An apparatus for sourcing an interrogation signal for use in a object identification system including a frequency hopping source for generation of an interrogation signal which is coupled to a homo dyne radio for transmission by a bi-directional antenna to a tag. Upon receipt, the tag provides...http://www.google.fr/patents/US5828693?utm_source=gb-gplus-shareBrevet US5828693 - Spread spectrum frequency hopping reader system
