GPS World, February 2019

Inertial Ranging eLoran Wi Fi Bluetooth MicroSat Constellation Geolocates RF Signals S pace Flight Laboratory SFL has launched three formationflying HawkEye 360 Pathfinder 15 kilogram 20 x 27 x 44 centimeter microsatellites designed to detect and geolocate radio frequency RF signals The target signals emanate from VHF radios maritime radar systems automatic identification system AIS beacons very small aperture terminal VSAT communication systems and emergency beacons HawkEye 360 applies advanced RF analytics to the data to assess suspicious vessel activity sur vey communication frequency interference and direct search and rescue Precise formation flying is critical as the relative position of each satellite must be known to accurately geolocate transmission sources The satellites carry space qualified GPS receivers and high performance attitude control systems to keep them stable in orbit Flying in formation two or all three satellites may receive the same transmission when it originates from their common footprint The signals different times of arrival at each satellite and their different apparent center frequencies Doppler will enable onboard comparison of timeof arrival and frequency of arrival measurements to then calculate the transmitters position The onboard GPS receivers provide precise estimates for the position and velocity of the receivers information required for 12 GPS WORLD WWW GPSWORLD COM FEBRUARY 2019 multilateration The satellites further synchronize their clocks using GPS receivers which also stabilize the phase locked loops governing the tuning frequency in the RF tuners The satellites were built by Deep Space Industries of San Jose California and University of Toronto Institute for Aerospace Studies Space Flight Laboratory UTIAS SFL They were launched in December 2018 into low Earth orbit P lanet has put about 300 satellites into space charged with photographing the entire land mass of the Earth every day The satellites weigh 5 kg 12 pounds and measure 20 x 20 x 44 centimeters about the size of a loaf of bread They are packed with commercial offthe shelf electronics and are built in downtown San Francisco Mission control consists of a single engineer for dozens of satellites Aptly named doves the birds circle the Earth in 90 minutes their cameras continuously rolling It gives you a perspective of the planet as a dynamic and evolving thing that we need to take care of said company co founder Will Marshall Each day the satellites transmit 12 million images at a spatial resolution of 3 5 meters far more than enough to fully occupy all the analysts at the National Geospatial Intelligence Agency NGA one of Planets more than 200 customers Historically the NGA has relied on 3 or 4 very large very expensive and to global adversaries very predictable spy satellites The agency has found Planets approach intriguing and challenging Planet has devised computer algorithms to look for new features day to day such as roads or buildings that may signal activity of a significant or nefarious sort Other customer uses are more mundane such as agricultural companies monitoring crop health Breadloaf Satellites Capture Earth Surface Hawkeye 360 Pathfinder satellite trio flies in formation seeking RF signals from Earth Image UTIAS Space Flight Laboratory Image Planet Labs Inc RF LOCATION SATELLITE IMAGERY Paris capable of going to 3 5m resolution