High precision multifrequency acoustic radar with an unequally spaced frequency array designed by simulated annealing

Multifrequency cw radar with a frequency array is realized by digital signal processing. However, the resolution is limited to the fundamental sampling spacing determined by the aperture width of the frequency array. Furthermore, it has a periodic structure with a usually used equally spaced frequen...

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Bibliographic Details
Published in:Japanese Journal of Applied Physics 1997-05, Vol.36 (5B), p.3192-3196
Main Author: MIYASHITA, T
Format: Article
Language:English
Subjects:
Acoustic signal processing
Acoustics
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
Physics
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Summary:Multifrequency cw radar with a frequency array is realized by digital signal processing. However, the resolution is limited to the fundamental sampling spacing determined by the aperture width of the frequency array. Furthermore, it has a periodic structure with a usually used equally spaced frequency array which results in the formation of periodic ghosts of an object. These fundamental problems are shown to be solved by the introduction of an unequally spaced frequency array (USFA) and a linear phase interpolation of the reconstructed impulse response between the fundamental sampling points. An amplitude-weighted USFA, which has minimized grating lobes, is designed by the method of simulated annealing from a previously described uniformly weighted USFA. The original level of the grating lobes is as large as -8.93 dB, and the minimized level is -12.5 dB. The resolution is not degraded by the minimization, and a superresolution of 1/60 to 1/300 of the wavelength is maintained.
ISSN:0021-4922
1347-4065
DOI:10.1143/jjap.36.3192