Range Reduction Detection Using Timer Logic
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Solution Overview
Problem
Current intrusion detection systems, particularly grade 4 detectors, fail to effectively detect a significant reduction in detection range as specified by EN 50131-2-4:2004 standards, which requires a 50% reduction within 180 seconds, and struggle with range reduction detection tests.
Innovation Solution
A detection apparatus that uses a timer to generate an alarm signal if the field of view is obscured by an object within a specified period, with the option to reset the timer upon receiving a subsequent input signal, utilizing a combination of microwave and passive infrared sensors to detect movement and range reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a timer-based blocking detection mechanism is implemented, then the ability to detect significant range reduction is improved, but the device complexity increases
Solution Approach 1:
The system performs preliminary actions by starting a timer when the first signal is received, establishing a time window before the blocking condition is confirmed. This preliminary timing mechanism allows the system to distinguish between temporary signal interruptions and actual blocking conditions, improving detection reliability without requiring complex additional hardware
Solution Approach 2:
The system uses feedback by monitoring whether a second signal is received within the predetermined time period and using this information to determine whether to generate a blocking detection signal. This feedback loop enables the system to dynamically adjust its detection behavior based on real-time signal patterns, achieving reliable blocking detection through intelligent signal processing rather than hardware complexity
2Reliability
If the detection system requires two independent sensing means outputs within a predetermined period, then the reliability of intrusion detection is improved, but the loss of time increases
Solution Approach 1:
The system applies dynamics by making the predetermined time period adjustable rather than fixed. The time window can be modified based on environmental conditions, detection requirements, and signal characteristics, allowing the system to optimize between reliability and response time dynamically. This dynamic adjustment enables faster detection when conditions permit while maintaining reliability when challenges arise
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
The apparatus successfully meets the EN 50131-2-4:2004 standards by detecting a significant reduction in range and generating an alarm when the field of view is obstructed, enhancing security system performance.
Implementation Method 1
Active intrusion monitoring apparatuses are also known which comprise a transmitter and a receiver. The transmitter emits radiation at a defined frequency and the receiver measures the Doppler shift in any reflected signal.
Implementation Method 2
Passive intrusion monitoring apparatuses can comprise a sensor that detects infrared radiation emitted by people. Typically, such passive apparatuses comprise a thermal detection apparatus consisting of one or more thermal detectors arranged to detect infrared radiation
Data Source
AI summary
Embodiments of the present invention relate to a range reduction detection apparatus that is able to detect blocking of its field of view. Detection of an event, due to movement or intrusion within the field of view, is arranged to start a timer, which will time-out thereby providing an indication of such blocking unless a subsequent event is detected within the time-period.