TD_DFFT2CONV Function | Teradata Vantage - TD_DFFT2CONV - Teradata Vantage

Database Unbounded Array Framework Time Series Functions

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2024-10-04
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TD_DFFT2CONV is a Fast Fourier Transform result converter that converts an ART generated by TD_DFFT2 into a different result form. Instead of running TD_DFFT2 a second time with the original input to produce results in a different format, this function can be used with the initial TD_DFFT2 result. The benefit is this function only does conversions and is far more efficient. Another benefit is that the original input passed to TD_DFFT2 is not needed.

For example, you have a TD_DFFT2 result that is in raw form and the payload types are COMPLEX. However, you need the result in human-readable form with payload type AMPL_PHASE_DEGREES. The TD_DFFT2 result can be passed to TD_DFFT2CONV to convert and produce an ART with the needed form.

TD_DFFT2CONV has the following applications:

  • Audio signal processing: Analyze the frequency components of an audio signal. The output of the function represents the amplitudes and phases of different frequency components in the signal. Converting this output into a human-readable format can help in tasks such as:
    • Displaying a spectrogram: The function converts the output into a spectrogram, which is a two-dimensional representation of the signal's frequency content over time. This visualization helps in analyzing and understanding the audio signal.
    • Identifying dominant frequencies: The function extracts the dominant frequencies from the output and display the frequencies in a readable format. This helps in audio classification or music analysis.
  • Image Processing: Process tasks such as image compression, noise reduction, and feature extraction. Converting the output into a human-readable format is helpful in the following scenarios:
    • Displaying frequency domain images: The function converts the output into a readable image representation in the frequency domain. This helps visualize the distribution of frequency components in an image.
    • Reconstructing images from the coefficients: The function converts the coefficients into a readable format and then reconstruct the image from these coefficients. This aids in applications such as image compression. The compressed image can be converted back to a readable format for display or further processing.

See TD_DFFT2.