Speaker Eavesdropping Prevention via Jamming Signal Masking
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Solution Overview
Problem
Speakers can be misused as eavesdropping devices due to their shared structure with microphones, allowing eavesdroppers to intercept conversations through the common signal line, posing a significant threat to privacy.
Innovation Solution
A device that generates a jamming noise signal, amplifies it, and outputs it to the speaker common signal line using a transformer, employing a masking effect to prevent eavesdropping by overpowering the conversation signal with a louder noise signal in the audible frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a speaker is used for broadcasting, then sound output is achieved, but electrical signals can be induced and transmitted through the common signal line enabling eavesdropping
Solution Approach 1:
The patent converts the harmful induced electrical signals into a beneficial masking effect by generating a jamming signal that utilizes the same speaker and common signal line infrastructure. The jamming signal, when transmitted through the speaker, creates acoustic noise that masks the original conversation sounds, thereby preventing eavesdropping while utilizing the existing system components.
Solution Approach 2:
The patent applies preliminary anti-action by generating and transmitting a jamming signal before eavesdropping can occur. The jamming signal is sent through the speaker common signal line in advance to create acoustic masking, which prevents the eavesdropper from capturing clear conversation signals. This preemptive measure blocks the eavesdropping path before the harmful effect can manifest.
2Reliability
If a jamming signal is transmitted through the speaker common signal line, then eavesdropping is prevented, but the speaker system must accommodate additional signal processing components
Solution Approach 1:
The patent applies universality by making the speaker system multi-functional. The speaker common signal line serves both its original purpose of transmitting audio signals to speakers and the additional function of transmitting jamming signals for eavesdropping prevention. The existing speaker infrastructure is utilized for dual purposes, reducing the need for separate dedicated eavesdropping prevention hardware.
Solution Approach 2:
The patent uses the speaker common signal line as an intermediary medium to transmit the jamming signal. Instead of requiring a separate communication channel for eavesdropping prevention, the existing signal line acts as a mediator that carries both the original audio signals and the jamming signals, thereby simplifying the overall system architecture.
3Reliability
If the jamming signal overpowering the conversation signal is implemented, then eavesdropping is blocked, but the audible frequency band is occupied by noise
Solution Approach 1:
The patent converts the harmful acoustic noise into a beneficial masking mechanism. The jamming signal, which appears as noise in the audible frequency band, is intentionally designed to overpower and mask the conversation signals. This noise is not merely interference but a functional element that prevents eavesdropping by creating acoustic confusion in the listener's perception.
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
Effectively prevents eavesdropping by ensuring that the eavesdropper cannot recognize conversation signals due to the masking effect, even when electrical signals are induced from the speaker, thereby protecting privacy.
Implementation Method 1
a transformer for receiving the amplified jamming signal from the amplifier and outputting the amplified jamming signal to a speaker common signal line
Implementation Method 2
a speaker includes a coil 102 surrounding a permanent magnet 101 and speaker cone 103 attached to the coil, which generates sound due to vibration of the speaker cone 103 caused by an electromagnetic force in accordance to the Lorentz force law
Implementation Method 3
a microphone, which is the same as the speaker, includes a coil 106 surrounding a permanent magnet 105 and speaker cone 107 attached to the coil. However, unlike the speaker, the microphone can receive sound information at an electrical signal receiver 108 by applying a current through the coil 106 due to electromagnetic induction when the speaker cone 107 is vibrated by external sound
Data Source
AI summary
Provided is a device for preventing eavesdropping through a speaker. More particularly, a device for preventing eavesdropping by transmitting a jamming signal through a speaker common signal line is provided, the device including: a jamming signal generator for generating a jamming signal comprising a noise signal; an amplifier for amplifying the jamming signal; and a transformer for receiving the amplified jamming signal from the amplifier and outputting the amplified jamming signal to a speaker common signal line. The device may transmit a jamming signal in an audible frequency band to the speaker common signal line, thereby rendering conversations unrecognizable to eavesdroppers when an electrical signal induced from a speaker is detected through the speaker common signal line.