John R . Potter | Norwegian University of Science and Technology (original) (raw)

Papers by John R . Potter

Frontiers in Marine Science, Apr 28, 2023

Scientific Reports, Nov 10, 2022

Frontiers in Marine Science, Jul 5, 2022

Journal of the Acoustical Society of America, Nov 1, 1990

arXiv (Cornell University), Sep 5, 2022

Secure digital wireless communication underwater has become a key issue as maritime operations sh... more Secure digital wireless communication underwater has become a key issue as maritime operations shift towards employing a heterogeneous mix of robotic assets and as the security of digital systems becomes challenged across all domains. At the same time, a proliferation of underwater signal coding and physical layer options are delivering greater bandwidth and flexibility, but mostly without the standards necessary for interoperability. We address here an essential requirement for security, namely a confirmation of asset identities also known as authentication. We propose, implement, verify and validate an authentication protocol based on the first digital underwater communications standard. Our scheme is applicable primarily to AUVs operating around offshore oil and gas facilities, but also to other underwater devices that may in the future have acoustic modems. It makes communication including command and control significantly more secure, and provides a foundation for the development of more sophisticated security mechanisms.

Sea Surface Sound '94, 1996

ABSTRACT

The Journal of the Acoustical Society of America, 1989

An acoustic propagation experiment was carried out in the Tyrrhenian Sea in October 1985 in which... more An acoustic propagation experiment was carried out in the Tyrrhenian Sea in October 1985 in which signals from a broadband source were recorded at a range of 5 km with a vertical 62-m hydrophone array over a period of 5 days. The experiment, named ‘‘NAPOLI 85,’’ was designed to investigate the transfer function of the ocean medium over an acoustic frequency range from 250–2000 Hz as a function of time and position down the vertical array. The present article describes the experiment and treats the pulse arrival times for one ray path, the lower refracted path. It is found that internal-wave models are not helpful in describing the environment of this experiment. In contrast to most previous experiments of this type, the sound-speed refractive index is dominated by noninternal-wave features. Some of the implications (regarding input to the scattering theory and acquiring environmental measurements) of this are explored. The experimental spatial structure function of the arrival time ...

The Journal of the Acoustical Society of America, 1997

Ambient noise imaging (ANI) between 8–80 kHz has been demonstrated to produce good images at 40-m... more Ambient noise imaging (ANI) between 8–80 kHz has been demonstrated to produce good images at 40-m range using a 3-m aperture. With the two classic forms of sonar, active and passive, marine mammal biosonar has always outperformed man-made sonar of comparable dimensions. It is then natural to ask whether marine mammals may also use this newly discovered ANI technique as part of their sensory arsenal. Twenty odontecetes, for example, may find advantage in not broadcasting their imminent presence in pursuit of an intelligent prey. An odontecete has been observed successfully pursuing live prey without vision and with no echolocation clinks detected on any of several monitoring hydrophones during pursuit. This surprising observation may be explained if biological ANI is a viable option. To test this idea, an ANI simulation model has been adapted to include realistic target responses of fish with swimbladders, and a model of the receiving performance of a tursiops dolphin has been used t...

Proceedings of the 2000 International Symposium on Underwater Technology (Cat. No.00EX418), 2000

ABSTRACT Experiments with channel soundings and acoustic communications were conducted in Norwegi... more ABSTRACT Experiments with channel soundings and acoustic communications were conducted in Norwegian waters. The shallow-water channels are characterized by dispersion in time, due to multipath propagation, and in frequency, due to surface interactions. The performances of two communication schemes, frequency-hopped (FHSS, JANUS) and direct-sequence (DSSS) spread spectrum, are examined. Both schemes use the same bandwidth, coding scheme, net data rate, and carrier frequency. The JANUS receiver is simple to use and fast. DSSS is equipped with a hypothesis-feedback equalizer and operates at high complexity. Inspection of channel-sounding and decoding results of a few thousand transmissions reveals that a basic JANUS decoder requires the presence of a dominant stable path in order to deliver, whereas DSSS more effectively harvests signal energy scattered in delay and frequency. JANUS performance can be greatly improved, however, by adding several optional improvements to the standard receiver.

Annual Reviews in Control, 2015

This paper presents two acoustic-based techniques for Autonomous Underwater Vehicle (AUV) navigat... more This paper presents two acoustic-based techniques for Autonomous Underwater Vehicle (AUV) navigation within an underwater network of fixed sensors. The proposed algorithms exploit the positioning measurements provided by an Ultra-Short Base Line (USBL) transducer on-board the vehicle to aid the navigation task. In the considered framework the acoustic measurements are embedded in the communication network scheme, causing timevarying delays in ranging with the fixed nodes. The results presented are obtained with post-processing elaborations of the raw experimental data collected during the CommsNet13 campaign, organized and scientifically led by the NATO Science and Technology Organization Centre for Maritime Research and Experimentation (CMRE). The experiment involved several research institutions and included among its objectives the evaluation of on-board acoustic USBL systems for navigation and localization of AUVs. The ISME groups of the Universities of Florence and Pisa jointly participated to the experiment with one Typhoon class vehicle. This is a 300 m depth rated AUV with acoustic communication capabilities originally developed by the two groups for archaeological search in the framework of the THESAURUS project. The CommsNet13 Typhoon, equipped with an acoustic modem/USBL head, navigated within the fixed nodes acoustic network deployed by CMRE. This allows the comparison between inertial navigation, acoustic self-localization and ground truth represented by GPS signals (when the vehicle was at the surface).

IEEE Journal of Oceanic Engineering, 2016

ABSTRACT A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sens... more ABSTRACT A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sensors and associated electronics, was designed, built, and tested for ambient noise imaging (ANI) potential in Singapore waters. The system, named Remotely Operated Mobile Ambient Noise Imaging System (ROMANIS), operates over 25–85 kHz, streaming real-time data at 1.6 Gb/s over a fiber optic link. By using sensors that are much larger than half-wavelength at the highest frequency of interest, so with some directionality, good beamforming performance is obtained with a small number of sensors compared to a conventional half-wavelength-spaced array. A data acquisition system consisting of eight single-board computers enables synchronous data collection from all 508 sensors. A dry-coupled neoprene cover is used to encapsulate the ceramic elements as an alternative to potting or oil filling, for easier maintenance. Beamforming is performed in real-time using parallel computing on a graphics processing unit (GPU). Experiments conducted in Singapore waters yielded images of underwater objects at much larger ranges and with better resolution than any previous ANI system. Although ROMANIS was designed for ANI, the array may be valuable in many other applications requiring a broadband underwater acoustic receiving array.

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003

Summary form only given. Male humpback whales (Megaptera novaeangliae) produce long, complex voca... more Summary form only given. Male humpback whales (Megaptera novaeangliae) produce long, complex vocalizations consisting of a hierarchically-structured sequence of distinctive broadband 'units', each of a few seconds' duration. The function of this 'song' remains unclear. Singers are often observed in a stationary position with their body inclined downwards while vocalizing for about 10-12 minutes. The posture is suggestive of the

The ability to effectively communicate underwater has numerous applications for researchers, mari... more The ability to effectively communicate underwater has numerous applications for researchers, marine commercial operators and defence organizations. As electromagnetic waves cannot propagate over long distances in seawater, acoustics provides the most obvious choice of channel. Although acoustics has been used effectively for point-to-point communications in deep-water channels, acoustics has had limited success for horizontal transmissions in shallow water. Time-varying multi-path propagation and non-Gaussian noise are two of the major factors that limit acoustic communication performance in shallow water. Although it is known that medium-range shallow water propagation is dominated by time-varying multipath arrivals, very few measurements of the variability of the multi-path structure are available. In this paper, we present channel measurements made in a shallow water channel (depth 15-20m) up to a range of 1km. An analysis of the temporal variability of the arrival structure is presented. Most communication systems make the assumption that the noise is additive and Gaussian. Snapping shrimp dominate the ambient noise spectrum above a few kHz in warm shallow waters. It is known that snapping shrimp noise is impulsive and highly non-Gaussian. These noise characteristics need to be taken into account when designing communication systems if robust and near-optimal performance is desired. An analysis of the ambient noise characteristics from some warm shallow water channels is also presented.

International Journal of Distributed Sensor Networks, Apr 1, 2012

IEEE Journal of Oceanic Engineering, Oct 1, 2019

W ELCOME to the fourth Special Issue (SI) arising from papers presented at the Underwater Communi... more W ELCOME to the fourth Special Issue (SI) arising from papers presented at the Underwater Communications and Networking (UComms) conferences. This issue brings you extended versions of selected papers that were presented during the last edition of the conference, held in Lerici, Italy, August 28-30, 2018 ("UComms18"). The conference series started in 2012 as a biennial event with the aim of bringing together key contributors in underwater communications to review the state of the art, discuss novel approaches, and share understanding of performance constraints and tradeoffs. Since its beginning, UComms has been gaining credibility as a top-quality international event, bridging the Americas, Europe, and Asia in the area of underwater communications. In total, 95 delegates participated in UComms18, representing institutions from 17 different countries (the largest attendance at a UComms conference). Underwater communication technologies have progressed rapidly in the past couple of decades. Such progress has been achieved both through the development of advanced coherent modulation, demodulation, and coding techniques and by moving from point-to-point systems to multihop networks. At higher communication layers, there have been significant advances in developing medium access control (MAC), routing, and other protocols to maintain efficient and reliable communications. It is also becoming an established fact that the underwater channels can be so diverse and dynamic that there will never be a "one-size-fits-all" solution, so communication systems will need to adaptively reconfigure themselves to the (continuously changing) network topology, environmental, and application needs. These notions are leading toward intelligent and self-adaptive approaches with a high degree of cross-layer connectivity. The 37 papers presented at UComms18 reflected these trends, with an emphasis on channel estimation, cross-layering, and adaptation at different layers of the stack. Below, we take you through the selected papers for this SI. The first paper, "Iterative sparse channel estimation and spatial correlation learning for multichannel acoustic OFDM systems" by Tadayon and Stojanovic, tackles the problem of coherent detection of OFDM signals using a sparse channel estimation that targets the physical propagation paths in a continuous-delay domain. The authors show the effectiveness of their proposed solution through simulation and experimental analysis.

IEEE Journal of Oceanic Engineering, Oct 1, 2017

OCEANS 2016 MTS/IEEE Monterey, 2016

The Centre for Maritime Research and Experimentation (CMRE) is a world-class NATO scientific rese... more The Centre for Maritime Research and Experimentation (CMRE) is a world-class NATO scientific research and experimentation facility located in La Spezia, Italy.

OCEANS 2015 - Genova, 2015

Frontiers in Marine Science, Apr 28, 2023

Scientific Reports, Nov 10, 2022

Frontiers in Marine Science, Jul 5, 2022

Journal of the Acoustical Society of America, Nov 1, 1990

arXiv (Cornell University), Sep 5, 2022

Secure digital wireless communication underwater has become a key issue as maritime operations sh... more Secure digital wireless communication underwater has become a key issue as maritime operations shift towards employing a heterogeneous mix of robotic assets and as the security of digital systems becomes challenged across all domains. At the same time, a proliferation of underwater signal coding and physical layer options are delivering greater bandwidth and flexibility, but mostly without the standards necessary for interoperability. We address here an essential requirement for security, namely a confirmation of asset identities also known as authentication. We propose, implement, verify and validate an authentication protocol based on the first digital underwater communications standard. Our scheme is applicable primarily to AUVs operating around offshore oil and gas facilities, but also to other underwater devices that may in the future have acoustic modems. It makes communication including command and control significantly more secure, and provides a foundation for the development of more sophisticated security mechanisms.

Sea Surface Sound '94, 1996

ABSTRACT

The Journal of the Acoustical Society of America, 1989

An acoustic propagation experiment was carried out in the Tyrrhenian Sea in October 1985 in which... more An acoustic propagation experiment was carried out in the Tyrrhenian Sea in October 1985 in which signals from a broadband source were recorded at a range of 5 km with a vertical 62-m hydrophone array over a period of 5 days. The experiment, named ‘‘NAPOLI 85,’’ was designed to investigate the transfer function of the ocean medium over an acoustic frequency range from 250–2000 Hz as a function of time and position down the vertical array. The present article describes the experiment and treats the pulse arrival times for one ray path, the lower refracted path. It is found that internal-wave models are not helpful in describing the environment of this experiment. In contrast to most previous experiments of this type, the sound-speed refractive index is dominated by noninternal-wave features. Some of the implications (regarding input to the scattering theory and acquiring environmental measurements) of this are explored. The experimental spatial structure function of the arrival time ...

The Journal of the Acoustical Society of America, 1997

Ambient noise imaging (ANI) between 8–80 kHz has been demonstrated to produce good images at 40-m... more Ambient noise imaging (ANI) between 8–80 kHz has been demonstrated to produce good images at 40-m range using a 3-m aperture. With the two classic forms of sonar, active and passive, marine mammal biosonar has always outperformed man-made sonar of comparable dimensions. It is then natural to ask whether marine mammals may also use this newly discovered ANI technique as part of their sensory arsenal. Twenty odontecetes, for example, may find advantage in not broadcasting their imminent presence in pursuit of an intelligent prey. An odontecete has been observed successfully pursuing live prey without vision and with no echolocation clinks detected on any of several monitoring hydrophones during pursuit. This surprising observation may be explained if biological ANI is a viable option. To test this idea, an ANI simulation model has been adapted to include realistic target responses of fish with swimbladders, and a model of the receiving performance of a tursiops dolphin has been used t...

Proceedings of the 2000 International Symposium on Underwater Technology (Cat. No.00EX418), 2000

ABSTRACT Experiments with channel soundings and acoustic communications were conducted in Norwegi... more ABSTRACT Experiments with channel soundings and acoustic communications were conducted in Norwegian waters. The shallow-water channels are characterized by dispersion in time, due to multipath propagation, and in frequency, due to surface interactions. The performances of two communication schemes, frequency-hopped (FHSS, JANUS) and direct-sequence (DSSS) spread spectrum, are examined. Both schemes use the same bandwidth, coding scheme, net data rate, and carrier frequency. The JANUS receiver is simple to use and fast. DSSS is equipped with a hypothesis-feedback equalizer and operates at high complexity. Inspection of channel-sounding and decoding results of a few thousand transmissions reveals that a basic JANUS decoder requires the presence of a dominant stable path in order to deliver, whereas DSSS more effectively harvests signal energy scattered in delay and frequency. JANUS performance can be greatly improved, however, by adding several optional improvements to the standard receiver.

Annual Reviews in Control, 2015

This paper presents two acoustic-based techniques for Autonomous Underwater Vehicle (AUV) navigat... more This paper presents two acoustic-based techniques for Autonomous Underwater Vehicle (AUV) navigation within an underwater network of fixed sensors. The proposed algorithms exploit the positioning measurements provided by an Ultra-Short Base Line (USBL) transducer on-board the vehicle to aid the navigation task. In the considered framework the acoustic measurements are embedded in the communication network scheme, causing timevarying delays in ranging with the fixed nodes. The results presented are obtained with post-processing elaborations of the raw experimental data collected during the CommsNet13 campaign, organized and scientifically led by the NATO Science and Technology Organization Centre for Maritime Research and Experimentation (CMRE). The experiment involved several research institutions and included among its objectives the evaluation of on-board acoustic USBL systems for navigation and localization of AUVs. The ISME groups of the Universities of Florence and Pisa jointly participated to the experiment with one Typhoon class vehicle. This is a 300 m depth rated AUV with acoustic communication capabilities originally developed by the two groups for archaeological search in the framework of the THESAURUS project. The CommsNet13 Typhoon, equipped with an acoustic modem/USBL head, navigated within the fixed nodes acoustic network deployed by CMRE. This allows the comparison between inertial navigation, acoustic self-localization and ground truth represented by GPS signals (when the vehicle was at the surface).

IEEE Journal of Oceanic Engineering, 2016

ABSTRACT A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sens... more ABSTRACT A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sensors and associated electronics, was designed, built, and tested for ambient noise imaging (ANI) potential in Singapore waters. The system, named Remotely Operated Mobile Ambient Noise Imaging System (ROMANIS), operates over 25–85 kHz, streaming real-time data at 1.6 Gb/s over a fiber optic link. By using sensors that are much larger than half-wavelength at the highest frequency of interest, so with some directionality, good beamforming performance is obtained with a small number of sensors compared to a conventional half-wavelength-spaced array. A data acquisition system consisting of eight single-board computers enables synchronous data collection from all 508 sensors. A dry-coupled neoprene cover is used to encapsulate the ceramic elements as an alternative to potting or oil filling, for easier maintenance. Beamforming is performed in real-time using parallel computing on a graphics processing unit (GPU). Experiments conducted in Singapore waters yielded images of underwater objects at much larger ranges and with better resolution than any previous ANI system. Although ROMANIS was designed for ANI, the array may be valuable in many other applications requiring a broadband underwater acoustic receiving array.

Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003

Summary form only given. Male humpback whales (Megaptera novaeangliae) produce long, complex voca... more Summary form only given. Male humpback whales (Megaptera novaeangliae) produce long, complex vocalizations consisting of a hierarchically-structured sequence of distinctive broadband 'units', each of a few seconds' duration. The function of this 'song' remains unclear. Singers are often observed in a stationary position with their body inclined downwards while vocalizing for about 10-12 minutes. The posture is suggestive of the

The ability to effectively communicate underwater has numerous applications for researchers, mari... more The ability to effectively communicate underwater has numerous applications for researchers, marine commercial operators and defence organizations. As electromagnetic waves cannot propagate over long distances in seawater, acoustics provides the most obvious choice of channel. Although acoustics has been used effectively for point-to-point communications in deep-water channels, acoustics has had limited success for horizontal transmissions in shallow water. Time-varying multi-path propagation and non-Gaussian noise are two of the major factors that limit acoustic communication performance in shallow water. Although it is known that medium-range shallow water propagation is dominated by time-varying multipath arrivals, very few measurements of the variability of the multi-path structure are available. In this paper, we present channel measurements made in a shallow water channel (depth 15-20m) up to a range of 1km. An analysis of the temporal variability of the arrival structure is presented. Most communication systems make the assumption that the noise is additive and Gaussian. Snapping shrimp dominate the ambient noise spectrum above a few kHz in warm shallow waters. It is known that snapping shrimp noise is impulsive and highly non-Gaussian. These noise characteristics need to be taken into account when designing communication systems if robust and near-optimal performance is desired. An analysis of the ambient noise characteristics from some warm shallow water channels is also presented.

International Journal of Distributed Sensor Networks, Apr 1, 2012

IEEE Journal of Oceanic Engineering, Oct 1, 2019

W ELCOME to the fourth Special Issue (SI) arising from papers presented at the Underwater Communi... more W ELCOME to the fourth Special Issue (SI) arising from papers presented at the Underwater Communications and Networking (UComms) conferences. This issue brings you extended versions of selected papers that were presented during the last edition of the conference, held in Lerici, Italy, August 28-30, 2018 ("UComms18"). The conference series started in 2012 as a biennial event with the aim of bringing together key contributors in underwater communications to review the state of the art, discuss novel approaches, and share understanding of performance constraints and tradeoffs. Since its beginning, UComms has been gaining credibility as a top-quality international event, bridging the Americas, Europe, and Asia in the area of underwater communications. In total, 95 delegates participated in UComms18, representing institutions from 17 different countries (the largest attendance at a UComms conference). Underwater communication technologies have progressed rapidly in the past couple of decades. Such progress has been achieved both through the development of advanced coherent modulation, demodulation, and coding techniques and by moving from point-to-point systems to multihop networks. At higher communication layers, there have been significant advances in developing medium access control (MAC), routing, and other protocols to maintain efficient and reliable communications. It is also becoming an established fact that the underwater channels can be so diverse and dynamic that there will never be a "one-size-fits-all" solution, so communication systems will need to adaptively reconfigure themselves to the (continuously changing) network topology, environmental, and application needs. These notions are leading toward intelligent and self-adaptive approaches with a high degree of cross-layer connectivity. The 37 papers presented at UComms18 reflected these trends, with an emphasis on channel estimation, cross-layering, and adaptation at different layers of the stack. Below, we take you through the selected papers for this SI. The first paper, "Iterative sparse channel estimation and spatial correlation learning for multichannel acoustic OFDM systems" by Tadayon and Stojanovic, tackles the problem of coherent detection of OFDM signals using a sparse channel estimation that targets the physical propagation paths in a continuous-delay domain. The authors show the effectiveness of their proposed solution through simulation and experimental analysis.

IEEE Journal of Oceanic Engineering, Oct 1, 2017

OCEANS 2016 MTS/IEEE Monterey, 2016

The Centre for Maritime Research and Experimentation (CMRE) is a world-class NATO scientific rese... more The Centre for Maritime Research and Experimentation (CMRE) is a world-class NATO scientific research and experimentation facility located in La Spezia, Italy.

OCEANS 2015 - Genova, 2015