Wideband Signal Generation via Narrowband Codebook Mapping
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Solution Overview
Problem
Current systems for generating wideband audio signals from narrowband signals, such as those transmitted over telephone systems, suffer from bandwidth limitations, resulting in degraded speech quality and increased network complexity, with existing solutions like codebooks leading to discontinuities and high computing demands.
Innovation Solution
A system that extracts a narrowband feature vector, correlates it with a narrowband codebook, and uses a signal mapper to generate an estimated wideband feature vector through mapping functions, with a stability analyzer ensuring filter stability and utilizing a wideband codebook when necessary, to produce a high-quality wideband signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If codebooks are used to generate wideband signals from narrowband signals, then speech quality is improved, but discontinuities and artifacts appear in the generated signal
Solution Approach 1:
The patent applies parameter changes by using a mapping function that transforms narrowband codebook parameters into wideband codebook parameters. Instead of directly using fixed wideband codebook entries, the system dynamically computes mapping parameters based on the selected narrowband codebook entry, allowing smooth transitions and reducing discontinuities while maintaining speech quality.
2Manufacturing precision
If large codebooks are employed to improve speech quality, then the accuracy of wideband signal generation is improved, but computing power requirements increase significantly
Solution Approach 1:
The patent segments the codebook into narrowband and wideband portions, where the narrowband codebook is used for initial signal analysis and the wideband codebook is used for final signal generation. The mapping function efficiently bridges these two segments, reducing the computational burden compared to using a single large codebook while maintaining high signal generation accuracy.
3Manufacturing precision
If higher bandwidth transmission channels are used to transmit speech signals, then speech quality is improved, but network complexity and costs increase
Solution Approach 1:
The patent introduces an intermediary processing system at the receiver end that includes the mapping function and codebook mechanisms. This intermediary converts narrowband received signals into wideband output signals without requiring the transmission channel itself to be wideband, thus maintaining network simplicity while achieving high speech quality through signal processing rather than channel infrastructure.
Data Source
AI summary
A system for use in providing a wideband signal from a received narrowband signal is set forth. The system comprises an extracted narrowband feature vector that corresponds to at least one characteristic of the narrowband signal. A narrowband codebook having one or more narrowband codebook index vectors is also employed, where each narrowband codebook index vector is associated with one or more corresponding narrowband codebook parameters. An analyzer is provided to correlate the extracted narrowband feature vector with an entry in the narrowband codebook. More particularly, the analyzer is responsive to the extracted narrowband feature vector to identify the narrowband codebook feature index vector that best matches the extracted narrowband feature vector. A signal mapper is provided to execute a mapping function of the extracted narrowband feature vector and/or the narrowband codebook index vector identified by the analyzer. In executing the mapping function, the signal mapper uses mapping parameters that correspond to the narrowband codebook entry associated with the narrowband codebook index vector identified by the analyzer. The signal mapper generates at least one estimated wideband feature vector through execution of the mapping function. The estimated wideband feature vector is used by a signal generator to generate a wideband signal that corresponds to an extended bandwidth version of the received narrowband signal.