Microwave Motion Detector Target Angle Detection
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Solution Overview
Problem
Dual technology sensors with microwave and passive infrared detectors face reliability issues due to the wide field of view of microwave detectors, which can detect motion outside protected areas, compromising accuracy and requiring the ability to distinguish between motion within and outside the protected space, as well as adjust the field of view based on specific conditions like time of day or location.
Innovation Solution
A method using two parallel receiving antennas in the microwave detector to process phase differences in reflected signals, allowing the system to limit the field of view to match the PIR sensor's detection pattern and generate alarms or warnings based on target ratios, with the capability to adjust the field of view dynamically based on predefined conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the microwave detector uses a wide field of view to cover the entire protected space, then the coverage area is improved, but the reliability deteriorates due to detecting motion outside the protected space
Solution Approach 1:
The microwave detector's field of view is segmented into multiple zones using a sector antenna that can be electronically steered to different angles. The detection space is divided into protected space zones and outside zones, allowing the system to distinguish between motion within the protected area and motion outside it, thereby maintaining reliability while preserving wide coverage.
Solution Approach 2:
The patent introduces an angular dimension to the detection problem by using a sector antenna that can scan through different azimuth angles. Instead of simply expanding or contracting the field of view radius, the system adds angular discrimination capability, creating concentric detection zones at different angles to differentiate between inside and outside motion.
2Reliability
If the microwave detector's field of view is narrowed to match the PIR sensor's detection pattern, then the reliability is improved by reducing false detections, but the coverage area deteriorates
Solution Approach 1:
The microwave detector employs dynamic field of view adjustment through electronic sector antenna steering, allowing the detection pattern to be dynamically configured. The system can switch between wide coverage modes (scanning multiple sectors) and focused detection modes (narrowing to specific angles), adapting the field of view to match PIR sensor patterns when needed while maintaining the capability for broader coverage at other times.
3Area of stationary object
If the microwave detector covers the entire protected space, then the coverage area is improved, but the device complexity increases due to the need for variable field of view control
Solution Approach 1:
The patent replaces mechanical field of view adjustment mechanisms with electronic sector antenna steering. Instead of physically moving or rotating antenna elements, the system uses electronic phase control to steer the detection beam across different angles, significantly reducing mechanical complexity while maintaining the capability for variable coverage areas and dynamic field of view adjustment.
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
Enhances the accuracy of intrusion detection by distinguishing between motion within and outside the protected space, allowing for adaptive field of view adjustments to match specific security needs, thereby improving the reliability and adaptability of dual technology sensors.
Implementation Method 1
the microwave detector transmits microwave frequency signals via the transmitting antenna that are reflected off of a target and back to the microwave detector and received by the receiving antenna and associated receivers
Implementation Method 2
two receiving antennas that are substantially parallel and separated from each other by a distance that is less than the wavelength of the transmitted microwave frequency signal... determining a target ratio from a phase difference between each received signal in the separate channels
Data Source
AI summary
The present invention is an alarm system that includes a dual technology motion sensor. The dual technology sensor includes a PIR sensor with a PIR detection pattern and a Doppler microwave frequency motion detector with a detection pattern wider than that of the PIR sensor. The microwave detector's processing circuitry distinguishes motion beyond the PIR detection pattern, and limits the microwave detector's field of view to match the PIR detector's detection pattern. The microwave detector has a transmitting antenna, two receiving antennas, and processing circuitry for processing received signals. The microwave detector's processing circuitry uses phase information from the two receiving antennas to distinguish motion beyond the PIR detection pattern.