Gain-ranging analog or digital seismic system

1974 ◽  
Vol 64 (1) ◽  
pp. 103-113 ◽  
Author(s):  
E. R. Kanasewich ◽  
W. P. Siewert ◽  
M. D. Burke ◽  
C. H. McCloughan ◽  
L. Ramsdell
Keyword(s):  
Dynamic Range ◽  
Wide Band ◽  
Low Noise ◽  
Active Filters ◽  
Operating Conditions ◽  
Natural Period ◽  
Analog System ◽  
Effective Dynamic ◽  
Different Levels ◽  
Seismic System

abstract A wide-band, gain-ranging amplifier is described that may be used for recording data with a dynamic range of 60 db in each of three different levels, 12 db apart, so that we achieve an “effective” dynamic ±160-v analog or 84-db digital, within a normal ±10-v analog system. As described, the ranging circuit reduces the gain of the amplifier by a factor of either 4 or 16 whenever the output signal approaches the maximum for the system. The wide-band response is achieved with low-noise operational amplifiers and second-order active filters. Signals with periods greater than 30 sec are amplified by 100 db and those with periods shorter than 1 sec are amplified by 70 db. The system works well in extending the useful output range of a Willmore Mark II seismometer with a natural period of 1.5 sec to over 40 sec under normal field operating conditions. When analog recording, the gain-range switching occurs when the input signal reaches ±8.1-v; when digital recording, the level is ±9.375 v. The period in a divide-by-4- or 16-state is preset by the experimentalist. The gain level is recorded on an extra channel which is also used to record absolute time.

A wide-band digital seismograph system

1970 ◽  
Vol 60 (5) ◽  
pp. 1417-1424 ◽  
Author(s):  
M. D. Burke ◽  
E. R. Kanasewich ◽  
J. D. Malinsky ◽  
J. F. Montalbetti
Keyword(s):  
Wide Spectrum ◽  
Broad Band ◽  
Seismic Energy ◽  
Wide Band ◽  
Low Noise ◽  
Operating Conditions ◽  
Operational Amplifiers ◽  
Natural Period ◽  
Novel Approach ◽  
Seismic System

Abstract A three-component, broad-band seismic system which records directly onto seven-track digital tape is described. A novel approach of synthesizing a desired response by a differential filtering and summing technic using low-noise operational amplifiers is demonstrated. As an example, the usable velocity sensitivity of a Willmore Mark II seismometer having a natural period of 1.5 sec is extended out to about 40 sec under normal operating conditions. Seismic energy over a wide spectrum may thus be recorded.

Design of a Front-End for Satellite Receiver

2016 ◽  
Vol 6 (5) ◽  
pp. 2282 ◽  
Author(s):  
Tran Van Hoi ◽  
Ngo Thi Lanh ◽  
Nguyen Xuan Truong ◽  
Nguyen Huu Duc ◽  
Bach Gia Duong
Keyword(s):  
Dynamic Range ◽  
Noise Figure ◽  
High Sensitivity ◽  
Wide Band ◽  
Local Oscillator ◽  
Low Noise ◽  
Voltage Controlled Oscillator ◽  
Front End ◽  
L Band ◽  
Satellite Receiver

<p>This paper focuses on the design and implementation of a front-end for a Vinasat satellite receiver with auto-searching mechanism and auto-tracking satellite. The front-end consists of a C-band low-noise block down-converter and a L-band receiver. The receiver is designed to meet the requirements about wide-band, high sensitivity, large dynamic range, low noise figure. To reduce noise figure and increase bandwidth, the C-band low-noise amplifier is designed using T-type of matching network with negative feedback and the L-band LNA is designed using cascoded techniques. The local oscillator uses a voltage controlled oscillator combine phase locked loop to reduce the phase noise and select channels. The front-end has successfully been designed and fabricated with parameters: Input frequency is C-band; sensitivity is greater than -130 dBm for C-band receiver and is greater than -110dBm for L-band receiver; output signals are AM/FM demodulation, I/Q demodulation, baseband signals.</p>

scholarly journals Design of a Front-End for Satellite Receiver

2016 ◽  
Vol 6 (5) ◽  
pp. 2282
Author(s):  
Tran Van Hoi ◽  
Ngo Thi Lanh ◽  
Nguyen Xuan Truong ◽  
Nguyen Huu Duc ◽  
Bach Gia Duong
Keyword(s):  
Dynamic Range ◽  
Noise Figure ◽  
High Sensitivity ◽  
Wide Band ◽  
Local Oscillator ◽  
Low Noise ◽  
Voltage Controlled Oscillator ◽  
Front End ◽  
L Band ◽  
Satellite Receiver

<p>This paper focuses on the design and implementation of a front-end for a Vinasat satellite receiver with auto-searching mechanism and auto-tracking satellite. The front-end consists of a C-band low-noise block down-converter and a L-band receiver. The receiver is designed to meet the requirements about wide-band, high sensitivity, large dynamic range, low noise figure. To reduce noise figure and increase bandwidth, the C-band low-noise amplifier is designed using T-type of matching network with negative feedback and the L-band LNA is designed using cascoded techniques. The local oscillator uses a voltage controlled oscillator combine phase locked loop to reduce the phase noise and select channels. The front-end has successfully been designed and fabricated with parameters: Input frequency is C-band; sensitivity is greater than -130 dBm for C-band receiver and is greater than -110dBm for L-band receiver; output signals are AM/FM demodulation, I/Q demodulation, baseband signals.</p>

scholarly journals NRAO 43-m telescope operation at 170-1700 MHz: a Bi-Static Radar Collaboration

2006 ◽  
Vol 2 (14) ◽  
pp. 367-367
Author(s):  
Glen Langston
Keyword(s):  
Dynamic Range ◽  
Wide Band ◽  
High Dynamic Range ◽  
Low Noise ◽  
Low Noise Amplifiers ◽  
Ionospheric Turbulence ◽  
Radio Stations ◽  
University Of Technology ◽  
Fm Radio ◽  
High Dynamic

AbstractThe NRAO 43m telescope has been refurbished and begun regular observations in the frequency range 170 - 1700 MHz. The 43 m operations support a Bi-Static Radar Collaboration to measure the Earth's ionospheric turbulence. Researchers from Chalmers University of Technology in Sweden have designed and built a unique design wide-band feed, 150 - 1700 MHz. Lincoln Laboratories/MIT has packaged the feed with room temperature low noise amplifiers. Lincoln Laboratories has installed a high-dynamic range RF system together with a wide-band sampler system. The NRAO operates the 43 m telescope according to schedules authored by Lincoln Laboratories. Currently the 43 m telescope is tracking spacecraft 48 hr a week. The tracking antenna operation is completely automated. A group at MIT/Haystack have installed a second radar experiment at the 43 m as well as an array of 6 ‘discone’ antennas. Their experiment is testing the use of reflected FM radio stations as probes of the ionosphere.

scholarly journals A Survey of MMIC Active Filters

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1680
Author(s):  
Leonardo Pantoli ◽  
Giorgio Leuzzi ◽  
Francois Deborgies ◽  
Petar Jankovic ◽  
Francesco Vitulli
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Low Noise ◽  
Active Filters ◽  
Low Loss ◽  
Practical Applications ◽  
High Q ◽  
The Past ◽  
Potential Applications ◽  
High Dynamic

High-Q filters are a critical component in many systems. However, high-Q filters require very low-loss passive elements that are not compatible with monolithic technology. Therefore, filters are often implemented as off-chip components. Tunable high-Q filters require even larger space and weight, and are usually quite bulky. Active filters have been proposed in the past for a monolithic implementation. However, it is not easy to fulfil such requirements as a high dynamic range, low power consumption, low noise, wide tunability, stability, etc. With this study, we propose a survey of the main solutions presented in the literature, investigating the fulfilment of all or most requirements and their potential applications and feasibility, to be used in practical applications.

A digital seismic recording system

1972 ◽  
Vol 62 (6) ◽  
pp. 1641-1647
Author(s):  
D. F. Allsopp ◽  
M. D. Burke ◽  
G. L. Cumming
Keyword(s):  
Seismic Reflection ◽  
Dynamic Range ◽  
Low Noise ◽  
Recording System ◽  
Low Noise Amplifiers ◽  
Deep Crust ◽  
Seismic Recording ◽  
Band Pass ◽  
Quality Recording ◽  
Seismic System

abstract A multi-channel seismic system which records directly on a nine-track synchronous digital tape is described. Low-noise amplifiers with a band-pass of 0.1 to 50 Hz coupled with a 14-bit A to D converter provide the wide-frequency response and dynamic range necessary for high-quality recording of seismic reflection signals from the deep crust.

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

scholarly journals Complex wavefront sensing based on coherent diffraction imaging using vortex modulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rujia Li ◽  
Liangcai Cao
Keyword(s):  
Phase Retrieval ◽  
Dynamic Range ◽  
A Priori ◽  
Measured Intensity ◽  
Physical Constraints ◽  
Coherent Diffraction Imaging ◽  
Effective Dynamic ◽  
Ill Posed ◽  
Retrieval Problem ◽  
Diffraction Imaging

AbstractPhase retrieval seeks to reconstruct the phase from the measured intensity, which is an ill-posed problem. A phase retrieval problem can be solved with physical constraints by modulating the investigated complex wavefront. Orbital angular momentum has been recently employed as a type of reliable modulation. The topological charge l is robust during propagation when there is atmospheric turbulence. In this work, topological modulation is used to solve the phase retrieval problem. Topological modulation offers an effective dynamic range of intensity constraints for reconstruction. The maximum intensity value of the spectrum is reduced by a factor of 173 under topological modulation when l is 50. The phase is iteratively reconstructed without a priori knowledge. The stagnation problem during the iteration can be avoided using multiple topological modulations.

scholarly journals Nanofabrication using home-made RF plasma coupled chemical vapour deposition system

2014 ◽  
Vol 32 ◽  
pp. 1460342
Author(s):  
Si Ci Ong ◽  
Usman Ilyas ◽  
Rajdeep Singh Rawat
Keyword(s):  
Chemical Vapour ◽  
Chemical Vapor ◽  
Wide Band ◽  
Zno Nanowires ◽  
Operating Conditions ◽  
Rf Plasma ◽  
Zno Nanostructures ◽  
Energetic Ions ◽  
Cvd Method ◽  
Etching Effect

Zinc oxide, ZnO , a popular semiconductor material with a wide band gap (3.37 eV) and high binding energy of the exciton (60 meV), has numerous applications such as in optoelectronics, chemical/biological sensors, and drug delivery. This project aims to (i) optimize the operating conditions for growth of ZnO nanostructures using the chemical vapor deposition (CVD) method, and (ii) investigate the effects of coupling radiofrequency (RF) plasma to the CVD method on the quality of ZnO nanostructures. First, ZnO nanowires were synthesized using a home-made reaction setup on gold-coated and non-coated Si (100) substrates at 950 °C. XRD, SEM, EDX, and PL measurements were used for characterizations and it was found that a deposition duration of 10 minutes produced the most well-defined ZnO nanowires. SEM analysis revealed that the nanowires had diameters ranging from 30-100 mm and lengths ranging from 1-4 µm. In addition, PL analysis showed strong UV emission at 380 nm, making it suitable for UV lasing. Next, RF plasma was introduced for 30 minutes. Both remote and in situ RF plasma produced less satisfactory ZnO nanostructures with poorer crystalline structure, surface morphology, and optical properties due to etching effect of energetic ions produced from plasma. However, a reduction in plasma discharge duration to 10 minutes produced thicker and shorter ZnO nanostructures. Based on experimentation conducted, it is insufficient to conclude that RF plasma cannot aid in producing well-defined ZnO nanostructures. It can be deduced that the etching effect of energetic ions outweighed the increased oxygen radical production in RF plasma nanofabrication.

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.

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