Bridget Benson

Graduate Student

University of California San Diego

Quotes by Ben Franklin

"Early to bed and early to rise makes a man healthy, wealthy, and wise."

"Energy and persistence conquer all things."

"An investment in knowledge always pays the best interest."

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.

Publication: Bridget Benson, Grace Chang, Frank Spada, Derek Manov, and Ryan Kastner" Real Time Telemetry Options for Ocean Observing Systems", European Telemetry Conference April 2008 (pdf)
Poster: Frank Spada, Derek Manov, Grace Chang, Bridget Benson, Ryan Kastner "Real Time Telemetry Technologies for Ocean Observing Systems", Ocean Sciences Meeting March 2008 (pdf)

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.

Publication: Bridget Benson, Grace Chang, Derek Manov, Brian Graham, Ryan Kastner" Design of a Low-cost Acoustic Modem for Moored Oceanographic Applications ", Proceedings of ACM International Workshop on Underwater Networks September 2006 (pdf)

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.

Poster: T. Fu, D. Doonan, C. Utley, B. Benson, R. Kastner, R. A. Iltis, and H. Lee "AquaModem Field Tests in Moorea ", Poster Presentation. Proceedings of ACM International Workshop on Underwater Networks September 2007 (pdf)

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 0.002�C) 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.

Poster: T. Fu, D. Doonan, C. Utley, B. Benson, R. Kastner, R. A. Iltis, and H. Lee "Determining Mechanisms for Mixing in the Benthic Boundary Layer Using Modern Instrumentation ", Poster Presentation. Arctic Long Term Ecological Research Annual Conference February 2007

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.