August 23, 2002
Researchers Continue to Examine HPWREN Connectivity Between Ground Station and Airplane
UCSD and SDSU researchers recently collaborated for a high performance data communications demonstration involving a research airplane and a ground station. The experiment is the second in a series of multiple tests that evaluate the use of radios that communicate using the unlicensed spectrum with a nearby airplane.
"During the April test we manually tracked the airplane from the ground, with ground antennas mounted on a tripod. This yielded excellent results, but the tracking was messy - primarily due to multiple cables that often entangled," explains Hans-Werner Braun, HPWREN principal investigator. "In this second test, we used a stationary antenna on the ground with no manual steering. Expectedly, this yielded worse connectivity results because (a) the antennas were not explicitly trained onto the airplane, and (b) the flying was (purposely) not very well defined (including lots of banking and flying out of reach), to learn more about the border conditions."
Braun says that the third test, which will take place later this fall, will repeat the same setup as this second test. However, the researchers will next work with defined flight patterns that specifically support the area underneath the airplane.
A second objective of the test was to remotely control a digital camera located on the airplane. This image illustrates a photograph of the Ramona area that was snapped via the airborne digital camera - by a researcher located at the ground station.
A third objective of the experiment was to utilize the ground station to:
provide local wireless connectivity close to the ground station;
provide for a direct link to an HPWREN backbone site on a mountain top; and
test the radios in an air-ground environment
These four goals were accomplished with a single ground station radio, connected via signal splitter to multiple antennas. Specifically, the USR2450 radio was equipped with Linux software, which allows for Ethernet-Ethernet bridging with topology discovery for point-to-multipoint links - while simultaneously functioning as an access point.
Participants in the demonstration included Rommel Zulueta, an SDSU doctoral student and the airplane pilot; Hal Holmerud, Outreach Administrator for the Crisis/Consequence Management Initiative at the SPAWAR Systems Center San Diego; Todd Hansen, systems coordinator for the NSF-funded ROADNet research project; Bryant; and Braun.
Additional photographs documenting the demonstration, as well as images taken of the nearby Pines Fire, are available at http://hpwren.ucsd.edu/Photos/20020807/.
Details regarding the first test, which was conducted in April, are available at http://hpwren.ucsd.edu/news/020430.html.
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