Ultra wideband measurement for arbitrary spectral response using double sideband modulation and low-frequency detection

2020 ◽  
Vol 460 ◽  
pp. 125198
Author(s):  
Danqi Feng ◽  
Ya Gao ◽  
Xiaohu Zhang ◽  
Tao Zhu ◽  
Rui Cao
Keyword(s):  
Spectral Response ◽  
Low Frequency ◽  
Ultra Wideband ◽  
Frequency Detection

scholarly journals Design and implementation of a jellyfish otolith-inspired MEMS vector hydrophone for low-frequency detection

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Renxin Wang ◽  
Wei Shen ◽  
Wenjun Zhang ◽  
Jinlong Song ◽  
Nansong Li ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Low Frequency ◽  
Directivity Pattern ◽  
Stress Distributions ◽  
Strong Response ◽  
Underwater Acoustic ◽  
Frequency Detection ◽  
Vector Hydrophone ◽  
Shock Resistance ◽  
Marine Applications

AbstractDetecting low-frequency underwater acoustic signals can be a challenge for marine applications. Inspired by the notably strong response of the auditory organs of pectis jellyfish to ultralow frequencies, a kind of otolith-inspired vector hydrophone (OVH) is developed, enabled by hollow buoyant spheres atop cilia. Full parametric analysis is performed to optimize the cilium structure in order to balance the resonance frequency and sensitivity. After the structural parameters of the OVH are determined, the stress distributions of various vector hydrophones are simulated and analyzed. The shock resistance of the OVH is also investigated. Finally, the OVH is fabricated and calibrated. The receiving sensitivity of the OVH is measured to be as high as −202.1 dB@100 Hz (0 dB@1 V/μPa), and the average equivalent pressure sensitivity over the frequency range of interest of the OVH reaches −173.8 dB when the frequency ranges from 20 to 200 Hz. The 3 dB polar width of the directivity pattern for the OVH is measured as 87°. Moreover, the OVH is demonstrated to operate under 10 MPa hydrostatic pressure. These results show that the OVH is promising in low-frequency underwater acoustic detection.

scholarly journals A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

2019 ◽  
Vol 9 (15) ◽  
pp. 3157 ◽  
Author(s):  
O ◽  
Jin ◽  
Choi
Keyword(s):  
Cognitive Radio ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Low Frequency ◽  
Loop Antenna ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Uwb Antenna ◽  
High Isolation ◽  
Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

Ultra-Wideband Aperture Array Element Design for Low Frequency Radio Astronomy

2011 ◽  
Vol 59 (6) ◽  
pp. 1808-1816 ◽  
Author(s):  
Eloy de Lera Acedo ◽  
Nima Razavi-Ghods ◽  
Luis Enrique Garcia ◽  
Peter Duffett-Smith ◽  
P. Alexander
Keyword(s):  
Radio Astronomy ◽  
Low Frequency ◽  
Array Element ◽  
Ultra Wideband ◽  
Aperture Array

High-resolution and wideband optical vector analysis using fixed low-frequency detection

2021 ◽  
Author(s):  
Ting Qing ◽  
Shupeng Li ◽  
Lihan Wang ◽  
Xiaohu Tang ◽  
Ping Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Low Frequency ◽  
Vector Analysis ◽  
Frequency Detection

scholarly journals Characterizing the Statistics of a Bunch of Optical Pulses Using a Nonlinear Optical Loop Mirror

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Olivier Pottiez ◽  
Rodrigo Paez-Aguirre ◽  
Hector Santiago-Hernandez ◽  
Manuel Duran-Sanchez ◽  
Baldemar Ibarra-Escamilla ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Least Squares Method ◽  
Low Frequency ◽  
Amplitude Distribution ◽  
Transfer Characteristic ◽  
Algebraic Equations ◽  
Optical Pulses ◽  
Nonlinear Optical Loop Mirror ◽  
Frequency Detection ◽  
Loop Mirror

We propose in this work a technique for determining the amplitude distribution of a wave packet containing a large number of short optical pulses with different amplitudes. The technique takes advantage of the fast response of the optical Kerr effect in a fiber nonlinear optical loop mirror (NOLM). Under some assumptions, the statistics of the pulses can be determined from the energy transfer characteristic of the packet through the NOLM, which can be measured with a low-frequency detection setup. The statistical distribution is retrieved numerically by approximating the solution of a system of nonlinear algebraic equations using the least squares method. The technique is demonstrated numerically in the case of a packet of solitons.

scholarly journals Fusion of GNSS and Speedometer Based on VMD and Its Application in Bridge Deformation Monitoring

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 694 ◽  
Author(s):  
Ruicheng Zhang ◽  
Chengfa Gao ◽  
Shuguo Pan ◽  
Rui Shang
Keyword(s):  
Real Time ◽  
High Precision ◽  
High Frequency ◽  
Spectral Response ◽  
Low Frequency ◽  
Deformation Monitoring ◽  
Full Time ◽  
Dynamic Displacement ◽  
Mode Decomposition ◽  
Acceleration Sensors

Real-time dynamic displacement and spectral response on the midspan of Jiangyin Bridge were calculated using Global Navigation Satellite System (GNSS) and a speedometer for the purpose of understanding the dynamic behavior and the temporal evolution of the bridge structure. Considering that the GNSS measurement noise is large and the velocity/acceleration sensors cannot measure the low-frequency displacement, the Variational Mode Decomposition (VMD) algorithm was used to extract the low-frequency displacement of GNSS. Then, the low-frequency displacement extracted from the GNSS time series and the high-frequency vibration calculated by speedometer were combined in this paper in order to obtain the high precision three-dimensional dynamic displacement of the bridge in real time. Simulation experiment and measured data show that the VMD algorithm could effectively resist the modal aliasing caused by noise and discontinuous signals compared with the commonly used Empirical Mode Decomposition (EMD) algorithm, which is guaranteed to get high-precision fusion data. Finally, the fused displacement results can identify high-frequency vibrations and low-frequency displacements of a mm level, which can be used to calculate the spectral characteristics of the bridge and provide reference to evaluate the dynamic and static loads, and the health status of the bridge in the full frequency domain and the full time domain.

scholarly journals Derivation of global ionospheric Sporadic E critical frequency ( f o Es) data from the amplitude variations in GPS/GNSS radio occultations

2020 ◽  
Vol 7 (7) ◽  
pp. 200320 ◽  
Author(s):  
Bingkun Yu ◽  
Christopher J. Scott ◽  
Xianghui Xue ◽  
Xinan Yue ◽  
Xiankang Dou
Keyword(s):  
Critical Frequency ◽  
Detection Threshold ◽  
Low Frequency ◽  
Satellite System ◽  
Global Scale ◽  
Satellite Mission ◽  
Frequency Detection ◽  
Sporadic E ◽  
The Uk ◽  
Global Navigation Satellite

The ionospheric sporadic E (Es) layer has a significant impact on the global positioning system (GPS)/global navigation satellite system (GNSS) signals. These influences on the GPS/GNSS signals can also be used to study the occurrence and characteristics of the Es layer on a global scale. In this paper, 5.8 million radio occultation (RO) profiles from the FORMOSAT-3/COSMIC satellite mission and ground-based observations of Es layers recorded by 25 ionospheric monitoring stations and held at the UK Solar System Data Centre at the Rutherford Appleton Laboratory and the Chinese Meridian Project were used to derive the hourly Es critical frequency ( f o Es) data. The global distribution of f o Es with a high spatial resolution shows a strong seasonal variation in f o Es with a summer maximum exceeding 4.0 MHz and a winter minimum between 2.0 and 2.5 MHz. The GPS/GNSS RO technique is an important tool that can provide global estimates of Es layers, augmenting the limited coverage and low-frequency detection threshold of ground-based instruments. Attention should be paid to small f o Es values from ionosondes near the instrumental detection limits corresponding to minimum frequencies in the range 1.28–1.60 MHz.

Glider-Based Passive Acoustic Monitoring in the Arctic

2014 ◽  
Vol 48 (5) ◽  
pp. 40-51 ◽  
Author(s):  
Mark F. Baumgartner ◽  
Kathleen M. Stafford ◽  
Peter Winsor ◽  
Hank Statscewich ◽  
David M. Fratantoni
Keyword(s):  
Real Time ◽  
Marine Mammal ◽  
Low Frequency ◽  
Acoustic Monitoring ◽  
Bowhead Whale ◽  
The Arctic ◽  
Mammal Species ◽  
Frequency Detection ◽  
Passive Acoustic ◽  
The Impact

AbstractPersistently poor weather in the Arctic makes traditional marine mammal research from aircraft and ships difficult, yet collecting information on marine mammal distribution and habitat utilization is vital for understanding the impact of climate change on Arctic ecosystems. Moreover, as industrial use of the Arctic increases with the expansion of the open-water summer season, there is an urgent need to monitor the effects of noise from oil and gas exploration and commercial shipping on marine mammals. During September 2013, we deployed a single Slocum glider equipped with a digital acoustic monitoring (DMON) instrument to record and process in situ low-frequency (<5 kHz) audio to characterize marine mammal occurrence and habitat as well as ambient noise in the Chukchi Sea off the northwest coast of Alaska, USA. The DMON was programmed with the low-frequency detection and classification system (LFDCS) to autonomously detect and classify sounds of a variety of Arctic and sub-Arctic marine mammal species. The DMON/LFDCS reported regularly in near real time via Iridium satellite detailed detection data, summary classification information, and spectra of background noise. The spatial distributions of bowhead whale, bearded seal, and walrus call rates were correlated with surface salinity measured by the glider. Bowhead whale and walrus call rates were strongly associated with a warm and salty water mass of Bering Sea origin. With a passive acoustic capability that allows both archival recording and near real-time reporting, we envision ocean gliders will become a standard tool for marine mammal and ocean noise research and monitoring in the Arctic.

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