Showing papers on "L band published in 2017"
01 Aug 2017
TL;DR: In this paper, a multibeam receiver for the FAST radiotelescope was described, which provides 19 dual polarised beams over a band of 1050-1450 MHz with an expected receiver noise temperature under 7 K and aperture efficiency of greater than 62%.
Abstract: We describe a multibeam receiver for the FAST radiotelescope. The receiver provides 19 dual polarised beams over a band of 1050–1450 MHz with an expected receiver noise temperature under 7 K and aperture efficiency of greater than 62%. The feed is currently undergoing final assembly and testing.
17 citations
TL;DR: A comprehensive compatibility evaluation methods based on effective carrier-to-noise ratio degradation for acquisition and code tracking indicates that CPM signal is easier to allow peaceful coexistence of other systems with minimal mutual interference in S band compared to other BDS candidates.
Abstract: With L band frequency allocations for satellite navigation getting more crowded, S band (2483.5–2500 MHz) is already allocated for navigation services, where Globalstar broadcasts downlink communications to user terminals. The Indian Regional Navigation Satellite System (IRNSS) is transmitting navigation signals and Galileo exploits some potential signals in S band. Also, several candidate S band signals based on binary offset carrier (BOC), binary phase shift keying (BPSK), continuous phase modulation (CPM) and minimum shift keying-BOC (MSK-BOC) are suggested for BeiDou system (BDS). In quite narrow S band, mutual interference among these systems is inevitable, thus the compatibility issue is particularly significant for S band signal design. To explore desired S band signals for BDS, the paper firstly describes a comprehensive compatibility evaluation methods based on effective carrier-to-noise ratio degradation for acquisition and code tracking. Then a real simulation is established using space constellations, modulation schemes and received power. Finally, the worst mutual interference of BDS candidate signals with Galileo, IRNSS and Globalstar is calculated and compared. The results indicate that CPM signal is easier to allow peaceful coexistence of other systems with minimal mutual interference in S band compared to other BDS candidates.
12 citations
01 Oct 2017
TL;DR: In this article, the performance of 1030/1090MHz aeronautical radio systems is estimated with some interference measures such as the received pulse densities, and the results of an analysis of 1090MHz signal environment which recorded by the flight experiments are provided.
Abstract: The operational performance of 1030/1090MHz aeronautical radio system is required to be estimated whether or not they will interfere harmfully with each other by sharing the frequency band. The performance of these systems will be estimated with some interference measures such as the received pulse densities. This paper provides the results of an analysis of 1090MHz signal environment which recorded by the flight experiments.
11 citations
TL;DR: An L-band horn antenna with modified radiation pattern is customized for ground penetrating radar (GPR) applications in this article, where the conventional horn antenna is loaded by a metallic wire medium to enhance the antenna radiation pattern, directivity and gain with reduction of the sidelobes level.
Abstract: An L-band horn antenna with modified radiation pattern is customized for ground penetrating radar (GPR) applications. The conventional horn antenna is loaded by a metallic wire medium to enhance the antenna radiation pattern, directivity and gain with reduction of the sidelobes level. These properties are strongly desirable for GPR applications.
9 citations
TL;DR: The possibilities for developing a spectrum sensing approach to detect idle band in the VHF spectrum are proposed and the possible interference between future L-band Digital Aeronautical Communication System (L-DACS) and legacy aeronautical systems are analyzed.
9 citations
01 Sep 2017
TL;DR: In this paper, the software controlled and assisted radio commanding of VZLUSAT-1 nanosatellite during the QB50 scientific mission is described with the aim to increase data throughput during commanding Software controlled autonomous and software assisted semi-autonomous modes allow effective commanding of satellite while keeping the operator to the satellite condition and keeping the full control over the radio transmission as radio amateur regulation requires.
Abstract: Nano- and pico-satellites are currently used as low cost in-orbit-demonstrators of new technologies or for the university research These satellites are launched to the low Earth orbits and radio commanded from the ground control stations Most of them are equipped with narrow band transceivers working in UHF radio amateur frequency band, reaching only low data transmission rates Low Earth orbits also limits the number and duration of satellite passing in the range of ground control station One ground control station has approximately six satellite passes per day, each with duration only in few minutes This strictly limits the amount of transmitted data between satellite and ground control station In this paper the software controlled and assisted radio commanding of VZLUSAT-1 nanosatellite during the QB50 scientific mission is described Two basic modes of satellite radio commanding are described with the aim to increase data throughput during commanding Software controlled autonomous and software assisted semi-autonomous modes allow effective commanding of satellite while keeping the attention of satellite operator to the satellite condition and keeping the full control over the radio transmission as radio amateur regulation requires Also the critical operational limits of satellite electronics faces to cosmic vacuum and radiation environment have to be continuously monitored for safety satellite operation
6 citations
08 Jun 2017
TL;DR: The first measurements with NeXtRAD are reported, looking primarily at sea clutter and some targets, as well as early attempts at calibration using corner reflectors, and an assessment of the polarimetric response of the system.
Abstract: NeXtRAD is a fully polarimetric, X/L Band radar network. It is a development of the older NetRAD system and builds on the experience gained with extensive deployments of NetRAD for sea clutter and target measurements. In this paper we will report on the first measurements with NeXtRAD, looking primarily at sea clutter and some targets, as well as early attempts at calibration using corner reflectors, and an assessment of the polarimetric response of the system. We also highlight innovations allowing for efficient data manipulation post measurement campaigns, as well as the plans for the coming years with this system.
6 citations
TL;DR: In this paper, the conditions for the transition of PSR J1023+0038 from high to low state to rotation-powered radio millisecond pulsar (MSP) state were studied.
Abstract: PSR J1023+0038 is a known transitional pulsar, which switches between the accretion-powered X-ray pulsar state and the rotation-powered radio millisecond pulsar (MSP) state. Here, we study the conditions for its state transition by ascribing similar to GHz radio pulse emission to the plasma cutoff oscillation frequency at the magnetosphere, which depends on the plasma density or accretion rate. With the accretion X-ray luminosity declining fromhigh to low state (e.g., similar to 10(35) erg s(-1) to similar to 10(32) erg s(-1)), the magnetosphere boundary expands to the light cylinder, where the plasma density is low enough to permit the emission of radio waves at the several-GHz frequency band. Thus, for a sufficiently low accretion-rate state (similar to 1032 erg s(-1)), the radio emission at the several-GHz band is not blocked by the plasma, and the radio pulsar can be detected in the favored "observational windows," i.e., the L band (1-2 GHz), S band (2-4 GHz), and C band (4-8 GHz). Furthermore, to evaluate the penetration characteristics of the outgoing radio wave of low frequency, we calculate its skin depth, which is found to be a couple of centimeters for the low X-ray luminosity of 10(34)-10(32) erg s(-1), a scale that is much shorter than the light cylinder radius of about 100 km for MSPs.
6 citations
01 Dec 2017
TL;DR: The measurement shows that the proposed antennae can operate in extra wide band frequency to detect the vital signs, and a transceiver antennae is proposed that allows to detects the thorax displacement at four band of frequencies, from L band to X band.
Abstract: A very wide band (from 900 MHz to 12 GHz), enhancing beam capacity patch antennae system is developed in FR4 substrate with a dielectric constant 4.4 and 1.2 mm of height for vital detection purposes. This work focuses on development of 3D-orthogonal patch antennae to detect the respiratory beat at different frequencies. A transceiver antennae is proposed that allows to detect the thorax displacement at four band of frequencies, from L band to X band. The measurement shows that the proposed antennae can operate in extra wide band frequency to detect the vital signs.
6 citations
Dissertation•
01 Jan 2017
TL;DR: In this article, the authors investigated the use of the KAT-7 (7 antennas) and MeerKAT (64 antennas) radio telescope receivers in a radar system to improve monitoring of small space debris and potentially hazardous asteroids.
Abstract: This thesis investigates the current knowledge of small space debris (diameter less than 10 cm) and potentially hazardous asteroids (PHA) by the use of radar systems. It clearly identifies the challenges involved in detecting and tracking of small space debris and PHAs. The most significant challenges include: difficulty in tracking small space debris due to orbital instability and reduced radar cross-section (RCS), errors in some existing data sets, the lack of dedicated or contributing instruments in the Southern Hemisphere, and the large cost involved in building a high performance radar for this purpose. This thesis investigates the cooperative use of the KAT-7 (7 antennas) and MeerKAT (64 antennas) radio telescope receivers in a radar system to improve monitoring of small debris and PHAs was investigated using theory and simulations, as a cost effective solution. Parameters for a low cost and high performance radar were chosen, based on the receiver digital back-end. Data from such radars will be used to add to existing catalogues thereby creating a constantly updated database of near Earth objects and bridging the data gap that is currently being filled by mathematical models. Based on literature and system requirements, quasi-monostatic, bistatic, multistatic, single input multiple output (SIMO) radar configurations were proposed for radio telescope arrays in detecting, tracking and imaging small space debris in the low Earth orbit (LEO) and PHAs. The maximum dwell time possible for the radar geometry was found to be 30 seconds, with coherent integration limitations of 2 ms and 121 ms for accelerating and non-accelerating targets, respectively.
4 citations
01 Jan 2017
TL;DR: Details are provided on the development of the FLAG digital back end, the real-time beamformer, and reports on the commissioning tests of theFLAG PAF receiver developed by the National Radio Astronomy Observatory, Green Bank Observatory, West Virginia University, and Brigham Young University for the Green Bank Telescope (GBT).
Abstract: Real-Time Beamforming Algorithms for the Focal L-band Array on the Green Bank Telescope (FLAG) Mark William Ruzindana Department of Electrical and Computer Engineering, BYU Master of Science A phased array feed (PAF) provides a contiguous, electronically synthesized wide field of view for large-dish astronomical observatories. Significant progress has been made in recent years in improving the sensitivity of PAF receivers though optimizing the design of the antenna array, cryogenic cooling of the front end, and implementation of real-time correlation and beamforming in digital signal processing. FLAG is a 19 dual-polarized element phased array with cryogenic LNAs, direct digitization of RF signals at the front end, digital signal transport over fiber, and a real time signal processing back end with up to 150 MHz bandwidth. The digital back end includes multiple processing modes, including real-time beamforming, real-time correlation, and a separate real-time beamformer for commensal radio transient searches. Following a polyphase filterbank operation performed in field programmable gate arrays (FPGAs), beamforming, correlation, and integration are implemented on graphical processing units (GPUs) that perform parallelized operations. Parallelization greatly increases processing speed and allows for real-time signal processing. During a recent test/commissioning of FLAG, Tsys/efficiency of approximately 28 K was measured across the PAF field of view and operating bandwidth, corresponding to a system temperature below 20 K. To demonstrate the astronomical capability of the receiver, a pulsar (PSR B1937+21) was detected with the real-time beamformer. This thesis provides details on the development of the FLAG digital back end, the real-time beamformer, and reports on the commissioning tests of the FLAG PAF receiver developed by the National Radio Astronomy Observatory (NRAO), Green Bank Observatory (GBO), West Virginia University (WVU), and Brigham Young University for the Green Bank Telescope (GBT).
01 Jul 2017
TL;DR: Center for Environmental Remote Sensing, Chiba University develops L Band circularly polarized synthetic aperture radar (SAR) sensor for microsatellite (150 kg class) that will be employed to monitor global land deformation.
Abstract: Center for Environmental Remote Sensing, Chiba University develops L Band circularly polarized synthetic aperture radar (SAR) sensor for microsatellite (150 kg class). This paper explains the project, specification, antenna deployment, RF system, and experiment of circularly polarized SAR in anechoic chamber. In the future, this sensor will be employed to monitor global land deformation.
01 Oct 2017
TL;DR: In this article, an overview of the system level RF design for the second generation architecture used in the Australian Square Kilometre Array Pathfinder (ASKAP) design enhancement (ADE) is presented.
Abstract: This is an overview of the system level RF design for the second generation architecture used in the Australian Square Kilometre Array Pathfinder (ASKAP) [1] design enhancement (ADE). ADE is a distributed antenna system (DAS) of 36 reflector antennas each 12m in diameter. Each antenna has a planar Phased Array Feed (PAF) at the prime focus. The PAF contains 188 broadband 700–1800MHz receptors. Inside a PAF the radioastronomy (RA) signals are amplified, band selected and converted to 188 individual broadband RF over (singlemode optical) fiber (RFoF) lightwaves [2]. The entire ADE array has 6840 RFoF links, this includes transmission line delay metrology for each reflector. The longest RFoF span is 6km. Optical to RF demodulation of the RF sky signal at the central site Digital Signal Processing (DSP) shielded building is direct sampled in 12bit analog to digital convertors (ADCs). Digital beamforming provides 36 pencil beams, each of 384MHz bandwidth. The scale of ADE represents a leap forward in applied RF and photonic techniques to enable a simpler, lower cost, more modular, EMC compliant, phased array receiver architecture. ADE will provide unprecedented high speed sky surveys with an instantaneous widefield of view (30deg2 at 1420MHz) capability for a new generation of radio astronomers.
01 Jul 2017
TL;DR: BelSAR is an ESA funded project for acquiring and analyzing airborne bistatic Synthetic Aperture Radar data at L band, in support of the SAOCOM passive radar satellite under study at the agency.
Abstract: BelSAR is an ESA funded project for acquiring and analyzing airborne bistatic Synthetic Aperture Radar data at L band, in support of the SAOCOM passive radar satellite under study at the agency. MetaSensing has built two L band SAR systems able to work in bistatic mode. A few test flights have been performed in The Netherlands and the paper reports the first results of the airborne bistatic campaign.
Patent•
20 Mar 2017
TL;DR: In this paper, the authors proposed an interface between the radio frequency splitter and a distance measurement equipment receiver, which can also include an interface to the bottom omni-directional antenna.
Abstract: Various wireless systems may benefit from suitable sharing of antennas and related equipment. For example a various avionics systems may benefit from systems and methods for providing a distance measurement equipment L-band shared antenna. Circuitry can include an interface to a bottom omni-directional antenna. The circuitry can also include a radio frequency splitter in switchable communication with the interface to the bottom omni-directional antenna. The circuitry can further include an interface between the radio frequency splitter and a distance measurement equipment receiver. The circuitry can additionally include an interface between the radio frequency splitter and a surveillance receiver.
01 Oct 2017
TL;DR: A novel stacked tri-band antenna which has three independent ports is proposed which has achieved a bandwidth of 3%, 3% and 18% at each band, respectively.
Abstract: Shared aperture multiband antenna has more application when the electromagnetic compatibility problem is more and more serious. This paper proposes a novel stacked tri-band antenna which has three independent ports. Many dual band compact microstrip patch antenna has been designed but the research about tri-band microstrip antenna which can work in L, S and C band was little. To obtain tri-band operation, a stacked four layers of microstrip antenna working at different frequency is presented. Each of them is fed by dual feed probes. The simulated results show that the antenna can work at L band 1.66GHz, S band 3.25GHz and C band 5.27GHz with high isolation. The proposed antenna has achieved a bandwidth of 3%, 3% and 18% at each band, respectively.
01 Jan 2017
01 Oct 2017
TL;DR: In this paper, a forward single-stage pump laser and EDFA structure was used for L band EDFA with an uncooled 980 nm pump laser with maximum optical output power of 250 mW.
Abstract: An experiment on L band EDFA is demonstrated by using forward single stage pump laser and EDFA structure. It uses an uncooled 980 nm pump laser with maximum optical output power of 250 mW. The L band EDFA used is 20 m in length with WDM 980/1550 nm couplers as pump power and signal combiner before entering into L band EDFA. The gain can achieve the value of 30 dB with gain variation within 1 dB in 30 nm from 1570–1610 nm spans of ITU grid wavelength. The lowest power starts at −20 dBm and can be amplified up to 3 dBm.
09 Nov 2017
TL;DR: The antenna can be used to receive information from polar orbit weather satellites in L band, at 1.7 GHz, and must be used with a rotor with synchronized movement in azimuth and elevation for the satellite tracking.
Abstract: This paper presents the design of a parabolic patch antenna. The reflector of primary focus has 120cm of diameter, the proposed feeder has double layer and air substrate between its layers. The upper and lower square layers are supported by non-conductive material. The experimental axial ratio obtained is 0.8dB at 1.7 GHz, phi=0deg. The gain obtained is 23.4dB, the reflection coefficient obtained in 1.7 GHz is -14dB. The antenna can be used to receive information from polar orbit weather satellites in L band, at 1.7 GHz. The antenna must be used with a rotor with synchronized movement in azimuth and elevation for the satellite tracking.
01 Jul 2017
TL;DR: In this article, the authors developed a L Band circularly polarized synthetic aperture radar (SAR) sensor for microsatellite (150kg class) using 3.6m diameter of gold coated parabolic mesh antenna.
Abstract: Our laboratory develops L Band circularly polarized synthetic aperture radar (SAR) sensor for microsatellite (150kg class) using 3.6m diameter of gold coated parabolic mesh antenna. This presentation explains the specification, antenna deployment system, RF system, and characteristics of parabolic mesh antenna for the developed sensor. This sensor will be employed to monitor global land deformation in the future.
19 Aug 2017
TL;DR: In this paper, a technique is presented to estimate the location on the ground of RFI sources using SMAP measurements, and the results of this technique have been validated against data derived by other means.
Abstract: RFI (Radio-Frequency Interference) in the 1400–1427 MHz band degrades the quality of measurements made by satellite missions such as SMAP (Soil Moisture Active/Passive), Aquarius and SMOS (Soil Moisture and Ocean Salinity). A technique is presented here to estimate the location on the ground of RFI sources using SMAP measurements. The results of this technique have been validated against data derived by other means.
01 Jul 2017
TL;DR: This paper presents the design and preliminary performance tests of an L-band synthetic aperture interferometic radiometer using the new sampling concept of clock scan to validate the concept of CS-MIR and solve the related technical problems.
Abstract: This paper presents the design and preliminary performance tests of an L-band synthetic aperture interferometic radiometer using the new sampling concept of clock scan. With the advantages of simple and deployable array structure, the concept of Clock Scanning Microwave Interferometric Radiometer (CS-MIR) has much potential to apply for the future Solar Polar Orbit (SPO) and Geostationary Earth Orbit (GEO) missions, where large antenna array with high angular resolution is the prime requirement. This L band demonstrator is developed to validate the concept of CS-MIR and solve the related technical problems.
01 Sep 2017
TL;DR: In this paper, a circularly polarized L Band antenna for terrestrial satellite observation services is presented, which is based on two crossed dipoles fed by a coaxial cable and a flat reflector to improve the characteristics of the radiation pattern.
Abstract: This work present an circularly polarized L Band antenna for terrestrial satellite observation services. The design is based on two crossed dipoles fed by a coaxial cable, and a flat reflector to improve the characteristics of the radiation pattern. The dipoles are implemented on PCB and the assembly is designed considering the weight and size constraints imposed by aerospace technology. Simulation results of the main characteristics of the antenna are shown as well as impedance and axial ratio measurements performed on a prototype built in FR4.
01 Jun 2017-World Academy of Science, Engineering and Technology, International Journal of Electronics and Communication Engineering
TL;DR: In this article, the design and simulation of a pyramidal horn antenna operating at L-band frequencies (12 GHz) to detect a landmine was explored. But the work in this paper is limited to the simulation of the ground penetrating radar (GPR).
Abstract: Landmine detection is an important and yet challenging problem remains to be solved. Ground Penetrating Radar (GPR) is a powerful and rapidly maturing technology for subsurface threat identification. The detection methodology of GPR depends mainly on the contrast of the dielectric properties of the searched target and its surrounding soil. This contrast produces a partial reflection of the electromagnetic pulses that are being transmitted into the soil and then being collected by the GPR. One of the most critical hardware components for the performance of GPR is the antenna system. The current paper explores the design and simulation of a pyramidal horn antenna operating at L-band frequencies (12 GHz) to detect a landmine. A prototype model of the GPR system setup is developed to simulate full wave analysis of the electromagnetic fields in different soil types. The contrast in the dielectric permittivity of the landmine and the sandy soil is the most important parameter to be considered for detecting the presence of landmine. L-band horn antenna is proved to be well-versed in the investigation of landmine detection. Keywords—Full wave analysis, ground penetrating radar, horn antenna design, landmine detection.
01 Mar 2017
TL;DR: An airborne experiment using Global Positioning System (GPS) satellite emitted signals to characterize the wave propagation channel from a satellite to an airborne platform is described and first results on ground reflected multipath are provided.
Abstract: Radio wave propagation from a satellite based emitter to an airborne located receiver is of interest for applications like passenger internet access during a flight, air traffic management or positioning by global navigation satellite systems (GNSSs). Especially for the last two applications that are related to safety-of-life functionality, accurate channel models for software based system testing are essential. Current state-of-the art channel models for the satellite-to-aircraft case lack of accuracy in terms of modeling all propagation impairments. In this contribution, we describe an airborne experiment using Global Positioning System (GPS) satellite emitted signals to characterize the wave propagation channel from a satellite to an airborne platform. First results on ground reflected multipath are provided.
01 Jul 2017
TL;DR: The conclusions drawn suggest that the azimuthal asymmetry is more pronounced at X than L band, potentially indicating that the directional asymmetry of the NRCS is gradually diminished as the frequency decreases.
Abstract: This paper reports the first results inferred from the investigation of sea clutter azimuthal variations and their dependence on the radar electromagnetic frequency. We summarize the results derived from the study of SAR data acquired simultaneously at X- and L-band by ONERA (The French aerospace laboratory) and compare them to results stemming from other experiments in the literature. The conclusions drawn suggest that the azimuthal asymmetry is more pronounced at X than L band, potentially indicating that the directional asymmetry of the NRCS is gradually diminished as the frequency decreases. This seems to entail that the asymmetry is likely associated to the small scales of roughness whose electromagnetic returns are measured at X band and not at L band.
01 Aug 2017
TL;DR: In this paper, a L-band multiple-beam phased array antenna with integrated structural design for satellite usage is described by using the integrated design, the height of the filters and the LNA modules are reduced, and all the radiating elements and modules are assembled on one integral panel.
Abstract: A L-band multiple-beam phased array antenna with integrated structural design for satellite usage is described in this paper By using the integrated design, the height of the filters and the LNA modules are reduced, and all the radiating elements and modules are assembled on one integral panel Meanwhile, a solder-less junction structure is developed between the radiating elements and the filters In this way, it is possible to realize the miniaturization and lightweight of the antenna