An advanced alien civilization would likely use spread-spectrum transmission coding (used in cellphones), which is more efficient than a single carrier wave because chunks of information are essentially carried on multiple low-powered carrier waves.

Claudio Maccone, co-chair of the SETI Permanent Study Group based in Paris, France, argues that SETI should use an algorithm known as the Karhunen-Loève Transform (KLT), which could find a buried conversation using spread-spectrum coding with a signal-to-noise ratio 1000 times lower than the Fast Fourier Transform algorithm currently used in SETI research.