There have been no detectable electromagnetic signals.
It's truly mind boggling just how much difference there is, power-wise, between a "strong signal" and a "barely detectable signal."
If cleavage occurs, the fluorophore will be separated from the quencher molecule generating a detectable signal.
The hapten label is recognized by anti-bodies, which in turn are coupled to a detectable signal (Gunderson et al. 2006).
This increases the rate at which detectable signals should be seen from one per tens of years of observation, to tens per year.
That action closes what amounts to the body's own electrical circuit, creating detectable electrical signals with each heartbeat.
Another potential hurdle is a magnetic "signature," or detectable signal.
Because of the different signal processing used, the minimum detectable signal to noise ratio will be different.
It has been suggested that a small black hole passing through the Earth would produce a detectable acoustic signal.
The subsequent reaction produces a detectable signal, most commonly a color change in the substrate.