RF Proximity Detection Using Leaked and Reflected Radio Signals
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Solution Overview
Problem
Existing proximity detection methods for radio devices, such as radar and thermal infrared detection, are ineffective in close proximity and incur additional costs due to the need for extra sensors or antennas, while capacitive detectors fail to distinguish between animate and inanimate objects, risking non-compliance with regulatory RF radiation limits.
Innovation Solution
Utilizing the existing transmitter and receiver components of a radio device to detect proximity by distinguishing between leaked and reflected RF signals, processing the received signal to estimate and subtract the leaked portion, and reducing power when a user is detected within a certain distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radar or thermal infrared detection is used for proximity detection, then detection capability is improved, but device complexity and cost increase due to additional sensors or antennas
Solution Approach 1:
The existing transmitter and receiver components are made to serve dual purposes: communication and proximity detection. The transmitter sends out RF signals that can both communicate data and detect proximity by analyzing reflected signals, while the receiver both receives communication signals and detects reflected signals for proximity determination. This eliminates the need for separate detection hardware.
Solution Approach 2:
The radio device uses its own transmitted signal to perform proximity detection. The transmitter's signal is reflected off nearby objects and detected by the receiver, allowing the device to self-monitor its proximity environment without external assistance or additional specialized components.
2Device complexity
If capacitive detectors are used for proximity detection, then device complexity is reduced, but reliability decreases due to inability to distinguish between animate and inanimate objects
Solution Approach 1:
The patent replaces simple capacitive sensing with RF signal-based detection. Instead of measuring electrical field changes that cannot distinguish object types, the system uses electromagnetic wave reflection characteristics that provide information about the reflecting object's properties, enabling better discrimination between animate and inanimate objects.
Solution Approach 2:
The transmitted RF signal acts as an intermediary that carries information about the reflected object back to the receiver. By analyzing the reflected signal's characteristics (phase, amplitude, frequency shifts), the system can infer properties of the object causing the reflection, thereby distinguishing between different object types.
3Measurement precision
If additional sensors or antennas are added for proximity detection, then proximity detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The existing transmitter and receiver components are made to serve dual purposes: communication and proximity detection. The transmitter sends out RF signals that can both communicate data and detect proximity by analyzing reflected signals, while the receiver both receives communication signals and detects reflected signals for proximity determination. This eliminates the need for separate detection hardware.
4Power
If RF power is maintained at high levels for communication, then communication performance is improved, but harmful factors increase due to exceeding RF radiation limits when user is in close proximity
Solution Approach 1:
The system continuously monitors the reflected signal strength from nearby objects and uses this information as feedback to adjust the transmitter power. When a strong reflected signal indicates close proximity to a user, the system reduces transmit power to stay within safe radiation limits. When no nearby objects are detected, the system can operate at higher power for optimal communication performance.
Solution Approach 2:
The transmitter power is made dynamic rather than static. The system adjusts power levels in real-time based on detected proximity conditions, transitioning between high-power communication mode and low-power safety mode as needed. This allows the system to optimize communication performance while ensuring user safety throughout operation.
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 proximity detection without additional hardware, ensuring compliance with RF radiation limits by using existing components for dual communication and detection purposes, reducing power consumption and costs, and avoiding interference.
Implementation Method 1
distinguishing a signal reflected from the user
Implementation Method 2
receiving a received signal via a receiver of the radio device
Data Source
AI summary
A system and method for detecting proximity of a user within a particular distance of a radio device is disclosed. The method includes transmitting a signal via a transmitter and antenna of the radio device, receiving a received signal via a receiver and the antenna, processing the received signal for distinguishing a signal reflected from the user from a leaked portion of the transmitted signal, and reducing power of the radio device in response to the processing.