China
Africa
Explore chapters and articles related to this topic
Sound Measurement and Analysis
Published in Lewis H. Bell, Douglas H. Bell, Industrial Noise Control, 2017
Lewis H. Bell, Douglas H. Bell
Most sound level meter detectors can measure only signal levels that vary over a range of 70 dB. Since the range of sound levels that one might wish to measure spans from 10–140 dB (a 130 dB dynamic range), a user-adjusted amplifier is employed. The range control amplifier allows the user to select a maximum full-scale level. All measurements that are below the full-scale sound level by less than the dynamic range (typically 70 dB as noted for most detectors) are valid. If measured levels fall outside of this range, then the full-scale level can be adjusted appropriately. Proper measurement procedure involves reducing the meter full-scale level until a signal overload indication has occurred. The full-scale level should then be increased one step to prevent overload. In this way the entire detector dynamic range can be utilized.
Measurement fundamentals and instrumentation
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
When procuring instruments, the manufacturer presents accuracy in terms relative to its “% Full Scale” value, i.e., the worst accuracy is compared to the gage’s highest reading. For example, if a pressure gage has a full-scale reading of 1,000 psig and a rated accuracy of ±1% F.S., it is expected to be accurate to within 1,000psig×0.01=±10 psig, high or low (see Figure 1.1). Now assume that this gage is installed on a system whose normal pressure is 100 psig. In this case, it is possible that the true pressure can fall anywhere between 90 psig to 110 psig and still be within specifications. Therefore, even though this gage has ±1% full-scale accuracy, in this application, its accuracy is really within ±10% when used in a 100-psig system: ±10psigdeviation100psigsystempressure×100=±10%accuracy
* Instruments
Published in James P. Lodge, Methods of Air Sampling and Analysis, 2017
To minimize errors when assuming linearity and a single point quality control sample, the standard gas concentration should be selected so as to optimize the most important segment of the data. For example, if peak excursions are important, the instrument should be calibrated at full scale or at the anticipated peak value. If no particular range of values is specially important, calibration should be carried out at mid-range. In some amperometric instruments, reagent deterioration is initially reflected in a falloff at near full-scale response. Such instruments should not be respanned to accommodate this behavior. The reagent should be replaced and the total instrument system completely recalibrated.
Genetic particle filter improved fuzzy-AEEMD for ECG signal de-noising
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Various artifacts are:Power-line interference: PLI or artifact consists of 50–60 Hz power-line frequencies and bandwidth of less than 1 Hz. The amplitude of PLI fluctuates up to 50% of full scale deflection (FSD) level.Baseline wander: Baseline wander artifact occurs mainly due to respiration at the drifting frequencies between 0.15 Hz and 0.3 Hz. Baseline wander artifact is also known as baseline shift or drift.Muscle noise/electromyographic artifact: Electrical bio-potential due to EMG or muscle contraction adulterates the ECG signal. The amplitude of muscle noise fluctuates up to 10% of FSD level with a frequency of 10 KHz.Motion artifact: Motion artifacts are produced due to motion of electrode or change in impedance between electrodes when it is superimposed on the ECG activity then it is known as motion artifact.Electrode contact noise: Contact noise originates due to loss of contact between the subject’s skin and the electrodes.Data-gathering device and electrosurgical noises: It is generated through medical apparatus and signal processing hardware at frequencies between 100 kHz and 1 MHz.
An improved Random Swapping Thermometer Coding (RSTC) Dynamic Element Matching (DEM) method
Published in International Journal of Electronics Letters, 2021
Mohammadreza Armuti, Mehdi Bandali, Omid Hashemipour
Table 1 shows the SFDR and Switching activity of the 6-Bit DAC at and 3.3% mismatch error while employing different DEM methods. According to the results of Table 1, only the SFDR of the RTC DEM method is higher than the SFDR of the proposed DEM method. However, this difference in SFDR is only 0.2 dB, while the Switching activity () of the RTC method is much higher than the Switching activity of the proposed DEM method. The SFDR of the proposed DEM method is 2.1 dB higher than the SFDR of ”RSTC with the restricted jumping technique”, while the difference in Switching activity is only 0.3. Considering that RSTC method’s performance in low frequencies is depended on full-scale and zero input signals (Shen et al., 2010), in lower amplitude than full-scale, the method does not work correctly whereas the proposed method’s performance in low frequencies is independent of input amplitude. In other words, jump technique in ”RSTC with restricted jumping technique” prevents the SFDR reduction in Full-scale and zero inputs, as a result, the RSTC is depended on input amplitude and for non-full-scale inputs, the jump technique triggering does not occur. The proposed method presents a new jump condition that is independent of input amplitude. Lin et al. (2014) and Lin, &Kuo. (2012) use a similar method (RRBS) that is not designed for reducing the switching activity. Therefore, the switching activity is very high in comparison to other DEM methods.
Dispenser-printed sound-emitting fabrics for applications in the creative fashion and smart architecture industry
Published in The Journal of The Textile Institute, 2019
Yi Li, Russel Torah, Yang Wei, Neil Grabham, John Tudor
The audio source emits all frequencies in the audible range from 20 Hz to 20 kHz in the sine sweep mode over a 20 s time span. The audio source output level is −3 dBFS. The unit of dBFS is equivalent to the decibel level relative to the full scale sine wave showing the maximum peak value. Sine sweeps are used as reference tones to observe the frequency response or identify the adverse effects of room modes; for example, the room background noise is typically in the range of 20 to 200 Hz. The sine sweep produces frequencies with a much higher energy compared to pink noise or white noise. A sine sweep produces only one frequency at a time unlike pink or white noise which produces many frequencies simultaneously. The advantage of the sine sweeps is that it ignores the ambient noise in the room offering better immunity for measuring the frequency response at each fixed frequency value.