to resonance at a frequency proportional to a measured parameter and a receiver circuit configured to receive a response signal from the sensor, the response signal being a continuous wave at the sensor resonance frequency. The wireless sensor reader may also comprise a circuit for determining the frequency of the sensor response signal, where the reader selects the transmit frequency of the energizing pulse from a plurality of discrete narrowband frequencies, the selection taking place before the determination of the frequency of the sensor response signal.