scholarly journals A High Performance Terahertz Photoconductive Antenna Array Detector With High Synthesis Efficiency

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei Shi ◽  
Zhiquan Wang ◽  
Lei Hou ◽  
Haiqing Wang ◽  
Meilin Wu ◽  
...  
Keyword(s):  
Antenna Array ◽  
High Performance ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Substrate Material ◽  
Array Detector ◽  
Photoconductive Antenna ◽  
Current Signal ◽  
Signal To Noise ◽  
Signal Output

A 2 × 2 terahertz photoconductive antenna (PCA) array detector with high efficiency synthesis characteristic that improves the signal-to-noise ratio (SNR) of the detected signals has been reported in this paper. By processing the substrate material through a special micromachining process, the current signal generated by the adjacent antenna elements as opposed to that generated by the antenna gap is eliminated. Experiments show that the amplitude of the current signal output by the PCA array detector is consistent with the amplitude of the synchronous superposition of the current signals output by antenna elements, and the synthesis efficiency of the device achieves 93.7%. At the same time, the antenna array detector has low current noise, and its highest SNR is 62 dB under the excitation of different light energy, which is related to the number of antenna array elements.

Rocket Experiment by Electronic Camera for Studying the Metallic Discontinuities in the Ultraviolet Spectrum of ‘A’ Stars

1971 ◽  
Vol 41 ◽  
pp. 361-362
Author(s):  
M. Combes
Keyword(s):  
Spectral Resolution ◽  
High Efficiency ◽  
Signal To Noise Ratio ◽  
Absolute Calibration ◽  
List Type ◽  
Signal To Noise ◽  
Concave Mirror ◽  
Rocket Experiment ◽  
Solar Blind ◽  
Noise Ratio

1.Ultraviolet spectra (1400–1800 Å) of Ap, Am and normal A stars are needed by F. Praderie, R. Bonnet and R. Cayrel.The spectral resolution has to be nearly 1 Å. Accurate relative photometry (5%) and absolute calibration (30–50%) are required.A rocket experiment, proposed to ESRO by M. Combes and P. Felenbok is planned for launch in 1972.2.As neutral silicon and magnesium are very efficient ultra-violet absorbents, A stars ultraviolet fluxes are very faint (Praderie, 1968).Then a very luminous optical set-up and a high efficiency receiver have to be used. A 30 cm in diameter concave objective grating is associated with a Lallemand electronic camera. The grating (2000 //mm; //l) is holographically made (Labeyrie, 1969). The electronic camera is electrostatically focussed. A semi-transparent solar-blind CsL photocathode is used (Carruthers, 1966).3.A little mirror, placed against the grating and forming a direct view of the sky, permits to establish an absolute wavelength scale.During the fly, before and after stellar observations, a little concave mirror mounted into the opening side-door is used to form on the photocathode a spectrum of a Deuterium calibrated lamp. Two photomultipliers, one on each side of the electronic camera, control the lamp stability.The complete mounting is calibrated in the laboratory using a thermopile as reference, before the launch and after the recovery of the waterproof payload.4.The chosen stars are the brightest Ap and Am stars: α Dra (Ap; mv = 3.64; equivalent type A 0) and α2 Lib (Am; mv = 2.75; equivalent type A3-A7).It seems to be possible to obtain spectra (1400-1800 Å) of the Ap star with a spectral resolution of 1 Å and a signal to noise ratio better than 40. But at a pinch one may accept a resolution of 2 Å and a signal to noise ratio of 15 for the shortest range of the Ap star spectrum.

Catecholamine sulfates as internal standards in HPLC determinations of sulfoconjugated catecholamines in plasma and urine

1991 ◽  
Vol 37 (2) ◽  
pp. 196-199 ◽  
Author(s):  
Gɒnther Strobel ◽  
HelmuT Weicker
Keyword(s):  
High Performance Liquid Chromatography ◽  
Human Plasma ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Reversed Phase ◽  
Signal To Noise ◽  
Internal Standards ◽  
Human Plasma And Urine ◽  
Plasma And Urine Samples ◽  
Respective Concentration

Abstract A method is described to measure catecholamine sulfates from human plasma and urine by isocratic reversed-phase high-performance liquid chromatography with electrochemical detection. For this measurement we use catecholamine 3-sulfate isomers as internal standards and determine the sulfoconjugates only after eliminating the catecholamines. Catecholamines that have previously been used as internal standards are shown to cause a significant overestimation (P less than 0.05) of the catecholamine sulfates--by 10% to 25% and 20% to 42% in human plasma and urine, respectively. The detection limits (signal-to-noise ratio greater than 3) in plasma and urine samples were about 80 pmol/L for each analyte. The intra-assay and interassay CVs were less than 4.0% and 10.6% in human plasma and less than 6.6% and 12.8% in human urine, respectively. The calibration curves for all catecholamine sulfates in human plasma and urine were linear (r greater than 0.96; P less than 0.001) over the respective concentration ranges of 0.1-100 nmol/L and 5-1000 nmol/L.

Occurrence of Naphthalene in Honey Consumed in Turkey as Determined by High-Pressure Liquid Chromatography

2007 ◽  
Vol 70 (7) ◽  
pp. 1735-1738 ◽  
Author(s):  
DİREN BEYOĞLU ◽  
GÜLDEN Z. OMURTAG
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
High Performance ◽  
Limit Of Detection ◽  
Array Detector ◽  
Diode Array ◽  
Diode Array Detector ◽  
Signal To Noise ◽  
Limit Of Quantification ◽  
Naphthalene Concentration

This study is the first report on an investigation of the naphthalene concentration in samples of contaminated honey consumed in Turkey. Naphthalene was detected using high-performance liquid chromatography with a diode array detector at 220 nm. In one suspected contaminated specimen, the presence of naphthalene was confirmed by gas chromatography with mass spectrometry (GC-MS) at a concentration of 1.13 μg/kg. The limit of detection was 0.023 μg/g and the limit of quantification was 0.078 μg/g with signal-to-noise ratios of 3 and 10, respectively. A total of 100 samples of commercially available honey obtained from markets (53 samples) and street bazaars (47 samples) were analyzed. Mean naphthalene recovery from honey known to be contaminated with 1 μg/g was 80.4% (SD = 4.84%, n = 7).

Homogeneity of the 18 QuickSIN™ Lists

2006 ◽  
Vol 17 (03) ◽  
pp. 157-167 ◽  
Author(s):  
Rachel A. McArdle ◽  
Richard H. Wilson
Keyword(s):  
Hearing Loss ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Normal Hearing ◽  
Signal To Noise ◽  
Speech In Noise ◽  
Performance Variability ◽  
Noise Test ◽  
Noise Ratio ◽  
Db Difference

The purpose of this study was to determine the list equivalency of the 18 QuickSIN™ (Quick Speech in Noise test) lists. Individuals with normal hearing (n = 24) and with sensorineural hearing loss (n = 72) were studied. Mean recognition performances on the 18 lists by the listeners with normal hearing were 2.8 to 4.3 dB SNR (signal-to-noise ratio), whereas the range was 10.0 to 14.3 dB SNR for the listeners with hearing loss. The psychometric functions for each list showed high performance variability across lists for listeners with hearing loss but not for listeners with normal hearing. For listeners with hearing loss, Lists 4, 5, 13, and 16 fell outside of the critical difference. The data from this study suggest nine lists that provide homogenous results for listeners with and without hearing loss. Finally, there was an 8.7 dB difference in performances between the two groups indicating a more favorable signal-to-noise ratio required by the listeners with hearing loss to obtain equal performance.

A methodology for increasing the signal to noise ratio for the misfire detection at high speed in a high performance engine

2006 ◽  
Vol 14 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Nicolò Cavina ◽  
Giovanni Cipolla ◽  
Francesco Marcigliano ◽  
Davide Moro ◽  
Luca Poggio
Keyword(s):  
High Speed ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Misfire Detection

scholarly journals Calibration of Siberian Radioheliograph antenna gains using redundancy

2021 ◽  
Vol 7 (4) ◽  
pp. 104-110
Author(s):  
Mariia Globa ◽  
Sergey Lesovoi
Keyword(s):  
Antenna Array ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
High Dynamic Range ◽  
Special Care ◽  
System Of Equations ◽  
Signal To Noise ◽  
Double Step ◽  
Phase Calibration ◽  
High Dynamic

The paper describes application of standard gain calibration using redundancy for a 48-antenna prototype of Siberian Radioheliograph. Traditionally, for calibration, the visibilities were measured only between adjacent antennas since they have the highest signal-to-noise ratio and are sufficient for phase calibration. We have shown that this limited set of visibilities did not allow using the antenna array redundancy potential and obtaining images with a high dynamic range on a permanent basis. Images without amplitude calibration contain many artifacts and require special care when analyzed. The inclusion of visibility measurement between antennas with a double step made it possible to significantly increase the accuracy of solving the system of equations for amplitudes. Images constructed using both phase and amplitude calibrations do not have visible artifacts and are more reliable.

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