OBSERVATIONAL VALIDATION OF AVIAN RADAR SYSTEMS Wendell Bunch Edwin Herricks, PhD
Dec 16, 2015
OBSERVATIONAL VALIDATION OF AVIAN RADAR SYSTEMS
Wendell BunchEdwin Herricks, PhD
Introduction
• Existing airport surveillance radars– Designed for air and ground traffic control– Not readily adaptable for wildlife purposes
• Avian radar systems– Digital processing added to COTS marine radar
and optimized for bird detection – X-band and S-band– New technology w/few users and no airport
experience
CEAT Performance Assessment
• Multiple year program assessing avian radar systems at civil airports
• Initial efforts intended to understand radar physics/system abilities
• A critical issue is validation of capabilities of avian target detection and tracking
• Visual observation of birds
CEAT Validation Efforts
• Address ground-truth issues• Validate in airport settings• Use target rich environment of Whidbey
Island to conduct long term observations• Coordinate with IVAR efforts• Evaluate methods
• Issues identified in ground-truth efforts and validation studies
– observers challenge radar detection– radars challenge observers and methods– visualizing the beam coverage (height and width)– locating specific targets– judging distance and altitude
Location: NAS Whidbey Island WA
Primary sensor X-band radar 3cm wave length
Method of visual observation– 30X spotting scope aligned to true north– radar computer and watch synced ± 1 sec– data collected in high and low clutter areas– viewing angles separated by 20 degrees– two view samples at each angle, high/low– 20 second sample periods– data collected: date/time, family or specie, number of
birds, general direction of travel, bearing target observed– time stamp when target on vertical center of spotting
scope
Findings• Detection Issues:
• Aspect/RCS• Aspect -relation of the target to radar beam• RCS - effective target area, changes with aspect• RCS must exceed level of clutter
Clutter: Ground and Sea Undesirable radar returns Sea clutter – tracks short high speed Wind speed/direction determined effect
Ground and Sea Clutter
Effects of sea clutter on tracking
Detection Issues: cont.• Position Relative to Clutter
– gulls: >20, <20, <5– Large sea ducks: CEAT and IVAR– RCS?
• Flight Behavior– constant heading = consistent tracking– un-predictable flight challenges all radar– shadowing in flocks
• Duration of Flight– must be long enough
Detection Issues: cont.
• Weather– rain/snow hinders detection and tracking– can generate large numbers of detections and tracks– tracks of short duration with speeds similar to birds
Observation Issues
• weather conditions hindered use of spotting scope in strong winds/rain
• range to targets difficult to estimate• limited to daylight hours
Validation Methods
• Requirements to validate target time, direction of travel, bearing, within beam dimensions for the bearing
• archived radar data replayed • two examples
Surf scoter - 305
Bonaparte’s Gull - 601
Conclusions
– Avian radar capable of tracking bird sized targets– Researchers have shown radar can track
movement over larger areas than visual observations
– Research needed: potential to monitor bird activities while evaluating limitations of location and radar physics
– NAS Whidbey research has shown limitations with the current technology
Conclusion cont.
• Factors Compromising Detection– target aspect– target size– flight behavior– target position relative to clutter– overall clutter environment– weather
Conclusions cont.
• Use of Avian Radar Systems– careful evaluation of clutter levels to ensure tracking in desired area– will require some level of validation– more complex environments = more validation
QUESTIONS?