whenever i heard of stuff like this, i think of ligo, the gravitational wave detectors. from what i understand, their signals are just huge amounts of noise, other signals, and then finally the actual signals (gravitational waves) that thy are looking for. but it so happens the gravitational waves is a miniscule amplitude compared to the other signals and noise. so what they do is model all the possible types of noise that is happening in the world, and then they have many models of the type of physical situations that can generate gravitational waves (like a black hole - black hole collision). so they do fancy dsp and filtering and do matches against expected events.
my naive assumption and pure guess would be that a lot of trading schemes looking for patterns do this thing to. they model what shows up as noise and other signals and also model what determines value, and then look for the signals that point to or away from value.
