Low-Power RF Receiver Using Sub-Sampling for Battery Life
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Solution Overview
Problem
Existing battery-powered wireless control devices for motorized window treatments and dimmer switches face challenges in prolonging battery life due to high current consumption by RF circuitry, which is often limited by the length of pre-sync pulse times in RF command signals.
Innovation Solution
A low-power RF receiver is developed that employs an RF sub-sampling technique to check for RF signals and then enters a sleep mode for a sleep time longer than the packet length, conserving battery power and extending device lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RF receiver checks for signals frequently to ensure reliable communication, then the communication reliability is improved, but the battery power consumption increases
Solution Approach 1:
The RF receiver operates in periodic cycles, alternating between active listening mode and sleep mode. During active mode, the receiver checks for RF signals; during sleep mode, it consumes minimal power. This periodic operation allows the system to maintain communication reliability by checking at appropriate intervals while significantly reducing average power consumption compared to continuous operation.
Solution Approach 2:
The receiver checks for the presence of a pre-sync pulse before committing to full signal reception. This preliminary check allows the receiver to detect incoming signals early and prepare for reception, ensuring reliable communication capture while minimizing the duration of high-power operation.
2Duration of action of moving object
If the sleep time of the RF receiver is increased to conserve battery power, then the battery life is extended, but the risk of missing RF signals increases
Solution Approach 1:
The receiver uses periodic wake-up cycles with optimized duration and frequency. By calculating appropriate sleep intervals based on expected signal transmission rates, the system maintains reliable signal detection while maximizing the sleep duration to extend battery life.
Solution Approach 2:
The receiver listens for pre-sync pulses that precede actual data transmission. This preliminary detection mechanism allows the receiver to wake up just in time to capture incoming signals, reducing the required sleep duration and extending battery life without compromising signal detection reliability.
3Reliability
If the RF receiver operates continuously to capture all RF signals, then the signal capture completeness is improved, but the current consumption increases
Solution Approach 1:
Instead of continuous operation, the receiver employs periodic activation with duty cycles optimized for the application. The receiver wakes up at predetermined intervals to check for signals and returns to sleep mode, achieving acceptable signal capture completeness with dramatically reduced current consumption compared to continuous operation.
Solution Approach 2:
The system uses preliminary detection of pre-sync pulses to trigger full signal reception. This two-stage approach allows the receiver to remain in low-power mode most of the time while still capturing complete signal data when transmissions occur, balancing signal capture completeness with current consumption.
Data Source
AI summary
A low-power radio-frequency (RF) receiver is characterized by a decreased current consumption over prior art RF receivers, such that the RF receiver may be used in control devices, such as battery-powered motorized window treatments and two-wire dimmer switches. The RF receiver uses an RF sub-sampling technique to check for the RF signals and then put the RF receiver to sleep for a sleep time that is longer than a packet length of a transmitted packet to thus conserve battery power and lengthen the lifetime of the batteries. The RF receiver compares detected RF energy to a detect threshold that may be increased to decrease the sensitivity of the RF receiver and increase the lifetime of the batteries. After detecting that an RF signal is being transmitted, the RF receiver is put to sleep for a snooze time period that is longer than the sleep time and just slightly shorter than the time between two consecutive transmitted packets to further conserve battery power.