Co-Located Radio Interference Detection via PTT and Audio Correlation

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Solution Overview

Problem

Signal interference between geographically co-located radios affiliated with different talkgroups causes communication degradation, such as crosstalk and blocking, which is unpredictable and difficult to mitigate due to varying factors like radio type, channel frequencies, and proximity, especially in dynamic public-safety scenarios.

Innovation Solution

An electronic computing device correlates logs of push-to-talk operations and audio quality values from co-located radios to detect signal interference by identifying time correlations between PTT operations and changes in audio quality exceeding a threshold, indicating potential interference from geographically co-located radios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple radios from different agencies operate in the same incident area, then communication coverage is expanded, but signal interference increases causing performance degradation

Engineering Contradiction:
Improvecommunication coverage areaVSAvoidsignal quality
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The system continuously monitors audio quality metrics from received signals and uses this feedback to identify interference patterns. By analyzing changes in audio quality over time and correlating them with PTT operations, the system can detect when interference is occurring and provide notifications to users, enabling real-time response to signal quality degradation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The electronic computing device serves as an intermediary between multiple radios, collecting logs of PTT operations and audio quality values from different devices, processing this data to identify interference patterns, and providing analysis results back to the radios and users. This central processing function enables interference detection without requiring direct interaction between individual radios.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If radios operate on different channel frequencies to avoid interference, then signal quality improves, but communication versatility decreases

Engineering Contradiction:
Improvesignal qualityVSAvoidcommunication flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system monitors audio quality metrics and provides feedback about interference conditions to users. This enables users to understand when frequency separation is causing interference and make informed decisions about whether to switch frequencies or adjust their operating parameters, maintaining communication versatility while improving signal quality when needed.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the system monitors audio quality continuously to detect interference, then interference detection accuracy improves, but energy consumption increases

Engineering Contradiction:
Improveinterference detection accuracyVSAvoidenergy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system performs audio quality monitoring at periodic intervals rather than continuously, analyzing audio quality metrics at specific sampling points during PTT operations. This periodic monitoring maintains sufficient detection accuracy to identify interference patterns while significantly reducing energy consumption compared to continuous monitoring.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system monitors audio quality only during specific conditions (when PTT operations are detected and audio quality changes exceed thresholds) rather than continuously, applying partial monitoring action to maintain detection accuracy while minimizing energy consumption during normal operation.

Inventive Principle:
Principle #16Partial or excessive action

4Measurement precision

If the system analyzes time correlations between PTT operations and audio quality changes to detect interference, then interference detection accuracy improves, but processing complexity increases

Engineering Contradiction:
Improveinterference detection accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system segments the analysis process into distinct components: collecting PTT operation logs, collecting audio quality values, determining audio quality changes, and correlating these data elements in time. This segmentation simplifies the overall processing complexity by breaking down the interference detection algorithm into manageable, sequential steps that can be implemented efficiently.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4527091B1Method and device for detecting signal interference among geographically co-located radios affiliated with different talkgroups
Publication Date: 2025.11.12 MOTOROLA SOLUTIONS INC
  • EP4527091B1 patent drawingFigure 1
  • EP4527091B1 patent drawingFigure 2
  • EP4527091B1 patent drawingFigure 3

AI summary

A process of detecting signal interference among geographically co-located radios affiliated with different talkgroups, An electronic computing device receives a log of push-to-talk (PTT) operations performed at a first radio and a log of audio quality values measured corresponding to audio communications received at a second radio. The first radio is affiliated with a first talkgroup and operates on a first channel frequency assigned to the first talkgroup. The second radio is affiliated with a second talkgroup and further operates on a second channel frequency assigned to the second talkgroup. The device detects that signal interference at the second radio is potentially caused by the first radio when there is a time correlation between a PTT operation performed at the first radio and a change in audio quality at the second radio and when the second radio was geographically co-located with the first radio during the time correlation.