Non-secure Warning Tone Application in Packetized Voice Signals

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Solution Overview

Problem

Existing methods for applying non-secure warning tones to voice signals, particularly in IP networks, often disrupt the voice call or fail to maintain intelligibility, and there is a need for a solution that can effectively integrate a warning tone into packetized voice signals without obscuring the original voice content.

Innovation Solution

A method and apparatus that selectively combine voice samples with tone samples to form weighted average combined samples, allowing for the application of a non-secure warning tone to packetized voice signals while minimizing disruption, by varying the relative and absolute levels of tone and voice samples, and applying the tone only during selected parts of the call to maintain intelligibility and prevent data signal corruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If tone samples are included in the voice signal by replacing voice samples, then the non-secure warning tone becomes audible, but the voice call intelligibility may be compromised and the tone may be difficult to listen to

Engineering Contradiction:
Improveaudibility of warning toneVSAvoidvoice call intelligibility
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent combines voice samples and tone samples by calculating a weighted average of corresponding samples from both signals. This merging approach allows the warning tone to be integrated into the voice signal in a way that maintains both the intelligibility of the voice call and the audibility of the warning tone, resolving the contradiction between making the tone audible and preserving voice quality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies gain factors to adjust the amplitude of voice samples and tone samples independently before combining them. By changing the parameter (gain) of each signal component, the system can control the relative levels to ensure the warning tone is audible while the voice remains intelligible, and can adapt to different playback volumes and user preferences.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the warning tone signal level is kept lower than the voice signal level, then the voice call remains intelligible, but the warning tone may not be sufficiently noticeable to alert the user

Engineering Contradiction:
Improvevoice call intelligibilityVSAvoidnoticeability of warning tone
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent dynamically adjusts the gain factors for voice and tone samples based on the current playback volume and user preferences. This dynamic adjustment allows the system to maintain voice intelligibility while ensuring the warning tone is sufficiently noticeable - the relative levels can change adaptively rather than being fixed, resolving the contradiction between keeping the tone subtle and making it noticeable.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the playback volume level and user preferences to adjust the gain factors appropriately. By monitoring the current state and adjusting the tone and voice levels accordingly, the system ensures the warning tone is noticeable enough to alert users while maintaining voice call intelligibility, resolving the level balancing contradiction.

Inventive Principle:
Principle #23Feedback

3Reliability

If voice samples are modified to include tone samples, then the non-secure warning is applied, but data signals transmitted across the voice path may be corrupted or blocked

Engineering Contradiction:
Improveapplication of warning toneVSAvoiddata signal integrity
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent applies the warning tone selectively to specific time intervals and voice samples rather than continuously modifying the entire voice signal. This local application approach allows the warning to be conveyed without systematically corrupting data signals that may be embedded in the voice path, as the modification is localized to specific samples rather than being pervasive throughout the signal stream.

Inventive Principle:
Principle #3Local quality

4Reliability

If continuous warning tone is applied throughout the voice call, then the non-secure warning is consistently present, but it may distract the receiving party from the call content

Engineering Contradiction:
Improveconsistency of warningVSAvoiddistraction to receiving party
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic application of the warning tone rather than continuous modification of the voice signal. By applying the tone at regular intervals or during specific time windows, the system maintains consistent warning presence while reducing distraction to the receiving party, as the intermittent nature allows natural speech flow to dominate during non-tone periods.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2676427B1Application of a non-secure warning tone to a packetised voice signal
Publication Date: 2019.06.12 BAE SYSTEMS PLC
  • EP2676427B1 patent drawingFigure 1
  • EP2676427B1 patent drawingFigure 2(a)~2(b)
  • EP2676427B1 patent drawingFigure 3

AI summary

A method (10) of applying a non-secure warning tone to a packetized voice signal comprises: receiving a voice signal comprising a sequence of voice samples (12); providing a non-secure warning tone signal comprising a plurality of tone samples (14); and modifying the voice signal by selectively including tone samples in the sequence of voice samples (16).