Sparse Ground Penetrating Radar Acquisition: Implication for Buried Landmine Localization and Reconstruction

The effectiveness of the ground penetrating radar (GPR) imaging process and its capability of correctly reconstructing buried objects is strictly bounded to a correct acquisition strategy, both in terms of data density and regularity. In some GPR applications, such as landmine detection, these requirements may not be fulfiled due to logistical limitations and environmental obstacles. In the light of autonomous platform, possibly driven by a positioning device, the knowledge of the maximum affordable grid irregularity is essential. This experimental work, employing a data set acquired at a landmine test site, provides a demonstration that the same information content could be maintained even with a sparser data grid, compared to the commonly adopted requirements, mitigating the pressing demand for a precise samples positioning

Performance Analysis of Tomographic Methods against Experimental Contactless Multistatic Ground Penetrating Radar

Ground-penetrating radar (GPR) technology for underground exploration consists of the transmission of an electromagnetic signal in the ground for sensing the presence of buried objects. While monostatic or bistatic configurations are usually adopted, a limited number of multistatic GPR systems have been proposed in the scientific literature. In this article, we investigate the recovery performance of a specific and unconventional contactless multistatic GPR system, designed at the Georgia Institute of Technology for the subsurface imaging of antitank and antipersonnel plastic mines. In particular, for the first time, tomographic approaches are tested against this experimental multistatic GPR system, while most GPR processing in the scientific literature processes multimonostatic experimental data sets. First, by mimicking the system at hand, an accurate theoretical as well as numerical analysis is performed in order to estimate the data information content and the performance achievable. Two different tomographic linear approaches are adopted, i.e., the linear sampling method and the Born approximation (BA) method, this latter enhanced by means of the compressive sensing (CS) theoretical framework. Then, the experimental data provided by the Georgia Institute of Technology are processed by means of a multifrequency CS- and BA-based method, thus generating very accurate 3D maps of the investigated underground scenario

REALISASI SISTEM RADAR STEPPED FREQUENCY CONTINUOUS WAVE (SFCW) MENGGUNAKAN UNIVERSAL SOFTWARE RADIO PERIPHERAL (USRP)

Radio Detection and Ranging (Radar) adalah suatu perangkat atau metode yang menggunakan gelombang elektromagnetik dalam frekuensi radio untuk mendeteksi jarak, kecepatan, serta karakteristik dari suatu objek. Sistem radar terdiri dari pemancar, penerima, antenna, unit pemrosesan sinyal dan unit pengolahan data. Berdasarkan sinyal yang dikirim, radar dapat dibagi dua yaitu pulse wave (Radar Pulsa) dan continuous wave. Salah satu jenis radar continuous wave yaitu Stepped Frequency Continous Wave (SFCW) radar. SFCW mampu menghasilkan jangkauan yang lebih luas dan dapat menghasilkan range yang lebih besar. Perangkat lunak yang dapat mengembangkan teknologi radar adalah Software Defined Radio (SDR). SDR merupakan salah satu contoh pengembangan pada bidang teknologi telekomunikasi. SDR dapat digunakan untuk perancangan rangkaian radio, fleksibilitas dalam operasi, biaya lebih rendah dan mempermudah untuk mendesain. Untuk mengimplementasikan SDR dapat menggunakan Universal Software Radio Peripheral (USRP). USRP berfungsi sebagai pengganti hardware yang bekerja sebagai transmitter dan receiver pada dua antenna. Implementasi pada perancangan sistem radar SFCW menggunakan USRP yang akan dioperasikan melalui perangkat lunak GNU Radio. GNU Radio berfungsi untuk menyediakan modul pemrosesan sinyal untuk mengimplementasikan sistem komunikasi radio. Pada pengujian sistem radar SFCW menggunakan USRP dapat dilakukan dengan frekuensi sebesar 1 GHz dan bandwidth sebesar 10 MHz. Hasil secara fungsional sudah sesuai dengan yang dibutuhkan, sinyal FFT yang dihasilkan pada saat delay diubah puncak sinyal FFT berubah sesuai dengan delay yang sudah diatur pada GNU Radio. Pada delay 400 ns 1.3 dB, delay 500 ns 1.25 dB dan delay 1.2 dB. Hasil deteksi pergeseran kecil untuk melihat fasa pada saat pergerakan pelan menjauhi antena dan mendekati antena. Hasil deteksi posisi objek pada saat delay diubah mengalamin perubahan, dilihat dari sinyal FFT semakin besar delay maka semakin besar nilai amplitude

Performance Analysis of Tomographic Methods Against Experimental Contactless Multistatic Ground Penetrating Radar

Ground-penetrating radar (GPR) technology for underground exploration consists of the transmission of an electromagnetic signal in the ground for sensing the presence of buried objects. While monostatic or bistatic configurations are usually adopted, a limited number of multistatic GPR systems have been proposed in the scientific literature. In this article, we investigate the recovery performance of a specific and unconventional contactless multistatic GPR system, designed at the Georgia Institute of Technology for the subsurface imaging of antitank and antipersonnel plastic mines. In particular, for the first time, tomographic approaches are tested against this experimental multistatic GPR system, while most GPR processing in the scientific literature processes multimonostatic experimental data sets. First, by mimicking the system at hand, an accurate theoretical as well as numerical analysis is performed in order to estimate the data information content and the performance achievable. Two different tomographic linear approaches are adopted, i.e., the linear sampling method and the Born approximation (BA) method, this latter enhanced by means of the compressive sensing (CS) theoretical framework. Then, the experimental data provided by the Georgia Institute of Technology are processed by means of a multifrequency CS- and BA-based method, thus generating very accurate 3D maps of the investigated underground scenario

Random Subsampling and Data Preconditioning for Ground Penetrating Radars

Ground penetrating radars (GPRs) for mine detection can profit from the many advantages that compressed sensing can offer through random subsampling in terms of hardware simplification, reduced data volume and measurement time, or imagery simplification. An intrinsic antenna-ground model is used, canceling the undesired reverberation effects and the very strong reflection from the air-soil interface, producing higher detection rates, or even unmasking shallowly buried mines. Extensive Monte Carlo simulations on real GPR measurements (800-2200 MHz) show an increase in the probability of detection, yielding globally promising exploitable results, whenever the principal component analysis technique is used as a preconditioner, as well as providing lower random subsampling bounds for frequency and spatial measurements (cross range), whether applied individually or combined

Global Observations and Understanding of the General Circulation of the Oceans

The workshop was organized to: (1) assess the ability to obtain ocean data on a global scale that could profoundly change our understanding of the circulation; (2) identify the primary and secondary elements needed to conduct a World Ocean Circulation Experiment (WOCE); (3) if the ability is achievable, to determine what the U.S. role in such an experiment should be; and (4) outline the steps necessary to assure that an appropriate program is conducted. The consensus of the workshop was that a World Ocean Circulation Experiment appears feasible, worthwhile, and timely. Participants did agree that such a program should have the overall goal of understanding the general circulation of the global ocean well enough to be able to predict ocean response and feedback to long-term changes in the atmosphere. The overall goal, specific objectives, and recommendations for next steps in planning such an experiment are included