Publications

2024

1. 

   Open Radar Code Architecture (ORCA): A Platform for Software-defined Coherent Chirped Radar Systems

   Thomas O. Teisberg^*, Anna L. Broome^*, and Dustin M. Schroeder
   *Equal contribution

   Accepted for publication in IEEE Transactions on Geoscience and Remote Sensing, 2024

   Abs PDF

   Ice-penetrating radar systems are critical instruments for observing the subsurface conditions on Earth’s ice sheets. Traditionally, ice-penetrating radars have not been widely accessible to the glaciological community (as in the case of resource-intensive airborne systems) and/or have been limited in their ability to be reconfigured and optimized for studying different glaciological targets (as in the case of hardware-defined radar systems). To alleviate the challenges associated with this situation, we have developed the Open Radar Code Architecture (ORCA), which is an open-source radar software codebase that allows commercially available software-defined radios (SDRs) to be used as coherent ice-penetrating radars. Here, we describe the architecture of our code, characterize coherence on SDRbased radars, and demonstrate techniques we use to improve SNR and overall performance. We also highlight the variety of SDR options available to potential users and discuss tradeoffs between different system configurations.

2. 

   A newly digitized ice-penetrating radar data set acquired over the Greenland ice sheet in 1971–1979

   Nanna B. Karlsson, Dustin M. Schroeder, Louise Sandberg Sørensen, Winnie Chu, Jørgen Dall, Natalia H. Andersen, Reese Dobson, Emma J. Mackie, Simon J. Köhn, Jillian E. Steinmetz, Angelo S. Tarzona, Thomas O. Teisberg, and Niels Skou

   Earth System Science Data, Jul 2024

   Abs HTML PDF

   We present an ice-penetrating radar data set acquired over the Greenland ice sheet by aircraft during the years 1971, 1972, 1974, 1978, and 1979. The data set comprises over 177 000 km of flight lines and contains a wealth of information on the state of the Greenland ice sheet, including information on ice thickness and englacial properties. During data collection in the 1970s, the data were recorded on optical film rolls, and in this paper, we document the digitization of these film rolls and their associated geographical information. Our data digitization enables interaction with and analysis of the data and facilitates comparison with modernday radar observations. The complete data set in full resolution is available in the Stanford Digital Repository (https://doi.org/10.25740/wm135gp2721; Karlsson et al., 2023), with the associated technical reports. Part of the data set is available as low-resolution JPG files at the Technical University of Denmark’s data repository (https://doi.org/10.6084/m9.figshare.c.7235299.v1; Karlsson et al., 2024), with associated technical reports and digitized geographical information . The Stanford Digital Repository serves as long-term storage, providing archival historic preservation in perpetuity, and is not intended as a primary data access point. The Technical University of Denmark (DTU) data repository serves as a primary entry point for data access, with files organized according to acquisition year and flight line in a simple folder structure. Here, we release the full data sets to enable the larger community to access and interact with the data (Karlsson et al., 2023).

2023

1. 

   Studying Climate Change With an Ice Radar Drone

   Thomas O. Teisberg

   IEEE Spectrum, Oct 2023

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2. 

   Digital Tools for Analog Data: Reconstructing the First Ice-Penetrating Radar Surveys of Antarctica and Greenland

   Thomas O. Teisberg, and Dustin M. Schroeder

   2023 IEEE International Geoscience and Remote Sensing Symposium, Jul 2023

   Abs HTML Website

   During the 1970s, the first large-scale ice-penetrating radar surveys were conducted over Antarctica and Greenland through a collaboration between the Scott Polar Research Institute at the University of Cambridge, the National Science Foundation, and the Technical University of Denmark [1]. This pioneering work represents the earliest available large-scale measurements of the sub-surface conditions of Earth’s two major ice sheets. In many cases, data collected as part of this survey pre-dates other available data in the area by decades. As we experience increasingly rapid changes in Antarctica and Greenland, understanding the historical states of these ice sheets takes on increased importance. Although 45-55 years is a short time in the evolution of continent-scale ice sheets, this dataset is unique in that it represents direct measurements over massive spatial scales. Unfortunately, integration of this data into models has proven extremely difficult due to unique challenges in how the data was collected and stored. We introduce our efforts to build digital tools for this analog dataset to bring this data into the modern era and make it accessible to researchers.

2022

1. 

   Development of a UAV-Borne Pulsed Ice-Penetrating Radar System

   Thomas O. Teisberg, Dustin M. Schroeder, Anna L. Broome, Franklin Lurie, and Dennis Woo

   2022 IEEE International Geoscience and Remote Sensing Symposium, Jul 2022

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   Ice-penetrating radar is the primary geophysical tool for large-scale measurements of the geometry and internal properties of the Antarctic and Greenland Ice Sheets. These low-frequency radar instruments are typically mounted on crewed aircraft or towed behind snowmobiles, both of which introduce significant logistical challenges and costs. The availability of inexpensive, portable, and fully-autonomous uncrewed aerial vehicles (UAVs) promises to reduce the cost, logistical complexity, and risk of collecting ice-penetrating radar data.

2021

1. 

   A Machine Learning Approach to Mass-Conserving Ice Thickness Interpolation

   Thomas O. Teisberg, Dustin M. Schroeder, and Emma J. MacKie

   2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, Jul 2021

   2nd Place, Student Paper Competition Abs HTML Website

   IEEE GRSS 2021 GRS-S Student 2nd Place Paper Award

   The subglacial topography of the Earth’s ice sheets is a critical input to models of the evolution of ice sheets and sea level rise. Direct measurements of ice thickness, however, are sparse, necessitating techniques for interpolating these measurements. One class of interpolation methods enforces physical constraints to transform the problem into an inversion. A challenge with these approaches is that multiple unknown parameters must be solved for simultaneously. We introduce a new numerical approach to solving for mass conservation-constrained ice thickness maps. This technique, based on a physics-informed neural network, allows for the flexible incorporation of a range of soft constraints. In the future, this could enable simultaneous estimation of ice velocity, bed topography, and sliding parameters.

2018

1. 

   Array Location Uncertainty in Imaging Radar: SAR vs. MIMO-SAR

   Babak Mamandipoor, Thomas O. Teisberg, Siavash Kananian, and Amin Arbabian

   2018 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM), Apr 2018

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   In this paper, we consider a type of MIMO-SAR architecture in which the elements are arranged along the axis of platform motion. We show that this architecture can be used to improve the robustness and accuracy of angular estimation compared to single-element SAR given array location uncertainty. We compare three different architectures for side-looking radars (SAR, SIMO, and SIMO-SAR) and show that in the presence of array location uncertainty, SIMO-SAR proves more resilient. Measurement results using a commercial automotive radar module have been performed to verify this effect.

2017

1. 

   Closed-Loop Ultrasonic Power and Communication with Multiple Miniaturized Active Implantable Medical Devices

   Max L Wang, Ting Chia Chang, Thomas Teisberg, Marcus J Weber, Jayant Charthad, and Amin Arbabian

   2017 IEEE International Ultrasonics Symposium, Apr 2017

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   An ultrasonic array system is designed for wirelessly powering and communicating with implantable medical devices. A flexible hardware interface is used to drive a 32-element linear phased array with emphasis on programmability and efficiency rather than bandwidth or peak power. Various beam patterns and data modulation schemes are verified at a depth of 6 cm in a tissue phantom with more than sufficient harvested power for typical implant applications. The power transfer efficiency is also characterized versus depth. Finally, a closed-loop test is performed with two mm-sized devices demonstrating both power and data transfer. This system provides a platform for more complex adaptive therapies combining sensing, communication, and stimulation.