Follow-Up Detection in Project Phoenix

Effective detection of extraterrestrial radio signals requires elimination of terrestrial interference. However, the sensitivity of standard, two element interferometry, depends on the geometric mean of the antenna areas. This is very disadvantageous if the antennas are not the same size. Project Phoenix performs pseudointerferometry by transmitting detailed signal descriptions to its second site where they are used for confirmation. The primary site uses the larger antenna and square-law detectors. Use of matched filtering and a lower threshold makes detection with the second, much smaller, antenna possible. The pseudointerferometer can handle up to 12 signals having bandwidths of order 1 Hz in a 10 MHz band. In Australia, it allowed observing to complete in less than half the time that would have been required using a single site system.