scholarly journals Electronic Optical Sky Surveys

1998 ◽  
Vol 179 ◽  
pp. 49-55
Author(s):  
T.A. McKay
Keyword(s):  
Dynamic Range ◽  
Large Fraction ◽  
High Sensitivity ◽  
High Dynamic Range ◽  
Low Noise ◽  
Computer Hardware ◽  
Optical Detectors ◽  
Small Fields ◽  
Technical Advances ◽  
High Dynamic

The introduction of of Charge Coupled Devices (CCDs) in the middle 1970s provided astronomy with nearly perfect (linear, high-sensitivity, low-noise, high dynamic-range, digital) optical detectors. Unfortunately, restrictions imposed by CCD production and cost has typically limited their use to observations of relatively small fields. Recently a combination of technical advances have made practical the application of CCDs to survey science. CCD mosaic cameras, which help overcome the size restrictions imposed by CCD manufacture, allow electronic access to a larger fraction of the available focal plane. Multi-fiber spectrographs, which couple the low-noise, high QE performance of CCDs with the ability to observe spectra for many objects at once, have improved the spectroscopic efficiency of telescopes by factors approaching half a million. An improved understanding of image distortion gives us telescopes on which we expect sub-arcsecond images a large fraction of the time. Finally, and perhaps most important, the performance of computer hardware continues to advance, to the point where analysis of multi-terabyte datasets, while still daunting, is at least conceivable.

High-dynamic-range low-noise microwave amplifier

1970 ◽  
Vol 6 (7) ◽  
pp. 202
Author(s):  
J.R. Collard ◽  
A.R. Gobat
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Low Noise ◽  
Microwave Amplifier ◽  
High Dynamic

scholarly journals The technology behind the exceptional visual experience via high dynamic range

2018 ◽  
Vol 7 ◽  
Author(s):  
Neeraj J. Gadgil ◽  
Qing Song ◽  
Guan-Ming Su ◽  
Samir N. Hulyalkar
Keyword(s):  
Dynamic Range ◽  
Transfer Functions ◽  
High Dynamic Range ◽  
Exciting Field ◽  
Optical Signals ◽  
Industry Applications ◽  
Wide Color Gamut ◽  
Technical Advances ◽  
Display Technology ◽  
High Dynamic

High dynamic range (HDR) technology is rapidly changing today's video landscape by offering spectacular visual experiences. The development in display technology to support higher luminance levels for commercial and consumer electronic devices such as TVs, smartphones, projectors etc., has created an exponential demand for delivering HDR content to viewers. The essential component of the HDR technology is “expanded contrast,” which allows richer black levels and enhanced brightness, providing dramatic contrast that reveals finer details. The use of “wide color gamut” allows wider color spectrum and richer colors providing aesthetically pleasing true-to-life feel. Such visual enhancements clearly establish HDR as one of the most significant upcoming video technologies.In this paper, we review major technical advances in this exciting field of study. Quantization of HDR signals is reviewed in the context of transfer functions that convert optical signals to electrical signals and vice versa. They mainly consist of Perceptual Quantization and Hybrid-Log-Gamma approaches. Compression of HDR content is another broad area of study involving several coding approaches, often categorized in terms of backward-compatibility and single/dual layer methods. Some key industry applications of HDR processing systems are also discussed, followed by some future directions of HDR technology.

Airborne TEM surveying with a SQUID magnetometer sensor

Geophysics ◽  
2002 ◽  
Vol 67 (2) ◽  
pp. 468-477 ◽  
Author(s):  
James B. Lee ◽  
David L. Dart ◽  
Robert J. Turner ◽  
Mark A. Downey ◽  
Arthur Maddever ◽  
...  
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Performance Measure ◽  
Low Noise ◽  
Induction Coil ◽  
Squid Magnetometer ◽  
Superior Performance ◽  
Frequency Noise ◽  
High Dynamic ◽  
Squid System

Traditionally airborne time-domain electromagnetic (AEM) survey systems use induction coils as the sensor (receiver). We have replaced the induction coil in a transient electromagnetic (TEM) system with a liquid-nitrogen cooled superconducting quantum interference device (SQUID) magnetometer sensor. Using this prototype system, we aimed to improve performance in detecting conductive mineralization, particularly where the conductive mineralization of interest is covered by a conductive regolith. We successfully demonstrated one- and three-component SQUID sensors in airborne TEM surveying, and achieved performance comparable to the induction-coil systems. Implementation of the SQUID system required development of devices capable of operating in magnetically unshielded environments with low noise, high slew rate, and wide bandwidth. Operation of the SQUID sensor in the highly dynamic environment of a towed bird was also necessary, and this implies a high dynamic range and high level of noise associated with the motion in Earth's magnetic field. The high dynamic range of the SQUID response was handled by a combination of resetting the SQUID flux locked loop, reducing the bandwidth, and providing high-gain feedback in parallel with the flux locked loop. A digital stacking filter was used to eliminate low-frequency noise associated with sensor motion. Isolation of the sensor from motion at the TEM signal frequencies required development of a sophisticated suspension system. The SQUID systems were tested over two known conductive targets, and their performance compared with the induction-coil TEM system. A comparative performance measure is developed to take the different sensitivities of the SQUID magnetometer and induction-coil receivers into account. This measure indicates that the SQUID system has superior performance for responses over earth structures with decay time constants greater than ∼6 ms when compared with the induction-coil signals. We also estimate the performance in comparison with integrated outputs of the induction-coil system and show that, at the demonstrated levels of SQUID performance, it is expected to have poorer performance by a factor of two or more. This disadvantage will be reduced for lower frequency, wider channel width TEM configurations or by improvements in the SQUID devices.

scholarly journals Missing flux in VLBI observations of SiO maser at 7 mm in IRC+10011

2017 ◽  
Vol 13 (S336) ◽  
pp. 387-388
Author(s):  
J.-F. Desmurs ◽  
J. Alcolea ◽  
V. Bujarrabal ◽  
F. Colomer ◽  
R. Soria-Ruiz
Keyword(s):  
Dynamic Range ◽  
High Sensitivity ◽  
High Dynamic Range ◽  
Total Flux ◽  
Agb Stars ◽  
Maser Emission ◽  
Spectral Channel ◽  
Emission Area ◽  
Vlbi Observations ◽  
High Dynamic

AbstractVLBI observations of SiO masers recover at most 40-50% of the total flux obtained by single dish observations at any spectral channel. Some previous studies seems to indicate that, at least, part of the lost flux is divided up into many weak components rather than in a large resolved emission area. Taking benefit of the high sensitivity and resolution of the HSA, we investigate the problem of the missing flux in VLBI observations of SiO maser emission at 7 mm in the AGB stars and obtain a high dynamic range map of IRC+10011. We conclude that the missing flux is mostly contained in many very weak maser components.

scholarly journals A wideband, low-noise superconducting amplifier with high dynamic range

2012 ◽  
Vol 8 (8) ◽  
pp. 623-627 ◽  
Author(s):  
Byeong Ho Eom ◽  
Peter K. Day ◽  
Henry G. LeDuc ◽  
Jonas Zmuidzinas
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Low Noise ◽  
High Dynamic
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