Abstract: A method of accurate friend-foe recognition on the basis of secondary radar through the provision additional special information in both the interrogation device and the responsor device during the formation of their respective signals. This additional information is solely practical and valid for the respective responsor device undergoing interrogation so that the answering signals provided are valued as answers coming from a friend-responsor device. Additional steps of utilizing the time position of the additional information and the uniqueness of such information with respect to a simultaneously available great number of responses makes it still more difficult for a foe-responsor to pass itself off as a counterfeit friend-responsor.