1,721,096 research outputs found
Orthogonal Coprime Synthetic Aperture Radar
No full textRecently, we have proposed a new synthetic aperture radar (SAR) technique, which we called “Coprime SAR”
(CopSAR), applicable to the case of bright targets over a dark background and therefore useful in ocean monitoring for ship
detection. The CopSAR technique is based on the adaptation of the coprime array beamforming concept to the case of SAR systems,
and, in its basic implementation, it is able to reduce the amount of data to be stored and processed, with no geometric resolution
loss. A more complex dual-frequency implementation allows us to additionally obtain a significant increase in the range swath size
with respect to the standard SAR technique. However, for both practical and theoretical reasons, the simplest single-frequency
implementation is preferable. Accordingly, here, we present an enhancement of the CopSAR basic implementation, based on the
transmission of (quasi) orthogonal waveforms, i.e., up- and downchirps: we name it “Orthogonal Coprime SAR” (OrthoCopSAR).
The proposed implementation is able to achieve both data reduction and range swath extension with no appearance of
ghosts, no resolution loss, and only a limited complication of the required technology. The only costs are the reduction in the
target-to-background ratio and the presence of a (nonstringent) limit on maximum ship size, as it is the case in all CopSAR
implementations
Coprime Synthetic Aperture Radar (CopSAR): A New Acquisition Mode for Maritime Surveillance
No full textIn this paper, we propose a synthetic aperture radar (SAR) technique able, in the case of bright targets over a dark
background, to reduce the amount of data to be stored and processed, and, at the same time, to increase the range swath, with no geometric resolution loss. Accordingly, the proposed approach can be usefully employed in ocean monitoring for ship detection. The technique consists of a new SAR acquisition mode and of very simple processing. It is based on the adaptation of the coprime array beamforming concept to the case of SAR systems: two interlaced sequences of pulses are transmitted, with two sub-Nyquist pulse repetition frequencies (PRFs) that are equal to the Nyquist PRF divided by two coprime integer numbers. Each sequence is separately processed via standard SAR processing, and the two final aliased images are combined in a very simple way to cancel aliasing. We call the proposed approach “coprime SAR” (CopSAR). Three different implementations are proposed, and the effectiveness of the CopSAR concept is demonstrated by using both simulated and real SAR data. It turns out that the significant data amount reduction and the range swath increase are only paid with a reduction of the target-to-background ratio and with the presence of a (nonstringent) limit on ship azimuth size
Passive beamforming with coprime arrays
No full textCoprime arrays have been recently proposed as effective sparse configurations suitable for radar beamforming and
angle-of-arrival estimation applications. In this study, a new approach for passive beamforming using coprime arrays is
presented. In particular, a new detection strategy is proposed, which outperforms the coprime processors presently available in the literature, both in terms of peak sidelobe ratio and integrated sidelobe ratio, without giving rise to ‘ghost’ targets in presence of multiple interferers. The advantage of the proposed detector is demonstrated through the simulation of appropriate array scanned responses and receiver operating characteristic curves
Polarimetric Two-Scale Two-Component Model for the Retrieval of Soil Moisture Under Moderate Vegetation via L-Band SAR Data
No full text
- …
