Proposals and instrument selection
In February 1997, a proposal
was submitted to the National Science Foundation Major Research
Instrumentation program, to establish at the University of Hawai'i
a facility for High Frequency (HF) Radio Oceanography in support of
coastal oceanography. The proposal received excellent peer reviews,
and was funded in October 1997. P. Flament was principal investigator,
with University of Hawai'i colleagues Eric Firing, Peter Hacker, Doug
Luther and Mark Merrifield as co-investigators.
The current state of the technology was first assessed, to select
the equipment to be purchased. At the onset, it was decided that a
research-grade instrument, flexibly modifiable and expandable to follow
the needs of specific experiments, would be preferable to a standard,
off-the-shelf production line instrument. Also, an instrument that would
allow estimation of the direction of targets through the more precise
beam-forming technique was desirable.
At that time, seven different beam-forming phased array HF systems
existed in the world; their differed principally by how they modulated
the radio signal. OSCR, the oldest system, formerly manufactured
by Marconi in the UK, was based on 15-year old technology and no
longer in production. COSRAD, the outcome of a joint venture between
James Cook University and Telstra in Australia, was soon dropped from
the market. PISCES in the UK and C-CORE in Canada were prototypes,
not ready for commercial production or duplication. Kokusai Kogyo Co.,
Ltd. in Tokyo, and Metratek in the US, both had plans to market marine
HF radio instruments, but neither had completed their development yet.
The WERA, designed by Klaus Werner Gurgel at the University of Hamburg
in Germany, was the best candidate. It was based on recent technology,
and used a simple signal (frequency modulated continuous wave), easy
to tune and monitor with standard laboratory equipment. The sharing
of software source code was a definite asset, encouraging future
developments at the University of Hawai'i. Finally, the Hamburg team had
abundant peer-reviewed publications, establishing the success of their
instruments. The WERA was selected for this project and approved by
the funding agency in September 1998. A formal contract to build three
phased array instruments was awarded to the University of Hamburg in
January 1999.
Design and construction
At the onset, it appeared that flexibility for future procurement and
maintenance would be gained by subcontracting the actual construction to
a commercial electronics firm, the University of Hamburg retaining the
overall design and specification of the system. Helzel Messtechnik, a
small business in Kaltenkirchen near Hamburg, was awarded the subcontract
in February 1999, and began construction. The University of Hawai'i
ordered a fourth instrument directly from Helzel.
Considerable progress in electronic components took place between the
initial 1992 design of the University of Hamburg, and the 1999 start of
this project. At the risk of introducing some delay, it was decided to
capitalize on the release of new chips, and let Helzel update the digital
side of the electronics. Specifically, Analog Devices had introduced
their new 9852-series of Direct Digital Synthetizers, offering a complete
single-chip solution to signal synthesis. Unfortunately, since Analog
Devices experienced delay in delivering a bug-free DDS chip,
a working synthetizer could not be completed until Spring 2000.
Construction of the first instrument then proceeded
swiftly, and was successfully tested in October 2000 in Gijon, Spain, using the opportunity of
the EuroROSE project. A progress review followed, and the University of
Hawai'i authorized the construction of the remaining three instruments.
However, a major procurement problem surfaced at the meeting.
The original WERA used off-the-shelf high resolution analog-to-digital
converters (ADC) commercially manufactured by Analogic, Inc., and
controlled by a DEC Alpha VME computer. Analogic had reorganized their
corporate strategy to concentrate on very high speed (ie. 100 MHz) 14 bit
ADCs, dropping the medium speed high resolution ADCs from their product
line. In addition, the takeover of DEC by Compaq, and later of Compaq
by Hewlett Packard, made the future of the line of Alpha VME computers
at best uncertain.
A redesign of the data acquisition subsystem became unavoidable. Since
no off-the-shelf ADC solution meeting the stringent signal-to-noise
performance of the WERA could be found without extensive testing,
custom circuits based on the same ADC chip as the old Analogic board
were designed and built by Helzel. A standard industrial Intel-based
compact-PCI computer would then be used as controller, the University
of Hamburg porting their VXWork software from the Alpha platform to the
Intel CPCI platform.
The four University of Hawai'i instruments with the new data acquisition
subsystem were completed in September 2001, and, following lab tests and
burn-in, were imported into the United States and shipped to Hawai'i
in December 2001, where they were integrated into field-deployable
containers, complete with air conditioning, power supply, and computer
and network interfaces.