The SAR imaging systems on board the Sentinel satellites operate within the same frequency range as many military radars. Credit: Ollie Ballinger, used with permission SAR images captured from two satellites can be overlaid to narrow the area in which a interfering radar emitter could be located. It gives the SAR a far higher spatial resolution than is possible using a traditional scanning beam radar. The technique allows the SAR to image the ground as if it had a much larger antenna than it actually does, thanks to the spacecraft’s motion. The SAR essentially uses the motion of the spacecraft to create a large “synthetic” antenna aperture for capturing radar images of the ground. The Sentinel-1A and Sentinel-1B satellites, operated by the European Space Agency (ESA), carry synthetic aperture radar (SAR) instruments operating in the C-band, the spectrum taking in frequencies from 4.0 to 8.0 GHz. After accidentally maximising the display of noise and interference on the synthetic images, he noticed strange bands appearing in various spots in the Middle East, and investigation into the cause began. Dan was looking at data captured by the synthetic aperture radar of the European Space Agency’s Sentinel satellites. The discovery that openly-available satellite data could reveal the locations of military radars came from the work of Harel Dan, a geospatial engineer from Israel. Open Data Reveals Surprising Things A diagram indicating how interference from military radars shows up on SAR satellite images. In fact, openly-available data captured via satellite can be used to find all manner of military radar emitters. However, a new tool built by geocomputation lecturer Ollie Ballinger shows this isn’t the case. Whether it’s early warning radar, those used for air defence, or for naval purposes, you’d think it was relatively difficult to intercept or track these emissions. When it comes to hunting down military radar installations and associated hardware, we typically think of equipment that is firmly in the price bracket of nation states and their military forces.
0 Comments
Leave a Reply. |