Wiktionary
n. An event or emanation to which a sensing device gives an undesired positive response.
Usage examples of "false signal".
The switches that nightly triggered the image conduits responded to a false signal and produced a waking dream.
She hauled her wind, not liking the look of us, and in doing so some of the more brilliant officers aboard, those who could count above three, I mean, made out that she had a false signal flying: one lantern short.
We can pulse a false signal and clear the system for five minutes of testing.
It offered a false signal for a space of about four feet around its wearer, evening out the heat signals, making the body appear a bright, amorphous mass, such as might be left behind by an explosion.
If nothing else, I want to find out why we got a false signal from the mining ship.