High-Frequency Spin-Based Devices for Nanoscale Signal Processing

2009 ◽  
Author(s):  
Robert A. Buhrman ◽  
Daniel C. Ralph ◽  
Bill Rippard ◽  
Tom Silva ◽  
Stephen Russek ◽  
...  
Keyword(s):  
Signal Processing ◽  
High Frequency

scholarly journals Location of agate geodes in Permian deposits of Simota gully using the GPR

2021 ◽  
Author(s):  
Michał Mierczak ◽  
Jerzy Karczewski
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Electromagnetic Energy ◽  
Reflection Coefficients ◽  
Electric Permittivity ◽  
Pyroclastic Deposits ◽  
High Attenuation ◽  
Subsurface Geology ◽  
Study Test

AbstractThe article describes the establishment of the location of agate geodes using the GPR method in the area of the Simota gully (Lesser Poland Voivodeship). Agates (a multicolored variety of gemstone of chalcedony group) have multifaceted values that informed their study. Traditional methods of geode location are less reliable, hence the attempt to use the GPR method. Measurements were taken at two study test sites with subsurface geology of weathered melaphyre and pyroclastic deposits using a GPR system (ProEx). A high-frequency antenna (1.6 GHz) was used along with the pre-established profiles of lengths of 6-m and 10-cm intervals. Furthermore, simple soil tests using the soil sampler tool were made prior to the GPR measurement. The GPR results show significant high attenuation of the electromagnetic energy interpreted to be due to clay components of the regolith. Advanced signal processing procedures (such as the attribute of the signal) were used on the data for better enhancement that aided interpretation. Other anomalies depicted on the radargrams were thought to be the presence of roots, pieces of melaphyres-targeted agates. Furtherance to ascertain the reflection coefficients as recorded on the GPR data, in situ samples (root pieces, melaphyres, agates) taken were tested in the laboratory for electric permittivity property. Based on the interpretation results, several agate geodes were dug out from the ground.

A SOLUTION TO STABILIZE THE RECEIVER BEAMWIDTH WHEN CHANGING THE OPERATING FREQUENCY OF HIGH-FREQUENCY SURFACE WAVE RADAR

2021 ◽  
pp. 2614-2624
Author(s):  
H. H. Dung, C. V. Linh
Keyword(s):  
Signal Processing ◽  
Surface Wave ◽  
Frequency Modulation ◽  
High Frequency ◽  
Operating Frequency ◽  
Design Solution ◽  
Processing Quality ◽  
Wave Radar ◽  
Single Station ◽  
Interference Frequency

A single-station High-Frequency Surface Wave Radar (HFSRR) consists of transmitting and receiving antennas in an area with a distance between them approximately ten times their wavelength. At the coast, these antennas are usually deployed at fixed optimal distances for an operating frequency in the HF band (3÷30Mhz). Because the signal used is linear frequency modulation (FMCW), the HFSWS always requires an interference-resistant frequency band. So, it is necessary to change the operating frequency in HFSWR to avoid strong interference, frequency bands. This also results in a change in the received waveform, which affects signal processing quality. In this article, a design solution is proposed to maintain a consistent beamwidth when changing the operating frequency in the HFSWS.

Observations of Meteors using an over-the-horizon Radar

1989 ◽  
Vol 8 (1) ◽  
pp. 88-93 ◽  
Author(s):  
R. M. Thomas ◽  
D. J. Netherway
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Meteor Shower ◽  
Upper Atmosphere ◽  
High Frequency Band ◽  
Meteor Detection ◽  
Signal Environment ◽  
Frequency Management ◽  
Sporadic Meteors ◽  
Selection Of

AbstractWhen metre wavelength radars were first operated in the 1940s, echoes were obtained which could be attributed to backscatter from ionised trains produced by the ablation of meteroids in the upper atmosphere at altitudes near 100 km. Modern over-the-horizon skywave radars operating in the HF (High Frequency) band employ digital techniques for both radar control and signal processing and are aided by frequency management subsystems for the selection of appropriate frequencies for meteor detection based on real-time monitoring of the HF signal environment.This paper describes the results of using such a radar for meteor observations. We report the detection of the Eta Aquarid meteor shower and demonstrate that a large increase in the echo rate due to sporadic meteors is obtained as frequencies are reduced below 15 MHz and the underdense echo ceiling rises in altitude. Finally, we present preliminary observations of highly Doppler shifted echoes which travel at meteoric velocities and which we identify as meteor ‘head echoes’.

scholarly journals Listener Performance with a Novel Hearing Aid Frequency Lowering Technique

2017 ◽  
Vol 28 (09) ◽  
pp. 810-822 ◽  
Author(s):  
Benjamin J. Kirby ◽  
Judy G. Kopun ◽  
Meredith Spratford ◽  
Clairissa M. Mollak ◽  
Marc A. Brennan ◽  
...  
Keyword(s):  
Signal Processing ◽  
Hearing Loss ◽  
Speech Perception ◽  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Sound Quality ◽  
Processing Strategy ◽  
Listening Effort ◽  
At Home

AbstractSloping hearing loss imposes limits on audibility for high-frequency sounds in many hearing aid users. Signal processing algorithms that shift high-frequency sounds to lower frequencies have been introduced in hearing aids to address this challenge by improving audibility of high-frequency sounds.This study examined speech perception performance, listening effort, and subjective sound quality ratings with conventional hearing aid processing and a new frequency-lowering signal processing strategy called frequency composition (FC) in adults and children.Participants wore the study hearing aids in two signal processing conditions (conventional processing versus FC) at an initial laboratory visit and subsequently at home during two approximately six-week long trials, with the order of conditions counterbalanced across individuals in a double-blind paradigm.Children (N = 12, 7 females, mean age in years = 12.0, SD = 3.0) and adults (N = 12, 6 females, mean age in years = 56.2, SD = 17.6) with bilateral sensorineural hearing loss who were full-time hearing aid users.Individual performance with each type of processing was assessed using speech perception tasks, a measure of listening effort, and subjective sound quality surveys at an initial visit. At the conclusion of each subsequent at-home trial, participants were retested in the laboratory. Linear mixed effects analyses were completed for each outcome measure with signal processing condition, age group, visit (prehome versus posthome trial), and measures of aided audibility as predictors.Overall, there were few significant differences in speech perception, listening effort, or subjective sound quality between FC and conventional processing, effects of listener age, or longitudinal changes in performance. Listeners preferred FC to conventional processing on one of six subjective sound quality metrics. Better speech perception performance was consistently related to higher aided audibility.These results indicate that when high-frequency speech sounds are made audible with conventional processing, speech recognition ability and listening effort are similar between conventional processing and FC. Despite the lack of benefit to speech perception, some listeners still preferred FC, suggesting that qualitative measures should be considered when evaluating candidacy for this signal processing strategy.

scholarly journals Acceleration Signal Processing Method of Impact Response of Floating Shock Platform Based on Rigid Body Motion Model

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Wenqi Zhang ◽  
Xiongliang Yao ◽  
Zhikai Wang ◽  
Jin Chen ◽  
Heng Yang
Keyword(s):  
Signal Processing ◽  
Rigid Body ◽  
High Frequency ◽  
Response Spectrum ◽  
Low Frequency ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Shock Acceleration ◽  
Motion Model ◽  
Acceleration Signal

Floating shock platform is generally used to test the antishock performance of large shipboard equipment. Shock acceleration signal will produce zero-shift phenomenon in the test measurement process, which will affect the subsequent shock response spectrum analysis. In this paper, a method of shock acceleration signal processing based on rigid body motion revision model is established. The rigid body motion revision model adopts the theory of ship’s seakeeping based on the hypothesis of KrylovFroude, in which the shock wave load of underwater explosion adopts the empirical formula. The bubble pulsation load adopts the GeersHunter spherical bubble model. The empirical mode decomposition method is used to eliminate the trend term of the low-frequency part of the acceleration signal, and the frequency filtering technology is used to eliminate the noise of the high frequency part. The response estimated by the rigid body motion model is used to modify the measured signal. The modified signal is analyzed by shock response spectrum to get the round design spectrum. The validity of the signal is determined by the Pauta criterion. Finally, the shock environment statistics of the whole platform is given. This method can eliminate the low-frequency trend term and high frequency noise and has good robustness. It can be applied to many kinds of signals. This method can provide technical support for antishock performance of shipboard equipment and also applied to other shock signal processing fields.

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