Accession Number:

AD0785850

Title:

An Approximate Fast Fourier Transform Technique for Vernier Spectral Analysis

Descriptive Note:

Technical rept.

Corporate Author:

NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON CT

Personal Author(s):

Report Date:

1974-08-16

Pagination or Media Count:

52.0

Abstract:

An approximate and quick fast Fourier transform technique for vernier spectral analysis is derived and tested for several candidate time-and delay- weightings, and for overlaps of the time weightings. For 50 percent overlap, the use of a simple cosine lobe for the time weighting yields spurious spectral sidelobes at least 23 dB below the main peak, whereas Dolph-Chebyshev time weighting achieves -33 dB sidelobes. For 75 percent overlap, use of a cosine sup 5 lobe for the time weighting yields sibelobes at least 54 dB down, whereas Dolph-Chebyshev time weighting achieves -86 dB sidelobes. In both cases of overlap, use of delay weighting is also required and is taken as a Hanning weighting. Extensions to other overlaps and weightings are possible from the fundamental relations presented and from the sample program furnished.

Subject Categories:

  • Cybernetics
  • Non-Radio Communications

Distribution Statement:

APPROVED FOR PUBLIC RELEASE