Microwave Curtain Sensor Phase Detection for Intruder Alarm
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Solution Overview
Problem
Existing motion sensors, particularly PIR sensors, struggle to effectively detect motion crossing a specific line, leading to potential false alarms and reduced security in monitored areas.
Innovation Solution
The implementation of microwave technology using Amplitude Monopulse and Phase Comparison Monopulse Radar methods, which involve two antennas receiving and processing microwave echoes to determine phase differences, enabling accurate detection of motion crossing a centerline by analyzing phase changes and signal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PIR sensor technology is used to detect motion crossing a curtain line, then the sensor can detect temperature differentials, but it produces false alarms and reduced reliability in security applications
Solution Approach 1:
The patent combines two microwave receiving antennas into a single sensor unit, allowing simultaneous reception of microwave signals from opposite sides of the curtain line. This merging enables comparison of phase differences between the two received signals to accurately determine when motion crosses the curtain line, eliminating false alarms while maintaining detection reliability.
Solution Approach 2:
The system dynamically processes microwave echoes by continuously monitoring phase differences between signals received from opposite sides of the curtain line. The sensor adapts to motion events in real-time by detecting phase sign changes, providing reliable and accurate motion detection across the monitored area.
2Measurement precision
If a single microwave antenna is used to detect motion, then the device complexity is reduced, but the measurement precision of motion crossing detection deteriorates
Solution Approach 1:
The patent merges two receiving antenna functions into a single sensor housing, with the microwave transmitter and two receiving antennas integrated in one unit. This consolidation maintains high measurement precision for curtain line crossing detection while avoiding the complexity of separate transmitter and receiver devices.
Solution Approach 2:
The single microwave sensor unit performs multiple functions: transmitting microwave signals, receiving echoes from both sides of the curtain line, processing phase differences, and determining motion crossing events. This multi-functionality achieves high detection precision without increasing overall device 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 the detection of intruders by reducing false alarms and improving the robustness of motion sensing, allowing for precise identification of motion crossing from one side to the other of a sensor's curtain line, thereby improving security system performance.
Implementation Method 1
The movement of the object may modulate the reflected signal due to the Doppler Effect. When a signal is reflected from a moving object (target), it is shifted in frequency. This shift in frequency is the measured Doppler Effect and is directly proportional to the target's velocity relative to the sensor.
Implementation Method 2
a first set of microwave echoes from opposing sides of a curtain line extending through a secure area can be received
Implementation Method 3
a first phase difference between the received first set of microwave echoes can be determined, and a first sign of the determined phase difference can be determined
Data Source
AI summary
A method and apparatus are provided for detecting an intruder. The method includes the steps of receiving an echo from opposing sides of a curtain line extending through the secure area, determining a difference between the received echoes, determining a phase difference of the signal and generating an alarm when the determined phase changes sign between successively received echoes.