JFK's motorcade

When the first shots were fired at JFK's motorcade, police couldn't [immediately:fastly] locate the gunman based on sound alone. Today, the technology exists for them to it with their smartphones, less than a second after the first shot.Here's how. Most bullets travel at supersonic speeds, [generating:generalising] a shock wave along their path. To track that path, researchers built a small bluetooth sensor for smartphones. The sensor uses four mics to measure the shock wave's angle and its time of arrival. Then each phone [networks:signal] with nearby phones to triangulate the sniper's location, mapping it on the smartphone screen within a second of the gun blast. Researchers tested the system with an AK-47 and were able to calculate the shooter's bearings with less than seven degrees of error and get a decent [estimate:calculation] of his range. They [presented:showed] the method at the Conference on Information Processing in Sensor [Networks:Items] in Philadelphia.