Location, identification and telemetry system using strobed signals at predetermined intervals

• US 6,222,440 B1
• Filed: 02/23/1998
• Issued: 04/24/2001
• Est. Priority Date: 02/23/1998
• Status: Expired due to Fees

• Current Assignee: FreshLoc Technologies Incorporated
• Original Assignee: FreshLoc Technologies Incorporated
• Inventors: Heller, Alan C.
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Dalencourt, Yves
• Application Number:
  US09/027,968
• Time in Patent Office: 1,156 Days
• Field of Search: 340/10.1, 340/825.31, 340/825.52, 340/825.34, 340/825.69, 342/463
• US Class Current: 340/10.3
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08

Abstract

A tracking system is implemented according to the invention in which the identification data of a wireless transmitter is divided into multiple bursts. Instead of transmitting the entire identification in a single burst, the identification is split among bursts, so that it takes a period of time to uniquely identify a particular transmitter. However, the time between bursts falls under tight tolerance, so once a transmitter is identified, it can be further identified based on when it transmits as opposed to what it transmits. In this way, high tractability can be maintained without repeatedly transmitting the entire identification code of the transmitter.

Claims

1. A method of identifying a transmitter that has identifying information, comprising the steps of:

transmitting portions of the identifying information from the transmitter at predetermined intervals;

receiving the transmitted portions of the identifying information;

positively identifying the transmitter after receiving a plurality of the transmitted portions of the identifying information based on the identifying information; and

subsequently identifying the transmitter based on the time of arrival of subsequently received transmitted portions of the identifying information relative to the time of arrival of previously received transmitted portions of identifying information.

2. The method of claim 1, wherein the positively identifying step further comprises the step of further comprising positively identifying the transmitter based on the entire identifying information after the entire identifying information has been received in portions.

3. The method of claim 1, further comprising the steps of:

verifying the subsequent identification of the transmitter based on time of arrival by comparing subsequently transmitted portions of the identified information with previously received portions of the identifying information.

4. The method of claim 1, wherein the step of receiving transmitted portions further comprises the step of receiving the transmitted portions of identifying information at more thin one receiver.

5. The method of claim 1, wherein the step of receiving transmitted portions further comprises the step of receiving transmitted portions from both a first and second transmitter.

6. The method of claim 5, wherein the step of positively identifying the transmitter further comprises the step of:

discriminating between the portions of identifying information transmitted by the first transmitter and portions of identifying information received from the second transmitter based on intervals between the transmission of the portions from each transmitter.

7. The method of claim 1, wherein the step of transmitting further comprises the step of:

transmitting using a radio frequency signals.

8. The method of claim 1, wherein the step of transmitting portions of identifying information at predetermined intervals further comprises the step of transmitting at intervals of about one second and transmissions of about one millisecond.

9. The method of claim 1, wherein the step of receiving transmitted portions further comprises the steps of:

receiving the transmitted portions of the identifying information at a receiver;

time-stamping the transmitted portions of identifying information; and

transmitting over a network the time-stamped portions of the identifying information to a processor.

10. The method of claim 1, wherein the step of receiving the transmitted portions further comprises the steps of:

receiving the transmitted portions of identifying information at a receiver;

creating a pulse map representative of the received transmitted portions of identifying information;

transmitting the pulse map from the receiver to a processor; and

determining at the processor the meaning of information embedded within the pulse map.

11. The method of claim 1, wherein the step of transmitting portions-of identifying information further comprises the step of transmitting a signal bit of information regarding each transmission of portions of identifying information.

12. The method of claim 1, wherein the step of transmitting portions of identifying information further comprises the step of transmitting four bits of information during each transmission of portions of identifying information.

13. The method of claim 1, wherein the identifying information comprises a nine bit code.

14. The method of claim 1, wherein the identifying information comprises a thirty-two bit code.

15. The method of claim 1, wherein the step of transmitting portions of identifying information further comprises the step of encrypting the identifying information before transmitting the portions of identifying information.

16. A method for transmitting data, as described in claim 1, wherein each predetermined interval is the same length.

17. A method for transmitting data, as described in claim 1, wherein each transmission is followed by a significantly longer non-transmit period.

18. A method for transmitting data, as described in claim 1, wherein each transmission pulse has a duty cycle of less than 0.1%.

19. A transmitter for transmitting identifying information, comprising:

identifying information stored within the transmitter;

transmit circuitry for transmitting a portion of the identifying information; and

control circuitry that separates the identifying information into a plurality of portions of identifying information, and automatically transmits the portions of identifying information at predetermined intervals, wherein the portions of identifying information are subsets of the identifying information, the predetermined intervals providing time of arrival information to a receiving device, the time of arrival being relative to a time of arrival of previously transmitted portions of identifying information.

20. The transmitter of claim 19, wherein the control circuitry further comprises:

circuitry for encoding the identifying information with a counter and a digital signature.

21. The transmitter of claim 19, wherein the control circuitry is an embedded processor.

22. The transmitter of claim 19, wherein the transmitter is a radio frequency transmitter.

23. The transmitter of claim 19, wherein the control circuitry transmits the portions of identifying information at intervals of approximately one second, and wherein the transmission takes approximately one millisecond.

24. A system for receiving transmitted identifying information comprising:

a receiver for receiving transmitted portions of identifying information; and

a processor for receiving from the receiver the transmitted portions of identifying information and positively identifying a transmitter based on accumulated portions of the identifying information received from the receiver, and subsequently identifying a transmitter based on the time of arrival of portions of the identifying information to the receiver relative to the time of arrival of previously received transmitted portions of identifying information.

25. The system of claim 24, wherein the receiver is a radio frequency receiver.

26. The system of claim 24, wherein the receiver time-stamps received portions of identifying information before transmission to the processor.

27. The system of claim 24, wherein the receiver encodes received portions of identifying information in a pulse map and transmits the pulse map to the processor, and wherein the processor determines the meaning of the portions of identifying information transmitted from the receiver based on the contents of the pulse map.

28. The system of claim 24, wherein the receiver and processor are connected via a network.