Combined Waveform Generation for Seamless Vehicle Alert Sound Loops
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Solution Overview
Problem
In vehicle approaching notification devices, noise sounds often occur at the connection points between tone generation data pieces, disrupting the smooth output of vehicle approaching sounds.
Innovation Solution
A combined-wave data generation method that calculates and generates data series by combining sound data pieces with different frequencies, ensuring the first and last sample values are identical, thereby minimizing rapid sound level changes and noise at connection points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tone generation data pieces are sequentially read out from memory and connected to generate vehicle approaching sound, then the vehicle approaching notification device can output sound efficiently, but noise sound occurs at the connecting portion between data pieces
Solution Approach 1:
The patent applies preliminary action by pre-calculating and setting the rotation angles of sound data pieces before connection. The control part determines rotation angles in advance based on the number of samples and sampling interval, ensuring that the first and last samples of connected data pieces have identical values. This preliminary configuration prevents noise generation at connection portions while maintaining efficient sound output.
Solution Approach 2:
The patent changes the rotation angle parameter of sound data pieces to ensure smooth connection. By adjusting the rotation angle based on the number of samples and sampling interval, the system modifies the phase relationship between connected data pieces, making the first and last samples identical in value. This parameter adjustment eliminates discontinuities that cause noise while preserving the efficiency of sequential data output.
2Reliability
If synthetic sound data is used for vehicle approaching notification, then the sound can represent realistic vehicle noise, but rapid change of sound level occurs at connecting portions causing uncomfortable feeling
Solution Approach 1:
The control part performs preliminary calculation of rotation angles based on the number of samples and sampling interval before connecting sound data pieces. This advance preparation ensures that the first and last samples of each data piece have identical values, preventing rapid sound level changes at connection points while preserving the realistic characteristics of the synthetic vehicle noise.
Solution Approach 2:
The system modifies the rotation angle parameter of the sound data pieces to achieve smooth transitions at connection points. By calculating and applying specific rotation angles derived from the sample count and sampling interval, the patent eliminates abrupt sound level changes that cause discomfort, while maintaining the authentic vehicle noise representation through the synthetic sound data.
Data Source
AI summary
The present invention generates data series indicating respective combined-wave data pieces by a first step of obtaining a reference time length as a reference of a time length of one combined wave, a sampling interval time, and a frequency fluctuation rate, a second step of calculating a total number of samples in the data series indicating the one combined wave on the basis of the reference time length, the sampling interval time, and the frequency fluctuation rate, a third step of calculating a rotation angle with respect to the sampling interval time on the basis of the total number of samples for each of plural sound data pieces, a fourth step of calculating combined values for the total number of samples, the combined values being obtained by combining respective values of the plural sound data pieces, the values being calculated on the basis of the rotation angles for the respective sampling interval times, a fifth step of generating a series of the combined values for the total number of samples for the respective sampling time intervals as a data series of the one combined-wave data piece, and performing a sequence of the processes of the second to the fifth steps by a predetermined times while changing the frequency fluctuation rate every time when the sequence of the processes is executed once.