Claims
- 1. A method of tracking objects comprising:
- generating an energy field at a fixed location in a tracking area, which energy field is composed of a number of discrete and fixed radio frequency signals of different frequencies,
- disposing different coded arrays of passive tuned electrical circuits on a plurality of objects to be tracked which objects may pass said known location, and wherein each of said coded arrays of circuits defines a code which is different from the codes defined by the other objects so that each object has an array of such circuits which is different from the arrays of circuits defining the codes of the other objects, and
- when an object with a coded array of tuned electrical circuits comes within a given range of said fixed location in said tracking area, indicating the presence of said object thereat by detecting the presence of its tuned electrical circuits by sensing the absorption of energy of said field by said passively tuned circuits and generating a corresponding electrical signal for each frequency of the field which experiences energy absorption, and
- generating a code signal defined by the combination of said tuned electrical circuits detected when said object is within said given range of said field and employing said code signal to indicate the presence of said object at said known location.
- 2. A method in accordance with claim 1 including generating a code signal which is indicative of the location of said energy field in said tracking area when said coded array of circuits comes within a given range of said known location and the energy field thereof.
- 3. A method in accordance with claim 1 wherein each of said coded arrays of circuits is disposed in a single housing, further including securing said housings at predetermined locations on said objects.
- 4. A method in accordance with claim 3 including encapsulating said coded arrays of circuits in said housings.
- 5. A method in accordance with claim 1 wherein said energy field is generated by a voltage controlled oscillator operable to produce a number of discrete stable short wave frequencies defining said energy field.
- 6. A method in accordance with claim 5 wherein said code signal is generated by means of a staircase generator which is operable to determine the code by generating signals defining the voltage steps in its output resulting from the frequencies of the oscillator which are partly absorbed by said passive tuned electrical circuits.
- 7. A method in accordance with claim 1 wherein two successive indications of the absorption of energy by each of said tuned electrical circuits is received and said successive indications are compared to determine the parity of the two successive indications.
- 8. The method in accordance with claim 1 wherein said energy field produces said number of discrete and fixed radio frequency signals in a serial manner and wherein with said code signal defined by the combination of said tuned electrical circuits is in parallel form.
RELATED APPLICATIONS
This is a continuation-in-part of Ser. No. 84,429 filed Oct. 12, 1979 now U.S. Pat. No. 4,288,689; issued Sept. 8, 1981.
US Referenced Citations (16)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
84429 |
Oct 1979 |
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