A high‐resolution fundamental frequency determination based on phase changes of the FFT.

1992 ◽  
Vol 91 (4) ◽  
pp. 2375-2375
Author(s):  
Judith C. Brown
Keyword(s):  
High Resolution ◽  
Fundamental Frequency ◽  
Phase Changes ◽  
Frequency Determination

The method of fundamental harmonic frequency determination

2021 ◽  
Vol 63 (1) ◽  
pp. 38-42
Author(s):  
Tomasz Szczepański ◽  
Stanisław Traczyk ◽  
Paweł Dziedziak
Keyword(s):  
Fundamental Frequency ◽  
Patent Application ◽  
Diagnostic Methods ◽  
Main Process ◽  
Harmonic Frequency ◽  
Frequency Determination ◽  
The Subject ◽  
Mechanical Devices ◽  
Vibroacoustic Signals ◽  
Better Than

Analysis of vibroacoustic signals is one of the more frequently used mechanical devices diagnostic methods occurring among others in car diagnostics. Often, it happens that the most important element of the recorded course is the fundamental harmonic frequency of vibrations. Fundamental frequency indicates the main process related to the operation of the device and allows to follow its course. In the article the author's method of determining the fundamental frequency in the signal will be presented which is the subject of a patent application. Its theoretical basis and application examples were discussed comparing the accuracy of its use with the accuracy of other methods. The frequency range where the method finds application is shown. That is, where its accuracy turns out to be better than the accuracy of popular used methods to fundamental harmonic frequency determination.

scholarly journals Alpha-Null Defocus: an Optimum Defocus Condition with Relevance for Focal-Series Reconstruction

2001 ◽  
Vol 7 (S2) ◽  
pp. 916-917 ◽  
Author(s):  
Michael A. O’Keefe
Keyword(s):  
High Resolution ◽  
Spatial Frequency ◽  
Super Resolution ◽  
High Resolution Electron Microscopy ◽  
Phase Changes ◽  
Objective Lens ◽  
Microscope Objective ◽  
Reconstruction Methods ◽  
Electron Microscopes ◽  
Microscope Objective Lens

Two optimum defocus conditions are well known to users of high-resolution transmission electron microscopes. Scherzer defocus is useful in high-resolution electron microscopy (HREM) because it produces an image of the specimen “projected potential” to the resolution of the microscope. Lichte defocus is useful in electron holography because it optimizes sampling in frequency-space by minimizing the slope of the microscope objective lens phase change out to the highest spatial frequency in the hologram, consequently minimizing dispersion. For focal-series reconstruction, the requirement to maximize transfer into the image of high-frequency diffracted beam amplitudes leads to a third optimum defocus condition.Image reconstruction methods allow the achievement of super-resolution - resolution beyond the native (Scherzer) resolution of the microscope - by correction of the phase changes introduced by the microscope objective lens. One such method is focal-series reconstruction, in which diffracted-beam information obtained at several different focus values is combined. to produce a valid super-resolution result, it is necessary to ensure that every spatial frequency is represented appropriately. Suitable choice of an optimum defocus produces optimum transfer of diffracted-beam amplitudes at any chosen spatial frequency.

scholarly journals Fast fundamental frequency determination via adaptive autocorrelation

2016 ◽  
Vol 2016 (1) ◽  
Author(s):  
Michael Staudacher ◽  
Viktor Steixner ◽  
Andreas Griessner ◽  
Clemens Zierhofer
Keyword(s):  
Fundamental Frequency ◽  
Frequency Determination

scholarly journals Dissociation of tonotopy and pitch in human auditory cortex

2020 ◽  
Author(s):  
Emily J. Allen ◽  
Juraj Mesik ◽  
Kendrick N. Kay ◽  
Andrew J. Oxenham
Keyword(s):  
High Resolution ◽  
Auditory Cortex ◽  
Fundamental Frequency ◽  
Auditory Processing ◽  
Hierarchical Organization ◽  
Spectral Content ◽  
Bold Responses ◽  
Complex Tones ◽  
Pure Tones ◽  
Cortical Regions

SUMMARYFrequency-to-place mapping, or tonotopy, is a fundamental organizing principle from the earliest stages of auditory processing in the cochlea to subcortical and cortical regions. Although cortical maps are referred to as tonotopic, previous studies employed sounds that covary in spectral content and higher-level perceptual features such as pitch, making it unclear whether these maps are inherited from cochlear organization and are indeed tonotopic, or instead reflect transformations based on higher-level features. We used high-resolution fMRI to measure BOLD responses in 10 participants as they listened to pure tones that varied in frequency or complex tones that independently varied in either spectral content or fundamental frequency (pitch). We show that auditory cortical gradients are in fact a mixture of maps organized both by spectral content and pitch. Consistent with hierarchical organization, primary regions were tuned predominantly to spectral content, whereas higher-level pitch tuning was observed bilaterally in surrounding non-primary regions.

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