A digital correlation spectrometer employing multiple-level quantization

1973 ◽  
Vol 61 (9) ◽  
pp. 1339-1343 ◽  
Author(s):  
F.K. Bowers ◽  
D.A. Whyte ◽  
T.L. Landecker ◽  
R.J. Klingler
Keyword(s):  
Multiple Level ◽  
Digital Correlation ◽  
Correlation Spectrometer ◽  
Level Quantization

scholarly journals SARAS CD/EoR Radiometer: Design and Performance of the Digital Correlation Spectrometer

2020 ◽  
Vol 09 (02) ◽  
pp. 2050006
Author(s):  
B. S. Girish ◽  
K. S. Srivani ◽  
Ravi Subrahmanyan ◽  
N. Udaya Shankar ◽  
Saurabh Singh ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Range ◽  
Neutral Hydrogen ◽  
Radio Spectrum ◽  
High Spectral Resolution ◽  
Cosmic Radio ◽  
Antenna Measurement ◽  
Digital Correlation ◽  
Correlation Spectrometer ◽  
Luminous Objects

In the currently accepted model for cosmic baryon evolution, Cosmic Dawn (CD) and the Epoch of Reionization (EoR) are significant times when first light from the first luminous objects emerged, transformed and subsequently ionized the primordial gas. The 21[Formula: see text]cm (1420[Formula: see text]MHz) hyperfine transition of neutral hydrogen, redshifted from these cosmic times to a frequency range of 40[Formula: see text]MHz to 200[Formula: see text]MHz, has been recognized as an important probe of the physics of CD/EoR. The global 21[Formula: see text]cm signal is predicted to be a spectral distortion of a few 10’s to a few 100’s of mK, which is expected to be present in the cosmic radio background as a trace additive component. Shaped Antenna measurement of the background RAdio Spectrum (SARAS) is a spectral radiometer purpose designed to detect the weak 21[Formula: see text]cm signal from CD/EoR. An important subsystem of the radiometer, the digital correlation spectrometer, is developed around a high-speed digital signal processing platform called pSPEC. pSPEC is built around two quad 10-bit analog-to-digital converters (EV10AQ190) and a Virtex 6 (XC6VLX240T) field programmable gate array, with provision for multiple Gigabit Ethernet and 4.5[Formula: see text]Gbps fiber-optic interfaces. Here, we describe the system design of the digital spectrometer, the pSPEC board, and the adaptation of pSPEC to implement a high spectral resolution (61[Formula: see text]kHz), high dynamic range ([Formula: see text]:1) correlation spectrometer covering the entire CD/EoR band. As the SARAS radiometer is required to be deployed in remote locations where terrestrial radio frequency interference (RFI) is a minimum, the spectrometer is designed to be compact, portable and operating off internal batteries. The paper includes an evaluation of the spectrometer’s susceptibility to RFI and capability to detect signals from CD/EoR.

Design and calibration of an IVEM for general 3-dimensional imaging of non-diffracting materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1040-1041
Author(s):  
Neil Rowlands ◽  
Jeff Price ◽  
Michael Kersker ◽  
Seichi Suzuki ◽  
Steve Young ◽  
...  
Keyword(s):  
3D Imaging ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3 Dimensional ◽  
3D Microstructure ◽  
Image Translation ◽  
Digital Correlation ◽  
On Line ◽  
Mechanical Stage ◽  
Projection Angle

Three-dimensional (3D) microstructure visualization on the electron microscope requires that the sample be tilted to different positions to collect a series of projections. This tilting should be performed rapidly for on-line stereo viewing and precisely for off-line tomographic reconstruction. Usually a projection series is collected using mechanical stage tilt alone. The stereo pairs must be viewed off-line and the 60 to 120 tomographic projections must be aligned with fiduciary markers or digital correlation methods. The delay in viewing stereo pairs and the alignment problems in tomographic reconstruction could be eliminated or improved by tilting the beam if such tilt could be accomplished without image translation.A microscope capable of beam tilt with simultaneous image shift to eliminate tilt-induced translation has been investigated for 3D imaging of thick (1 μm) biologic specimens. By tilting the beam above and through the specimen and bringing it back below the specimen, a brightfield image with a projection angle corresponding to the beam tilt angle can be recorded (Fig. 1a).

Reconstruction of Chitin-Protein Complexes Using Correlation Averaging Methods: Ovipositor of the Ichneumon Fly Megarhyssa

1980 ◽  
Vol 38 ◽  
pp. 38-39
Author(s):  
L. T. Germinario ◽  
J. Blackwell ◽  
J. Frank
Keyword(s):  
Protein Complexes ◽  
Hexagonal Lattice ◽  
Uranyl Acetate ◽  
Optical Diffraction ◽  
Insect Cuticle ◽  
High Dose ◽  
Wide Angle ◽  
X Ray ◽  
Averaging Methods ◽  
Digital Correlation

This report describes the use of digital correlation and averaging methods 1,2 for the reconstruction of high dose electron micrographs of the chitin-protein complex from Megarhyssa ovipositor. Electron microscopy of uranyl acetate stained insect cuticle has demonstrated a hexagonal array of unstained chitin monofibrils, 2.4−3.0 nm in diameter, in a stained protein matrix3,4. Optical diffraction Indicated a hexagonal lattice with a = 5.1-8.3 nm3 A particularly well ordered complex is found in the ovipositor of the ichneumon fly Megarhyssa: the small angle x-ray data gives a = 7.25 nm, and the wide angle pattern shows that the protein consists of subunits arranged in a 61 helix, with an axial repeat of 3.06 nm5.

A Digital Correlation System for Preliminary Signal Processing in Multiplexed Frequency Bands

1997 ◽  
Vol 51 (6-7) ◽  
pp. 25-27
Author(s):  
V. N. Frankov ◽  
G. Y. Osokin ◽  
O. V. Gavrentiuk ◽  
A. I. Samokhvalov
Keyword(s):  
Signal Processing ◽  
Frequency Bands ◽  
Digital Correlation ◽  
Correlation System
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