Identification system for monitoring the presence/absence of members of a defined set

• US 6,611,556 B1
• Filed: 10/10/2000
• Issued: 08/26/2003
• Est. Priority Date: 05/21/1999
• Status: Active Grant

• Current Assignee: Ralph J. Koerner, Steve J. Koerner
• Original Assignee: Ralph J. Koerner, Steve J. Koerner
• Inventors: Koerner, Steve J., Koerner, Ralph J.
• Primary Examiner(s): Liu, Shuwang
• Application Number:
  US09/673,116
• Time in Patent Office: 1,050 Days
• Field of Search: 375/224, 340/531, 340/573.4, 340/572.8, 340/539, 340/572.1, 340/10.1, 340/10.2, 340/10.52, 342/44
• US Class Current: 375/224
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• 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 7/10059 transponder driven

Abstract

A system which allows multiple senders to asynchronously transmit identification codes via a common communication channel (e.g., RF) to enable a central monitor to identify the presence (or absence) of each sender within the monitor'"'"'s detection zone. Each sender is configured to repeatedly transmit a uniquely encoded identification frame. A frame, in accordance with the invention, is comprised of pulses spaced to minimize pulse collisions and configured to tolerate occasional collisions without impairing the monitor'"'"'s ability to separately identify each transmitting sender. Each sender is configured to repeatedly transmit a unique identification frame characterized by a pulse pattern comprised of active intervals spaced by inactive (or “quiet”) intervals. The inactive intervals have variable length durations which are preferably pseudorandomly selected so that each sender defines a unique sequence of inactive interval durations.

Claims

1. A system for monitoring the presence or absence of members of a defined set of members, said system comprising:

a plurality of senders each capable of asynchronously transmitting a uniquely encoded identification frame on a common communication channel to form a composite signal on said channel including identification frames from said plurality of senders, each sender being uniquely physically associated with a different one of said members;

each of said senders including electronic circuitry for repeatedly transmitting an a uniquely encoded identification frame comprised of alternating active and inactive intervals and where each uniquely encoded identification frame is characterized by a unique sequence of inactive interval durations;

said electronic circuitry including a controller for controlling the duration of each of said inactive intervals; and

a monitor responsive to said composite signal for recognizing individual identification frames therein for determining the presence or absence of an identification frame unique to each sender, said monitor including;

storage means for storing a repertoire of identification frames;

accumulating means for accumulating a history of said composite signal; and

comparator means for comparing said stored identification frames and said composite signal history to recognize the presence of individual identification frames in said composite signal.

2. The system of claim 1 wherein said electronic circuitry transmits at least one pulse during each active interval.

3. The system of claim 1 wherein said electronic circuitry transmits a coded pulse burst during at least one of said active intervals, said coded pulse burst defining a unique sender identification code.

4. The system of claim 1 wherein said electronic circuitry transmits a coded pulse burst during each of said active intervals, said coded pulse burst defining a unique sender identification code.

5. The system of claim 1 wherein said electronic circuitry of each of said senders introduces a common synchronization pulse pattern into each of said identification frames.

9. The system of claim 1 wherein said electronic circuitry in each of said senders includes a transmitter for generating a carrier signal and a controller for amplitude controlling said carrier signal to define said uniquely encoded identification frame.

10. The system of claim 9 wherein each transmitter in said plurality of senders generates a common carrier signal.

11. The system of claim 10 wherein said common carrier signal is a radio frequency signal.

6. A system for monitoring the presence or absence of members of a defined set of members, said system comprising:

a plurality of senders each capable of asynchronously transmitting a uniquely encoded identification frame on a common communication channel to form a composite signal on said channel including identification frames from said plurality of senders, each sender being uniquely physically associated with a different one of said members;

each of said senders including electronic circuitry for repeatedly transmitting an identification frame comprised of alternating active and inactive intervals;

said electronic circuitry of each of said senders generating a uniquely encoded identification frame comprised of a unique sequence of inactive interval durations and including a controller for controlling the duration of each of said inactive intervals,

a monitor for and processing said composite signal for determining the presence or absence of an identification frame unique to each sender, said monitor including;

storage means storing a repertoire comprised of a different inactive interval duration sequence for each sender; and

a detector for indicating whether said composite signal includes identification frames matching each sequence stored in said storage means.

7. The system of claim 6 further including:

an output device responsive to said detector indicating a match for reporting the presence of a member.

8. The system of claim 6 further including:

an output device responsive to said detector failing to report a match for a stored inactive interval duration sequence for reporting the absence of a member.

12. A system for detecting the presence or absence of one or more members from a defined set of members, said system comprising:

a plurality of senders each capable of asynchronously transmitting a uniquely encoded identification frame on a common communication channel to form a composite signal on said channel including identification frames from said plurality of senders, each sender configured to be uniquely physically associated with a different one of said members;

each of said senders including a power supply, a transmitter configured to be driven by said power supply to generate a common carrier signal, and a controller for controlling said carrier signal to repeatedly transmit a uniquely encoded identification frame uniquely identifying the sender;

each of said identification frames comprising a pulse identification pattern comprised of a sequence of quiet intervals, each of said quiet intervals being bounded by successive pulse intervals; and

wherein the pulse identification pattern produced by each sender is characterized by a unique sequence of quiet interval durations; and

a monitor for receiving said composite signal comprising multiple pulse identification patterns transmitted by said plurality of senders and for recognizing each different transmitted pulse identification pattern therein;

repertoire means in said monitor for storing the characteristics of a plurality of different pulse identification patterns; and

means for comparing said composite signal received by said monitor and the pulse identification patterns stored by said repertoire means to recognize the presence of individual identification frames therein.

13. The system of claim 12, wherein said means for comparing generates a match signal when said composite signal contains a pattern matching a stored pulse identification pattern;

and

an output device responsive to said match signal.

14. The system of claim 13 further including:

a timer defining a time-out period for each of said senders; and

means responsive to the generation of a match signal for resetting the timer associated with the sender identified by that stored pulse identification pattern.

15. The system of claim 12 wherein each of said senders repeatedly transmits its unique pulse identification pattern.

21. The system of claim 12 wherein the durations of said quiet intervals are pseudorandomly determined.

16. A system for detecting the presence or absence of one or more members from a defined set of members, said system comprising:

a plurality of senders each capable of asynchronously transmitting a uniquely encoded identification frame on a common communication channel to form a composite signal on said channel including identification frames from said plurality of senders, each sender configured to be uniquely physically associated with a different one of said members;

each of said senders including a power supply, a transmitter configured to be driven by said power supply to generate a common carrier signal, and a controller for controlling said carrier signal to repeatedly transmit a uniquely encoded identification frame uniquely identifying the sender;

each of said identification frames comprising a pulse identification pattern comprised of a sequence of quiet intervals, each of said quiet intervals being bounded by successive pulse intervals; and

wherein the pulse identification pattern produced by each sender is characterized by a unique sequence of quiet interval durations; and

a monitor for receiving said composite signal comprising multiple pulse identification patterns transmitted by said plurality of senders and for recognizing each different transmitted pulse identification pattern therein; and

wherein

each of said senders repeatedly transmits a coded pulse burst defining a unique sender identification code during at least one pulse interval of said identification pulse pattern.

17. The system of claim 16 wherein each of said controllers further controls said carrier signal to impose thereon a pulse synchronization pattern common to all of said senders.

18. The system of claim 17 wherein the pulse identification pattern of each sender is synchronized to said pulse synchronization pattern.

19. The system of claim 18 including means in said monitor for detecting a pulse synchronization pattern in said received composite signal;

and

means responsive to the detection of said pulse synchronization pattern for searching for a pulse identification pattern.

20. The system of claim 18 wherein said monitor includes means for storing a pulse synchronization pattern and a plurality of pulse identification patterns;

means responsive to said received composite signal containing a pattern matching said stored synchronization pattern for producing a sync match signal; and

means responsive to said sync match signal for comparing said received composite signal with said stored pulse identification patterns.

22. A system for detecting the presence or absence of one or more members from a defined set of members, said system comprising:

a plurality of senders each capable of asynchronously transmitting a uniquely encoded identification frame on a common communication channel to form a composite signal on said channel including identification frames from said plurality of senders, each sender configured to be uniquely physically associated with a different one of said members;

each of said senders including a power supply, a transmitter configured to be driven by said power supply to generate a common carrier signal, and a controller for controlling said carrier signal to repeatedly transmit a uniquely encoded identification frame uniquely identifying the sender;

each of said identification frames comprising a pulse identification pattern comprised of a sequence of quiet intervals, each of said quiet intervals being bounded by successive pulse intervals; and

wherein the pulse identification pattern produced by each sender is characterized by a unique sequence of quiet interval durations; and

a monitor for receiving said composite signal comprising multiple pulse identification patterns transmitted by said plurality of senders and for recognizing each different transmitted pulse identification pattern therein; and

wherein

the durations of said quiet intervals fall within a range having an average duration considerably longer than the duration of a pulse interval.

23. A method for determining whether or not each of a plurality of sender is present within a detection zone, comprising the steps of:

causing each of said senders to generate a unique identification frame comprised of active and inactive intervals wherein the identification frame of each sender includes at least one pulse during each active interval and a unique ID sequence comprising a unique identification pulse pattern defining a unique sequence of inactive interval durations;

causing each of said senders to repeatedly apply its identification frame to a common communication channel;

allowing said Plurality of senders to asynchronously apply their respective identification frames to said common communication channel to form a composite signal;

causing each of said senders to introduce a common synchronization pulse pattern into each identification frame applied to said common communication channel;

monitoring said common communication channel to process said composite signal;

storing a repertoire of ID sequences, each uniquely associated with a different one of said defined plurality of senders;

processing said repertoire to ascertain whether each stored ID sequence is presented in said composite signal;

determining from said processing step whether or not each sender has applied its unique identification frame to said common communication channel; and

determining whether said composite signal contains said common synchronization pulse pattern prior to processing said repertoire.

24. A method for determining whether or not each of a plurality of senders is present within a detection zone, comprising the steps of:

causing each of said senders to generate a unique identification frame comprised of active and inactive intervals wherein the identification frame of each sender includes a unique ID sequence of inactive interval durations;

causing each of said senders to repeatedly apply its identification frame to a common communication channel;

allowing said Plurality of senders to asynchronously apply their respective identification frames to said common communication channel to form a composite signal;

monitoring said common communication channel to process said composite signal;

storing a repertoire of ID sequences, each uniquely associated with a different one of said defined plurality of senders;

processing said repertoire to ascertain whether each stored ID sequence is presented in said composite signal;

determining from said processing step whether or not each sender has applied its unique identification frame to said common communication channel;

maintaining a history of inactive interval durations of said composite signal; and

wherein

said step of processing includes the step of comparing said stored repertoire with said composite signal history.

25. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal; and

wherein said monitor includes;

a register for accumulating a history of composite signal pulses;

a memory for storing a repertoire of pulse patterns; and

a comparator module for comparing pulse patterns stored in said memory with said history of composite signal pulses.

26. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal; and

wherein

each said first pulse pattern is synchronized relative to said second pulse pattern in each of said identification frames.

27. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal;

said monitor including a controller for recognizing when said composite signal presents said common first pulse pattern; and

wherein

said monitor controller responds to said recognition for generating a check-in signal for each sender when said composite signal presents a second pulse pattern associated with that sender.

28. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal;

said monitor including a controller for generating a first match signal when said composite signal presents said common first pulse pattern;

said monitor controller including means storing a repertoire of sender second pulse patterns; and

means responsive to said first match signal for comparing each of said repertoire of second pulse patterns to said composite signal.

29. The system of claim 28 wherein said means for comparing includes means for sequentially comparing said repertoire of second pulse patterns to generate a sender check-in signal when a compared second pulse pattern matches a pulse pattern presented by said composite signal.

30. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal; and

wherein

each of said second pulse patterns is comprised of at least three pulse intervals bounding a unique sequence of quiet interval durations in said identification frame.

31. The system of claim 30 wherein each frame first pulse pattern is comprised of at least first and second pulse intervals fixedly positioned in said frame;

and wherein

at least one of said first pulse pattern pulse intervals coincides with one of said second pulse pattern pulse intervals in each of said identification frames.

32. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal; and

wherein each of said sender second pulse patterns is comprised of at least first and second subpatterns;

said monitor including a controller for recognizing when said composite signal presents said common first pulse pattern; and

wherein

said monitor controller is responsive to said recognition for separately identifying said first and second subpatterns.

33. A system for monitoring the presence or absence of each of a plurality of senders within the detection zone of a monitor, said system comprising:

each of said senders including a controller for generating an identification frame including first and second pulse patterns wherein said first pulse pattern is common to said plurality of senders and said second pulse pattern is comprised of a unique sequence of inactive interval durations uniquely associated with the generating sender;

a common communication channel;

said sender controllers being operable to asynchronously and repeatedly apply their respective identification frames to said communication channel to collectively form a composite signal on said channel;

a monitor coupled to said channel for processing said composite signal to separately identify each sender identification frame contained in said composite signal; and

wherein

said common first-pulse pattern is comprised of at least two pulses fixedly positioned in each identification frame and spaced by a quiet interval of fixed duration; and

wherein

each sender second pulse pattern is comprised of at least three pulses in each identification frame spaced to define multiple quiet intervals, each sender second pulse pattern being comprised of a unique sequence of quiet interval durations.

34. The system of claim 33 wherein said first and second pulse patterns in each identification frame are interleaved.

35. The system of claim 33 wherein said first pulse pattern and each of said second pulse patterns are synchronized in each of said identification frames.