Signal scramblers were devices that prevented others from tracking the sources of transmissions in the area.
The Sith Lord Fulminiss used several to hide his base on the planet Voss.
In 32 BBY, only a week before the Boonta Eve Classic, Anakin Skywalker constructed and gifted a device to his friend, Pala Kwi'teksa, to protect her from Gardulla the Hutt, against whom both children had conspired to rescue from her clutches several Ghostling children, whom Gardulla had kidnapped to use as ornaments in her luxurious if notorious pleasure garden.
Uulshos Manufacturing's LAVr QH-7 Chariot had a sophisticated signal scrambler used to encode outgoing transmissions as part of its communications bay. The signals made it impossible to intercept and decode the transmissions.