scholarly journals Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

2004 ◽  
Vol 4 (3) ◽  
pp. 621-626 ◽  
Author(s):  
D. Janches ◽  
M. C. Nolan ◽  
M. Sulzer
Keyword(s):  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Side Lobe ◽  
Beam Axis ◽  
Main Beam ◽  
High Signal ◽  
Precise Knowledge ◽  
Dual Beam ◽  
Arecibo Observatory ◽  
Meteoric Material

Abstract. Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metalic layers observed by radars and lidars respectively.

scholarly journals Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz dual-beam radar

2004 ◽  
Vol 4 (1) ◽  
pp. 207-225
Author(s):  
D. Janches ◽  
M. C. Nolan ◽  
M. Sulzer
Keyword(s):  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Side Lobe ◽  
Beam Axis ◽  
Main Beam ◽  
High Signal ◽  
Precise Knowledge ◽  
Dual Beam ◽  
Arecibo Observatory ◽  
Meteoric Material

Abstract. Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and radar observations. They also may be the source of the observed high altitude ions and metallic layers observed by radars and lidars respectively.

scholarly journals Fourier Rotman Lens Enabled Directional Modulation Transmitter

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yuan Ding ◽  
Yunhua Zhang ◽  
Vincent Fusco
Keyword(s):  
Bit Error Rate ◽  
Data Streams ◽  
Data Transmission ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Independent Data ◽  
Time Data ◽  
Dual Beam ◽  
Directional Modulation ◽  
Ber Performance

A 10 GHz Fourier Rotman lens enabled dynamic directional modulation (DM) transmitter is experimentally evaluated. Bit error rate (BER) performance is obtained via real-time data transmission. It is shown that Fourier Rotman DM functionality enhances system security performance in terms of narrower decodable low BER region and higher BER values associated with BER sidelobes especially under high signal to noise ratio (SNR) scenarios. This enhancement is achieved by controlled corruption of constellation diagrams in IQ space by orthogonal injection of interference. Furthermore, the paper gives the first report of a functional dual-beam DM transmitter, which has the capability of simultaneously projecting two independent data streams into two different spatial directions while simultaneously scrambling the information signals along all other directions.

scholarly journals Tips and tricks in linear imaging polarimetry of extended sources with FORS2 at the VLT

2020 ◽  
Vol 634 ◽  
pp. A70
Author(s):  
S. González-Gaitán ◽  
A. M. Mourão ◽  
F. Patat ◽  
J. P. Anderson ◽  
A. Cikota ◽  
...  
Keyword(s):  
Optical System ◽  
Signal To Noise Ratio ◽  
Broad Band ◽  
Good Control ◽  
High Signal ◽  
Tips And Tricks ◽  
Dual Beam ◽  
Instrumental Polarization ◽  
Imaging Polarimetry ◽  
Extended Sources

Context. Polarimetry is a very powerful tool for uncovering various properties of astronomical objects that otherwise remain hidden in standard imaging or spectroscopic observations. While common observations only measure the intensity of light, polarimetric measurements allow us to distinguish and measure the two perpendicular components of the electric field associated with the incoming light. By using polarimetry it is possible to unveil asymmetries in supernova explosions, properties of intervening dust, characteristics of atmosphere of planets, among others. However, the reliable measurement of the low polarization signal from astronomical sources requires a good control of spurious instrumental polarization induced by the various components of the optical system and the detector. Aims. We perform a detailed multi-wavelength calibration study of the FORS2 instrument at the VLT operating in imaging polarimetric mode to characterize the spatial instrumental polarization that may affect the study of extended sources. Methods. We used imaging polarimetry of high signal-to-noise ratio blank field BVRI observations during the full moon, when the polarization is expected to be constant across the field of view and deviations originate from the instrument, and a crowded star cluster in broad-band RI and narrow-band Hα filters, where the individual polarization values of each star across the field can be measured. Results. We find an instrumental polarization pattern that increases radially outwards from the optical axis of the instrument reaching up to 1.4% at the edges, depending on the filter. Our results are closely approximated by an elliptical paraboloid down to less than ∼0.05% accuracy, and ∼0.02% when using non-analytic fits. We present 2D maps to correct for this spurious instrumental polarization. We also give several tips and tricks for analyzing polarimetric measurements of extended sources. Conclusions. FORS2 is a powerful instrument that allows the linear polarimetry of extended sources to be mapped. We present and discuss a methodology that can be used to measure the polarization of such sources, and to correct for the spatial polarization induced in the optical system. This methodology could be applied to polarimetric measurements using other dual-beam polarimeters.

Absorption Spectroscopy Measurements in Optically Dense Explosive Fireballs Using a Modeless Broadband Dye Laser

2009 ◽  
Vol 63 (9) ◽  
pp. 1075-1080 ◽  
Author(s):  
Nick Glumac
Keyword(s):  
Absorption Spectroscopy ◽  
Scaling Laws ◽  
Signal To Noise Ratio ◽  
Dye Laser ◽  
Good Time ◽  
Main Beam ◽  
High Signal ◽  
Single Shot ◽  
High Explosives ◽  
Good Time Resolution

A modeless broadband dye laser is applied to probe inside optically dense fireballs generated by high explosives using single-shot, high resolution absorption spectroscopy. Despite attenuation of the main beam by 98%, high signal-to-noise ratio absorption spectra of Al, Ti, and AlO are readily obtained at resolutions of 0.007 nm, and luminosity from the fireball is strongly rejected. Detection limits for atomic species are less than 200 ppb. The method offers good time resolution of chemistry within the fireball, and scaling laws suggest that this technique should be valid in explosives tests at least up to the gram scale.

scholarly journals On the Subpulse Drift in PSR 2303+30

1992 ◽  
Vol 128 ◽  
pp. 278-279 ◽  
Author(s):  
J. A. Gil ◽  
T. H. Hankins ◽  
L. Nowakowski
Keyword(s):  
Magnetic Field ◽  
Signal To Noise Ratio ◽  
Pulse Sequences ◽  
Rotation Period ◽  
Single Pulse ◽  
Quantitative Prediction ◽  
High Signal ◽  
Magnetic Pole ◽  
Signal To Noise ◽  
Arecibo Observatory

AbstractWe present an analysis of high signal-to-noise ratio, 430-MHz total intensity single pulse observations from PSR 2303+30 recorded at the Arecibo Observatory in August 1986. We believe that the regular subpulse modulation observed in this pulsar can be explained only in terras of subpulse-associated emission beams rotating around the axis of the pulsar beam. This idea was first introduced by Ruderman and Sutherland (1975) in their spark model. We use the quantitative prediction of this model to calculate the pulsar magnetic field. For this reason we need to estimate the rotation period of a spark around the magnetic pole. We estimate this period by reproducing the observed pulse sequences within an angular beaming model of subpulse emission and fitting this model to the data.

Tunable Diode Laser Quantification of Isomeric Partially Deuterated Cyclobutanes and Ethenes

1989 ◽  
Vol 43 (2) ◽  
pp. 283-288 ◽  
Author(s):  
David A. Glenar ◽  
David K. Lewis
Keyword(s):  
Shock Tube ◽  
Diode Laser ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Single Pulse ◽  
Tunable Diode Laser ◽  
Frequency Resolution ◽  
High Signal ◽  
Dual Beam ◽  
Cis And Trans Isomers

A specially designed tunable diode laser (TDL) absorption spectrometer which operates near 900 and 1300 cm−1 has been constructed in order to identify and measure very low concentrations of product gases extracted from a single-pulse shock-tube experiment. The ultra-high-frequency resolution of the TDL spectrometer (5 to 10 MHz) shows the rotational fine structure in an absorption spectrum, clearly distinguishing between isomers of the same compound. The spectrometer features dual-beam detection in order to simultaneously acquire source and reference gas spectra for unambiguous labeling of the product gases, and rapid sweep averaging, which minimizes the effects of low-frequency mechanical vibrations and achieves very high signal-to-noise ratio. Cis and trans isomers of 1,2-d2-cyclobutane were detected and measured in quantities of shock-tube products as small as 75 cm3-Torr. Several conformations of deuterated ethenes were also detected in samples smaller than 1 cm3-Torr.

A compact guided-wave EMAT with pulsed electromagnet for ferromagnetic tube inspection

2020 ◽  
Vol 64 (1-4) ◽  
pp. 951-958
Author(s):  
Tianhao Liu ◽  
Yu Jin ◽  
Cuixiang Pei ◽  
Jie Han ◽  
Zhenmao Chen
Keyword(s):  
Power Plants ◽  
Signal To Noise Ratio ◽  
Small Diameter ◽  
Performance Testing ◽  
Guided Wave ◽  
High Signal ◽  
Receiver Coil ◽  
Signal To Noise ◽  
Corrosion Defects

Small-diameter tubes that are widely used in petroleum industries and power plants experience corrosion during long-term services. In this paper, a compact inserted guided-wave EMAT with a pulsed electromagnet is proposed for small-diameter tube inspection. The proposed transducer is noncontact, compact with high signal-to-noise ratio and unattractive to ferromagnetic tubes. The proposed EMAT is designed with coils-only configuration, which consists of a pulsed electromagnet and a meander pulser/receiver coil. Both the numerical simulation and experimental results validate its feasibility on generating and receiving L(0,2) mode guided wave. The parameters for driving the proposed EMAT are optimized by performance testing. Finally, feasibility on quantification evaluation for corrosion defects was verified by experiments.

Structured methods for improving flow measurement accuracy in pipelines

2020 ◽  
pp. 30-35
Author(s):  
Gurami N. Akhobadze
Keyword(s):  
Flow Measurement ◽  
Measurement Accuracy ◽  
Directional Coupler ◽  
Signal To Noise Ratio ◽  
Scattered Wave ◽  
Orthogonal Polarization ◽  
Flow Sensors ◽  
Information Signal ◽  
Mass Flows ◽  
Processing Device

In the age of digital transformation of production processes in industry and science the development and design of intelligent flow sensors for granular and liquid substances transferring through pipelines becomes more important. With this in view new approaches for improving the accuracy of microwave flowmeters are proposed. Taking into account the characteristics ofelectromagnetic waves propagating through a pipeline, a wave scattered by inhomogeneities of the controlled medium is analyzed. Features of the transformation of the polarized scattered wave limiting the geometric dimensions of the pipeline and optimizing the values of the useful scattered signal are revealed. Expediency of collection of the information signal with orthogonal polarization of the scattered wave and through a directional coupler is substantiated. The method of estimating the measurement accuracy with reference to the signal-to-noise ratio at the input of the processing device is given. The research results can be used in cryogenic machine engineering to measure volume and mass flows of liquid cryogenic products.

Application of Novel Low Current OBIRCH Amplifier and Nanoprobing to Identify Subtle Leakages in Advanced Node Technologies

2018 ◽  
Author(s):  
Satish Kodali ◽  
Liangshan Chen ◽  
Yuting Wei ◽  
Tanya Schaeffer ◽  
Chong Khiam Oh
Keyword(s):  
Signal To Noise Ratio ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Ring Oscillator ◽  
High Signal ◽  
The Novel ◽  
Resistance Change ◽  
Three Samples ◽  
Relative Threshold ◽  
First Time

Abstract Optical beam induced resistance change (OBIRCH) is a very well-adapted technique for static fault isolation in the semiconductor industry. Novel low current OBIRCH amplifier is used to facilitate safe test condition requirements for advanced nodes. This paper shows the differences between the earlier and novel generation OBIRCH amplifiers. Ring oscillator high standby leakage samples are analyzed using the novel generation amplifier. High signal to noise ratio at applied low bias and current levels on device under test are shown on various samples. Further, a metric to demonstrate the SNR to device performance is also discussed. OBIRCH analysis is performed on all the three samples for nanoprobing of, and physical characterization on, the leakage. The resulting spots were calibrated and classified. It is noted that the calibration metric can be successfully used for the first time to estimate the relative threshold voltage of individual transistors in advanced process nodes.

scholarly journals VS2 as saturable absorber for Q-switched pulse generation

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2569-2576 ◽  
Author(s):  
Lu Li ◽  
Lihui Pang ◽  
Qiyi Zhao ◽  
Yao Wang ◽  
Wenjun Liu
Keyword(s):  
Saturable Absorber ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Signal To Noise Ratio ◽  
Transition Metal Dichalcogenides ◽  
Laser Cavity ◽  
Pulse Generation ◽  
High Signal ◽  
Power Pulse ◽  
Metal Dichalcogenides

AbstractTransition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

Sign in / Sign up

Export Citation Format

Share Document