Transmitter/responder systems.

摘要

A memory suitable for use as a responder, comprising: (a) receiver means for receiving a transmitted signal S1; (b) generator means (76) for generating a carrier component of a transmittable signal S2; (c) logic means (L2) for enabling signal S2 to be in mathematical relationship with signal S1, said logic means comprising: (i) at least one memory means (60) for storing code; (ii) at least one modulation means (65) for modulating said carrier component of signal S2, the modulating being under control of at least a portion of said stored code such that signal S2 is in coded mathematical relationship with signal S1; and (d) transmitter means (T2) for transmitting signal S2.