Mathematical Handbook for Scientists and Engineers

Persistent Scatterer Interferometry (PSI) is a powerful remote sensing technique able to measure and monitor displacements of the Earth’s surface over time. Specifically, PSI is a radar-based technique that belongs to the group of differential interferometric Synthetic Aperture Radar (SAR). This paper provides a review of such PSI technique. It firstly recalls the basic principles of SAR interferometry, differential SAR interferometry and PSI. Then, a review of the main PSI algorithms proposed in the literature is provided, describing the main approaches and the most important works devoted to single aspects of PSI. A central part of this paper is devoted to the discussion of different characteristics and technical aspects of PSI, e.g. SAR data availability, maximum deformation rates, deformation time series, thermal expansion component of PSI observations, etc. The paper then goes through the most important PSI validation activities, which have provided valuable inputs for the PSI development and its acceptability at scientific, technical and commercial level. This is followed by a description of the main PSI applications developed in the last fifteen years. The paper concludes with a discussion of the main open PSI problems and the associated future research lines.

https://zenodo.org/record/45568/files/Persistent_Scatterer_Interferometry.pdf

Persistent Scatterer Interferometry: A review

A method and apparatus for managing institutional telephone activity utilizes a computer control unit to control a trunk management unit, which connects institutional telephones to outside telephone lines. The computer control unit contains a database for storing the calling privileges and restrictions of institutional users and for recording calling transactions made by the users. The computer control unit implements a prospective call screening feature whereby outside recipients of undesired calls from the institution may enter a code that directs the computer control unit to prohibit similar calls in the future.

Computer-based method and apparatus for controlling, monitoring, recording and reporting telephone access

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Spotlight Synthetic Aperture Radar Signal Processing Algorithms

Communication systems: An introduction to signals and noise in electrical communication

Nonlinear FM waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.

/pdf/generating-nonlinear-fm-chirp-waveforms-for-radar-2f0c7mz63k.pdf

Generating nonlinear FM chirp waveforms for radar.

Lynx is a high resolution, synthetic aperture radar (SAR) that has been designed and built by Sandia National Laboratories in collaboration with General Atomics (GA). Although Lynx may be operated on a wide variety of manned and unmanned platforms, it is primarily intended to be fielded on unmanned aerial vehicles. In particular, it may be operated on the Predator, I-GNAT, or Prowler II platforms manufactured by GA Aeronautical Systems, Inc. The Lynx production weight is less than 120 lb. and has a slant range of 30 km (in 4 mm/hr rain). It has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode. In ground moving target indicator mode, the minimum detectable velocity is 6 knots with a minimum target cross-section of 10 dBsm. In coherent change detection mode, Lynx makes registered, complex image comparisons either of 0.1 m resolution (minimum) spotlight images or of 0.3 m resolution (minimum) strip images. The Lynx user interface features a view manager that allows it to pan and zoom like a video camera. Lynx was developed under corporate finding from GA and will be manufactured by GA for both military and commercial applications. The Lynx system architecture will be presented and some of its unique features will be described. Imagery at the finest resolutions in both spotlight and strip modes have been obtained and will also be presented.

/pdf/lynx-a-high-resolution-synthetic-aperture-radar-4i2qj6f7jq.pdf

Lynx: A High-Resolution Synthetic Aperture Radar

This paper details a Video SAR (Synthetic Aperture Radar) mode that provides a persistent view of a scene centered at
the Motion Compensation Point (MCP). The radar platform follows a circular flight path. An objective is to form a
sequence of SAR images while observing dynamic scene changes at a selectable video frame rate. A formulation of
backprojection meets this objective. Modified backprojection equations take into account changes in the grazing angle
or squint angle that result from non-ideal flight paths.
The algorithm forms a new video frame relying upon much of the signal processing performed in prior frames. The
method described applies an appropriate azimuth window to each video frame for window sidelobe rejection.
A Cardinal Direction Up (CDU) coordinate frame forms images with the top of the image oriented along a given
cardinal direction for all video frames. Using this coordinate frame helps characterize a moving target’s target response.
Generation of synthetic targets with linear motion including both constant velocity and constant acceleration is
described. The synthetic target video imagery demonstrates dynamic SAR imagery with expected moving target
responses. The paper presents 2011 flight data collected by General Atomics Aeronautical Systems, Inc. (GA-ASI)
implementing the video SAR mode. The flight data demonstrates good video quality showing moving vehicles.
The flight imagery demonstrates the real-time capability of the video SAR mode. The video SAR mode uses a circular
shift register of subapertures. The radar employs a Graphics Processing Unit (GPU) in order to implement this
algorithm.

An application of backprojection for video SAR image formation exploiting a subaperature circular shift register

A vibration estimation method for synthetic aperture radar (SAR) is presented based on a novel application of the discrete fractional Fourier transform (DFRFT). Small vibrations of ground targets introduce phase modulation in the SAR returned signals. With standard preprocessing of the returned signals, followed by the application of the DFRFT, the time-varying accelerations, frequencies, and displacements associated with vibrating objects can be extracted by successively estimating the quasi-instantaneous chirp rate in the phase-modulated signal in each subaperture. The performance of the proposed method is investigated quantitatively, and the measurable vibration frequencies and displacements are determined. Simulation results show that the proposed method can successfully estimate a two-component vibration at practical signal-to-noise levels. Two airborne experiments were also conducted using the Lynx SAR system in conjunction with vibrating ground test targets. The experiments demonstrated the correct estimation of a 1-Hz vibration with an amplitude of 1.5 cm and a 5-Hz vibration with an amplitude of 1.5 mm.

/pdf/sar-based-vibration-estimation-using-the-discrete-fractional-j0cu5ltm8v.pdf

SAR-Based Vibration Estimation Using the Discrete Fractional Fourier Transform

Sandia National Laboratories is a leader in the development of airborne, real-time, fine-resolution, high image quality Synthetic Aperture Radar (SAR), highperformance Interferometric SAR (IFSAR), advanced SAR algorithms, and S A R hardware. Recently designed Sandia airborne systems are the most capable and flexible SARs and IFSARs in existence, offering unprecedented performance and image quality. Sandia designed SARs are currently operational on several platforms for a variety of users. Applications of these systems include surveillance, arms control non-proliferation and treaty verification, military and civilian intelligence, precision guidance and targeting, environmental monitoring, and other issues of interest to the Department of Energy, and the nation at large. Additionally, Sandia continues its strong tradition of research and development in even higher performance SARs, new operating modes, and extensions to basic SAR capabilities and underlying technologies. Experimental systems include; a novel LIS band foliage penetration S A R , a “VidwSAR’ mode that creates “movie-like’’ images that uniquely allow monitoring of moving targets, and a radar responsive tag system. Current R&D efforts include; a new Ka band SAR capable of unprecedented ultra-fine resolutions, a 20 pound full functional SAR, and a digital Kurt Sorensen Sandia National Laboratories Synthetic Aperture Radar Department PO Box 5800 MS 0529 Albuquerque, NM 87185-0529 phone505 I 845-9583 email: kwsoren @ sandia.gov Brett Remund Sandia National Laboratories RF Remote Sensing PO Box 5800 MS 0519 Albuquerque, NM 87185-0519 phone505 1844-1767 email: blremnun @sandia.gov radar receiver. This paper will provide a brief overview of these selected Sandia SAR development efforts.

Armin W. Doerry

Papers

Generating nonlinear FM chirp waveforms for radar.

Lynx: A High-Resolution Synthetic Aperture Radar

An application of backprojection for video SAR image formation exploiting a subaperature circular shift register

SAR-Based Vibration Estimation Using the Discrete Fractional Fourier Transform

Developments in sar and ifsar systems and technologies at sandia national laboratories