Stereo Signal ITD Detection With Adaptive Cross-Spectrum Weighting

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for estimating inter-channel time difference (ITD) in stereo signals, such as the GCC-PHAT method, face performance degradation when the signal contains a large number of frequency components with zero amplitude, leading to inaccurate ITD estimation.

Innovation Solution

Adaptive adjustment of the weighting coefficient based on the maximum amplitude of the cross spectrum and spectral flatness measurement (SFM) to improve ITD estimation accuracy, even in signals with high tonality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the GCC-PHAT method is used for ITD estimation, then the estimation process is simple, but the estimation accuracy deteriorates when the signal contains a large number of frequency components with zero amplitude

Engineering Contradiction:

Improvesimplicity of estimation processVSAvoidITD estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent modifies the weighting coefficient parameter in the cross spectrum based on spectral flatness measurement. When the signal has high tonality (low spectral flatness), the weighting coefficient is adjusted to suppress frequency components with zero amplitude, thereby improving ITD estimation accuracy while maintaining the GCC-PHAT framework

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The weighting coefficient is made dynamic rather than fixed. It is adjusted according to the spectral flatness measurement of the signal, allowing the system to adapt to different signal characteristics (tonal vs. noise-like) and maintain accurate ITD estimation across varying conditions

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If adaptive weighting based on spectral flatness is applied, then ITD estimation accuracy improves for signals with high tonality, but the processing complexity increases

Engineering Contradiction:

ImproveITD estimation accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The spectral flatness measurement is performed in advance on the cross spectrum before ITD estimation. This preliminary analysis allows the system to determine the appropriate weighting coefficient beforehand, avoiding iterative adjustments and keeping the additional processing burden minimal

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The weighting is applied selectively to specific frequency components based on their individual amplitude values. Frequency components with zero amplitude are suppressed while other components maintain their original weighting, allowing precise control over which parts of the spectrum contribute to ITD estimation

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20260018178A1Signal processing device and signal processing method

Publication Date: 2026.01.15 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

This signal processing device comprises: a control circuit that, in accordance with a parameter relating to a stereo signal, alters a weighting coefficient based on the amplitude of the cross spectrum of the stereo signal; and a detection circuit that detects the inter-channel time difference of the stereo signal on the basis of the cross spectrum weighted using the weighting coefficient.