The SETI Institute predicts that we'll detect an extraterrestrial transmission within twenty years. If that turns out to be true, it'll probably be the folks at UC Berkeley's Hat Creek radio observatory who will have heard the call. Right now, the Allen Telescope Array of more than three-hundred dishes is under construction at Hat Creek five hours north of San Francisco. Within a year, the first thirty dishes will be operational, forming the basis of a giant ear that listens for intelligent beings in space while simultaneously gathering data for groundbreaking astronomy research.William "Jack" Welch, UC Berkeley professor of electrical engineering and astronomy, has been a driving force in the design and construction of the Allen Telescope Array (ATA) since the project first got off the ground five years ago as a joint effort between UC Berkeley and the SETI Institute. Named for major donor Paul Allen, co-founder of Microsoft, the array will eventually consist of 350 6.1-meter radio dishes electronically networked together into a radio telescope with unprecedented sensitivity. Precisely distributed across 2.6-acres on the Hat Creek grounds, the combined dishes will have far greater sensitivity than much more expensive 100-meter telescopes.The SETI project scours millions of radio channels for narrow-band signals, indicative of intelligent origin. It's like listening for a station as you twist your car radio's tuning knob past all the static. Until now, SETI has used limited time from myriad radio telescopes around the world, limiting the number of stars that can be observed. However, the ATA will be dedicated to the project, speeding up the SETI search by a factor of 100. Meanwhile, the unique design of the system enables astronomers to monitor a huge range of wavelengths to observe other cosmic phenomena simultaneously with the SETI search.