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

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METHOD #5: AUTOMATIC TRACKING OF UNMANNED AERIAL VEHICLES (UAV).<br />

Remote controlled helicopters (RCH) can be used to validate that the automatic tracking<br />

coordinates produced by the digital radar processor (DRP) used in eBirdRad <strong>and</strong> the AR-1 <strong>and</strong><br />

AR-2 radars are accurate within sensor resolution limits. By placing a GPS onboard the RCH,<br />

the coordinates of the RCH during flight tests can be recorded <strong>and</strong> compared subsequently to<br />

radar tracks of the RCH produced by the radar. The method can be described as follows:<br />

1. Fly the RCH within the coverage zone of the radar <strong>and</strong> at detectible ranges recording the<br />

helicopter's trajectory with onboard GPS<br />

2. Operate the radar to track RCH - record raw data for subsequent reprocessing<br />

3. Extract helicopter trajectory coordinates from GPS <strong>and</strong> provide in suitable format<br />

4. Extract helicopter radar track coordinates by reprocessing raw radar data <strong>and</strong> outputting<br />

helicopter tracks<br />

5. Compare radar track coordinates <strong>and</strong> GPS coordinates by overlaying onto common graph or<br />

display<br />

6. Analyze radar <strong>and</strong> GPS coordinates <strong>and</strong> assess accuracy given sensor resolution limits<br />

Achieving (1) above is perhaps the most challenging part of the method. An RCH is typically<br />

small, <strong>and</strong> if it is flown at any significant distance from the radar (say 1-2 km), then the radar<br />

operator will likely not be able to see the helicopter. It is also difficult for the RCH pilot to<br />

estimate the height of the RCH needed to ensure that the helicopter is flying in the radar beam.<br />

As a result, it can be quite challenging for the radar operator <strong>and</strong> pilot to ensure that the<br />

helicopter remains in the radar beam for sufficient time to collect meaningful data. This is<br />

particularly true at locations such as commercial airports (e.g., Seattle Tacoma International<br />

Airport) where the radar location is fixed, <strong>and</strong> where authorizations to fly the RCH are provided<br />

only at certain locations.<br />

Recording raw data throughout the test ensures that whenever the helicopter was in the beam of<br />

the radar (to be confirmed off-line through analyses of the GPS coordinates), the radar data is<br />

available for comparison.<br />

If the RCH dynamics can be reasonably controlled to mimic birds in flight, <strong>and</strong> if the RCH<br />

remains in the beam for sufficient periods of time, then radar tracks can be compared directly<br />

against the GPS coordinates; otherwise, radar detections can be compared against GPS<br />

coordinates.<br />

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