Communication Device RF Load Detection with Free-Running Clock
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Solution Overview
Problem
Radio frequency communication devices, such as NFC and RFID, face inefficiencies in power consumption due to continuous polling for external communication devices, particularly in battery-powered systems like vehicles, reducing device availability and battery life.
Innovation Solution
A communication device utilizing a free-running oscillator-based clock generator for low-power detection, supplemented by a crystal oscillator for calibration, reduces power consumption by enabling efficient detection of external devices with minimal current draw, and switches to a more accurate clock for regular communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous polling is used to detect external communication devices, then detection reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic polling instead of continuous polling, where the transmitter sends RF signal pulses at defined intervals (e.g., every few milliseconds or seconds) to detect external devices. This periodic approach maintains detection capability while significantly reducing average power consumption compared to continuous operation.
Solution Approach 2:
The system uses the existing RF signal transmission function to simultaneously perform both communication and detection tasks. The same transmitter and detection unit that handle normal communication also detect external devices by monitoring load changes during RF signal pulses, eliminating the need for separate dedicated detection hardware and reducing overall power consumption.
2Measurement precision
If a crystal oscillator is used for clock generation, then clock accuracy is improved, but power consumption increases
Solution Approach 1:
The patent divides clock generation into two segments: a free-running oscillator handles low-power detection operations where moderate accuracy suffices, while a crystal oscillator is activated only when high accuracy is needed for actual communication transactions. This segmentation allows the system to optimize power consumption by keeping the high-power crystal oscillator dormant during detection phases.
Solution Approach 2:
The system dynamically switches between different clock sources based on operational mode. During low-power detection mode, the free-running oscillator is used; when communication mode is activated, the crystal oscillator is engaged. This dynamic adaptation allows the system to match clock accuracy to actual operational requirements, avoiding unnecessary power consumption from continuously running the crystal oscillator.
3Speed
If the communication device remains in active mode, then response speed is improved, but battery life decreases
Solution Approach 1:
The system alternates between active detection phases and low-power sleep phases. During sleep phases, the device consumes minimal power; during active phases, it quickly polls for external devices and processes communications. This periodic activation pattern extends battery life while maintaining acceptable response times for external device detection.
Solution Approach 2:
The system performs preliminary detection using low-power RF signal pulses and load change detection before activating full communication mode. This preliminary action allows the device to identify external devices early and wake up only when necessary, reducing the duration of high-power operation and extending battery life while maintaining responsive detection 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
This approach significantly reduces power consumption during low-power detection modes while maintaining reliable detection and communication capabilities, extending battery life in devices like vehicles.
Implementation Method 1
a first clock generator (206) comprising a free-running oscillator (510), wherein the first clock generator is configured to provide a clock signal to the transmitter and the detection unit
Implementation Method 2
the communication device further comprises a second clock generator including a crystal oscillator, wherein the second clock generator is configured to calibrate or recalibrate the first clock generator
Implementation Method 3
a transmitter configured to transmit one or more radio frequency signal pulses
Implementation Method 4
a detection unit configured to detect one or more load changes at a radio frequency interface occurring in response to the radio frequency signal pulses transmitted by the transmitter, wherein the load changes are indicative of the presence of an external communication device
Data Source
AI summary
In accordance with a first aspect of the present disclosure, a communication device is provided, comprising: a transmitter configured to transmit one or more radio frequency signal pulses; a detection unit configured to detect one or more load changes at a radio frequency interface occurring in response to the radio frequency signal pulses transmitted by the transmitter, wherein said load changes are indicative of the presence of an external communication device; a first clock generator comprising a free-running oscillator, wherein said first clock generator is configured to provide a clock signal to the transmitter and the detection unit while said transmitter transmits said radio frequency signal pulses and the detection unit detects said load changes. In accordance with a second aspect of the present disclosure, a corresponding method of operating a communication device is conceived.