A More Capable Array Infrastructure

2021 ◽  
Author(s):  
Tim Parker ◽  
Val Hamilton ◽  
Andrew Moores
Keyword(s):  
Dynamic Range ◽  
Low Noise ◽  
Low Frequencies ◽  
Corrosion Resistant ◽  
Dual Sensor ◽  
Local Earthquake ◽  
Array Performance ◽  
New Instruments ◽  
Higher Sensitivity

<p>A more capable infrastructure would enable greater monitoring capabilities. We propose a deeper grouted casing and using borehole best practices to ensure improved coupling and a better environment for reducing site and emplacement noise in both high and low frequencies and specifically the horizontal component recording. Casing emplacements should be a one to two day operation for installation. Stations using the new Trillium T120PH Slim or dual sensor Cascadia Slim in a single cased hole will have wider bandwidth, larger dynamic range, resiliency and low noise recording that would enable new observations along with higher sensitivity for local earthquake recording. Dry cased holes are the standard for long term geophysical observatories and a better investment when all the associated costs of operating observatories are considered. Facilities are both renewing old stations and trying to improve array performance through these new instruments.  This line of Trillium borehole instruments are very robust with low SWaP (Size, Weight and Power), a 300 meter continuous immersion rating and of corrosion resistant construction.  These sensors can be installed in bedding material or with a hole lock and are compatible with the ultimate installation, grouting it in!</p>

scholarly journals An Improved Difference Temperature Compensation Method for MEMS Resonant Accelerometers

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1022
Author(s):  
Pengcheng Cai ◽  
Xingyin Xiong ◽  
Kunfeng Wang ◽  
Jiawei Wang ◽  
Xudong Zou
Keyword(s):  
Temperature Compensation ◽  
Dynamic Range ◽  
Compensation Method ◽  
Frequency Drift ◽  
Long Term Stability ◽  
Frequency Output ◽  
Resonant Accelerometer ◽  
Difference Temperature ◽  
Higher Sensitivity

Resonant accelerometers are promising because of their wide dynamic range and long-term stability. With quasi-digital frequency output, the outputs of resonant accelerometers are less vulnerable to the noise from circuits and ambience. Differential structure is usually adopted in a resonant accelerometer to achieve higher sensitivity to acceleration and to reduce common noise at the same time. Ideally, a resonant accelerometer is only sensitive to external acceleration. However, temperature has a great impact on resonant accelerometers, causing unexcepted frequency drift. In order to cancel out the frequency drift caused by temperature change, an improved temperature compensation method for differential vibrating accelerometers without additional temperature sensors is presented in this paper. Experiment results demonstrate that the temperature sensitivity of the prototype sensor is reduced from 43.16 ppm/°C to 0.83 ppm/°C within the temperature range of −10 °C to 70 °C using the proposed method.

scholarly journals Μελέτη, ανάλυση και βελτίωση της λειτουργίας αερομεταφερόμενου ραντάρ συνθετικής απεικόνισης (SAR) χαμηλών συχνοτήτων

2002 ◽  
Author(s):  
Αθανάσιος Πότσης
Keyword(s):  
Data Processing ◽  
High Performance ◽  
Dynamic Range ◽  
Low Frequency ◽  
Low Noise ◽  
Electromagnetic Spectrum ◽  
System Operation ◽  
Low Frequencies ◽  
Technological Advances ◽  
Sar Data

Because of its high resolution, frequency scattering properties and indifference to day/night or cloud cover, Synthetic Aperture Radar (SAR) has become into vogue in the last years. The field of SAR remote sensing has changed dramatically with the operational introduction of new high performance signal processing techniques and new operational modes, like the polarimetry in 1980’s and the interferometry in 1990’s. Additionally, technological advances in antenna design, low noise amplifiers, band-pass filters, digital receiver technology and high frequency digital sampling devises, increase the availability and the performance of airborne as well as spaceborne SAR sensors. All these technological advances result to real time SAR system operation and in most of the frequency bands of the electromagnetic spectrum. These advanced hardware components combined with the new radar techniques result to large variety of operational and research applications. In several of the new coming applications there is the need for a SAR system to penetrate vegetation and foliage. As a result of this, a new class of SAR systems, using low frequencies, has emerged. The combination of low frequency with high bandwidth allows a variety of new military as well as civilian applications. In the frame of this thesis, several hardware and software modifications made in the E-SAR P-Band system operated by DLR aiming the improvement of the collected and processed data quality is described. The basic P-Band inherent problems like the low Signal-To-Noise-Ratio (SNR), the presence of Radio Frequency Interferences (RFI) as well as the high dynamic range of the backscattered signal are addressed. A new mode of operation called “Listen Only” (LO) channel mode gave us the unique opportunity to study and analyze the special characteristics of the interfering signals and the nature of the low frequency backscattered signal. Based on this analysis new RFI suppression algorithms have been developed and the system operation parameters have been set to the correct value resulting to high quality collected data. The effect of RFI signals in fully polarimetric SAR data processing and applications are analyzed in detail. One of the principal items of this thesis is the development of a new robust sub-aperture algorithm for improved Motion Compensation (MoCo) in wide azimuth beam SAR data processing. The new algorithm is incorporated to the Extended Chirp Scaling SAR data processing algorithm. The improved MoCo algorithm results to focused images with high SNR, contrast, higher resolution and better geometric correctness. The performance and the correction accuracy of the proposed algorithms are analyzed by using mainly real data collected by the E-SAR system of DLR.

Design of Low Power Underwater Acoustic Receiving Circuit with Digital Gain Control

2013 ◽  
Vol 718-720 ◽  
pp. 1416-1421
Author(s):  
Ya Fei Tang ◽  
Jian Ping Xiong
Keyword(s):  
Low Power ◽  
High Precision ◽  
Dynamic Range ◽  
Gain Control ◽  
Low Noise ◽  
Large Dynamic Range ◽  
Underwater Acoustic ◽  
Underwater Acoustic Signal ◽  
To Receive

We propose a design of low power underwater acoustic receiving circuit by inverted echo sounder (IES) for observing the internal waves of the ocean in a long term. To receive the echo of the underwater targets, the underwater acoustic signal processor is required to be insensitive to strong noise and work in large dynamic range. In this work, with the variant application environments, to reduce the load of the subsequent processing modules, the circuit with digital gain control is employed to amplify the weak signals. Then, the out-of-band noise and higher harmonic are filtered out. The output is finally obtained by the 24-bit high-precision A/D sampling. Experiments demonstrate that the proposed design of the circuit performs with low power consumption, low noise, large dynamic range, flexible frequency selectivity, high precision and anti-inference.

scholarly journals Responses of Vertebrate Wildlife to Oil and Natural Gas Development: Patterns and Frontiers

2021 ◽  
Author(s):  
A. D. Chalfoun
Keyword(s):  
Natural Gas ◽  
Anthropogenic Activities ◽  
Spatial Scales ◽  
Habitat Type ◽  
Population Level ◽  
Low Frequencies ◽  
Natural Gas Development ◽  
The Usa ◽  
Oil And Natural Gas

Abstract Purpose of Review Anthropogenic activities can lead to the loss, fragmentation, and alteration of wildlife habitats. I reviewed the recent literature (2014–2019) focused on the responses of avian, mammalian, and herpetofaunal species to oil and natural gas development, a widespread and still-expanding land use worldwide. My primary goals were to identify any generalities in species’ responses to development and summarize remaining gaps in knowledge. To do so, I evaluated the directionality of a wide variety of responses in relation to taxon, location, development type, development metric, habitat type, and spatiotemporal aspects. Recent Findings Studies (n = 70) were restricted to the USA and Canada, and taxonomically biased towards birds and mammals. Longer studies, but not those incorporating multiple spatial scales, were more likely to detect significant responses. Negative responses of all types were present in relatively low frequencies across all taxa, locations, development types, and development metrics but were context-dependent. The directionality of responses by the same species often varied across studies or development metrics. Summary The state of knowledge about wildlife responses to oil and natural gas development has developed considerably, though many biases and gaps remain. Studies outside of North America and that focus on herpetofauna are lacking. Tests of mechanistic hypotheses for effects, long-term studies, assessment of response thresholds, and experimental designs that isolate the effects of different stimuli associated with development, remain critical. Moreover, tests of the efficacy of habitat mitigation efforts have been rare. Finally, investigations of the demographic effects of development across the full annual cycle were absent for non-game species and are critical for the estimation of population-level effects.

scholarly journals Development of a Transient Magnetic Field Sensor Based on Digital Integration and Frequency Equalization

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4268
Author(s):  
Hongzhi Ouyang ◽  
Xueling Yao ◽  
Jingliang Chen
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Compatibility ◽  
Dynamic Range ◽  
Finite Impulse Response ◽  
Low Noise ◽  
Magnetic Field Sensor ◽  
Fiber System ◽  
Digital Integrator ◽  
Transient Magnetic Field ◽  
Field Sensor

Transient magnetic field sensors are used in various electromagnetic environment measurement scenarios. In this paper, a novel magnetic field sensor based on a digital integrator was developed. The antenna was a small B-DOT loop. It was designed optimally for the simulation. The magnetic field signal was digitally integrated with the improved Al-Alaoui algorithm, resulting in less integration error. To compensate for the bandwidth loss of the optical fiber system, we specially designed an FIR (finite impulse response) filter for frequency compensation. The circuit was described, and the transimpedance amplifier was specially designed to ensure the low noise characteristic of the receiver. The sensitivity of the sensor was calibrated at 68.2 A·m−1/mV, the dynamic range was 50 dB (1–300 kA/m), the linear correlation coefficient was 0.96, and the bandwidth was greater than 100 MHz. It was tested and verified under the action of an A-type lightning current. The sensor exhibited high-precision performance and flat amplitude-frequency characteristics. Therefore, it is suitable for lightning positioning, partial discharge testing, electromagnetic compatibility management, and other applications.

Crevice Corrosion Studies on Corrosion Resistant Alloys in Stagnant Natural Seawater

2012 ◽  
Vol 610-613 ◽  
pp. 276-279
Author(s):  
Laura L. Machuca ◽  
Stuart I. Bailey ◽  
Rolf Gubner
Keyword(s):  
Crevice Corrosion ◽  
Corrosion Potential ◽  
Natural Seawater ◽  
Corrosion Resistant ◽  
Testing Procedures ◽  
Corrosion Studies ◽  
Long Term Performance ◽  
Term Performance ◽  
Positive Effect

Crevice corrosion (CC) was investigated for a number of selected corrosion resistant alloys in natural seawater containing microorganisms for up to 18 months under stagnant conditions. Experimental controls consisted of tests in natural seawater filtered in accordance with hydrostatic testing procedures. The corrosion potential of alloys was monitored throughout exposure and corrosion was evaluated by weight loss and 3D optical microscopy. CC was initiated on several alloys and corrosion rates in time indicated a positive effect of seawater filtration on the long-term performance of the alloys. Microbial adhesion, as indicated by fluorescence microscopy, occurred mainly outside the crevice and differed according to the nature of the substratum surface.

TREMOR: A Wireless MEMS Accelerograph for Dense Arrays

2005 ◽  
Vol 21 (1) ◽  
pp. 91-124 ◽  
Author(s):  
John R. Evans ◽  
Robert H. Hamstra ◽  
Christoph Kündig ◽  
Patrick Camina ◽  
John A. Rogers
Keyword(s):  
Spatial Resolution ◽  
Dynamic Range ◽  
Strong Motion ◽  
The United States ◽  
Companion Paper ◽  
Low Noise ◽  
Practical Reasons ◽  
Wireless Internet ◽  
Urban Centers ◽  
Strong Motion Network

The ability of a strong-motion network to resolve wavefields can be described on three axes: frequency, amplitude, and space. While the need for spatial resolution is apparent, for practical reasons that axis is often neglected. TREMOR is a MEMS-based accelerograph using wireless Internet to minimize lifecycle cost. TREMOR instruments can economically augment traditional ones, residing between them to improve spatial resolution. The TREMOR instrument described here has dynamic range of 96 dB between ±2 g, or 102 dB between ±4 g. It is linear to <1% of full scale (FS), with a response function effectively shaped electronically. We developed an economical, very low noise, accurate (<1%FS) temperature compensation method. Displacement is easily recovered to 10-cm accuracy at full bandwidth, and better with care. We deployed prototype instruments in Oakland, California, beginning in 1998, with 13 now at mean spacing of ∼3 km—one of the most densely instrumented urban centers in the United States. This array is among the quickest in returning (PGA, PGV, Sa) vectors to ShakeMap, ∼75 to 100 s. Some 13 events have been recorded. A ShakeMap and an example of spatial variability are shown. Extensive tests of the prototypes for a commercial instrument are described here and in a companion paper.

scholarly journals Measurement of synchrotron-radiation-excited Kossel patterns

2016 ◽  
Vol 23 (1) ◽  
pp. 214-218 ◽  
Author(s):  
G. Bortel ◽  
G. Faigel ◽  
M. Tegze ◽  
A. Chumakov
Keyword(s):  
High Resolution ◽  
Dynamic Range ◽  
Structural Information ◽  
Photon Counting ◽  
Spot Size ◽  
Low Noise ◽  
X Rays ◽  
Technical Problems ◽  
Pixel Detectors ◽  
Exciting Beam

Kossel line patterns contain information on the crystalline structure, such as the magnitude and the phase of Bragg reflections. For technical reasons, most of these patterns are obtained using electron beam excitation, which leads to surface sensitivity that limits the spatial extent of the structural information. To obtain the atomic structure in bulk volumes, X-rays should be used as the excitation radiation. However, there are technical problems, such as the need for high resolution, low noise, large dynamic range, photon counting, two-dimensional pixel detectors and the small spot size of the exciting beam, which have prevented the widespread use of Kossel pattern analysis. Here, an experimental setup is described, which can be used for the measurement of Kossel patterns in a reasonable time and with high resolution to recover structural information.

A Low-Noise, Low-Power, Wide Dynamic Range Logarithmic Amplifier for Biomedical Applications

2018 ◽  
Vol 27 (07) ◽  
pp. 1850104 ◽  
Author(s):  
Yuwadee Sundarasaradula ◽  
Apinunt Thanachayanont
Keyword(s):  
Low Power ◽  
Biomedical Applications ◽  
Dynamic Range ◽  
Supply Voltage ◽  
Low Noise ◽  
Power Supply Voltage ◽  
Wide Dynamic Range ◽  
Dc Offset ◽  
Limiting Amplifier ◽  
Logarithmic Amplifier

This paper presents the design and realization of a low-noise, low-power, wide dynamic range CMOS logarithmic amplifier for biomedical applications. The proposed amplifier is based on the true piecewise linear function by using progressive-compression parallel-summation architecture. A DC offset cancellation feedback loop is used to prevent output saturation and deteriorated input sensitivity from inherent DC offset voltages. The proposed logarithmic amplifier was designed and fabricated in a standard 0.18[Formula: see text][Formula: see text]m CMOS technology. The prototype chip includes six limiting amplifier stages and an on-chip bias generator, occupying a die area of 0.027[Formula: see text]mm2. The overall circuit consumes 9.75[Formula: see text][Formula: see text]W from a single 1.5[Formula: see text]V power supply voltage. Measured results showed that the prototype logarithmic amplifier exhibited an 80[Formula: see text]dB input dynamic range (from 10[Formula: see text][Formula: see text]V to 100[Formula: see text]mV), a bandwidth of 4[Formula: see text]Hz–10[Formula: see text]kHz, and a total input-referred noise of 5.52[Formula: see text][Formula: see text]V.

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