Summary

My research interests span computer engineering and aquatic sciences, focusing on selecting and devloping technology to advance marine science research. This page gives of brief description of each of my current and past research projects. For a complete list of my publications and presentations click here.

Adaptive Sampling Underwater Node

When deploying underwater sensors, marine scientists must select a sampling rate that they think will be fast enough to sample their phenomenon of interest (eddies, harmful algal blooms, turbulence, etc.), but slow enough to allow for a long deployment.  It is difficult to choose the 'ideal' sampling rate and therefore the sensor may fail to capture the event of interest.  Scientists recognize that the solution to this sampling rate problem would be to 'talk' to their instruments from shore and dynamically adjust the sampling rate according to weather conditions and/or what is seen in the already collected data.  For example, if a scientist detects that a harmful algal bloom is forming, she could choose to increase the sampling rate of the instrument.  When the scientist notices that the algal bloom is over, she can decrease the sampling rate to save power and thus extend the deployment time.  Few real-time technologies exist for marine scientists to remotely 'talk' to their deployed instruments, thus this poster describes our work in progress of an adaptively sampled underwater node.  This node facilitates the communication between a shore node (connected to a desktop computer) and a remote node (connected to an underwater instrument) through the use of a wireless underwater acoustic modem.   

Design of a Low-Cost Analog Front End for a Short-Range Underwater Acoustic Modem

Underwater acoustic modems consist of three main components: 1. the analog front end consisting of an underwater transducer and matching pre-amp and amplifier for acoustic communication, 2. a hardware platform (microcontroller, digital signal processor (DSP), or field programmable gate array (FPGA)) for control and signal processing, and 3. interfaces to oceanographic sensors.  The costs of the hardware platform and interfaces are negligible compared to the cost of the analog front end. Custom commercial transducers cost on the order of $2000 primarily because of the relatively low market demand for these devices. Therefore, much of the design for the low-cost modem lies in finding an appropriate substitute for the custom commercial transducer. Thus, our work looks at the the design of an analog front end for a short-range underwater acoustic modem starting with the most critical component from a cost perspective – the transducer. The design substitutes a commercial underwater transducer with a home-made underwater transducer using cheap piezoceramic material and builds the best possible electronics around the transducer to extract as much performance as possible.  With a low-cost, low-power analog front end, different hardware platforms and different communications schemes can be tested to obtain a low-cost, low-power short range underwater acoustic modem. 

FPGA-Based Fish Detection Using Haar Classifiers

The quantification of abundance, size, and distribution of fish is critical to properly manage and protect marine ecosystems and regulate marine fisheries.  Currently, fish surveys are conducted using fish tagging, scientific diving, and/or capture and release methods (i.e. net trawls).  All of these methods require many man hours and ship time which are costly and time consuming.  Therefore, providing an automated way to conduct fish surveys could provide a real benefit to marine managers.  In order to provide automated fish counts and classification we propose an automated fish species classification system using computer vision.  This computer vision system can count and classify fish found in underwater video images using a classification method known as Haar classification.  We have partnered with the Birch Aquarium to obtain underwater images of a variety of fish species, and present in this paper the implementation of our vision system and its detection results for the Scythe Butterfly fish, our first test species, and the fish in the Birch Aquarium's logo.

Detection of Scythe Butterfly Fish in Aquarium

Real-Time Telemetry Options for Ocean Observing Systems

Ocean observing systems provide a means to monitor oceanic variables on a variety of temporal and spatial scales. Data from ocean observing systems are most useful when they are collected in real-time; real-time data allow the detection of important events as they occur. Various realtime telemetry options exist for transferring data from sea to shore and from the subsurface to the surface. We survey these telemetry options to highlight the research problems associated with subsea to surface to shore networking and include a comparison of existing real-time technologies for three specific ocean observing system network topologies with respect to data transmission rates, power requirements, and cost. We conclude that cellular technology may prove to be the best means for sea to shore transmission in nearshore regions whereas Iridium satellite communications are ideal for locations not covered by cellular service. Further advances in cabled mooring lines and inductive and acoustic modem technologies will make these more attractive options for subsurface to surface data transmissions.

 

 

Design of a Low-cost Acoustic Modem for Moored Oceanographic Applications

This work discusses the current state of the art systems of real time telemetry on oceanographic moorings and describes the design requirements for making acoustic modem data telemetry a more widely used form of data telemetry for moored oceanographic applications. We present the design of a low cost "mooring modem" and the results of an initial pool test for its prototype. Based on these results, we describe how the mooring modem meets the design requirements for moored oceanographic applications by looking at how it meets the requirements for a specific mooring example - the SB CHARM. We conclude by presenting the future work required to create a prototype mooring modem, which will be tested on the CHARM mooring. The end goal is the production of a cheap, low power acoustic modem for real-time data collection in moored oceanographic applications.

AquaModem Field Tests in Moorea

The UCSB AquaModem is an acoustic modem designed for short range (< 1km) eco-sensing applications in a shallow horizontal underwater channel. The AquaModem operates at a center frequency of 24 kHz and a double-sided bandwidth of 6 kHz, with a bit rate of approximately 160 bps. It uses M-ary direct sequence spread spectrum signaling, with joint detection and channel estimation performed by matching pursuits to effectively handle multipath interference. From July 24th - July 28th 2007, the AquaModem was field tested in Cook's Bay and in the Viapahu Lagoon off the UC Berkeley Richard B. Gump South Pacific Research Station, on the French Polynesian island of Moorea. This site is part of the Moorea Coral Reef Long Term Ecological Research (LTER) program established by the National Science Foundation to support research of long-term ecological phenomenon. At ranges up to 440 m, the UCSB AquaModem yielded symbol error rates averaging < 1% in water less than 4 m deep, while Doppler spreads from modem channel estimates were found, on average, to be on the order of 0.01 Hz.

Determining Mechanisms for Mixing in the Benthic Boundary Layer Using Modern Instrumentation

Advances in science are often coupled with advances in instrumentation. Improved scientific instrumentation and procedures allow scientists to better observe the environment and answer important environmental questions. We illustrate the use of high precision thermistors (accuracy 0.002C) and Acoustic Doppler Current Profilers (ADCPs, RD Instruments, Mode 11, resolution a few mm/sec) to determine the mechanisms for mixing in the benthic boundary layer in Toolik Lake. Mixing in the benthic boundary layer will entrain regenerated nutrients, dissolved gases, and methyl mercury. If mixing in the benthic boundary layer is coupled with mixing higher in the water column, nutrients will reach the euphotic zone and support primary production, and methyl mercury can be released to the atmosphere. This poster describes recent theory on mixing mechanisms in lakes and presents data collected from Toolik Lake during summer 2006 that support the existence of these mechanisms. We conclude by addressing further improvements which could be made to modern instrumentation to link hydrodynamics to ecosystem function.

Real-Time Thermistor Chain

Real-time retrieval of thermistor and meterological data on lakes allows scientists to calculate lake numbers in real time. The Lake Number is a dimensionless index used to quantify the extent of tilting of the thermocline due to wind and the resulting potential internal wave formation and mixing. A low Lake Number is indicative of a tilting thermocline and likely increased mixing. Being able to calculate lake numbers in real time inform scientist when a mixing event is occurring, prompting them to futher capture the event with intensive nutrient sampling and micro-profiling instruments. I had the opportunity to work with Professor Sally MacIntyre, to implement an interface between a Precision Measurement Engineering thermistor chain and a Campbell Scientific CR10X data logger to enable acquisition of near real time temperature data of the water column at the Toolik Lake meteorological station. I also wrote a program to calculate lake numbers, using the real time temperature and meterological data from Toolik Lake.
Campbell Scientific Press Release
PME Newsletter