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

Table 6-9 demonstrates quantitatively that the Accipiter® DRP measures and records the spatial
coordinates approximately every 2.5 seconds (the scan period of the radar) throughout the
duration of a track. Figure 6-21 depicts how those data can be used to visualize the spatial
position of a target through time.
Conclusion
The results of the study presented in this section successfully demonstrate the eBirdRad avian
radar system meets the performance metric for PA2.1 in that it is records the 3D spatial
coordinates of a target throughout the period during which the target was tracked.
6.1.1.3 Track Capacity [PA3.1]
Objective
We designed PA3.1, Track Capacity, as a primary Performance Criterion that would demonstrate
the capability of the avian radar systems evaluated by the IVAR project can track large numbers
of birds simultaneously in real time. This capacity is an important prerequisite for many
applications of avian radars, in particular studying bird migration, where hundreds of birds may be
in the radar’s coverage at the same time.
We established as our Success Criterion for PA3.1 that the eBirdRad must be capable of tracking
100 or more birds simultaneously in real time.
Methods
We selected Edisto Island (see Section 4.6) as the study location for demonstrating PA3.1
because of its generally high abundance of birds, particularly during spring and fall migration.
The plots and tracks dataset we used for this analysis was recorded by the eBirdRad DRP at
Edisto Island as part of the thermal validation studies there in the fall of 2008 (see Section
6.1.1.1.2 for a complete description of the methods and results of the thermal validation studies
at Edisto Island). We replayed these plots and tracks data through a TVW and captured the data
from a single scan (i.e., antenna revolution) recorded between 01:18:20 and 01:18:22 UTC
(21:18:20 to 21:18:22 EST) on 4 October 2008. Then we used the TDV software to capture the
track histories for all targets being tracked during the prescribed 2.5-second scan period.
The DRP records Update Time values to the nearest millisecond, but the TDV software only
displays these values to the nearest second. This loss in precision required us to include track
records with one of three Update Time values - 01:18:20, 01:18:21, or 01:18:22 - to encompass
the 2.5-second scan period of the radar in our analysis. A consequence of this was to make it
appear that some targets had been sampled twice during the scan period. A target sampled at
01:18:20.00 and again 2.5 seconds later at 01:18:22.50 would, upon rounding to the nearest
second, appear to have been sampled at 01:18:20 and 01:18:22 in the same scan. When this
occurred, we deleted the older record (i.e., 01:18:20) and used only the single, most recent record
for that target in our analysis.
Results
Figure 6-22 is a screen capture of the TVW display at the end of the specified 2.5-second scan
period. The white numeric label at the head of some tracks is the unique Track ID of that track;
tracks with no Track ID label are no longer being tracked by the radar at the time we generated
the screen capture. We included only “active” targets, those with a Track ID label, when
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