(IVAR) - Final Report - Strategic Environmental Research and ...

To evaluate the capabilities of the avian radar system to track a UAV, we conducted a trial at
SEA on 14 September 2008 using the SEAAR1m radar there. A new third runway (34L/16R)
was constructed at SEA as part of a multiple-year runway expansion program; the runway was
not yet in use at the time of our test. After the Federal Aviation Administration granted the Port
of Seattle permission to fly a RCH near Runway 34L/16R we selected several sites along it to
use in the trials. The method of testing is described as follows:
1. Fly the RCH within the coverage zone of the radar and at detectable ranges while
recording the helicopter's trajectory with an onboard GPS device.
2. Operate the radar to track the RCH, recording both raw digital data and plots and tracks
data for subsequent reprocessing and analysis.
3. Extract helicopter position from the onboard GPS device in suitable format
4. Extract helicopter radar track coordinates by reprocessing radar digital data
5. Compare radar track coordinates of the helicopter and GPS coordinates by overlaying
them onto a common graph or display
6. Determine the radar's tracking accuracy by determining the deviation between the two
sets of data, taking into consideration the uncertainty of the GPS coordinates.
We designed the radar trials to provide repetitive flight patterns along the length of the new
runway, which would allow acquisition, loss, and reacquisition of the RCH target along the full
length of the 2500 m runway. We controlled the RCH from a moving vehicle that traveled the
perimeter road at SEA, approximately 2 m lower than the runway elevation. The pilot flew the
RCH from near the surface of the perimeter road to an altitude of approximately 150 m above the
road, and then returned to near the road surface. This flight path produced a target arc where
altitude increased and decreased along the runway. When the target flew near the surface of the
perimeter road, it was below the level of the runway and thus shadowed from the radar beam.
We implemented this flight path to test detection capabilities at different distances from the fixed
radar location, assess detection differences with altitude, assess capabilities for acquisition of the
target when it rises above the radar horizon, and characterize track generation with target loss.
For this test we used an Appareo Systems GAU 1000 GPS unit with a data logging and recording
system. The GAU 1000 provides GPS coordinates at 1 second intervals, with an accuracy of ±10
m. We mounted the GPS unit on the RCH and retrieve the data records following the flight.
We operated the SEAAR1m radar in the normal surveillance mode used for bird detection and
tracking. The DRP was set to record both digitized raw data and extracted plots and tracks data.
We used an Accipiter® DRP to reprocess the raw digital data file into plots and tracks and then
to isolate the helicopter data from all other plots and tracks based on location, timing, and
velocity criteria. We used the extracted plots and tracks data in the field to verify radar
functionality.
Results
We successfully flew the RCH, shown in Figure 6-14, for the entire length of the new runway
from the pilot vehicle along the adjacent perimeter road. We achieved our planned flight path so
that it had multiple arcs from near the surface of the perimeter road to approximately 150 m above
ground level (AGL) along the runway.
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