Fifty years of amplitude control

Geophysics ◽  
1998 ◽  
Vol 63 (2) ◽  
pp. 750-762 ◽  
Author(s):  
Klaus Helbig
Keyword(s):  
Ground Motion ◽  
Dynamic Range ◽  
Automatic Gain Control ◽  
Full Range ◽  
Seismic Signal ◽  
Floating Point ◽  
Magnetic Storage ◽  
Photographic Recording ◽  
Amplitude Control ◽  
Electromechanical Transduction

The amplitudes of seismic waves have always been a foremost concern of the seismologist to which considerable ingenuity was devoted. In the 1920s the problem was to magnify the ground motion sufficiently for detection. This was done at first by simple levers that moved mechanical pens. But at the start of exploration seismology, this had already been superseded by optical levers, photographic recording, and (soon after) electromechanical transduction followed by amplification. From the 1930s to about the early ’60s, devices of increasing complexity were introduced to compress the large amplitude difference between the first arrivals and the weakest reflections of interest to the limited dynamic range of the recording medium: first the paper record, then magnetic storage media, and finally the digital magnetic tape. This period can be identified with techniques known as automatic gain control (AGC). Soon after the introduction of digital recording techniques, the emphasis shifted: with intermediate digital storage, the limit to the dynamic range was no longer controlled by the properties of the storage medium. Now everything that passed through the acquisition unit could, in principle, be stored on magnetic disk or tape. At that time the aim became to record the ground motion as faithfully as possible. There were several technical developments on the way to achieve “true amplitudes” that, in turn, made exploration concepts like bright spots, seismic stratigraphy, and amplitude‐versus‐offset evaluation possible. However, the most significant innovation was what became known as floating‐point amplifier. It dominated seismic acquisition for about 25 years. Floating‐point representation of seismic signals allowed storage of the entire dynamic range in relatively economic words of about 18 bits. During the last decade, the quest for ever‐greater resolution—and the availability of mass‐produced components for hi‐fi audio equipment—led to the introduction of the sigma‐delta (Σ-δ) converter. With this device, the full range of the seismic signal (or rather the geophone output) is recorded in binary fixed‐point formats with 24 bits. With this development, the full seismic signal can be stored without distortion or loss of resolution.

scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals Receiver Designs for Electronic Toll Collection Systems : A Survey

2020 ◽  
pp. 576-581
Author(s):  
Rarika Ravi ◽  
Anu Assis
Keyword(s):  
Dynamic Range ◽  
Supply Voltage ◽  
Automatic Gain Control ◽  
Power Level ◽  
Cmos Technology ◽  
Electronic Toll Collection ◽  
Chip Area ◽  
Advantages And Disadvantages ◽  
Digitally Controlled ◽  
Toll Collection

<p>This paper discusses about different receiver designs adopted so far for various electronic toll collection systems. A comparative analysis based on the discussions is also provided. It shows that each design has it's own advantages and disadvantages compared to others. The main aim of this paper is to identify the most suitable design. The researches shows that the receiver design described in the 5.8GHz digitally controlled DSRC receiver for Chinese electronic toll collection system is the most suitable one. Here all RF, IF blocks and digital baseband for on-chip automatic gain control, are integrated on an RF-SoC. The proposed digitally controlled LNA and mixer circuits are elaborated. The technology used is 0.13μm CMOS technology. The RF block occupies a chip area of 0.75mm2. It consumes 22mA under a 1.5V supply voltage. The bit error rate maintains better than 10-6, the input power level varies from -75dBm to -8dBm. This design provides a receiver sensitivity improvement of at least 25%, and a dynamic range enhancement of at least 12%.</p>

scholarly journals NULL Convention Floating Point Multiplier

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Anitha Juliette Albert ◽  
Seshasayanan Ramachandran
Keyword(s):  
High Precision ◽  
Dynamic Range ◽  
Digital Signal ◽  
High Dynamic Range ◽  
Floating Point ◽  
Single Precision ◽  
Critical Part ◽  
Point Multiplication ◽  
Null Convention Logic ◽  
High Dynamic

Floating point multiplication is a critical part in high dynamic range and computational intensive digital signal processing applications which require high precision and low power. This paper presents the design of an IEEE 754 single precision floating point multiplier using asynchronous NULL convention logic paradigm. Rounding has not been implemented to suit high precision applications. The novelty of the research is that it is the first ever NULL convention logic multiplier, designed to perform floating point multiplication. The proposed multiplier offers substantial decrease in power consumption when compared with its synchronous version. Performance attributes of the NULL convention logic floating point multiplier, obtained from Xilinx simulation and Cadence, are compared with its equivalent synchronous implementation.

scholarly journals 14.85 µW Analog Front-End for Photoplethysmography Acquisition with 142-dBΩ Gain and 64.2-pArms Noise

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 512
Author(s):  
Binghui Lin ◽  
Mohamed Atef ◽  
Guoxing Wang
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Gain Control ◽  
Low Noise ◽  
Total Power ◽  
Cmos Process ◽  
Control Block ◽  
Silicon Area ◽  
Front End ◽  
Analog Front End

A low-power, high-gain, and low-noise analog front-end (AFE) for wearable photoplethysmography (PPG) acquisition systems is designed and fabricated in a 0.35 μm CMOS process. A high transimpedance gain of 142 dBΩ and a low input-referred noise of only 64.2 pArms was achieved. A Sub-Hz filter was integrated using a pseudo resistor, resulting in a small silicon area. To mitigate the saturation problem caused by background light (BGL), a BGL cancellation loop and a new simple automatic gain control block are used to enhance the dynamic range and improve the linearity of the AFE. The measurement results show that a DC photocurrent component up-to-10 μA can be rejected and the PPG output swing can reach 1.42 Vpp at THD < 1%. The chip consumes a total power of 14.85 μW using a single 3.3-V power supply. In this work, the small area and efficiently integrated blocks were used to implement the PPG AFE and the silicon area is minimized to 0.8 mm × 0.8 mm.

scholarly journals Multifunctional Ultrahigh Sensitive Microwave Planar Sensor to Monitor Mechanical Motion: Rotation, Displacement, and Stretch

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1184 ◽  
Author(s):  
Mohammad Abdolrazzaghi ◽  
Mojgan Daneshmand
Keyword(s):  
Dynamic Range ◽  
Full Range ◽  
Electric Circuit ◽  
High Sensitivity ◽  
Parameter Extraction ◽  
Split Ring Resonator ◽  
Displacement Sensor ◽  
Rotation Sensor ◽  
Mechanical Deformations ◽  
Electric Circuit Model

This paper presents a novel planar multifunctional sensor that is used to monitor physical variations in the environment regarding distance, angle, and stretch. A double split-ring resonator is designed at 5.2 GHz as the core operating sensor. Another identical resonator is placed on top of the first one. The stacked configuration is theoretically analyzed using an electric circuit model with a detailed parameter extraction discussion. This design is first employed as a displacement sensor, and a compelling high sensitivity of 500 MHz/mm is observed for a wide dynamic range of 0-5 mm. Then, in another configuration, the stacked design is used as a rotation sensor that results in a high sensitivity of 4.5 MHz/ ° for the full range of 0-180 ° . In addition, the stacked resonator is utilized as a strain detector, and a 0–30% stretch is emulated with a linear sensitivity of 12 MHz/%. Measurements are well in congruence with simulated results, which proves the accurate functionality of the sensor in tracking mechanical deformations, all in a single compact contraption.

Efficient Propagation of Epistemic Uncertainty in the Median Ground‐Motion Model in Probabilistic Hazard Calculations

2019 ◽  
Vol 109 (5) ◽  
pp. 2063-2072 ◽  
Author(s):  
Maxime Lacour ◽  
Norman A. Abrahamson
Keyword(s):  
Ground Motion ◽  
Traditional Approach ◽  
Epistemic Uncertainty ◽  
Hazard Analysis ◽  
Full Range ◽  
Motion Model ◽  
Uncertainty Distribution ◽  
Earthquake Scenarios ◽  
Ground Motion Model ◽  
Pc Method

Abstract A computationally efficient methodology for propagating the epistemic uncertainty in the median ground motion in probabilistic seismic hazard analysis is developed using the polynomial chaos (PC) approach. For this application, the epistemic uncertainty in the median ground motion for a specific scenario is assumed to be lognormally distributed and fully correlated across earthquake scenarios. In the hazard calculation, a single central ground‐motion model (GMM) is used for the median along with the epistemic standard error of the median for each scenario. A set of PC coefficients is computed for each scenario and each test ground‐motion level. The additional computation burden in computing these PC coefficients depends on the order of the approximation but is less than computing the median ground motion from one additional GMM. With the PC method, the mean and fractiles of the hazard due to the epistemic uncertainty distribution of the median ground motion are computed as a postprocess that is very fast computationally. For typical values of the standard deviation of epistemic uncertainty in the median ground motion (<0.2 natural log units), the methodology accurately estimates the epistemic uncertainty distribution of the hazard over the 1%–99% range. This full epistemic range is not well modeled with just a small number of GMM branches uses in the traditional logic‐tree approach. The PC method provides more accuracy, faster computation, and reduced memory requirements than the traditional approach. For large values of the epistemic uncertainty in the median ground motion, a higher order of the PC expansion may be needed to be included to capture the full range of the epistemic uncertainty.

scholarly journals A 640×512 CMOS image sensor with ultrawide dynamic range floating-point pixel-level ADC

1999 ◽  
Vol 34 (12) ◽  
pp. 1821-1834 ◽  
Author(s):  
D.X.D. Yang ◽  
A.E. Gamal ◽  
B. Fowler ◽  
H. Tian
Keyword(s):  
Dynamic Range ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Floating Point

scholarly journals A fixed-point implementation of tone mapping operation for HDR images expressed in floating-point format

2014 ◽  
Vol 3 ◽  
Author(s):  
Toshiyuki Dobashi ◽  
Atsushi Tashiro ◽  
Masahiro Iwahashi ◽  
Hitoshi Kiya
Keyword(s):  
Fixed Point ◽  
Dynamic Range ◽  
Floating Point ◽  
Tone Mapping ◽  
Fixed Point Arithmetic ◽  
Memory Cost ◽  
Point Data ◽  
Point Arithmetic ◽  
Intermediate Format ◽  
Hdr Image

A tone mapping operation (TMO) for HDR images with fixed-point arithmetic is proposed. A TMO generates a low dynamic range (LDR) image from a high dynamic range (HDR) image by compressing its dynamic range. Since HDR images are generally expressed in a floating-point data format, a TMO also deals with floating-point data even though resulting LDR images have integer data. As a result, conventional TMOs require many resources such as computational and memory cost. To reduce the resources, an integer TMO which treats a floating-point number as two 8-bit integer numbers was proposed. However, this method has the limitation of available input HDR image formats. The proposed method introduces an intermediate format to relieve the limitation of input formats, and expands the integer TMO for the intermediate format. The proposed integer TMO can be applied for multiple formats such as the RGBE and the OpenEXR. Moreover, the method can conduct all calculations in the TMO with fixed-point arithmetic. Using both integer data and fixed-point arithmetic, the method reduces not only the memory cost, but also the computational cost. The experimental and evaluation results show that the proposed method reduces the computational and memory cost, and gives almost same quality of LDR images, compared with the conventional method with floating-point arithmetic.

scholarly journals High-Radix Formats for Enhancing Floating-Point FPGA Implementations

2021 ◽  
Author(s):  
Julio Villalba ◽  
Javier Hormigo
Keyword(s):  
Execution Time ◽  
Digital Filters ◽  
Dynamic Range ◽  
Floating Point ◽  
Input Output ◽  
Point Support ◽  
Point Representation ◽  
High Radix ◽  
The Cost ◽  
Very High

AbstractThis article proposes a family of high-radix floating-point representation to efficiently deal with floating-point addition in FPGA devices with no native floating-point support. Since variable shifter implementation (required in any FP adder) has a very high cost in FPGA, high-radix formats considerably reduce the number of possible shifts, decreasing the execution time and area highly. Although the high-radix format produces also a significant penalty in the implementation of multipliers, the experimental results show that the adder improvement overweights the multiplication penalty for most of the practical and common cases (digital filters, matrix multiplications, etc.). We also provide the designer with guidelines on selecting a suitable radix as a function of the ratio between the number of additions and multiplications of the targeted algorithm. For applications with similar numbers of additions and multiplications, the high-radix version may be up to 26% faster and even having a wider dynamic range and using higher number of significant bits. Furthermore, thanks to the proposed efficient converters between the standard IEEE-754 format and our internal high-radix format, the cost of the input/output conversions in FPGA accelerators is negligible.

Use of a vibrating beam MEMS accelerometer for surface microgravimetry

2021 ◽  
Author(s):  
Adrian Topham ◽  
Milind Pandit ◽  
Zhijun Du ◽  
Guillermo Sobreviela ◽  
Douglas Young ◽  
...  
Keyword(s):  
Ground Motion ◽  
Dynamic Range ◽  
Digital Signal ◽  
Statistical Correlation ◽  
Earth Tides ◽  
Integration Time ◽  
Mems Accelerometer ◽  
Loading Effects ◽  
Ocean Loading ◽  
Teleseismic Events

&lt;p&gt;A vibrating beam MEMS gravimeter with an Allan deviation of 9 &amp;#956;Gal for a 1000 s integration time, a noise floor of 10 &amp;#956;Gal/&amp;#8730;Hz, and measurement over the full &amp;#177;1 g dynamic range (1 g = 9.81 ms&lt;sup&gt;&amp;#8722;2&lt;/sup&gt;) is presented. In addition to a direct digital signal output, the sensor system possesses built-in tilt compensation capabilities and a 2-stage temperature control that is stable to 500 &amp;#181;K.&lt;/p&gt;&lt;p&gt;Instances of Earth tidal tracking and ground motion records corresponding to several teleseismic events are demonstrated. The output response from tracking of the Earth tides is compared to the data obtained from the software TSoft and a statistical correlation R of 0.92 is obtained between the conditioned MEMS dataset over a period of ~4 days and the predicted Earth tides model from TSoft following correction for ocean loading effects.&lt;/p&gt;&lt;p&gt;The device also recorded the ground motion from several teleseismic events during the testing period, a prominent event among them is the 6.2 M&lt;sub&gt;L&lt;/sub&gt; earthquake near to Petrinja, Croatia, which occurred on December 29&lt;sup&gt;th&lt;/sup&gt;, 2020. The MEMS sensor has demonstrated excellent performance as a long-period seismometer and the response is compared to the seismograms recorded by two nearby BGS broadband seismic stations.&amp;#160;&lt;/p&gt;&lt;p&gt;Advances in microgravity sensor detection capability will be shown to match feasibility modelling for void detection. Results demonstrate that a vibrating beam MEMS accelerometer can be used for measurements requiring high levels of stability and resolution with wider implications for precision measurement. Gravimetry use to warn of imminent failures due to a range of shallow hazards include assessing damage in the built environment, transmission losses in utilities, territory breach and storage containment loss.&lt;/p&gt;

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