Browsing by Author "Coelho, Bruno"
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- Design of pulsed waveforms for space debris detection with ATLASPublication . Pandeirada, João; Bergano, Miguel; Marques, Paulo; Barbosa, Domingos; Freitas, José; Coelho, Bruno; Ribeiro, ValerioATLAS is the first Portuguese radar system that aims to detect space debris. The article introduces the system and provides a brief description of its capabilities. The sys tem is capable of synthesizing arbitrary amplitude modu lated pulse shapes with a resolution of 10 ns. Given that degree of freedom we decided to test an amplitude mod ulated chirp signal developed by us and a nested barker code. These waveforms are explained as well as their ad vantages and drawbacks for space debris detection. An experimental setup was developed to test the system re ceiver and waveforms are processed by digital matched filtering. The experiments test the system using different waveform shapes and noise levels. Experimental results are in agreement with simulation and show that the chirp signal is more resilient to Doppler shifts, has higher range resolution and lower peak-to-sidelobe ratio in compari son with the nested barker code. Future work in order to increase detection capabilities is discussed at the end.
- Developing a data fusion concept for radar and optical ground based SST stationPublication . Coelho, Bruno; Barbosa, Domingos; Berganoa, Miguel; Pandeirada, João; Marques, Paulo; Correia, Alexandre C. M.; Freitas, José Matias deAs part of the Portuguese Space Surveillance and Tracking (SST) program, a tracking radar and a double Wide Field of View Telescope system (4.3° x 2.3°) are being installed at the Pampilhosa da Serra Space Observatory (PASO) in the centre of continental Portugal, complementing an already installed deployable optical sensor for MEO and GEO surveillance. The tracking radar will track space debris in Low Earth Orbit (LEO) up to 1000 km and at the same time the telescope will also have LEO tracking capabilities. This article intends to discuss possible ways to take advantage of having these two sensors at the same location. Using both types of sensors takes advantage of the radar measurements which give precise radial velocity and distance to the objects, while the telescope gives better sky coordinates measurements. With the installation of radar and optical sensors, PASO can extend observation time of space debris and correlate information from optical and radar provenances in real time. During twilight periods both sensors can be used simultaneously to rapidly compute new TLEs for LEO objects, eliminating the time delays involved in data exchange between sites in a large SST network. This concept will not replace the need for a SST network with sensors in multiple locations around the globe, but will provide a more complete set of measurements from a given object passage, and therefore increase the added value for initial orbit determination, or monitoring of reentry campaigns of a given location. PASO will contribute to the development of new solutions to better characterize the objects improving the overall SST capabilities and constitute a perfect site for the development and testing of new radar and optical data fusion algorithms and techniques for space debris monitoring.
- Development of the first portuguese radar tracking sensor for space debrisPublication . Pandeirada, João; Bergano, Miguel; Neves, João; Marques, Paulo; Barbosa, Domingos; Coelho, Bruno; Ribeiro, ValerioCurrently, space debris represents a threat for satellites and space-based operations, both in-orbit and during the launching process. The yearly increase in space debris represents a serious concern to major space agencies leading to the development of dedicated space programs to deal with this issue. Ground-based radars can detect Earth orbiting debris down to a few square centimeters and therefore constitute a major building block of a space debris monitoring system. New radar sensors are required in Europe to enhance capabilities and availability of its small radar network capable of tracking and surveying space objects and to respond to the debris increase expected from the New Space economy activities. This article presents ATLAS, a new tracking radar system for debris detection located in Portugal. It starts by an extensive technical description of all the system components followed by a study that estimates its future performance. A section dedicated to waveform design is also presented, since the system allows the usage of several types of pulse modulation schemes such as LFM and phase coded modulations while enabling the development and testing of more advanced ones. By presenting an architecture that is highly modular with fully digital signal processing, ATLAS establishes a platform for fast and easy development, research, and innovation. The system follows the use of Commercial-Off-The-Shelf technologies and Open Systems which is unique among current radar systems.
- New SST optical sensor of Pampilhosa da Serra – studies on image processing algorithms and multi-filter characterization of space debrisPublication . Coelho, Bruno; Barbosa, Domingos; Bergano, Miguel; Correia, A.; Freitas, José; Marques, Paulo; Pandeirada, João; Ribeiro, ValerioAs part of the Portuguese Space Surveillance & Tracking (SST) System, two new Wide Field of View (2.3ºx2.3º) small aperture (30cm) telescopes will be deployed in 2021, at the Pampilhosa da Serra Space Observatory (PASO), located in the center of the continental Por tuguese territory, in the heart of a certified Dark Sky area. These optical systems will provide added value ca pabilities to the Portuguese SST network, complement ing the optical telescopes currently in commissioning in Madeira and Azores. These telescopes are optimized for GEO and MEO survey operations and besides the required SST operational capability, they will also pro vide an important development component to the Por tuguese SST network. The telescopes will be equipped with filter wheels, being able to perform observations in several optical bands including white light, BVRI bands and narrow band filters such as H(alpha) and O[III] to study potential different object’s albedos. This config uration enables us to conduct a study on space debris classification/characterization using combinations of dif ferent colors aiming the production of improved color in dex schemes to be incorporated in the automatic pipelines for classification of space debris. This optical sensor will also be used to conduct studies on image processing algo rithms, including source extraction and classification so lutions through the application of machine learning tech niques. Since SST dedicated telescopes produce a large quantity of data per observation night, fast, efficient and automatic image processing techniques are mandatory. A platform like this one, dedicated to the development of Space Surveillance studies, will add a critical capability to keep the Portuguese SST network updated, and as a consequence it may provide useful developments to the European SST network as well.