Search

Space debris (SD) is an important problem for space operations and a hot topic for space surveillance research. A structured network of radar sensors is available worldwide, offering vital information about debris status. Recently, the Sardinia Radio Telescope (SRT), a 64-m dish located in Sardinia, Italy, was introduced in the European plan for SD monitoring. Because the SRT is devoted to radio astronomy applications and is not optimized for SD echo detection, the need for an SD-dedicated channel has emerged. In this article, we present a detailed description and characterization of the new P-band receiving chain for SRT’s space debris-monitoring purposes. As a test of its capabilities, the new channel was used to detect the echoes that emanated from the Chinese space station Tiangong-1 when it reentered Earth’s atmosphere on its latest mission.

We present the status of the Sardinia Radio Telescope (SRT) and its forthcoming update planned in the next few years. The post-process scenario of the upgraded infrastructure will allow the national and international scientific community to use the SRT for the study of the Universe at high radio frequencies (up to 116 GHz), both in single dish and in interferometric mode. A telescope like SRT, operating at high frequencies, represents a unique resource for the scientific community. The telescope will be ideal for mapping quickly and with relatively high angular resolution extended radio emissions characterized by low surface brightness. It will also be essential for spectroscopic and polarimetric studies of both Galactic and extragalactic radio sources. With the use of the interferometric technique, SRT and the other Italian antennas (Medicina and Noto) will operate within the national and international radiotelescope network, allowing astronomers to obtain images of radio sources at very high angular resolution.

Space debris is internationally recognized as a planetary threat. Efforts to enhance the worldwide radar monitoring networks have been intensified in the last years. Among the new radars employed for the observations, one of the most promising is the Bistatic Radar for Low Earth Orbit (LEO) Tracking (BIRALET), which employs the Sardinia Radio Telescope as a receiving segment. The Sardinia Radio Telescope (SRT) has recently been proven to be a reliable instrument for space debris monitoring and, for this purpose, over the years has undergone some substantial modifications in order to be able to rise to the status of a fully functional radar receiver. However, an extensive measurement campaign, in order to assess the real potential of the radar, has never been done before. In this paper, the authors present the first real space debris measurement campaign of the SRT, made between December 2018 and October 2019 using the new dedicated channel of the P-band receiver. A total of 27 objects were correctly detected during this campaign, characterized by a radar cross section (RCS) interval between 0.13 and 13.4 m2 and a range interval between 459 and 1224 km.

We describe the beamforming strategy and the preliminary laboratory characterization results of the beam pattern synthesized by the PHAROS2 Phased Array Feed (PAF), a 4-8 GHz PAF with digital beamformer for radio astronomy application. The PAF is based on an array of 10×11 dual-polarization Vivaldi antennas cryogenically cooled at 20 K along with low noise amplification modules (LNAs) cascaded with a multi-channel Warm Section (WS) receiver. We present the beamforming and test procedures used to, respectively digitally synthesize and characterize the PHAROS2 antenna array beam pattern at 6 GHz. The tests of the array were carried out at room temperature by directly connecting 24 antenna elements to the WS and iTPM digital beamformer in a laboratory measurement setup.

The Internet of Things has a high impact on upgrade and transformation of the traditional greenhouse agricultural techniques. It is necessary to control the environmental factors for obtaining the optimum growth conditions for the crop and extend the production season to get the optimum yield. These aspects are fundamental for Agriculture 4.0, that uses technology not simply for the sake of innovation but to improve and address the real needs of consumers. In this paper, a prototype of a low-cost electronic platform for real time greenhouse environment monitoring has been designed, developed and built. The prototype has been developed with the purpose of firmware and software prototyping, in order to make the most of device performances. The electronic board is composed by a Main Board, a Green House Core, a Wi-Fi Module, a RS485 Module, an Analog-to-Digital Converter Module and a USB Module. The system permits to collect data by external sensors, elaborate and send them to external devices as laptop, smartphone and internet gateway, using both wired and wireless connection. These data concern to main greenhouse environmental parameters, such as air temperature, humidity, solar radiation, air velocity and CO2 concentration. A Web application has been implemented to allow users a consultation of greenhouse environmental state in a simple and fast way.

The space debris population is continuously growing and it represents a potential issue for spacecraft. New collisions could exponentially rise the amount of debris and so the level of risk represented by these objects. The monitoring of space environment is necessary to prevent new collisions. For this reason, radar measurements are relevant, in particular to observe objects in Low Earth Orbit. Regarding the Italian contribution, there are two radars based on two different radio telescopes as receivers: the BIRALES and the BIRALET systems. We propose a detailed description of these systems, focusing on hardware and software components that permit to perform range and range rate measurement of resident space objects.

We describe the development of a multi-channel “warm receiver section” (WS) and of a digital beamformer for the PHAROS2 Phased Array Feed (PAF), a PAF demonstrator for radio astronomy application across the 4-8 GHz radio frequency (RF) band. The PAF is based on an array of 10×11 dual-polarization Vivaldi antennas cryogenically cooled at 20 K along with low noise amplification modules (LNAs). The WS receiver can process the signals from a subset of 24 antenna elements of the array by downconverting them to an intermediate frequency (IF) range, 375-650 MHz, suitable for digitization by the digital beamformer. The latter is based on the iTPM (Italian Tile Processing Module), developed for the Square Kilometer Array (SKA) Low Frequency Aperture Array (LFAA). We modified the iTPM firmware to synthesize four independent beams across the 275 MHz instantaneous IF bandwidth in the iTPM FPGAs (Field Programmable Gate Arrays). The 24 signals are sent from the WS to the iTPM through analogue IFoF (IF over fiber) optical links. In this paper we present the design and performance of the WS and of the digital bemaformer for PHAROS2.

The population of space debris is continuously growing and it represents a potential problem for satellites and spacecraft. In fact, new collisions could exponentially rise the number of debris and so the level of threat represented by these objects. To prevent new collisions, the monitoring of space environment is necessary. For this reason, radar measurements are relevant, in particular to observe Space Debris in Low Earth Orbit. In recent years, the Sardinia Radio Telescope, a fully steerable wheel-and-track 64-m antenna, located in Sardinia (Italy), has been used as a receiver in a Pband bi-static radar for space debris monitoring purposes. In this paper the authors investigate the advantages of using a Phased Array Feed in C-band for space debris monitoring (e.g. improved sensitivity and gain, detection of the object trajectory allowed by multiple beams, improvement of the orbit determination of known and unknown debris), as a receiver of the Sardinia Radio Telescope compared to the already used mono-beam P-band receiver.

This paper describes the design, fabrication, and test results of a room temperature multi-channel heterodyne receiver operating across the 2.3&ndash, 8.2 GHz radio frequency (RF) band. Such a &ldquo, Warm Section&rdquo, (WS) receiver is part of phased arrays for reflector observing systems 2 (PHAROS2), a C-band phased array feed (PAF) demonstrator with digital beamformer for radio astronomy application. The WS receiver is cascaded to the PHAROS2 cryostat, which includes an array of Vivaldi antennas with low noise pre-amplification stages. The WS can handle up to 32 RF signals and, for each of them, realizes the operations of filtering, RF amplification and down-conversion from the RF to the 375&ndash, 650 MHz intermediate frequency (IF). Also, the WS incorporates an IF-to-optical signal conversion through analogue wavelength division multiplexing IF over fiber (IFoF) and fiber-optic transmitters (OTXs). The 32-channel WS receiver consists of four eight-channel WS RF/IF modules, one local oscillator (LO) splitter module and one monitoring and control module, all hosted in a standard 6U &times, 19-inch rack.

We describe the design, fabrication and test results of a multi-channel heterodyne receiver operating at room temperature across the 2.3-8.2 GHz Radio Frequency (RF) band. Such a “Warm Section” (WS) receiver is part of a Phased Array Feed (PAF) demonstrator that is being built for radio astronomy application. The WS receiver is cascaded to the PAF cryogenic section that incorporates an antenna array with low noise pre-amplification stages. The WS receiver consists of four rack-mountable modules, each of which can process eight RF inputs. Four modules are arranged in a standard 19” rack to allow handling a total of 32 RF signals. The modules perform filtering (through four-way switch filter bank) and down-conversion (to the 375-650 MHz IF band). The IF signals are converted to optical through analogue Wavelength Division Multiplexing IFoF (IF over fiber) transmitters incorporated into the WS receiver. The signals are sent through optical fibers to a backend, where they are converted back to IF before digitization by an Analog-to-Digital Unit.

Space debris represent a major risk for every spacecraft and satellite. In fact, other than cause serious damages to these structures, new collisions could exponentially increase the amount of debris and so the level of threat represented by the objects. To avoid new impacts, the monitoring of the space environment with space-based and ground-based measurement campaigns is necessary. The ground-based measurement can be implemented with optical or radar technologies. In this paper the upgrade of the Italian BIRALES radar system for space debris, that initially performed only Doppler measurements, is described. With its new features the BIRALES will be able to perform even range measurements.

We describe the design and architecture of PHAROS2, a cryogenically cooled 4–8 GHz Phased Array Feed (PAF) demonstrator with digital beamformer for radio astronomy application. The instrument will be capable of synthesizing four independent single-polarization beams by combining 24 active elements of an array of Vivaldi antennas. PHAROS2, the upgrade of PHAROS (PHased Arrays for Reflector Observing Systems), features: a) commercial cryogenic LNAs with state-of-the-art performance, b) a “Warm Section” for signal filtering, conditioning and single downconversion to select $\text{a}\approx 275\ \text{MHz}$ : Intermediate Frequency (IF) bandwidth within the 4–8 GHz Radio Frequency (RF) band, c) an IF signal transportation by analog WDM (Wavelength Division Mutiplexing) fiber-optic link, and d) a FPGA-based Italian Tile Processing Module (iTPM) digital backend. PHAROS2 will be mounted at the primary focus of the 76-m diameter Lovell radio telescope (Jodrell Bank Observatory, UK) for technical and scientific validation.

Space debris are orbiting objects that represent a major threat for space operations. The most used countermeasure to face this threat is, by far, collision avoidance, namely the set of maneuvers that allow to avoid a collision with the space debris. Since collision avoidance is tightly related to the knowledge of the debris state (position and speed), the observation of the orbital debris is the key of the problem. In this work a bistatic radar configuration named BIRALET (BIstatic RAdar for LEO Tracking) is used to detect a set of space debris at 410 MHz, using the Sardinia Radio Telescope as the receiver antenna. The signal-to-noise ratio, the Doppler shift and the frequency spectrum for each debris are reported.

We present the control system of the 84-116 GHz (3 mm band) Superconductor-Insulator-Superconductor (SIS) heterodyne receiver to be installed at the Gregorian focus of the Sardinia Radio Telescope (SRT). The control system is based on a single-board computer from Raspberry, on microcontrollers from Arduino, and on a Python program for communication between the receiver and the SRT antenna control software, which remotely controls the backshorttuned SIS mixer, the receiver calibration system and the Local Oscillator (LO) system.