Object monitoring method and apparatus

• US 4,217,588 A
• Filed: 03/16/1978
• Issued: 08/12/1980
• Est. Priority Date: 04/16/1975
• Status: Expired due to Term

• Current Assignee: Information Identification Company Incorporated
• Original Assignee: Information Identification Company Incorporated
• Inventors: Freeny, Charles C. Jr.
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US05/887,192
• Time in Patent Office: 880 Days
• Field of Search: 340/22, 340/23, 340/24, 340/346, 325/4, 325/39, 325/53, 325/55, 325/64, 325/67, 325/113, 325/117, 325/158, 325/185, 325/186, 343/112 D, 455/11, 455/18, 455/54
• US Class Current: 342/458
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

An improved method and apparatus for automatically monitoring objects, such as vehicles, for example, wherein signpost units are positioned at predetermined locations and each signpost unit transmits a binary signpost code for reception via units installed in the objects being monitored and the objects being monitored receive the signpost codes and store object location information. In one aspect, the present invention contemplates a method and an apparatus which has a multi-mode operation capability wherein the location of the monitored objects is reported when the monitored object enters a different coverage region in an automatic reporting mode, wherein only those monitored objects within a predetermined region or on a predetermined route report to the base station in a region or route reporting mode, and wherein only the locations of predetermined monitored objects are reported to the base station in a polling mode. In another aspect, the present invention contemplates an improved method and an apparatus for locating and operating the signpost units to reduce the total number of signpost units required to cover a given number of locations wherein each signpost unit establishes a uniquely identifiable near-field region and a uniquely identifiable far-field region, the signpost units being located to establish uniquely identifiable overlap regions wherein a portion of the far-field region of at least one of the signpost units overlaps a portion of the far-field region on another signpost unit. The method and apparatus of the present invention also provides a non-polling location technique eliminating the necessity of interrogating the monitored objects at regular intervals and reducing the radio channel time required for reporting object location.

Claims

1. Apparatus for use in monitoring objects within a predetermined monitored area comprising:

a signpost unit positioned within the monitored area and having a predetermined signpost code encoded therein uniquely identifying the signpost unit and providing an output signal encoded with the signpost code, the signpost unit output signal establishing a near field region extending a distance generally from the signpost unit and encompassing a predetermined coverage region at least large enough to encompass a monitored object and the signpost unit output signal establishing a far-field region extending a distance generally from the signpost unit and encompassing a predetermined coverage region, the far-field region extending a distance from the signpost unit greater than the distance of the near-field region from the signpost unit and the strength of the signpost unit output signal within the near-field region being greater than the strength of the signpost unit output signal within the far-field region; and

means in the monitored object receiving the signpost unit output signal having a portion detecting the strength of the received signpost unit output signal for providing one output signal in response to a received signpost unit output signal having a signal strength less than a predetermined signal strength level thereby indicating the location of the monitored object within the far-field region of the signpost unit identified via the signpost code encoded in the received signpost unit output signal, and providing another output signal in response to a received signpost unit output signal having a signal strength greater than the predetermined signal strength level thereby indicating the location of the monitored object within the near-field region of the signpost unit identified via the signpost code encoded in the received signpost unit output signal, the means in the monitored object defined further as comprising;

a receiver for receiving the signpost unit output signal and providing a receiver output signal encoded with the signpost code encoded in the received signpost unit output signal;

a power level detector receiving the receiver output signal and providing a power level signal in one state in response to a received receiver output signal having a signal strength indicating a received signpost unit output signal having a signal strength corresponding to the strength of the signpost unit output signal in the far-field region thereby indicating the location of the monitored object within the far-field region of the signpost unit and providing a power level signal in another state in response to a received receiver output signal having a signal strength indicating a received signpost unit output signal having a signal strength corresponding to the strength of the signpost unit output signal within the near-field region thereby indicating the location of the monitored object within the near-field region;

a decoder receiving the receiver output signal and providing the signpost code encoded in the received receiver output signal via a decoder output signal, the decoder receiving the power level signal provided via the power level detector and providing the received power level signal along with the signpost code via the decoder output signal, the state of the power level signal indicating the location of the monitored object within the near-field region of the signpost unit identified via the signpost code encoded in the receiver output signal in one state of the power level signal and indicating the location of the monitored object within the far-field region of the signpost unit identified via the signpost code encoded in the receiver output in one other state of the power level signal;

a storage unit receiving the signpost codes and accompanying power level signals from the decoder and storing the received signpost code and accompanying power level signal in one condition of the storage unit, the storage unit providing the signpost code and accompanying power level signal therein in one other condition of the storage unit in response to receiving a signal;

a comparison logic network receiving the signpost code and accompanying power level signal provided via the decoder and the signpost code and accompanying power level signal provided via the storage unit, the comparison logic network comparing the signpost code and accompanying power level signal received from the decoder with the signpost code and accompanying power level signal received from the storage unit and providing an output signal in response to the signpost code and accompanying power level signal received from the decoder being identical to the signpost code and accompanying power level signal received from the storage unit, and the comparison logic network providing another output signal in response to the signpost code and accompanying power level signal received from the decoder being different from the signpost code and accompanying power level signal received from the storage unit;

a location encoder receiving the signpost code and accompanying power level signal from the storage unit; and

means in the monitored object providing the signal for conditioning the storage unit to provide the signpost code and accompanying power level signal for storing in the location encoder in response to a signal from the comparison logic network indicating a difference between the signpost code and accompanying power level signal received from the decoder and the signpost code and accompanying power level signal received from the storage unit.

2. The apparatus of claim 1 wherein the decoder is defined further as providing a valid data signal in response to receiving a signpost code via the receiver output signal having a predetermined code format.

3. The apparatus of claim 1 wherein the signpost unit is defined further as repeatably providing a time division binary signpost code uniquely identifying the signpost unit;

and wherein the decoder provides a valid data signal in response to receiving a signpost code via the receiver output signal having the predetermined code format and repeatable a predetermined number of times.

4. The apparatus of claim 1 defined further to include a plurality of signpost units positioned within the monitored area, the far-field region and the near-field region of each signpost unit encompassing predetermined coverage regions within the monitored area and the signpost units being spaced within the monitored area to substantially assure the passing through at least one of the coverage regions by a monitored object entering and leaving the monitored area.

5. The apparatus of claim 1 defined further to include a plurality of signpost units positioned within the monitored area, the far-field region and the near-field region of each signpost unit encompassing predetermined coverage regions within the monitored area, the coverage regions encompassing some of the space within the monitored area and the remaining space within the coverage region defining open regions, the signpost units being spaced within the monitored area to substantially assure the passing of the monitored object from at least one of the coverage regions upon entering one of the open regions and to substantially assure the passing of the monitored object into at least one of the coverage regions upon leaving one of the open regions during the movement of the monitored object within the monitored area.

6. The apparatus of claim 1 wherein the signpost unit is defined further to include:

a signpost encoder encoded with a predetermined time division binary signpost code and providing the signpost code via an output signal; and

a transmitter for transmitting the signpost code provided via the signpost encoder output signal in a relatively high frequency range to produce a radiation pattern establishing a relatively steep radiation field gradient thereby establishing the near-field region extending the predetermined distance from the signpost unit and the far-field region extending the predetermined distance from the signpost unit greater than the distance of the near-field region from the signpost unit, the strength of the transmitted signal within the near-field region being greater than the strength of the transmitted signal within the far-field region.

7. The apparatus of claim 1 wherein the signpost unit is defined further to include:

a signpost encoder encoded with a predetermined time division binary signpost code and providing the signpost code via an output signal;

an FSK generator receiving the signpost encoder output signal and providing an output signal having one frequency (fs) in response to receiving a signpost code bit representing a logical "zero" and another frequency (fm) in response to receiving a signpost code bit representing a logical "one";

a transmitter modulator providing a transmitter modulator output signal; and

a transmitter receiving the transmitter modulator output signal and providing an output signal having a predetermined frequency modulated via the received transmitter modulator output signal.

8. The apparatus of claim 1 defined further to include:

means connected to the location encoder for receiving and transmitting the codes stored in the location encoder in response to the location encoder receiving a code from the storage unit in an automatic reporting mode, said means having a portion receiving a code identifying one of the coverage regions within the monitored area and comparing the received code with the code stored in the location encoder, and transmitting the code stored in the location encoder in response to an identical comparison of the received code with the code stored in the location encoder identifying one of the coverage regions in a region reporting mode.

9. The apparatus of claim 1 wherein the location encoder is defined further as having a vehicle code stored therein for identifying the monitored object, and wherein the apparatus is defined further to include:

means connected to the location encoder for receiving and transmitting the codes stored in the location encoder in response to the location encoder receiving a code from the storage unit in an automatic reporting mode, said means having a portion for receiving a vehicle code identifying one of the monitored objects and comparing the received vehicle code with the vehicle code stored in the location encoder, and transmitting the codes stored in the location encoder in response to an identical comparison of the received vehicle code with the vehicle code stored in the location encoder in a vehicle polling mode.

10. The apparatus of claim 9 wherein the means for transmitting the codes in the location encoder is defined further as having a portion for receiving a code identifying one of the coverage regions within the monitored area and comparing the received code with the code stored in the location encoder identifying one of the coverage regions and transmitting the codes stored in the location encoder in response to an identical comparison of the received code with the code stored in the location encoder identifying one of the coverage regions in a region reporting mode.

11. The apparatus of claim 10 defined further to include:

means for receiving operating mode bits and conditioning the means for transmitting the codes in the location encoder in the automatic reporting mode in response to one received predetermined operating mode bit, and conditioning the means for transmitting the codes in the vehicle reporting mode in response to another received predetermined operating mode bit, and conditioning the means for transmitting the codes in the region reporting mode in response to one other received predetermined operating mode bit.

12. The apparatus of claim 1 defined further to include:

means for transmitting the codes stored in the location encoder in one condition; and

means for transmitting the means for transmitting the codes in the condition for transmitting the codes stored in the location encoder.

13. The apparatus of claim 1 wherein the signpost unit is defined further as providing the output signal establishing the near-field region extending a distance of at least ten feet (10 ft.) from the signpost unit.

14. The apparatus of claim 13 wherein the signpost unit is defined further as providing the output signal establishing the far-field region extending a distance of about one hundred feet (100 ft.) from the signpost unit.

15. The apparatus of claim 1 wherein the signpost unit is defined further as providing the output signal establishing the near-field region extending a distance in a range of about ten feet (10 ft.) to about one hundred feet (100 ft.) from the signpost unit.

16. The apparatus of claim 15 wherein the signpost unit is defined further as providing the signpost unit establishing the far-field region extending a distance in a range of about one hundred feet (100 ft.) to about one thousand feet (1,000 ft.) from the signpost unit.

17. An apparatus for monitoring objects within a predetermined monitored area wherein signpost units are positioned within the monitored area and each signpost unit transmits a signpost code uniquely identifying the signpost unit, each signpost unit including means for transmitting a signal encoded with at least one operating mode bit for conditioning the apparatus in the monitored objects in an automatic reporting mode in one condition of the operating mode bit and in a region reporting mode in one other condition of the operating mode bit, said signals also being encoded with a location code identical to one predetermined signpost code when operating in the region reporting mode, the apparatus in each of the monitored objects comprising:

means for receiving the signpost codes transmitted via the signpost units and for storing the received signpost codes;

means for transmitting the signpost code stored in the means for storing the received signpost codes in one condition; and

means for receiving the signal encoded with at least one operating mode bit and conditioning the means for transmitting the signpost code in a condition for transmitting the signpost code stored in the means for storing the signpost codes in response to receiving the signal encoded with the operating mode bit in the one condition for conditioning the apparatus in the monitored object in the automatic reporting mode, and for conditioning the means for transmitting the signpost code in a condition for transmitting the signpost code stored in the means for storing signpost codes in response to receiving the signal encoded with a location code identical to the signpost code stored in the means for storing codes and encoded with an operating mode bit in the one other condition for conditioning the apparatus in the monitored object in the region reporting mode.

18. The apparatus of claim 17 defined further to include:

means for storing a vehicle code uniquely identifying the monitored object; and

wherein the signals encoded with the operating code bits are encoded with a predetermined vehicle code in a polling mode, and wherein the means in the monitored object for receiving the signals encoded with the operating mode bits and for conditioning the apparatus in the monitored objects in the automatic reporting mode and in the region reporting mode is defined further as receiving the signals encoded with predetermined vehicle codes and conditioning the means for transmitting the signpost code in a condition for transmitting the signpost code stored in the means for storing signpost codes in response to receiving the signal encoded with a vehicle code identical to the vehicle code stored in the means for storing the vehicle code and in the polling mode.

19. The apparatus of claim 18 defined further to include:

a base station having a portion for transmitting the operating mode bits for conditioning the apparatus in the monitored object in the automatic reporting mode, in the region reporting mode and in the polling mode from a remote base station location.

20. The apparatus of claim 18 wherein the means in the monitored object receiving the signals encoded with the operating mode bits and the vehicle code is defined further as conditioning the means for transmitting the vehicle code in condition for transmitting the vehicle code in the automatic reporting mode, in the region reporting mode and in the polling mode.

21. The apparatus of claim 17 wherein the means for receiving and storing the signpost codes is defined further to include:

means for receiving the signpost codes transmitted via the signpost units;

a storage unit for storing the signpost code received by the means for receiving the signpost codes;

a location encoder for storing the signpost code in the storage unit in one condition;

a comparison logic network for comparing each received signpost code with the previously received signpost code and storing the signpost code received via the means for receiving the signpost codes in response to a difference between the received signpost code and the previously received signpost code.

22. The apparatus of claim 21 wherein the means in the monitored object receiving the signals encoded with the operating mode bits is defined further as conditioning the means for transmitting the signpost code stored in the means for storing the signpost codes in a condition for transmitting the stored signpost code in response to a signpost being received different from the previously received signpost code and in the automatic reporting mode.

23. The apparatus of claim 17 defined further to include:

a base station having a portion for transmitting the operating mode bits for conditioning the apparatus in the monitored object in the automatic reporting mode and in the region reporting mode from a remote base station location.

24. An apparatus for monitoring objects within a predetermined monitored area wherein signpost units are positioned within the monitored area and transmit signpost codes uniquely identifying each of the signpost units, each signpost code thereby uniquely identifying the location of the signpost unit transmitting the signpost code, each monitored object including apparatus comprising:

means for receiving the signpost codes transmitted via the signpost units and for storing the received signpost code;

means for transmitting the signpost code stored in the means for storing the received signpost code in response to a signpost code being stored in the means for storing the received signpost code and in an automatic reporting mode;

means for receiving a code identifying one of the coverage regions, comparing the received code with the signpost code stored in the means for storing the received signpost code, and transmitting the signpost code stored in the means for storing the received signpost code in response to an identical comparison of the received code identifying one of the coverage regions and the signpost code stored in the means for storing the received signpost code and in a region reporting mode; and

means for storing a vehicle code, and for receiving a vehicle code uniquely identifying one of the monitored objects and comparing the received vehicle code with the stored vehicle code and transmitting the signpost code stored in the means for storing the received signpost code in response to an identical comparison between the received vehicle code and the stored vehicle code and in a polling mode.

25. A method for monitoring objects within a predetermined monitored area wherein signpost units are positioned within the monitored area and transmit signpost codes uniquely identifying the signpost units and wherein each monitored object includes apparatus for receiving the transmitted signpost codes and signals encoded with at least one operating mode bit and wherein the apparatus in the monitored objects has an automatic reporting mode of operation wherein the received signpost codes are transmitted, comprising the steps of:

receiving the signals encoded with at least one operating mode bit via the apparatus in each monitored object;

conditioning the apparatus in the monitored object in the automatic reporting mode in response to receiving a signal encoded with a predetermined operating mode bit for conditioning the apparatus in the automatic reporting mode;

comparing the signpost code received via the apparatus in the monitored object with the signpost code previously received via the apparatus in the monitored object; and

transmitting the received signpost code via the apparatus in the monitored object in response to a difference between the received signpost code and the previously received signpost code and in the automatic reporting mode.

26. The method of claim 25 wherein the apparatus in the monitored object includes a region reporting mode of operation wherein the apparatus transmits the received signpost code in response to receiving a location code identical to the received signpost code and wherein the apparatus in the monitored objects receives signals encoded with predetermined locations codes, the method defined further to include the steps of:

receiving the signals encoded with the location codes;

conditioning the apparatus in the monitored objects in the region reporting mode in response to receiving a signal encoded with an operating mode bit for conditioning the apparatus in the monitored object in the region reporting mode;

comparing the received location code with the received signpost code; and

transmitting the received signpost code via the apparatus in the monitored object in response to a received location code identical to a received signpost code.

27. The method of claim 26 defined further to include the step of:

transmitting the operating mode bits for conditioning the apparatus in the monitored object in the region reporting mode and in the automatic reporting mode from a remotely located base station.

28. The method of claim 25 wherein the apparatus in the monitored object includes a polling mode of operation and wherein the apparatus in the monitored object receives signals encoded with the vehicle codes, the method defined further to include the steps of:

storing a vehicle code in the apparatus in the monitored object, the stored vehicle code uniquely identifying the monitored object;

receiving the signals encoded with the vehicle codes;

conditioning the apparatus in the monitored object in the polling mode in response to receiving a signal encoded with an operating mode bit for conditioning the apparatus in the monitored object in the polling mode;

comparing the received vehicle code with the stored vehicle code; and

transmitting the received signpost code via the apparatus in the monitored object in response to a received vehicle code identical to the stored vehicle code.

29. The method of claim 28 defined further to include the step of:

transmitting the operating mode bits for conditioning the apparatus in the automatic reporting mode, in the region reporting mode and in the polling mode from a remotely located base station.

30. A method for monitoring objects within a predetermined monitored area wherein signpost units are positioned and transmit signpost codes uniquely identifying the signpost units and wherein the monitored objects each include an apparatus for receiving the signpost codes and signals encoded with at least one operating mode bit, the method comprising the steps of:

receiving the signals encoded in the operating mode bits; and

conditioning the apparatus in the monitored object in the automatic reporting mode in response to receiving the signal encoded with the operating mode bit in one condition of the operating mode bit and conditioning the apparatus in the monitored object in one other operating mode in response to receiving the signal encoded with the operating mode bit in one other condition of the operating mode bit.

31. A method for identifying an overlap region formed via the overlapping portions of the far-field regions of two signpost units wherein each signpost unit has a signpost code comprising a predetermined number of bits encoded therein uniquely identifying the signpost unit and wherein each signpost unit provides an output signal establishing a far-field region and wherein the signpost units are positioned such that a portion of the far-field region of one of the signpost units overlaps a portion of the far-field region of the other signpost unit to form the overlap region, the method comprising the steps of:

receiving in the overlap region the signpost unit output signal of one of the signpost units;

detecting the signpost code encoded in the received signpost unit output signal;

storing the signpost code encoded in the received signpost unit output signal;

receiving in the overlap region the signpost unit output signal of the other signpost unit;

detecting the signpost code encoded in the received other signpost unit output signal;

storing the signpost code encoded in the received other signpost unit output signal;

substituting a predetermined number of bits of one of the received signpost codes for the same predetermined number of bits of the other received signpost code thereby generating pseudo-signpost code uniquely identifying the overlap region formed via the overlapping portions of the far-field regions of the two received signpost codes.