Ping Rate Research Articles

Measurements and Analyses of 4G/5G Mobile Broadband Networks: An Overview and a Case Study

Mobile data has become an integral part of everyday life, making Internet trends more and more profound and deeply embedded in life and the future. Mobile broadband (MBB) is one of the main aims of fifth-generation (5G) networks due to unprecedented growth in data demand. However, 5G networks are not yet deployed in many countries, whereas existing MBB networks, such as third generation (3G) and fourth generation (4G), are available in most world countries. As a result, there is a need to monitor and troubleshoot end-to-end network performance and ensure a better user experience. This paper provides an overview of MBB networks in terms of deployment environments, performance metrics, and implementation scenarios. It highlights the most important criteria for assessing MBB performance and the applications and measurement methods utilized, such as external and internal measurements and the classification of geographical areas. In addition, it provides measurement-based performance analyses of two existing mobile network operators (MNOs) (Omantel and Ooredoo) in the Sultanate of Oman. This performance analysis uses data measurements in various indoor and outdoor environments in five cities (Muscat, Ibra, Sur, Bahla, and Al kamil Wal Wafi). Several performance metrics are considered, such as signal level and quality, throughput, ping rate, and handover. Experimental results demonstrate that the 4G networks were the dominant networks in all measured locations for indoor and outdoor scenarios. Moreover, 5G data measurements are also recorded in the capital city of Oman, Muscat. The results of the 5G measurements show that both MNOs achieved a higher data rate with a lower ping rate.

Compression of Multibeam Echosounders Bathymetry and Water Column Data

Over the past decade, Multibeam Echosounders (MBES) have become one of the most used techniques in sea exploration. Modern MBES are capable of acquiring both bathymetric information on the seafloor and the reflectivity of the seafloor and water column. Water column imaging MBES surveys acquire significant amounts of data with rates that can exceed several GB/h depending on the ping rate. These large file sizes obtained from recording the full water column backscatter make remote transmission difficult if not prohibitive with current technology and bandwidth limitations. In this paper, we propose an algorithm to decorrelate water column and bathymetry data, focusing on the KMALL format released by Kongsberg Maritime in 2019. The pre-processing stage is integrated into FAPEC, a data compressor originally designed for space missions. Here, we test the algorithm with three different datasets: two of them provided by Kongsberg Maritime and one dataset from the Gulf of Mexico provided by Fugro USA Marine. We show that FAPEC achieves good compression ratios at high speeds using the pre-processing stage proposed in this paper. We also show the advantages of FAPEC over other lossless compressors as well as the quality of the reconstructed water column image after lossy compression at different levels. Lastly, we test the performance of the pre-processing stage, without the constraint of an entropy encoder, by means of the histograms of the original samples and the prediction errors.

Are universal beamformers passive cognitive sonar systems?

Cognitive sonars dynamically tune system parameters to improve performance in pursuit of specific goals. Most research on cognitive sonar focuses on active sonar, varying the transmitted waveform and ping rate. Although passive sonar also faces the challenges of pursuing goals in varying and unknown environments, little research has been done exploring cognitive approaches to passive beamforming for sonar arrays. Universal beamformers provide one implementation of a cognitive approach to passive sonar. Practical adaptive beamformers generally regularize the sample covariance matrix before estimating the array weights. Universal beamformers blend the array weights across a family of beamformers competing on different choices for the regularization parameters. The blend of array weights is performance driven based, including the largest portion from the beamformers best suited for the current environment. Universal are “doubly adaptive” in that each competing beamformer is adapting its array weight vector in response to the data observed at the sensor array, the universal algorithm is then meta-adapting the blend of these array weight vectors used to process the data based on the performance of each competing beamformer. We will present examples of beamformers, which are universal over dominant subspace dimension and beam pattern notch width for moving interferers. [Work supported by ONR 321US.]

A miniature biomimetic sonar and movement tag to study the biotic environment and predator-prey interactions in aquatic animals

How predators find, select and capture prey is central to understanding trophic cascades and ecosystem structure. But despite advances in biologging technology, obtaining in situ observations of organisms and their interactions remains challenging in the marine environment. For some species of toothed whales, echoes from organisms insonified by echolocation clicks and recorded by sound logging tags have provided a fine-scale view of prey density, and predator and prey behaviour during capture attempts, but such information is not available for marine predators that do not echolocate. Here the development and performance of a miniature biomimetic sonar and movement tag capable of acquiring similar data from non-echolocating marine predators is reported. The tag, weighing 200 g in air, records wide bandwidth sonar data at up to 50 pings a second synchronously with fast-sampling sensors for depth, acceleration, magnetic field and GPS. This sensor suite enables biotic conditions and predator behaviour to be related to geographic location over long-duration foraging trips by apex marine predators. The sonar operates at 1.5 MHz with a 3.4° beamwidth and a source level of 190 dB re 1 μPa at 1 m. Sonar recordings from a trial deployment of the tag on a southern elephant seal contained frequent targets corresponding to small organisms up to 6 m ahead of the tagged animal. Synchronously sampled movement data allowed interpretation of whether the seal attempted to capture organisms that it approached closely while the high sonar ping rate revealed attempts by prey to escape. Results from this trial demonstrate the ability of the tag to quantify the biotic environment and to track individual prey captures, providing fine-scale information on predator-prey interactions which has been difficult to obtain from non-echolocating marine animals.

Retention and effects of miniature transmitters in juvenile American eels

The purpose of this study was to assess the effects of an acoustic micro transmitter (tag) on survival and swimming ability of juvenile American eels (Anguilla rostrata). The transmitter was designed for implantation through a<3mm opening into the body cavity of anguilliform fishes without the need for sutures. Potential transmitter effects on swimming performance were examined by comparing critical swimming speeds (Ucrit, an index of prolonged swimming performance) for six size groups (n=120, 113–175 mm) of tagged and non-tagged eels. There was no significant difference in Ucrits between tagged and non-tagged eels. Median Ucrits for tagged eels ranged from 50.2cm/s for the smallest group tested (113–119mm) to 63.9cm/s for eels 141–150mm in length. Non-tagged group median Ucrits ranged from 47.2cm/s for the smallest group to 66.9cm/s for the 141–150mm group. An additional 26 eels (115–208mm) were tagged and held for 38days (without undergoing swimming performance tests) to assess survival and tag loss. No mortality occurred during the holding period and a tag loss of 3.8% (n=1) was observed within the first 20days post-tagging, which is the current projected battery life of the tag at a 5s ping rate interval. Tag loss increased to 50% overall (n=13) for eels held up to 38days. Our results indicate that micro acoustic tags can be successfully implanted in juvenile American eels with no apparent effects on swimming ability or survival, and would be a viable option for examining eel movement patterns in river systems and near hydroelectric facilities.

Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally

Abstract Calise, L., and Knutsen, T. 2012. Multifrequency target strength of northern krill (Meganyctiphanes norvegica) swimming horizontally. – ICES Journal of Marine Science, 69: 119–130. Multifrequency acoustic measurements on ex situ horizontally swimming krill were made in a novel experimental setting. An ensemble of northern krill (Meganyctiphanes norvegica) was introduced to a large enclosure (a mesocosm), and acoustic backscatter was sampled using a multifrequency (70, 120, and 200 kHz) echosounder (Simrad EK60). Two submerged lamps were placed at opposite sides of the mesocosm and switched on and off to induce the krill, by light attraction, to swim horizontally through the acoustic beams. By tracking echoes, animal displacement, swimming speed, and target strength (TS) by frequency were estimated. The dominant and secondary modes of the total-length distribution were 21.8 ± 3.0 and 27.8 ± 2.7 mm, respectively. Although krill orientation was assumed stable and the ping rate was high, the range and inter-ping variability of the average TS values were large, decreasing and increasing with frequency, respectively. The overall TS frequency response observed and concurrent measurements at 120 and 200 kHz confirm the theoretical expectation that the acoustic backscatter from the investigated organisms were confined to the Rayleigh and Geometric scattering regions, a finding that might both aid acoustic identification and size-group separation of in situ northern krill.

Evaluation of a gravel transport sensor for bed load measurements in natural flows

A recent acoustic instrument (Gravel Transport Sensor, GTS) was tested for predicting sediment transport rate (bed load rate) in gravel bed streams. The GTS operation is based on the particle collision theory of submerged obstacles in fluids. When particles collide with the GTS cylinder their momentum is recorded in the form of ping rates. The GTS is attractive for further consideration here because of its potential to provide continuous unattended local bed load measurements, especially in areas found in streams that access may be difficult under extreme conditions. Laboratory experiments coupled with numerical simulations for the same flow conditions were performed in order to determine the conditions under which particles of different size will hit the GTS cylinder and be able to register a ping rate. The GTS was able to detect the number of particles with diameter in the range of 15.9 to 25.4 mm, with reasonable accuracy, if the applied Shields effective stress τ *e = τ * − τ *cr was in the range of 0.006 to 0.015. A drawback of the tested prototype GTS, however, was that it exerted increased resistance on the incoming particles. The added drag effects increased the overall resistance that was exerted by the flow on particles and thus increased the likelihood that particles will rest in the ambient region of the cylinder instead of hitting it. Numerical simulation of the flow around the GTS cylinder revealed that changing the prototype geometry from cylindrical to ellipsoid or rhomboid will increase the likelihood of the particles hitting the instrument under the same flow conditions failed by the original tested GTS cylinder.

Applications of compression techniques for reducing the size of multibeam sonar records

High efficiency of multibeam sonar system (MBS) hardware due to operational requirements (i.e., high frequency, high ping rate, and high resolution of collected data) results in very large volumes of datasets stored on local hard drives of operator's station. In this context, the process of archiving of such warehouse of data collected in previous surveys becomes crucial problem. The paper investigates various lossy and lossless compression methods that can be applied to multibeam sonar data to reduce the size of acquired files without loosing relevant information. The specific character of MBS data allows applying various signal, image, and video compression methods to achieve better results than when using standard ones. Various techniques of reordering the data were analysed to achieve best possible compression ratio.

Multibeam sonar observations of near-surface bubbles during a storm

In October 2006, a reson SeaBat 7125 multibeam sonar (400 kHz) mounted on the drop keel of the R/V Hugh Sharp was used to collect acoustic backscatter from bubbles generated by breaking wind-waves in the Gulf of Maine. The multibeam sonar has a very high spatial resolution, with 256 1.0×0.5 deg beams. The data of interest here were collected as the ship returned to port because of bad weather (sustained 15 m/s wind speed), traveling through the plumes of breaking waves. Data were collected at a ping rate that varied between 5–10 pings/s. These observations show frequent breaking wave bubble plumes extending up to 12 m deep. The data also show that preferential concentrations of bubbles (clusters) were often present. Correlation functions (e.g., the pair correlation) describing the bubble clustering have been extracted from this data, and their affect on acoustic propagation characteristics (sound speed, attenuation) will be presented. [Work supported by ONR Ocean Acoustics.]

The impact of observer dynamics on sonar perception

The minimum information necessary for a moving observer to track objects depends on body dynamics, sensor design, sensor configuration, and environmental perturbations. This paper will present governing equations relating sonar measurements to 6 DOF dynamics, and eight nondimensional parameters describing the transitions between various regimes. Using nondimensional analysis, it will be shown that to minimize second-order effects, an observer should increase its ping rate as it approaches a target. Bats have been observed to increase their ping rate as they approach a target [Altringham, Bats: Biology and Behavior (1996)]. Alternatively, an observer might use a target’s angular rate to predict second-order range effects. This requires the angular rate to become observable prior to second-order range effects becoming observable. This yields a design constraint relating velocity, ping rate, and aperture, but not wavelength. Based on this constraint, it appears some marine mammals could track objects in the second-order regime [Au, The Sonar of Dolphins (1993)]. [Work supported by ONR.]

Uncertainties in Estimates of Reynolds Stress and TKE Production Rate Using the ADCP Variance Method

The use of acoustic Doppler current profilers (ADCPs) to measure turbulent parameters via the variance method involves uncertainties due to instrument noise and flow-related errors in measurement. For weak flows, the uncertainty in Reynolds stress measurements arises mainly from instrument noise and is proportional to the square of the velocity standard deviation, while the uncertainty in the corresponding estimates of the rate of production of turbulent kinetic energy (TKE) is proportional to the cube of the velocity standard deviation. For stronger flows, the principal determining parameter is the number of individual independent velocity measurements over which the variance is calculated. These results are validated by detailed analyses of two datasets from an RD Instruments 1.2-MHz Workhorse ADCP, using a ping rate of 2 Hz with ensemble averaging at 0.5 Hz, and a ping rate of 10 Hz with ensemble averaging at 1 Hz, respectively. While increasing ping rate generally reduces the effects of instrument noise, it will not alleviate the influence of flow-related noise once the sampling interval is less than the autocovariance time scale of the turbulence. Using the fast ping rate, the uncertainty in the Reynolds stress due to instrument noise is reduced by a factor of more than 3 to ∼0.02 Pa; in higher energy environments there is a reduction in the uncertainty of about 30%. The observational and theoretical estimates for the reduction in the uncertainty using the fast ping rate are in good agreement.

New system for remotely monitoring the three-dimensional movement of acoustically tagged fish

A passive acoustic tag system was developed to monitor the three-dimensional movements of migrating fish with submeter resolution. The acoustic tag receiver monitors an array consisting of up to 16 omnidirectional hydrophones, with received signals synchronized to determine the arrival times for each pulse transmitted by the acoustic tag. Arrival times are then used to calculate the three-dimensional position of a tagged fish as it moves through the array. Algorithms were developed to precisely calculate the three-dimensional positions of the hydrophones, and of each acoustic tag. Over the last 4 years, this system was used at several dams in the United States. Most studies to date monitored downstream migrating juvenile salmonids as they approached and passed turbine intakes, spillways, and juvenile bypass systems at hydroelectric dams. Fish movement patterns were tracked in three dimensions over time, typically with submeter resolution. Tagged fish were 160–240 mm long. Acoustic tags were approximately 7 mm in diameter by 23 mm long, weighted 2 g, and transmitted at 307 kHz. Tag codes (up to 500), pulse width (typically 1–5 ms), and ping rate (typically 0.3–3 pings/s) were field programmable. Current tags incorporate signal encoding for an improved signal-to-noise ratio, and weigh as little as 1 g.

An evaluation of a steerable sidescan sonar for surveys of near-surface fish

A towed 330 kHz sector scanning sonar was evaluated for surveys of near-surface migratory salmonids ( Oncorhynchus sp.) and other fish in the Strait of Georgia near the mouth of the Fraser River near Vancouver, BC (Canada). Detection of large near-surface fish presents a serious challenge to conventional net trawls or echo-sounder surveys due to vessel avoidance behaviour by the fish. The sonar was towed beside a research vessel on a custom-built towfish at a nominal depth of 18 m. The optimum configuration was determined to be with the sonar scanning a 30° vertical sector oriented perpendicular to the tow direction, at a ping rate of 5 Hz and a sector scan period of 5 s. Fish were detected up to a range of 100 m, limited by systemic noise and backscattered reverberation from the sea surface. Some evidence of vessel-avoidance behaviour by the fish was observed. Near surface temperature and salinity gradients are shown to induce downwards refraction of the sonar beam, resulting in biases in apparent depth and target strength of the fish. A simple model of the sonar performance in this scanning mode, including beam-pattern effects, is used to generate curves of fish target detectability and beam-pattern induced bias as a function of range and fish target strength. After correction for refraction effects, beam-pattern bias, and detectability, the survey results show reasonable agreement with net trawl and riverine escapement data.

Motion compensated high-frequency synthetic aperture sonar

The Coastal Systems Station has recently completed a set of sea tests using a high-frequency synthetic aperture sonar (HFSAS) mounted on a towed underwater vehicle. The processed results from these tests demonstrate that 2.5-cm resolution can be achieved in shallow water from a small physical array. This system had a Doppler unit to control the ping rate, but had no inertial navigation system and depended entirely upon acoustic backscatter from the seabed to correct for vehicle deviations in the line of sight. In these sea tests the dual overlapped phase center technique [Sheriff, Symposium on Autonomous Underwater Vehicle Technology, pp. 236–245, 1992] was used as the motion compensation algorithm. The tests were conducted over a target field in the Gulf of Mexico that contained a variety of targets, both small sphere and minelike targets. This paper will present results from the HFSAS in the form of a point response function and an acoustic image. The HFSAS achieved between 2.5- and 3-cm resolution on the smallest sphere and produced excellent images of the remaining targets out to a range of approximately 70 m. [Work supported by ONR.]

Multibeam sonar image processing and three-dimensional analysis of fish schools

Digital data from a high-resolution multibeam sonar were processed to provide 3-D fish school descriptors. The multibeam sonar operates at a carrier frequency of 455 kHz, with 60 beams of 1.5° each, allowing an observation angle of 90°. The envelope of the signal is sampled every 5 cm. The usual operating range is 100 m with a ping rate of 7 pings/s. This huge amount of data provides larger biovolume samples with higher data resolution than standard fisheries research vertical echosounders used until now to describe fish school structure [C. Scalabrin et al., ICES J. Mar. Sci. 53, 181–188 (1996)]. Furthermore, the use of a multibeam sonar allows construction of 3-D images of fish schools. Data were processed by specially designed image algorithms in order to account for anisotropy in the range and vessel movement direction planes. Three-dimensional analyses such as smoothing, segmentation, visualization of the segmented volume, and its quantification were performed. Three-dimensional patterns description tools (invariant with respect to translation, rotation, and scaling) were studied. These tools might lead to the classification of the detected structures using pattern recognition methods.

Prediction of ping-to-ping cross talk in fisheries sonar

Faster ping rates in fish assessment sonars yield higher spatial resolution information, and can reduce the variance of the target strength estimate by taking multiple measurements on single targets [J. E. Ehrenberg and T. C. Torkelson, ICES J. Mar. Sci. 53, 329–334 (1996)]. However, an effect of this corresponding shorter trigger interval is a decrease in spreading time, causing a reduction of spreading loss from the previous ping such that false echoes can result in deep water if the ping rate is too high. This ping-to-ping cross talk is a function of the ping rate, bottom depth and type, applied TVG, and sound absorption. A method has been developed which estimates the energy loss from a previous ping based on those variables, thus allowing one to establish a maximum ping rate for a desired echo-integration threshold. Deep-water measurements of ping-to-ping cross talk were then taken to validate this method. [Work supported by EVOSTC.]

Constrained iterative deconvolution applied to SeaMARC I sidescan sonar imagery

Images collected by any sidescan sonar system represent the convolution of the acoustic beam pattern of the instrument with the true echo amplitude distribution over the seafloor. At typical low speeds, the 1.7 degrees beam width of SeaMARC I (seafloor mapping and remote characterization) results in multiple insonification of individual targets, particularly at the outside of the swath. A nonlinearly constrained iterative deconvolution technique developed for radar applications can be applied to SeaMARC I imagery to reduce the effect of the beam pattern and equalize the spectral content of the image across the swath. Since the deconvolution is implemented in the along-track direction, the registration of individual scan lines must be precisely corrected before the operator is applied. The deconvolution operator must be modeled to account for beam shape, vehicle speed, swath width, slant range, and ping rate. The method is numerically stable and increases the effective resolution of the image, but results in some loss of dynamic range. The technique is applied to target recognition and imagery from volcanic terrains of the central Juan de Fuca Ridge.

Light activated acoustic pinger

A light activated acoustic pinger that is useful for underwater three dimional homing. The pinger includes a spherical lens system, a tone burst generator electronics system and a high pressure water tight encasement. When a light source used by an underwater diver, submersible, underwater television system or navigator is panned on the pinger lens system in either the X or Y planes the ping rate will vary depending upon the incident angle of the light received by the spherical lens. In addition, moving the light toward the pinger in the Z direction will increase the ping rate. From the ping rate and the movement of the light source in the X, Y and Z directions an underwater navigator can determine the direction of the pinger and target. There is no battery drain until the pinger is activated by light and therefore targets that have been lost for several years may still be found based on battery shelf life.