A method and apparatus for determining whether a received signal is transmitted via a repeater is described. A source signal to be conveyed via a particular repeater may include, or be modified to include, a variety of signal characteristics having a predictable relationship that remains relatively constant, which may be taken together as a signature of the repeater. The signature may reflect a composite of distinct signals. A database of repeater signature references may be developed, and an adequate match between characteristics of an unknown received signal and such signature references indicates that at least part of the unknown signal is transmitted via a repeater. Useful signal characteristics for repeater signatures may include some representative of signal strength, and time of arrival information, among many other possibilities.