Agencies Must Make Sure Webcams Don’t Interfere with Nature
To swap out equipment or do repairs to the eagle cam, the NCTC team waits until October or November, when the baby birds have long since left the nest and the adults are starting to wind down their nesting activity for the winter.
A professional tree service comes out to climb the 100-foot-tall sycamore tree to reach the camera there. And if a storm takes out the eagle cam in the middle of nesting season, repairs — and the eagle fans — will have to wait.
“We wouldn’t disturb the birds to appease the public,” Robinson says.
The VLA scientists had a different concern when the webcam was first proposed: the possibility that the webcam itself might interfere with the ultrasensitive antennas.
The array receives signals from nebulae, stars and any object or matter that radiates radio frequency energy and gives off heat. The webcam is one of those objects.
Any digital device is an “unintentional transmitter,” says Dan Mertely, the RFI engineer for the Very Large Array, noting that such devices emit heat and send radio waves.
Before installing the webcam, Mertely tested it in the reverberation chamber at the agency’s headquarters in Charlottesville, Va., to find out how much radio frequency it put out. He discovered that the camera would have to sit about 500 meters away from the antennas to avoid interference.
To get the webcam closer to the array, Mertely built an aluminum box and sealed it to keep the escaped radio frequency energy at a minimum. A plastic film shield over the hole for the lens lets optics reach the camera but reduces any signal going back out.