scholarly journals The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

2013 ◽  
Vol 30 ◽  
Author(s):  
S. J. Tingay ◽  
R. Goeke ◽  
J. D. Bowman ◽  
D. Emrich ◽  
S. M. Ord ◽  
...  
Keyword(s):  
Signal Processing ◽  
System Level ◽  
Radio Frequency Interference ◽  
Astronomy Observatory ◽  
Square Kilometre Array ◽  
Expected Performance ◽  
Low Levels ◽  
Radio Frequencies ◽  
Murchison Widefield Array ◽  
Aperture Arrays

AbstractThe Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.

scholarly journals Square Kilometre Array Station Configuration Using Two-Stage Beamforming

2013 ◽  
Vol 30 ◽  
Author(s):  
Aziz Jiwani ◽  
Tim Colegate ◽  
Nima Razavi-Ghods ◽  
Peter J. Hall ◽  
Shantanu Padhi ◽  
...  
Keyword(s):  
Signal Processing ◽  
Radio Astronomy ◽  
Effective Area ◽  
The Other ◽  
Processing Load ◽  
Two Stage ◽  
Square Kilometre Array ◽  
Cost Benefits ◽  
Sparse Aperture ◽  
Aperture Arrays

AbstractThe lowest frequency band (70–450 MHz) of the Square Kilometre Array (SKA) will consist of sparse aperture arrays grouped into geographically localised patches or stations. Signals from thousands of antennas in each station will be beamformed to produce station beams which form the inputs for the central correlator. Two-stage beamforming within stations can reduce SKA-low signal processing load and costs, but has not been previously explored for the irregular station layouts now favoured in radio astronomy arrays. This paper illustrates the effects of two-stage beamforming on sidelobes and effective area, for two representative station layouts (regular and irregular gridded tiles on an irregular station). The performance is compared with a single-stage, irregular station. The inner sidelobe levels do not change significantly between layouts, but the more distant sidelobes are affected by the tile layouts; regular tile creates diffuse, but regular, grating lobes. With very sparse arrays, the station effective area is similar between layouts. At lower frequencies, the regular tile significantly reduces effective area, hence sensitivity. The effective area is highest for a two-stage irregular station, but it requires a larger station extent than the other two layouts. Although there are cost benefits for stations with two-stage beamforming, we conclude that more accurate station modelling and SKA-low configuration specifications are required before design finalisation.

scholarly journals The Low-Frequency Environment of the Murchison Widefield Array: Radio-Frequency Interference Analysis and Mitigation

2015 ◽  
Vol 32 ◽  
Author(s):  
A. R. Offringa ◽  
R. B. Wayth ◽  
N. Hurley-Walker ◽  
D. L. Kaplan ◽  
N. Barry ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Low Frequency ◽  
Digital Tv ◽  
Frequency Resolution ◽  
Interference Detection ◽  
Radio Frequency Interference ◽  
Receiver Design ◽  
Square Kilometre Array ◽  
Atmospheric Propagation ◽  
Murchison Widefield Array

AbstractThe Murchison Widefield Array is a new low-frequency interferometric radio telescope built in Western Australia at one of the locations of the future Square Kilometre Array. We describe the automated radio-frequency interference detection strategy implemented for the Murchison Widefield Array, which is based on the aoflagger platform, and present 72–231 MHz radio-frequency interference statistics from 10 observing nights. Radio-frequency interference detection removes 1.1% of the data. Radio-frequency interference from digital TV is observed 3% of the time due to occasional ionospheric or atmospheric propagation. After radio-frequency interference detection and excision, almost all data can be calibrated and imaged without further radio-frequency interference mitigation efforts, including observations within the FM and digital TV bands. The results are compared to a previously published Low-Frequency Array radio-frequency interference survey. The remote location of the Murchison Widefield Array results in a substantially cleaner radio-frequency interference environment compared to Low-Frequency Array’s radio environment, but adequate detection of radio-frequency interference is still required before data can be analysed. We include specific recommendations designed to make the Square Kilometre Array more robust to radio-frequency interference, including: the availability of sufficient computing power for radio-frequency interference detection; accounting for radio-frequency interference in the receiver design; a smooth band-pass response; and the capability of radio-frequency interference detection at high time and frequency resolution (second and kHz-scale respectively).

PSK Transciever designing using SystemVue

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Deepali Chaurasia
Keyword(s):  
Signal Processing ◽  
System Integration ◽  
Communication Systems ◽  
Energy Savings ◽  
Electronic Devices ◽  
Physical Space ◽  
Electronic System ◽  
System Level ◽  
Complex Nature ◽  
Wide Range

Since, the industrial electronics is trending towards more compact components and system integration, innovative products offering greater flexibility, quality, safety, reliability, energy savings, wide range of connectivity with long operating lifetime. Now, Electronics is widely used in information processing, telecommunication and signal processing. Due to the complex nature of electronics theory, laboratory experimentation is an important part of development of electronic devices. These experiments are used to test or verify the proposed design and detect errors. Historically, electronics labs have consisted of electronic devices and equipment located in the physical space. Although in more recent years, the trend has been towards electronics lab simulation softwares and SystemVue is also one of them. SystemVue is a focussed electronic design automation (EDA) environment for electronic system-level (ESL) design. It enables system architects and algorithm developers to innovate the physical layer (PHY) of wireless and aerospace/defence communication systems and provide unique value to RF, DSP and FPGA/ASIC implementers. As a dedicated platform for ESL design and signal processing realization, SystemVue replaces general-purpose digital, analog and math environments. SystemVue “speaks RF”, cuts PHY development and verification time in half and connects to your mainstream EDA flow.

The square kilometre array and the transient universe

2013 ◽  
Vol 371 (1992) ◽  
pp. 20120284 ◽  
Author(s):  
B. W. Stappers
Keyword(s):  
Radio Emission ◽  
Large Range ◽  
Great Sensitivity ◽  
Wide Field ◽  
Power Mean ◽  
Computing Power ◽  
Square Kilometre Array ◽  
Wide Field Of View ◽  
Two Phases ◽  
Aperture Arrays

The square kilometre array (SKA) is a next generation radio telescope that will be built in southern Africa and Australasia. It will be built in two phases and will use a range of detectors, from aperture arrays to dishes, to span the frequency range from a few tens of megahertz to a few gigahertz. The combination of great sensitivity, wide field of view and unprecedented computing power mean that the SKA will be an excellent instrument for studying the transient radio universe. Transient radio emission is generated in extremes of: gravitational and magnetic fields, velocity, temperature, pressure and density. While we know about plenty of source classes for this type of short duration radio emission, there is still a large range of transient parameter space that has not yet been sampled owing to the limitations of current generation radio telescopes.

scholarly journals Source counts and confusion at 72–231 MHz in the MWA GLEAM survey

2019 ◽  
Vol 36 ◽  
Author(s):  
T. M. O. Franzen ◽  
T. Vernstrom ◽  
C. A. Jackson ◽  
N. Hurley-Walker ◽  
R. D. Ekers ◽  
...  
Keyword(s):  
Thermal Noise ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Area ◽  
Design Study ◽  
Array Design ◽  
Square Kilometre Array ◽  
Noise Limit ◽  
Murchison Widefield Array ◽  
Extended Emission

Abstract The GaLactic and Extragalactic All-sky Murchison Widefield Array survey is a radio continuum survey at 72–231 MHz of the whole sky south of declination +30º, carried out with the Murchison Widefield Array. In this paper, we derive source counts from the GaLactic and Extragalactic All-sky Murchison data at 200, 154, 118, and 88 MHz, to a flux density limit of 50, 80, 120, and 290 mJy respectively, correcting for ionospheric smearing, incompleteness and source blending. These counts are more accurate than other counts in the literature at similar frequencies as a result of the large area of sky covered and this survey’s sensitivity to extended emission missed by other surveys. At S154 MHz > 0.5 Jy, there is no evidence of flattening in the average spectral index (α ≈ −0.8 where S ∝ vα) towards the lower frequencies. We demonstrate that the Square Kilometre Array Design Study model by Wilman et al. significantly underpredicts the observed 154-MHz GaLactic and Extragalactic All-sky Murchison counts, particularly at the bright end. Using deeper Low-Frequency Array counts and the Square Kilometre Array Design Study model, we find that sidelobe confusion dominates the thermal noise and classical confusion at v ≳ 100 MHz due to both the limited CLEANing depth and the undeconvolved sources outside the field-of-view. We show that we can approach the theoretical noise limit using a more efficient and automated CLEAN algorithm.

scholarly journals PV System Predictive Maintenance: Challenges, Current Approaches, and Opportunities

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1398 ◽  
Author(s):  
Lisa B. Bosman ◽  
Walter D. Leon-Salas ◽  
William Hutzel ◽  
Esteban A. Soto
Keyword(s):  
Solar Energy ◽  
The United States ◽  
Predictive Maintenance ◽  
Third Party ◽  
System Level ◽  
Pv System ◽  
Actual Performance ◽  
Call To Action ◽  
Expected Performance ◽  
Solar Energy Industry

Within the United States solar energy industry, there is a general motto of “set it and forget it” with solar energy. This notion is derived from much of the research and reliability studies around the photovoltaic (PV) panels themselves, not necessarily the PV system as a whole (including the inverter and other components). This implies that maintenance and regular monitoring is not needed. Yet many things can go wrong to cause the actual performance to deviate from the expected performance. If failures and/or unanticipated degradation issues go undetected, they will lead to reduced energy generation (and associated electricity credits) and/or potential loss of component warranty because of manufacturer turnover. Given the size of the problem and gaps with current solutions, the authors propose that PV system owners need an unbiased third-party off-the-shelf system-level predictive maintenance tool to optimize return-on-investment and minimize time to warranty claim in PV installations. This paper reviews the literature highlighting challenges, current approaches, and opportunities for PV predictive maintenance. The paper concludes with a call to action for establishing a collaborative agenda toward prioritizing PV predictive maintenance.

scholarly journals Science with the Murchison Widefield Array

2013 ◽  
Vol 30 ◽  
Author(s):  
Judd D. Bowman ◽  
Iver Cairns ◽  
David L. Kaplan ◽  
Tara Murphy ◽  
Divya Oberoi ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Early Universe ◽  
Western Australia ◽  
Space Weather ◽  
Time Domain ◽  
Angular Resolution ◽  
Low Frequency ◽  
Performance Properties ◽  
Square Kilometre Array ◽  
Murchison Widefield Array

AbstractSignificant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.

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