Interrogated transponder system

A method of selectively interrogating the individual transponders of a group of transponders wherein each transponder includes logic circuitry which aides in determining information to be returned to a central station, the information being provided by a selected one of a plurality of input sources, and means for returning information to a central station by means of preselected return frequencies and wherein predetermined subgroups of transponders are adapted to be selectively actuated in response to the receipt of preselected address tones received in a preselected sequence, comprising

• selecting a subgroup of transponders by transmitting to all of said transponders k address tones from an available number of n tones,
• and then transmitting to all of said transponders interrogation tones taken from the remaining n-k tones to cause each of the transponders of said selected subgroup to transmit its stored information on its return frequencies to the central station,
• and identifying the individual transponders within said desired subgroup by the frequencies of the return signals from the transponders within said desired subgroup.

A method of selectively interrogating the individual transponders of a group of transponders wherein each transponder includes information to be returned to a central station, the information being provided by a selected one of a pluality of input sources, and means for returning information to a central station by means of preselected information to a central station by means of preselected return frequencies and wherein predetermined subgroups of transponders are adapted to be selectively actuated in response to the receipt of preselected address tones received in a preselected sequence, comprising

• selecting a subgroup of transponders by transmitting to all of said transponders k address tones from an available number of n tones,
• and then transmitting to all of said transponders interrogation tones taken from the remaining n-k tones to cause each of the transponders of said selected subgroup to transmit its information on its return frequencies to the central station,
• and identifying the individual transponders within said desired subgroup by the frequencies of the return signals from the transponders within said subgroup.

A method of selectively interrogating the individual transponders of a group of transponders wherein each transponder includes means for returning information to a central station by means of preselected return frequencies and wherein predetermined subgroups of transponders are adapted to be selectively actuated in reponse to the receipt of preselected address tones received in a preselected sequence, comprising

• selecting a subgroup of transponders by transmitting to all of said transponders k address tones from an available number of n tones,
• and then transmitting to all of said transponders interrogation tones taken from the remaining n tones to cause each of the transponders of said selected subgroup to transmit its return frequencies to the central station,
• and identifying the individual transponders within said desired subgroup by the frequencies of the return signals from the transponders within said desired subgroup.

A method of selectively interrogating the individual transponders of a group of transponders wherein each transponder includes means for returning information to a central station by means of preselected return frequencies and wherein predetermined subgroups of transponders are adapted to be selectively actuated in response to the receipt of preselected address tones received in a preselected sequence, comprising

• selecting a subgroup of transponders by transmitting to all of said transponders k address tones from an available number of n tones,
• and then transmitting to all of said transponders interrogation tones taken from the n tones to cause each of the transponders of said selected subgroup to transmit its return frequencies to the central station,
• an identifying the individual transponders within said desired subgroup by the frequencies of the return signals from the transponders within said desired subgroup.

A method of selectively interrogating the individual transponders of a group of transponders wherein each transponder includes means for returning information to a central station by means of preselected return frequencies and wherein predetermined subgroups of transponders are adapted to be selectively actuated in response to the receipt of preselected tones received in a preselected sequence, comprising:

• selecting a subgroup of transponders by transmitting to all of said transponders a set of k address tones from an available number of n tones,
• then transmitting to all of said transponders a second set of tones, including I interrogating tones taken from the remaining n-k tones for interrogating each of the transponders of said selected subgroup, to cause the interrogated transponders to transmit their return frequencies to the central station,
• and identifying the individual transponders within said desired subgroup by the frequencies of the return signals from the transponders within said desired subgroup.