System for identifying particular objects

In combination in a system including a reader and a transponder displaced from the reader for identifying an object associated with the transponder,

• means at the reader for transmitting interrogating signals at a particular frequency to the transponder,
• means disposed at the transpnder and responsive to the interrogating signals for generating successive pluralities of signals cycles in a pattern individual to the object, the signal cycles in each plurality including one signal cycle at a first frequency and two signal cycles at a second frequency constituting the second harmonic of the first frequency, the signal cycles at the second frequency preceding the signal cycle at the first frequency in each plurality representatitve of a binary "1" and the signal cycles at the first frequency preceding the signal cycle at the second frequency for each plurality representing a binary "0",
• means at the transponder for transmitting the successive pluralities of signal cycles at the first and second frequencies to the reader, and
• means at the reader for decoding the pattern of the frequencies of the signal cycles in each of the successive pluralities to identify the object.

In combination in a system including a reader and a transponder displaced from the reader for identifying an object associated with the transponder,

• means at the reader for interrogating the transponder,
• means disposed at the transponder and responsive to the interrogation from the reader for generating successive pluralities of signal cycles in an individual pattern identifying the object, the signal cycles in each plurality having patterns of signal cycles at both first and second frequencies to identify a binary "1" or a binary "0",
• means for transmitting the successive pluralities of signal cycles to the reader,
• means at the reader for receiving the transmitted signal cycles,
• means at the reader for delaying the successive pluralities of the received signal cycles by a first delay time,
• first means at the reader for comparing the received signal cycles and the signal cycles delayed by the first delay time to obtain a demodulation of the information represented by the signal cycles in the successive pluralities,
• means at the reader for delaying the successive pluralities of the received signal cycles by a second delay time different from the first delay time,
• second means at the reader for comparing the received signal cycles and the signal cycles delayed by the second delay time to generate phase-locked signals,
• means responsive at the reader to the phase-locked signals for generating clock signal cycles at the reader to facilitate the decoding of the information represented by the signal cycles in the successive pluralities,
• means at the reader for delaying the successive pluralities of the received signal cycles by a third delay time different from the first and second delay times,
• third means at the reader for comparing the received signal cycles and the signal cycles delayed by the third delay time to generate control signals, and
• means responsive to the control signals for generating additional phase-locked signals at times synchronous with the pahse-locked signals generated by the second comparing means to facilitate the generation of the clock signal cycles on a periodic basis.

In combination in a reader for identifying an object associated with a transponder displaced from the reader wherein the transponder generates, in a particular pattern identifying the object, pluralities of signal cycles at first an second frequencies in a first sequence to identify a binary "0" and in a second sequence, different from the first sequence, to identify a binary "1" and transmits the pluralities of signal cycles in the particular pattern of the first and second sequences to the reader,

• first means for receiving the pluralities of signal cycles in the particular pattern of the first and second sequences,
• second means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a first time period to detect the information coded by the received pluralities of signal cycles,
• third means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a second time period different from the first time period to generate phase-locked signals,
• fourth means for comparing the received pluralities of signal cycles and the received pluralities of signal cycles delayed by a third time period different from the first and second time periods to generate additional phase-locked signal cycles at times different from the phase-locked signals generated by the third means, and
• fifth means responsive to the phase-locked locked signals generated by third and fourth means for synchronizing the detection of the information generated by the received pluralities of signals with the generation of the phase-locked signals and the additional phase-locked signals.

In combination in a reader for identifying an object associated with a transponder displaced from the reader wherein the transponder generates, in a particular pattern identifying the object, pluralities of signal cycles at first and second frequencies in a first sequence to identify a binary "0" and in a second sequence, different from the first sequence, to identify a binary "1" and transmits the signal cycles in the particular pattern of the first and second sequences to the reader,

• means for receiving signals in the particular pattern of the first and second sequences,
• means for delaying the signal cycles for a first particular time period related to the first and second frequencies,
• means for delaying the signal cycles for a second particular time period related to the first and second frequencies but different from the first particular time period,
• means for delaying the signal cycles for a third particular time period related to the first and second frequencies but different from the first and second particular time periods,
• means for comparing the received signal cycles and the signal cycles delayed by the first time period for generating phase-locked signals,
• means for comparing the received signals and the signals delayed by the second time period for generating additional phase lock signals at the times not generated by the first comparing means,
• means for comparing the received signal cycles and the signal cycles delayed by the third time period for generating demodulated signals, and
• means responsive to the demodulated signals and the phase-locked signal cycles and the additional phase-locked signal cycles for recovering the code identifying the object.

In combination in a system for identifying an object,

• means displaced from the object for transmitting interrogating signals to the object,
• means responsive at the object to the interrogating signals for generating signals in a first pattern of signals at first and second frequencies representative of a binary "1" and in a second pattern of signals at the first and second frequencies representative of a binary "0", the first frequency being a harmonic of the second frequency and the duration of the signals representing a binary "0" being the same as the duration of the signals representing a binary "1",
• means disposed at the object for transmitting the successive pluralities of signals at the first and second frequencies in representation of the binary "0's" and the binary "1's",
• means at the displaced position for receiving the transmitted signals, and
• means at the displaced position for decoding the received signals to identify the pattern of binary "0's" and binary "1's" represented by such signals.

In combination in a reader for identifying an object associated with a transponder displaced from the reader wherein the transponder generates, in a particular pattern identifying the object, pluralities of signal cycles at first and second frequencies in a first sequence to identify a binary "1" and in a second sequence, different from the first sequence, to identify a binary "0"

• switching means having first and second states of operation and normally being operative in the first state,
• charge storage means,
• means responsive to the operation of the switching means in the first state for charging the charge storage means,
• means responsive to first particular patterns of the signals in the first and second states for generating phase-locked signals at a particular frequency,
• means responsive to second particular patterns of the signals in the first and second states for obtaining an operation of the switching means in the second state,
• means responsive to the operation of the switching means in the second state for obtaining a discharge of the charge storage means, and
• means responsive to the discharge of the charge storage means for obtaining the generation of additional phase-locked signals at the particular frequency.