Comparison of OLI and TM Multi-spectral Satellite Imagery Land-use and Land-cover Mapping Using Hierarchical Concept of Earth Surface Matrix

The present study compares the capabilities of Thematic Mapper (TM) and Operational Land Imager (OLI) sensors of Landsat satellite and analyzes the results of image classification on their multi-spectral data. To achieve this, LANDSAT 5-TM (2011) and LANDSAT 8-OLI (2016) imageries were used to map the land-use and land-cover for a study area located on Pelasjan sub-basin, in Isfahan, Iran. First, radiometric and atmospheric corrections were performed, and then the overall status of the area was determined by reviewing topographic maps, visual interpretation of the satellite imageries and field studies.  Consequently, a three-level land matrix hierarchy including 1) General level, 2) Mid-level, and 3) The level of details was established. Land matrix hierarchy maps were produced with proper methods using hybrid classification. The comparative analysis in this study showed that the hybrid classification method generates accurate results from the OLI sensor data in comparison to TM imageries. This was particularly evident for residential areas, irrigated agriculture, rain-fed agriculture, sparse, and dense rangelands. Although the results of image classification showed more accuracy for the OLI imagery, the error matrix in Z-test did not identify any statistically significant difference between the two datasets. This highlights the importance of image classification method selection, which can overcome the possible limitations of satellite imageries in land-use and land-cover mapping. Keywords: OLI and TM Sensors, land matrix hierarchy, hybrid classification, LULC, error matrix

Maturing Satellite Kinematics into a Competitive Probe of the Galaxy-Halo Connection

The kinematics of satellite galaxies moving in a dark matter halo are a direct probe of the underlying gravitational potential. Thus, the phase-space distributions of satellites represent a powerful tool to determine the galaxy-halo connection from observations. By stacking the signal of a large number of satellite galaxies this potential can be unlocked even for haloes hosting a few satellites on average. In this work, we test the impact of various modelling assumptions on constraints derived from analysing satellite phase-space distributions in the non-linear, 1-halo regime. We discuss their potential to explain the discrepancy between average halo masses derived from satellite kinematics and gravitational lensing previously reported. Furthermore, we develop an updated, more robust analysis to extract constraints on the galaxy-halo relation from satellite properties in spectroscopic galaxy surveys such as the SDSS. We test the accuracy of this approach using a large number of realistic mock catalogues. Furthermore, we find that constraints derived from such an analysis are complementary and competitive with respect to the commonly used galaxy clustering and galaxy-galaxy lensing observables.Comment: 24 pages, 15 figures; resubmitted to MNRAS after first referee repor

Optimization of intersatellite routing for real-time data download

The objective of this study is to develop a strategy to maximise the available bandwidth to Earth of a satellite constellation through inter-satellite links. Optimal signal routing is achieved by mimicking the way in which ant colonies locate food sources, where the 'ants' are explorative data packets aiming to find a near-optimal route to Earth. Demonstrating the method on a case-study of a space weather monitoring constellation; we show the real-time downloadable rate to Earth

Use of supervised machine learning for GNSS signal spoofing detection with validation on real-world meaconing and spoofing data : part I

The vulnerability of the Global Navigation Satellite System (GNSS) open service signals to spoofing and meaconing poses a risk to the users of safety-of-life applications. This risk consists of using manipulated GNSS data for generating a position-velocity-timing solution without the user's system being aware, resulting in presented hazardous misleading information and signal integrity deterioration without an alarm being triggered. Among the number of proposed spoofing detection and mitigation techniques applied at different stages of the signal processing, we present a method for the cross-correlation monitoring of multiple and statistically significant GNSS observables and measurements that serve as an input for the supervised machine learning detection of potentially spoofed or meaconed GNSS signals. The results of two experiments are presented, in which laboratory-generated spoofing signals are used for training and verification within itself, while two different real-world spoofing and meaconing datasets were used for the validation of the supervised machine learning algorithms for the detection of the GNSS spoofing and meaconing

Technology Assessment and Experimentation Plan

An assessment is given of the critical and enhancing technologies necessary to build the basic personal terminal (BPT), the supplier, and the Network Management Center (NMC). The experimentation plan for testing the Personal Access Satellite System (PASS) utilizing ACTS is detailed. The experiment plan gives a list of candidate experiments and describes the proposed experimental set-up. ACTS will be used in the Microwave Switch Matrix (MSM) mode. The Microwave Switch Matrix - Link Evaluation Terminal (MSM-LET) at the NASA Lewis Research Center will serve as the microwave front-end for the PASS supplier and the NMC. Link budgets are given for both the forward and return links between the supplier and the basic personal terminal. The equipment required for the experiments is identified

On testing frame-dragging with LAGEOS and a recently announced geodetic satellite

Recently, Ciufolini and coworkers announced the forthcoming launch of a new cannonball geodetic satellite in 2019. It should be injected in an essentially circular path with the same semimajor axis $a$ of LAGEOS, in orbit since 1976, and an inclination $I$ of its orbital plane supplementary with respect to that of its existing cousin. According to their proponents, the sum of the satellites' precessions of the longitudes of the ascending nodes $\Omega$ should allow one to test the general relativistic Lense-Thirring effect to a $\simeq 0.2\%$ accuracy level, with a contribution of the mismodeling in the even zonal harmonics $J_\ell,~\ell=2,4,6,\ldots$ of the geopotential to the total error budget as little as $0.1\%$. Actually, such an ambitious goal seems to be hardly attainable because of the direct and indirect impact of, at least, the first even zonal $J_2$. On the one hand, the lingering scatter of the estimated values of such a key geophysical parameter from different recent GRACE/GOCE-based global gravity field solutions is representative of an uncertainty which may directly impact the summed Lense-Thirring node precessions at a $\simeq 70-80\%$ in the worst scenarios, and to a $\simeq 3-10\%$ level in other, more favorable cases. On the other hand, the phenomenologically measured secular decay $\dot a$ of the semimajor axis of LAGEOS (and, presumably, of the other satellite as well), currently known at a $\sigma_{\dot a}\simeq 0.03~\textrm{m~yr}^{-1}$ level after more than 30 yr, will couple with the sum of the $J_2$-induced node precessions yielding an overall bias as large as $\simeq 20-40\%$ after $5-10$ yr. A further systematic error of the order of $\simeq 2-14\%$ may arise from an analogous interplay of the secular decay of the inclination $\dot I$ with the oblateness-driven node precessions.Comment: LaTex2e, 27 pages, 3 tables, 7 figures. Accepted for publicatio

Development and implementation of an adaptive digital beamforming network for satellite communication systems

The use of adaptive digital beamforming techniques has, until recently, been largely restricted to high performance military radar systems. Recent advances in digital technology, however, have enabled the design of single chip digital beamforming networks. This, coupled with advances in digital signal processor technology, enables complete beamforming systems to be constructed at a lower cost, thus making the application of these techniques to commercial communications systems attractive. The design and development of such an adaptative digital beamforming network are described. The system is being developed as a proof of concept laboratory based demonstrator to enable the feasibility of adaptive digital beamforming techniques for communication systems to be determined. Ultimately, digital beamforming could be used in conjunction with large array antennas for communication satellite systems. This will enable the simultaneous steering of high gain antenna beams in the direction of gr...Peer ReviewedPostprint (published version