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

6.4 DATA INTEGRATION
6.4.1 Quantitative Performance Criteria
6.4.1.1 Near Real-Time Integration For Expanded Local Coverage [SD1.1]
Objective
We designed Performance Criterion SD1.1, Near-Real-Time Integration for Expanded Local
Coverage, to assess the capacity for streaming bird track data from two or more radars separated
by at least 9 km (5 nmi) in near-real time to side-by-side TVW displays. The difference in the
time (i.e., the latency) the track data from the two radars reaches the side-by-side displays
impacts the level of situational awareness that can be provided to system users. Ideally, we
would expect this latency to be 10 seconds or less (i.e., the equivalent of approximately 4 scan
periods).
We established as the performance metric for SD1.1 that screen captures would be taken of sideby-side
TVW displays from two widely separated radars every five minutes for one hour (for a
total of 12 screen captures), and that the latency in each of the TVW displays should not to
exceed 10 seconds. The two radars to be used in this demonstration were to be selected from the
following set of four locations: NASWI, SEA, Edisto, or ARTI (if needed).
Methods
We selected as the two radars for the demonstration of Performance Criterion SD1.1: One
(SEAAR2u) of the dual rooftop radars at SEA, and one (AR1 CEAT) of the mobile radars at
NASWI. The SEA and NASWI radars are 104 km apart. The plots and tracks data from these
two radars were streamed to an RDS at ARTI. The dual-monitor workstation we selected for this
demonstration resided at ARTI on the same network as the RDS.
In order to measure the latency in each of the TVW displays simultaneously, we ran a separate
instance of the TVW in full-screen mode on each monitor. We connected each TVW to the
appropriate schema on the RDS in order to stream radar data in near-real time to the displays.
We installed Meinberg NTP client software on each DRP and on the dual-monitor workstation to
ensure that each machine was synchronized to the same time source (i.e., 0.us.pool.ntp.org).
We used software to capture images of the extended desktop at 5-minute intervals for one hour,
while each TVW was streaming live radar data from the RDS. The timestamp of the most recent
radar scan is visible at the bottom of the TVW screens in the screen captures. The filename of
the images generated by this process included the timestamp of the local workstation. We
highlighted and enlarged the timestamps in each screen capture to facilitate comparing the times
of the two TVWs. (e.g., Figure 6-98)
The Accipiter® DRPs insert the current time (UTC) from their system clock into the plots and
tracks records as they are generated. The DRP can, optionally, stream those records across a
LAN and/or WAN (the Internet) to an RDS. For this demonstration, the RDS was at ARTI.
There the records are streamed into a database schema for that DRP and redistributed to one of
the two TVWs running on the dual-monitor workstation. Since the system clock on the dualmonitor
workstation and the clocks on the DRPs were synchronized to the same NTP time
source, we defined the latency of these systems as: For any given target track record, latency is
the difference between the DRP-generated timestamp displayed by the TVW and the system time
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