Definition of signal-to-noise ratio and its critical role in split-beam measurements

Kieser, R.; Reynisson, Páll; Mulligan, T. J.

doi:10.1016/j.icesjms.2004.09.006

Cited by 33 publications

(14 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This implies that all hydroacoustic methods (and their limitations), which have been established for assessment of fish size spectrum and abundance (e.g., Kieser et al 2005;Simmonds and MacLennan 2005), can also be applicable for quantification of bubbles rising from the sediments. On the other hand, similarity of the acoustic sizes of fish and bubbles may require the elaboration of special approaches for hydroacoustic differentiation of both types of targets in the water column.…”

Section: Discussionmentioning

confidence: 99%

Quantifying gas ebullition with echosounder: the role of methane transport by bubbles in a medium‐sized lake

Ostrovsky

Mcginnis

Lapidus

et al. 2008

Limnology & Ocean Methods

160

165

View full text Add to dashboard Cite

In lakes and reservoirs with variable water level, gas ebullition can play a substantial role in methane transport in the water column and to the atmosphere. However, measuring methane ebullition from sediment is difficult as releases are highly heterogeneous and intermittent on macro- and micro-scales. In contrast to conventional gas traps and optical methods, hydroacoustic technology allows rapid scanning over large volumes of the water column synoptically to quantify gas bubble abundance. A 120-kHz dual beam downward-looking echosounder was used to measure the size distributions of bubbles that do not resonate at the sonar frequency. Data obtained with this sonar permit accurate calculation and evaluation of ebullition flux from the bottom. A robust relationship was established between gas volumes and backscattering cross-section of individual bubbles in experimental conditions, and rise velocities of bubbles were precisely measured. The volume backscattering coefficient was shown to be a good gauge of the total volume of bubbles per cubic meter of water, allowing the use of a single-beam sonar for measuring volumetric bubble concentrations. Data obtained from hydroacoustic surveys on Lake Kinneret, where gaseous methane is emitted from randomly dispersed sediment sources, indicated that ~90% of bubbles escaping from soft sediments ranged from 1.3 mm to 4.5 mm and ~50% ranged from 2.0 mm to 3.2 mm in equivalent radius. In summer-fall 2001, the gaseous methane fluxes from hypolimnetic sediments was ~10 mmol m-2 d-1, accounting for one-third of the observed methane accumulation in the hypolimnion. This relatively high ebullition rate could be attributed to the gradual decreasing of the mean water level in preceding years

show abstract

Section: Discussionmentioning

confidence: 99%

Quantifying gas ebullition with echosounder: the role of methane transport by bubbles in a medium‐sized lake

Ostrovsky

Mcginnis

Lapidus

et al. 2008

Limnology & Ocean Methods

160

165

View full text Add to dashboard Cite

show abstract

“…Additionally to the mentioned loss of small fish near the beam border, the additive noise increases the average TS level and affects the single fish detectors of the split or dual beam techniques. The expected additional bias is about 0.2 to 0.5 dB, for a standard 7 0 beam-width transducer, with 38 kHz pulses on targets of -30 dB size (on-axis values), insonified at 150-200 m depth (Kieser et al, 2005). For smaller targets this bias can be higher.…”

Section: Simulated Fish Trackingmentioning

confidence: 94%

“…Specifically, small pelagic species backscatter echoes with low signal-to-noise ratio (SNR). Experimental (Reynisson & Sigurdsson, 1996) as well as simulation studies (Ehrenberg & Torkelson, 1996;Kieser et al, 2005) predict that a decrease in SNR tends to increase the bias in TS estimates. Additionally to the mentioned loss of small fish near the beam border, the additive noise increases the average TS level and affects the single fish detectors of the split or dual beam techniques.…”

Section: Simulated Fish Trackingmentioning

confidence: 99%

Accuracy of Acoustic Methods in Fish Stock Assessment Surveys

Georgakarakos¹,

Trygonis²,

Haralabous³

2011

Sonar Systems

View full text Add to dashboard Cite

“…where L is the length of the signal vector and n(i) is the noise of the actual signal value. The noise is obtained by subtracting the actual signal value from the mean value of the entire signal vector [33]. Figure 12 shows the estimated inductance in case the actuator is at zero mean current and is fully opened (x = 8 mm).…”

Section: Noise Power Of the Discussed Approachesmentioning

confidence: 99%

Analysis of Current Ripples in Electromagnetic Actuators with Application to Inductance Estimation Techniques for Sensorless Monitoring

König¹,

Nienhaus²,

Grasso³

2020

Actuators

View full text Add to dashboard Cite

Techniques for estimating the plunger position have successfully proven to support operation and monitoring of electromagnetic actuators without the necessity of additional sensors. Sophisticated techniques in this field make use of an oversampled measurement of the rippled driving current in order to reconstruct the position. However, oversampling algorithms place high demands on AD converters and require significant computational effort which are not desirable in low-cost actuation systems. Moreover, such low-cost actuators are affected by eddy currents and parasitic capacitances, which influence the current ripple significantly. Therefore, in this work, those current ripples are modeled and analyzed extensively taking into account those effects. The Integrator-Based Direct Inductance Measurement (IDIM) technique, used for processing the current ripples, is presented and compared experimentally to an oversampling technique in terms of noise robustness and implementation effort. A practical use case scenario in terms of a sensorless end-position detection for a switching solenoid is discussed and evaluated. The obtained results prove that the IDIM technique outperforms oversampling algorithms under certain conditions in terms of noise robustness, thereby requiring less sampling and calculation effort. The IDIM technique is shown to provide a robust position estimation in low-cost applications as in the presented example involving a end-position detection.

show abstract

Definition of signal-to-noise ratio and its critical role in split-beam measurements

Cited by 33 publications

References 10 publications

Quantifying gas ebullition with echosounder: the role of methane transport by bubbles in a medium‐sized lake

Quantifying gas ebullition with echosounder: the role of methane transport by bubbles in a medium‐sized lake

Accuracy of Acoustic Methods in Fish Stock Assessment Surveys

Analysis of Current Ripples in Electromagnetic Actuators with Application to Inductance Estimation Techniques for Sensorless Monitoring

Contact Info

Product

Resources

About