Gunshot Detection with Fire Alarm Strobe Filtering
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Solution Overview
Problem
Accurate and timely detection of gunshots in indoor environments is challenging due to factors like sound reverberations, echoes, and interference from events like fire alarms, which can lead to false alerts or missed detections.
Innovation Solution
A processor-implemented method using a gunshot sensor system that includes both infrared and acoustic sensors to differentiate between gunshot signals and those from fire alarms by analyzing the frequency and duration of strobe occurrences, allowing for real-time detection and filtering out irrelevant data during fire alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic sensors are used to detect gunshots in indoor environments, then gunshot detection capability is improved, but false alarms increase due to sound reverberations and echoes
Solution Approach 1:
The patent combines acoustic sensors with infrared sensors to create a multi-modal detection system. The acoustic sensor detects gunshot sounds while the infrared sensor detects the thermal signature of the firearm and muzzle flash. By merging these different sensing modalities, the system achieves more reliable gunshot detection in indoor environments, as the combination of acoustic and thermal signatures reduces false alarms from reverberations and echoes that would trigger acoustic sensors alone.
2Measurement precision
If the system monitors all acoustic events continuously, then gunshot detection capability is improved, but interference from concurrent events like fire alarms increases
Solution Approach 1:
The system performs preliminary detection using the infrared sensor to identify fire alarm strobe patterns before they can interfere with gunshot detection. By detecting the characteristic thermal signature and temporal pattern of fire alarm strobes in advance, the system can temporarily suppress or filter out acoustic events that occur during these known interference periods, preventing false gunshot detections while maintaining sensitivity to actual gunshots.
Solution Approach 2:
The infrared sensor acts as an intermediary that provides contextual information about the environment. By monitoring thermal signatures and strobe patterns, the infrared sensor mediates between the acoustic sensor and the gunshot detection algorithm, allowing the system to distinguish between gunshots and fire alarms even when their acoustic signatures overlap, thereby reducing interference from concurrent events.
3Measurement precision
If multiple sensors are deployed to improve detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the detection system into distinct functional modules: an acoustic sensor module for sound detection, an infrared sensor module for thermal signature detection, and a processing module that integrates data from both sensors. This segmentation allows each sensor type to be optimized for its specific detection task while simplifying the overall system architecture, as each module operates semi-independently and contributes specific information to the final gunshot detection decision.
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
Enables accurate and timely identification of gunshots in indoor settings, reducing false alarms and improving response times by distinguishing between gunshot events and concurrent events like fire alarms, thus enhancing public safety.
Implementation Method 1
Indoor gunshot detection is based on detecting an infrared pulse and an acoustic impulse that result from discharging a firearm within an enclosed space.
Implementation Method 2
The acoustic components result from the muzzle blast expelling the projectile and any shock wave from a projectile traveling at supersonic velocities.
Data Source
AI summary
Indoor gunshot detection analysis is performed in the presence of a fire alarm. A gunshot sensor, which includes infrared and acoustic sensors, is used to detect an infrared pulse, whether the pulse originates from a muzzle flash or a fire alarm strobe. The infrared pulse is determined to correspond to a strobe occurrence. An evaluation determines that a gunshot did or did not occur based on the strobe occurrence. In another embodiment, a gunshot is detected while the fire alarm is occurring, where the gunshot occurs at a different time from the strobe occurrence and can be sensed by the acoustic sensor. A fire alarm strobe frequency and duration are determined, and further strobe occurrences are edited. Editing detection edits out a sensing time window by the infrared sensor. When the strobe stops, editing is eliminated, but if the strobe restarts, then editing is resumed.