Door Knock Detection Using Audio Properties to Reduce False Alarms
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Solution Overview
Problem
Smart doorbell motion sensors often generate false alarms due to detecting motion from vehicles, passersby, animals, and tree branches, leading residents to disable notifications, which can result in missed visits from individuals who choose not to press the doorbell button, such as those trying to avoid waking residents or pets.
Innovation Solution
A door knock detection system that uses audio properties to differentiate between door knocks and other sounds, integrating microphones to improve accuracy, and a monitoring system that can dynamically control devices like doorbell chimes and porch lights based on detected knocks, reducing false alarms and enhancing visitor detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motion sensors are used in smart doorbells to detect visitors, then visitor detection capability is improved, but false alarm rate increases due to detecting motion from vehicles, passersby, animals, and tree branches
Solution Approach 1:
The system segments the detection function into multiple independent sensors (motion sensor, audio sensor, temperature sensor) rather than relying on a single motion sensor. Each sensor detects different aspects of visitor presence, allowing the system to cross-validate signals and reduce false alarms from non-visitor motion sources.
Solution Approach 2:
The system introduces an intermediary processing layer that analyzes signals from multiple sensors before triggering notifications. This intermediary layer correlates data from motion detection, audio detection (knocking sounds), and environmental sensors to distinguish genuine visitor signals from false alarm sources like animals or tree branches.
2Loss of information
If motion sensor notifications are enabled to alert residents of approaching visitors, then visitor awareness is improved, but notification frequency increases due to false alarms from various motion sources
Solution Approach 1:
The system performs preliminary analysis of motion sensor data by correlating it with audio sensor data (detecting knocking sounds) and temperature sensor data (detecting body heat) before generating notifications. This preliminary multi-sensor validation ensures that only genuine visitor approaches trigger notifications, preventing premature or false alerts.
Solution Approach 2:
The system uses feedback from multiple sensor types to continuously validate motion detection signals. When motion is detected, the system checks for corresponding audio signals (knocking), temperature changes (body heat), and other contextual data before confirming a visitor notification, creating a feedback loop that filters out false alarms.
3Measurement precision
If audio sensors are added to detect door knocks, then knock detection accuracy is improved, but device complexity increases
Solution Approach 1:
The audio sensor serves multiple functions: detecting door knocks, identifying visitor presence, and providing contextual information for distinguishing genuine visitors from false alarm sources. This multi-functionality justifies the added complexity by maximizing the utility of each additional sensor component.
Solution Approach 2:
The system merges audio sensor detection with motion sensor detection and temperature sensor detection into a unified visitor detection framework. By combining these sensors into a single integrated system with centralized processing, the patent reduces the operational complexity that would otherwise arise from managing separate detection systems.
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 system effectively reduces false alarms and improves visitor detection by accurately identifying door knocks, allowing for tailored responses such as activating surveillance cameras or turning on lights when a visitor approaches without pressing the doorbell.
Implementation Method 1
A door knock detector can detect a person knocking on the door of a property based on the audio properties of the sound produced by the knock
Implementation Method 2
One example of a motion sensor typically found in smart doorbells is passive infrared (PIR) sensor. PIR sensors can detect moving heat signatures.
Implementation Method 3
Another example of a motion sensor typically found in smart doorbells is video motion detection. Video motion detection analyzes surveillance camera footage to detect for motion.
Data Source
AI summary
A monitoring system that is configured to monitor a property is disclosed. The monitoring system includes a microphone that is configured to detect sound within an area near a door of the property and generate audio data that represents the sound. The monitoring system includes a monitor control unit configured to obtain the audio data generated by the microphone; evaluate one or more characteristics of the audio data; based on evaluating the one or more characteristics of the audio data, determine that the audio data corresponds to a knock event at the door; and in response to determining that the audio data corresponds to a knock event at the door, perform a monitoring system action. The one or more characteristics of the audio data include one or more of a duration, a peak frequency, an amplitude, or a period.