نتایج جستجو برای: narrowband imaging
تعداد نتایج: 460782 فیلتر نتایج به سال:
Imaging is a valuable tool for solving inverse source problems. The achievable image quality is determined by the imaging system. Its performance can be evaluated by using the concept of point spread functions (PSFs). It is common to compute the PSFs using a numerical algorithm. However, in some cases the PSFs can be derived analytically. In this work, new analytical PSFs are presented. The res...
We consider the inverse problem of reconstructing surface displacements from noisy acoustic measurements collected at a distance from the surface that is comparable to the wavelength. As the detectors move closer to the surface and information from evanescent waves is recorded, the resolution of the image improves up to a level that is limited by the signal to noise ratio (SNR). We review this ...
Narrowband signals have fast and slow time scales. The transmission of narrowband signal features on both times cales, by spiking neurons, is demonstrated experimentally and theoretically. The interaction of the narrowband input and the threshold nonlinearity may create out-of-band interference, hindering the transmission of signals in a low-frequency range. The resultant out-of-band signal is ...
Many geophysical parameters can be determined with the aid of a passive microwave sensor. To achieve a high spatial resolution in passive microwave imaging the method of aperture synthesis can be applied. Narrowband radiometric measurements within a wide frequency range allow extracting more surface information on observed objects or materials and it is possible to obtain depth information on l...
This paper describes an artificial bandwidth extension (ABE) method that generates new high frequency components to a narrowband signal by folding specifically gained subbands to frequencies from 4 kHz to 7 kHz, and improves the quality and intelligibility of narrowband speech in mobile devices. The proposed algorithm was evaluated by subjective listening tests. In addition, rarely used convers...
Metamaterial absorbers are used in the terahertz frequency regime as photo-detectors, sensing elements, imaging applications, etc. Narrowband absorbers, on account of their ultra-slender bandwidth within spectrum, show a significant shift absorption peak when an extrinsic entity relative to absorber, like refractive index or temperature encircling medium, is altered. This property paves path fo...
We report the results of a wide-field narrowband survey for redshift z ∼ 5.7 Lyα emitters carried out with the 34 × 27 field-of-view SuprimeCam mosaic CCD camera on the Subaru 8.3-m telescope. Deep narrowband imaging of the SSA22 field through a 120 Å bandpass filter centered at a nominal wavelength of 8150 Å was combined with deep multicolor RIz broadband imaging with SuprimeCam, then suppleme...
In this paper we present a novel synthetic aperture radar imaging modality that uses ultra-narrowband sources of opportunity and passive airborne receivers to form an image of the ground. Due to its combined passive synthetic aperture and high Doppler resolution of the transmitted waveforms, we refer to this modality as the Doppler Synthetic Aperture Hitchhiker (DSAH) or Doppler-hitchhiker for ...
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