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EMC and Wireless Technologies
Published in Christos Christopoulos, Principles and Techniques of Electromagnetic Compatibility, 2022
The dynamic range is the ratio of the maximum to the minimum signal that can be measured. The maximum is normally determined by saturation and is typically the reference supply voltage. The minimum is set by noise and uncertainty. In an ADC, the number of bits N puts limits on the dynamic range. The least significant bit (LSB) determines the minimum detectable signal,and the maximum is therefore 2N–1. Hence, DR=20log((2N−1)LSBLSB)≈6N,dB
Analytical Techniques for Ultra-Wideband Signals
Published in James D. Taylor, Introduction to Ultra-Wideband Radar Systems, 2020
Muriladhar Rangaswamy, Tapan K. Sarkar
Broadband characterization can also be performed in the frequency domain. The measurements are generally done by sweeping a narrow band of frequencies across the entire spectrum of interest. In this way the complex (both magnitude and phase) transfer function of the system can be generated. Since the bandwidth of the measurement system can be made arbitrarily small (less than 0.01 %), the noise floor of the measurement system can be brought down drastically. Approximately 100 dB of dynamic range, equivalent to greater than 16 bits of data, can easily be obtained; however, the price paid for this is a very expensive and complex measurement setup. To perform the complex amplitude and phase measurements, one typically needs a vector network analyzer which itself costs approximately $250,000. In addition, an anechoic chamber is needed to eliminate the undesired responses and multiple reflections. The chamber itself can cost several hundred thousands to millions of dollars depending on the size. On the other hand, the measurement environment can be controlled quite accurately in an anechoic chamber contributing to a large dynamic range of the system.
Basic Physics of Ultrasound
Published in Asim Kurjak, Ultrasound and Infertility, 2020
When speaking about the dynamic range of bright dots seen on a TV screen, we mean the ratio of brightnesses of the brightest and the least bright spot still visible on the screen. If we speak of the dynamic range of echo intensities of interest, we mean the ratio of the largest and the smallest echo still interesting for our purpose. When speaking about the dynamic range of our amplifier, we mean the ratio of the largest and the smallest signal which can still correctly be amplified without being cut off or saturated. A broad dynamic range of gray-scale representation of echoes on the display means that we shall see the very large and the very small echoes represented at the same time in the same image with different shades of gray. The image is “soft”. A narrow dynamic range of echoes representation on a gray-scale display means that there will be fewer gray tones at our disposal for representing different echo intensities; the image is “hard”. For general examination where we wish to get some information on everything in the scanner field of view, a broad dynamic range is useful. If we wish to measure precisely only the most prominent structures like bones of a fetus, a lower dynamic and lower sensitivity image are more useful.
A Comprehensive Site Response and Site Classification of the Garhwal-Kumaun Himalaya, Central Seismic Gap (CSG), India
Published in Journal of Earthquake Engineering, 2022
Ramesh Pudi, Santosh Joshi, Tapas R. Martha, Rajeev Upadhyay, Charu C. Pant
We investigated the site response parameters of 97 sites using the data obtained from microtremor observations, strong ground motion (SGM), and broadband seismic records as shown in Fig. 2. The details of site locations and their corresponding geology are given in table S1 (Appendix-I). We carried out the site response analysis from 37 microtremor site observations in the Kumaun-Garhwal region for the period of 2017 with a recording duration of 45 to 60 minutes at each investigated site (Pudi et al. 2020). The data were collected using the MR 2002-CE data logger coupled with the MS 2003+ sensor (3 component triaxial velocity meter) from SYSCOME instrumentation. The MS 2003+ velocity sensor is highly sensitive and consists of three orthogonal components as two horizontal (or orthogonal and radial) components (H) and one vertical (V) component. The instrument is a 16-bit system with a dynamic range of 96 dB. The sensor frequency range is from 1 to 315 Hz with more than 110 dB Signal to Noise Ratio. The data recorded at a sampling rate of 200 samples per second and the baseline correction was done by leveling the instrument on the ground to ensure that the recorded signal is centred on zero (Pudi et al. 2020). Subsequently, we collected the strong ground motion (SGM) data from the Program for Excellence of Strong Motion Studies (PESMOS) network stations maintained by the Indian Institute of Technology (IIT) Roorkee (http://pesmos.in/2011/) and currently operated by the National Centre of Seismology (NCS), New Delhi. The recorded earthquake events from this network have been used in previous studies (e.g., Harinarayan and Kumar 2018a, b; Anbazhagan et al. 2019a; Sandhu et al. 2020). An example of time series data is depicted in Fig. 3. These strong-motion accelerograph stations were installed mainly in three geological entities such as hard rock, moderately soft and very soft soil sites which covered the seismic zones of III, IV, and V as per IS 1893–2002 (Part 1) (2002). The sites have been classified based on geology as reported by Mittal, Kumar, and Ramhmachhuani (2012). The PESMOS instrumentation consists of an internal AC-63 GeoSIG triaxial force-balanced accelerometer and GSR GeoSIG 18-bit digitizer with an external GPS. All the instruments across the region have a 200 Hz sampling frequency and comprise three components of recording in two orthogonal directions i.e., N-S or E-W and one in vertical direction i.e., Z component. The present study has used the database available from 2005 to 2017 that were already pre-processed along with baseline correction and smoothed by a low-pass filter with a cut-off frequency at 35 Hz. For the HVSR analysis, we have considered 58 events (magnitude> 3) that were recorded by 54 strong-motion stations (Table 1). Also, we have used the ambient noise data from the Seismic Network of the Kumaun Himalaya (SNKH) that consists of six broadband seismic stations operated by the Department of Geology, Kumaun University, Nainital. The seismic stations are equipped with a Trillium seismometer with a dynamic range of >138 dB, along with a 24-bit Taurus data logger and a Global Position System (GPS). The common frequency bandwidth range is between 0.003 Hz and 50 Hz with a sampling rate of 100 samples per second.