Sign in

username:

password:



Not a member?

Search Online Books



Search tips

Free Online Books

Sponsor

NEW! TMS320C6474: 3x the performance. 1/3 the cost. Three 1 GHz cores on 1 chip.

Chapters

Chapter Contents:

Search Spectral Audio Signal Processing

  

Book Index | Global Index


Would you like to be notified by email when Julius Orion Smith III publishes a new entry into his blog?

  

Spectral Interpolation

The need for spectral interpolation comes up in many situations. For example, we always use the DFT in practice, while conceptually we often prefer the DTFT. For time-limited signals, that is, signals which are zero outside some finite range, the DTFT can be computed from the DFT via spectral interpolation.5.1 Another application of DFT interpolation is spectral peak estimation; in this situation, we obtain a sampled spectral peak from a DFT, and interpolation is used to estimate the frequency of the peak more accurately than what is obtained by rounding to the nearest DFT bin frequency.

In this and the following section, we will discuss two types of spectral interpolation:

  • Ideal spectral interpolation (zero-padding in the time domain)
  • Parabolic interpolation (fitting a parabola at the sampled peak)
When these methods are used together, we have what we call the quadratically interpolated FFT (QIFFT) method [248,1]. The QIFFT method can be considered an approximate maximum likelihood method for spectral peak estimation, as we will see.



Subsections

Order a Hardcopy of Spectral Audio Signal Processing

Previous: Conclusion
Next: Ideal Spectral Interpolation

written by Julius Orion Smith III
Julius Smith's background is in electrical engineering (BS Rice 1975, PhD Stanford 1983). He is presently Professor of Music and Associate Professor (by courtesy) of Electrical Engineering at Stanford's Center for Computer Research in Music and Acoustics (CCRMA), teaching courses and pursuing research related to signal processing applied to music and audio systems. See http://ccrma.stanford.edu/~jos/ for details.


Comments


No comments yet for this page


Add a Comment
You need to login before you can post a comment (best way to prevent spam). ( Not a member? )