The availability of high quality copy machines provides a large amount of printed document counterfeits. Numerous authentication techniques based on security printing, graphical codes, hashing or local hashing have been suggested earlier. In this paper, we propose a novel printed document authentication system based on sensitivity of a new two level QR (2LQR) code to copying process. This 2LQR code contains specific textured patterns, which are sensitive to printing and copying processes. Therefore, it can be used to detect unauthorized document duplication. Experimental results show the efficiency of this 2LQR code for copy detection.

Surface Water and Ocean Topography (SWOT) is a future wide-swath radar altimetry mission. The main instrument is the Ka-band radar interferometer (KaRIn). It provides interferometric radar images that will be processed to obtain water elevation estimates worldwide. Due to the specific geometric and radiometric characteristics of KaRIn/SWOT, the phase-to-height conversion is one of the most critical processing steps. We propose methods to estimate water heights without using classical approaches based on spatial phase unwrapping and control points. Results obtained on the simulated SWOT data are shown.

The quick response (QR) code was designed for storage information and high-speed reading applications. In this paper, we present a new rich QR code that has two storage levels and can be used for document authentication. This new rich QR code, named two-level QR code, has public and private storage levels. The public level is the same as the standard QR code storage level; therefore, it is readable by any classical QR code application. The private level is constructed by replacing the black modules by specific textured patterns. It consists of information encoded using q-ary code with an error correction capacity. This allows us not only to increase the storage capacity of the QR code, but also to distinguish the original document from a copy. This authentication is due to the sensitivity of the used patterns to the print-and-scan (P&S) process. The pattern recognition method that we use to read the second-level information can be used both in a private message sharing and in an authentication scenario. It is based on maximizing the correlation values between P&S degraded patterns and reference patterns. The storage capacity can be significantly improved by increasing the code alphabet q or by increasing the textured pattern size. The experimental results show a perfect restoration of private information. It also highlights the possibility of using this new rich QR code for document authentication.

The principal instrument of the NASA/CNES wide-swath altimetry mission Surface Water and Ocean Topography (SWOT) is the Ka-band Radar Interferometer (KaRIn), a bistatic synthetic aperture radar (SAR) system operating on near-nadir swaths on both sides of the satellite track. There are limited reports on backscattering from natural surfaces at this short wavelength and particular observation geometry. Near-field backscattering measurements on water, as well as the first interferometric airborne SAR acquisitions at Ka-band covering the 0.6 °-3.9 ° incidence range of KaRIn, were therefore conducted. The experimental results confirm expected characteristics of near-nadir Ka-band interferometric SAR imagery, such as strong water/land radiometric contrast (typically in the order of 10 dB) and very high interferometric coherence on water.

The principal instrument of the wide-swath altimetry mission SWOT is KaRIn, a Ka-band interferometric SAR system operating on near-nadir swaths on both sides of the satellite track. Due to the short wavelength and particular observation geometry, there are very limited reports on the backscattering from natural surfaces. Models and simulators that cover radiometric and geometric aspects have therefore been developed. This article describes airborne acquisitions and ground measurements that are used to validate the models and simulators, and shows some preliminary results.

The principal instrument of the SWOT (Surface Water and Ocean Topography) altimetry mission is KaRIn, a Ka-band interferometric SAR system operating on near-nadir swaths on both sides of the satellite track. This article briefly describes the measurement principle, the processing steps and the specificities of the interferometric SAR data of KaRIn as compared to conventional spaceborne SAR systems.

An important question with respect to the performance of the interferometric cartwheel and similar bistatic SAR systems, is whether the ambiguities combine coherently and introduce artifacts in the resulting interferograms. We here review the theoretical behavior of range and azimuth ambiguities and extend the description to the case of non-zero Doppler processing. Simulation results confirm that ambiguities cannot significantly degrade the performance of an L-band interferometric cartwheel