Speed Estimation Using Spectrogram Template Matching
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Solution Overview
Problem
Existing methods for estimating the speed of a moving sound source, such as those based on the Doppler effect, fail to accurately calculate speed when the signal-to-noise ratio is low or when the sound has an unclear peak frequency, particularly for sounds with wideband frequency components like those from moving vehicles.
Innovation Solution
A speed estimation device and method that involves storing spectrogram template information for various movement speeds, performing frequency analysis on incoming sound signals to generate spectrograms, and estimating sound source speed based on these templates, allowing for accurate speed estimation even with unclear peak frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If peak frequency is used for speed estimation based on Doppler effect, then speed estimation is simple and direct, but accuracy deteriorates when signal-to-noise ratio is small or peak frequency is unclear
Solution Approach 1:
The invention transitions from analyzing only peak frequency (one-dimensional approach) to analyzing the entire frequency spectrum structure (multi-dimensional approach). By comparing spectrograms across multiple frequency components rather than relying solely on peak frequency, the system achieves more robust and accurate speed estimation, particularly in noisy environments where peak frequency may be unclear.
2Measurement precision
If the entire frequency spectrum is analyzed instead of just peak frequency, then measurement precision improves, but device complexity increases
Solution Approach 1:
The invention creates spectrogram templates for various known speeds and compares the actual spectrogram against these templates. This copying approach allows the system to use pre-computed reference patterns, simplifying the analysis process while maintaining high accuracy through comprehensive frequency spectrum comparison.
Solution Approach 2:
The system pre-calculates and stores spectrogram templates corresponding to different known speeds before actual speed estimation is performed. This preliminary preparation of reference data enables faster and more accurate comparison during operation, reducing computational complexity during real-time analysis while maintaining high measurement precision.
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
Enables accurate estimation of moving sound source speeds by analyzing the entire frequency structure rather than just peak frequencies, improving performance and accuracy in noisy or disturbed environments.
Implementation Method 1
when a sound source is moving, a movement speed of the sound source is estimated by using occurrence of a frequency difference due to the Doppler effect between a frequency of sound emitted from the sound source and a frequency of sound observed at a sound receiving position
Data Source
AI summary
A sound signal corresponding to a sound emitted by a sound source is inputted to a frequency analysis unit (101), and the frequency analysis unit (101) performs frequency analysis of the sound signal and generates a spectrogram. Spectrogram template information indicating spectrograms corresponding to each of at least a plurality of predetermined movement speeds, the spectrograms being for cases in which the sound source is moved, is stored in a model storage unit (102). An estimation unit (103) estimates the movement speed of the sound source on the basis of the spectrogram generated by the frequency analysis unit (101) and the plurality of spectrograms indicated by the spectrogram template information stored in the model storage unit (102).