U.S. patent application number 11/845706 was filed with the patent office on 2007-12-20 for system and method for locating individuals and equipment, airline reservation system, communication system.
This patent application is currently assigned to KEYSTONE TECHNOLOGY SOLUTIONS, LLC. Invention is credited to John R. TUTTLE.
Application Number | 20070290849 11/845706 |
Document ID | / |
Family ID | 25196933 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070290849 |
Kind Code |
A1 |
TUTTLE; John R. |
December 20, 2007 |
System and Method for Locating Individuals and Equipment, Airline
Reservation System, Communication System
Abstract
A system for locating an individual in a facility, the system
comprising a portable wireless transponder device borne by the
individual; an interrogator; and a plurality of antennas
distributed in the facility, the antennas being selectively
separately connected to the interrogator, the interrogator when
connected to any of the antennas having a communications range
covering less than the area of the entire facility, the
interrogator being configured to repeatedly transmit a wireless
command to the portable wireless transponder device using
alternating antennas, the portable wireless transponder device
being configured to transmit data identifying the portable wireless
transponder device in response to a command if the portable
wireless transponder device is within communications range of the
antenna sending the command, the individual being locatable by
determining with which antenna the interrogator was able to
establish communications with the portable wireless transponder
device.
Inventors: |
TUTTLE; John R.; (Boise,
ID) |
Correspondence
Address: |
GREENBERG TRAURIG, LLP (SV);IP DOCKETING
2450 COLORADO AVENUE
SUITE 400E
SANTA MONICA
CA
90404
US
|
Assignee: |
KEYSTONE TECHNOLOGY SOLUTIONS,
LLC
Boise
ID
83716-9632
|
Family ID: |
25196933 |
Appl. No.: |
11/845706 |
Filed: |
August 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11271935 |
Nov 10, 2005 |
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11845706 |
Aug 27, 2007 |
|
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|
10326762 |
Dec 20, 2002 |
7030732 |
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|
11271935 |
Nov 10, 2005 |
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|
09628876 |
Jul 26, 2000 |
6509829 |
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10326762 |
Dec 20, 2002 |
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09305182 |
May 3, 1999 |
6127917 |
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09628876 |
Jul 26, 2000 |
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08807678 |
Feb 27, 1997 |
5914671 |
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09305182 |
May 3, 1999 |
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Current U.S.
Class: |
340/572.1 |
Current CPC
Class: |
H04M 2242/30 20130101;
G01S 13/04 20130101; G06K 17/0022 20130101; G06Q 10/02 20130101;
G06Q 10/025 20130101; G08B 31/00 20130101; G08B 3/1083 20130101;
G07C 9/28 20200101; G06K 17/00 20130101; G01S 13/74 20130101 |
Class at
Publication: |
340/572.1 |
International
Class: |
G08B 13/14 20060101
G08B013/14 |
Claims
1. A system for locating an object, the system comprising: an
output device; a plurality of databases; a plurality of
interrogators, each interrogator electrically coupled to a
plurality of antennas, each of the interrogators configured to
communicate with radio frequency identification (RFID) tags within
communication range of each respective interrogator; and a
plurality of controllers, each controller communicatively coupled
to one or more of the interrogators and to one or more of the
databases, each controller being further configured to store in one
or more of the databases information associated with RFID tags
within communication range of each respective interrogator, each of
the controllers being further configured to receive an object
identifier associated with the object and to access the databases
to locate the object, each controller causing the output device to
output a location of the object.
2. The system of claim 1, wherein the output device comprises a
display.
3. The system of claim 2, wherein the display is incorporated on
the RFID tags.
4. The system of claim 1, wherein the plurality of interrogators is
communicatively coupled to each other and each interrogator is
configured to share information with other interrogators.
5. The system of claim 1, wherein the plurality of databases
comprises log files stored on each of the controllers.
6. The system of claim 1, wherein the object identifier comprises a
unique number assigned to a person.
7. The system of claim 1, wherein the object comprises a
person.
8. The system of claim 1, wherein the object comprises
inventory.
9. A system for managing objects in a geographically dispersed
environment, the system comprising: a plurality of sites, each of
the sites being remotely located from other sites; a plurality of
radio frequency identification (RFID) tags, each RFID tag being
associated with an object; one or more interrogators located at
each site, each interrogator being communicatively coupled to one
or more antennas and configured to communicate with and to log a
presence of any RFID tag within communication range of the
antennas; a network communicatively coupling the one or more
interrogators; and an access system communicatively coupled to the
network, the access system configured to receive identifying
information associated with the object and to access a log to
locate the object.
10. The system of claim 9, wherein the log comprises a
database.
11. The system of claim 9, wherein the log comprises a log file
stored on each respective interrogator.
12. The system of claim 9, wherein each of the one or more
interrogators are communicatively coupled to the network via a
controller.
13. The system of claim 9, wherein each interrogator is configured
to share information with other interrogators.
14. The system of claim 9, wherein each interrogator is further
configured to triangulate to determine a position of an RFID tag
when the RFID tag is detected by a plurality of antennas.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of U.S. patent application Ser. No.
11/271,935, filed Nov. 10, 2005, titled "System and Method for
Locating Individuals and Equipment, Airline Reservation System,
Communication System", which is a continuation of U.S. patent
application Ser. No. 10/326,762, filed Dec. 20, 2002, now U.S. Pat.
No. 7,030,732, issued Apr. 18, 2006, which in turn is a
continuation of U.S. patent application Ser. No. 09/628,876, filed
Jul. 26, 2000, now U.S. Pat. No. 6,509,829, issued Jan. 21, 2003,
which in turn is a continuation of U.S. patent application Ser. No.
09/305,182, filed May 3, 1999, now U.S. Pat. No. 6,127,917, issued
Oct. 3, 2000, which in turn is a continuation of U.S. patent
application Ser. No. 08/807,678, filed Feb. 27, 1997, now U.S. Pat.
No. 5,914,671, issued Jun. 22, 1999, all of which are incorporated
herein by reference.
TECHNICAL FIELD
[0002] The invention relates to personnel locating systems, travel
reservation systems, airport security systems, radio frequency
identification devices.
BACKGROUND OF THE INVENTION
[0003] Travel reservation and baggage tracking systems are known in
the art. Passengers typically purchase tickets in advance of
travel, and are included in a database of a reservation system as
having a reservation. On the date of travel, they must check in, or
their seat will be given up to other passengers. Because statistics
show that there will always be a number of passengers who will not
show up on the designated date of travel, carriers typically
"overbook" by selling a number of seats over the number of seats
that are actually available, based on mathematical calculations. If
the passenger does not check in, their seat may be used to
accommodate overbooking, or may be given to standby passengers. The
following U.S. patents relate to reservation systems and are
incorporated herein by reference: U.S. Pat. Nos. 5,401,944;
5,151,692; 5,051,565; 5,010,240; 4,984,156; 4,931,932; 4,449,186;
4,247,795; 3,750,103.
[0004] When a passenger enters a travel depot (e.g., an airport),
they must therefore check in to make sure the carrier (e.g.,
airline) knows they are present and to make sure that their seat is
not given away to someone else. This typically involves standing in
line and waiting for an employee to verify that the correct
traveler is bearing a ticket. The employee receives the ticket and,
using a reservation system, issues a boarding pass, with a seat
assignment, indicating to the system that the seat is no longer
available to be given away.
[0005] Traditionally, check in occurred simultaneously with a
baggage check-in, with an employee marking the traveler's luggage
with a tag indicting the destination where the bag is to be sent,
printing a baggage receipt for the customer, and logging the bag in
the reservation and baggage handling system.
[0006] Business travelers, however, typically do not have any bags
to check and prefer not to wait in line. Also, many airports offer
curbside check-in, which allows a passenger to check in bags at the
curb before entering the airport, where lines are shorter because a
gratuity is expected. The business travelers and travelers who have
used the curbside check in typically go directly to the podium
adjacent the departure gate and check in there. While the line at
the podium may be shorter, it is still a line. Travelers needing to
check in baggage must wait in lines.
[0007] There are many reasons why it would be useful to determine
the presence of an individual in an airport or other travel depot.
If a flight is about to leave, airline staff may desire to make an
attempt to determine if a checked in passenger is in the airport.
It is also frequently desirable to locate airline staff, such as
pilots, flight attendants, wheelchair attendants, mechanics etc.,
or airport staff, such as security, or merchants or other persons
who work in airports, for a variety of reasons. This is presently
attempted through paging, which is sometimes difficult to hear, and
is often annoying or competing with more important messages, such
as gate change announcements, or information about which rows are
boarding.
[0008] It is also useful to determine the location of a passenger
in evaluating terrorist threats. A terrorist who has planted a bomb
in his or her luggage is likely to leave the premises and not board
the flight for which the luggage was checked.
[0009] Passengers in airports typically need gate and flight
information in a hurry. Such information may be obtained from
airline staff, but this typically involves standing in long lines.
This information is therefore more typically gathered by reading a
monitor which lists flight numbers, destinations, gates, and
status. A problem is that in some airports, each airline has their
own monitors, so a traveler may have to walk a great distance to
try to find a monitor for a particular airline. Monitors also
contain vast amounts of information, most of it of no interest to a
particular traveler. This makes it difficult to find useful
information in a hurry.
[0010] Switching antennas connected to an interrogator is disclosed
in commonly assigned U.S. patent application Ser. No. 08/772,173,
filed Dec. 18, 1996, titled "Communication System Including
Diversity Antenna Queuing," and listing Clifton W. Wood, Jr. as
inventor, now U.S. Pat. No. 5,842,118. Antenna switching for this
application is performed for diversity purposes.
SUMMARY OF THE INVENTION
[0011] The invention provides a system for locating an individual
in a facility. The system comprises a portable wireless transponder
device borne by the individual; an interrogator; and a plurality of
antennas distributed in the facility. The antennas are selectively
separately connected to the interrogator. The interrogator, when
connected to any of the antennas has a communications range
covering less than the area of the entire facility. The
interrogator repeatedly transmits a wireless command to the
portable wireless transponder device using alternating antennas.
The portable wireless transponder device transmits data identifying
the portable wireless transponder device in response to a command
if the portable wireless transponder device is within
communications range of the antenna sending the command. Thus, the
individual is located by determining with which antenna the
interrogator was able to establish communications with the portable
wireless transponder device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Preferred embodiments of the invention are described below
with reference to the following accompanying drawings.
[0013] FIG. 1 is a plan view of a travel depot facility, such as an
airport, including a system, embodying the invention, for locating
an individual.
[0014] FIG. 2 is a block diagram of the system of FIG. 1, further
including an interface with an airline reservation and baggage
tracking system, and further including monitors for displaying
information of particular interest to passengers in the area of the
monitor.
[0015] FIG. 3 is a perspective view showing a monitor included in
the system of FIG. 2.
[0016] FIG. 4 is a front view of a card used in the system of FIG.
1 or 2.
[0017] FIG. 5 is a circuit schematic of an interrogator included in
the system of FIG. 1 or 2.
[0018] FIG. 6 is a circuit schematic of circuitry included in card
of FIG. 4.
[0019] FIG. 7 is a block diagram of an interrogator included in the
system of FIG. 1 or 2.
[0020] FIG. 8 is a circuit schematic of DPSK circuitry included in
the interrogator of FIG. 7.
[0021] FIG. 9 is a circuit schematic of RF circuitry included in
the interrogator of FIG. 7.
[0022] FIG. 10 is a plan view of a card in accordance with an
alternative embodiment of the invention.
[0023] FIG. 11 is a block diagram illustrating assembly of the card
of FIG. 10.
[0024] FIG. 12 is a flow chart illustrating a routine run by the
system of FIG. 1 or 2 to log locations of individuals.
[0025] FIG. 13 is a flow chart illustrating a routine run by the
system of FIG. 1 or 2, used in connection with the routine of FIG.
12, to determine the location of an individual.
[0026] FIG. 14 is a flow chart illustrating a routine run by the
system of FIG. 2 to check in a passenger using the card of FIG. 4
or 10 as an electronic boarding pass.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] This disclosure of the invention is submitted in furtherance
of the constitutional purposes of the U.S. Patent Laws "to promote
the progress of science and useful arts" (Article 1, Section
8).
[0028] FIG. 1 shows a travel depot facility 10, such as an airport,
including a system 12 (see FIG. 2) for locating an individual. The
facility 10 includes various areas of a typical facility such as a
main terminal area 14 which typically includes a baggage check in
area 16, shops, restaurants, etc. The facility 10 further includes
a terminal concourse area 18 which one enters after passing a
security check point 20. The terminal concourse area 18 includes
multiple gate doors 22 defining controlled access points. More
particularly, the gate doors 22 are typically locked until a flight
is available for departure or is being deplaned. Airline staff
control passage through the gate doors and only permit people with
boarding passes through the gate doors 22. The gate doors 22 lead
to jetways 24 which are movable to define a path into an airplane.
The terminal area 18 typically includes podiums 28 where airline
personnel are located. The terminal area 18 also includes multiple
seating areas 30 which may be grouped off by gate.
[0029] The system 12 (see FIG. 2) includes portable wireless
transponder devices 32 borne by passengers, airport employees,
contractors, airline and contractor employees, etc. In the
illustrated embodiment, the devices 32 include circuitry such as
the circuitry described in detail in commonly assigned U.S. patent
application Ser. No. 08/705,043, filed Aug. 29, 1996, now U.S. Pat.
No. 6,130,602, and incorporated herein by reference. In one
embodiment, the portable transponder devices 32 have card shaped
housings with length and width dimensions corresponding to standard
length and width dimensions of credit cards. In one embodiment, the
transponder devices 32 include photographs of the respective
individuals associated with the devices. The transponder devices 32
are, more particularly, intelligent radio frequency identification
devices or remote intelligent communications (RIC) devices which
communicate at microwave frequencies.
[0030] FIG. 4 shows but one example of a housing for a device 32,
in the form of an employee identification badge or card including
an intelligent radio frequency identification device integrated
circuit 34. The integrated circuit 34 includes a transmitter, a
receiver, a microprocessor, and a memory. The housing for the
device 32 shown in FIG. 4 includes a card 36 made of plastic or
other suitable material. In one embodiment, the integrated circuit
34 is laminated to the back face of the card 36, and the card forms
a visible portion of the badge. In another embodiment, the
integrated circuit 34 is bonded to the back face of the card by
embedding it within a thin bond line of epoxy-based material.
Alternatively, the integrated circuit 34 is embedded into the
plastic card 36. In one embodiment, the front face of the badge has
visual identification features including a photograph 38 of the
bearer as well as identifying text. The device 32 further includes
a send/receive antenna 40 coupled to the integrated circuit 34, and
a battery 42 coupled to the integrated circuit 34 to supply power
to the integrated circuit. The battery 42 and antenna 40 are
embedded or supported inside the plastic card 36.
[0031] The battery 42 can take any suitable form. Preferably, the
battery type will be selected depending on weight, size, and life
requirements for a particular application. In one embodiment, the
battery 42 is a thin profile button-type cell forming a small, thin
energy cell more commonly utilized in watches and small electronic
devices requiring a thin profile. A button-type cell has a pair of
electrodes, an anode formed by one face and a cathode formed by an
opposite face. Exemplary button-type cells are disclosed in several
pending U.S. patent applications including U.S. patent application
Ser. No. 08/205,957, "Button-Type Battery Having Bendable
Construction and Angled Button-Type Battery," listing Mark E.
Tuttle and Peter M. Blonsky as inventors, now U.S. Pat. No.
5,432,027; U.S. patent application Ser. No. 08/321,251,
"Button-Type Batteries and Method of Forming Button-Type
Batteries," listing Mark E. Tuttle as inventor, now U.S. Pat. No.
5,494,495; and U.S. patent application Ser. No. 08/348,543, "Method
of Forming Button-Type Batteries and a Button-Type Battery
Insulating and Sealing Gasket," listing Mark E. Tuttle as inventor.
These patent applications and resulting patents are hereby
incorporated by reference. In an alternative embodiment, the
battery 42 comprises a series connected pair of button type cells.
Alternative power supplies can be used instead of batteries, in
alternative embodiments.
[0032] FIG. 5 illustrates but one alternative housing supporting
the circuit 34. More particularly, FIG. 5 illustrates a miniature
housing 42 encasing the circuit 34 to define a tag which can be
supported by a person or object. The housing 42 preferably has the
general shape and size, in plan view, of a postage stamp. The
embodiment of FIG. 5 also houses a card 44 supporting the circuit
34 in the housing 42. The card 44 is formed of plastic or other
suitable material having a thickness of about 0.040 inches, a width
of about 1.25 inches, and a height of about 1.25 inches. In one
embodiment, the circuit 34 is bonded to a back face of the card 44
with a thin layer of non-conductive epoxy material that cooperates
with the card to define the housing 42. The circuit 34 is coupled
to a send antenna 48, and a receive antenna 46, and receives power
from a battery 42 which can be similar to the battery included in
the embodiment of FIG. 4. The battery 42, and antennas 46 and 48
are supported in the housing 42 by the card 44.
[0033] Although two particular types of housings have been
disclosed, the circuit 34 can be included in any appropriate
housing. The circuit 34 is of a small size that lends itself to
applications employing small housings, such as cards, miniature
tags, etc. Larger housings can also be employed. The circuit 34,
housed in any appropriate housing, can be supported from a person,
or attached to a object (or a peoples possessions) in any desired
manner; for example using double sided tape, glue, lanyards, leash,
nails, staples, rivets, or any other fastener. The housing can be
sewn on to an object, hung from an object, implanted in an object
(hidden), etc.
[0034] Various configurations are possible for the antenna
connected to the circuit 34. In one embodiment, separate antennas
46 and 48 are provided for receiving and sending (FIG. 5). In
another embodiment, a single antenna 40 is shared by the receiver
and transmitter (FIG. 4). In one embodiment, one or more antennas
are defined by conductive epoxy screened onto a card or housing. In
the illustrated embodiment, the antenna is conductively bonded to
the integrated circuit 34 via bonding pads.
[0035] The system 12 further includes an interrogator 50. The card
36 transmits and receives radio frequency communications to and
from the interrogator 50. The system 12 further includes an array
of antennas 52 (or send/receive antenna pairs) alternately coupled
to the interrogator 50. The interrogator 50 includes transmitting
and receiving circuitry, similar to that implemented in the circuit
34. In one embodiment, the system 12 further includes a controller
54. In the illustrated embodiment, the controller 54 is a computer.
The controller 54 acts as a master in a master-slave relationship
with the interrogator 50. The controller 54 includes an
applications program for controlling the interrogator 50 and
interpreting responses, and a library of radio frequency
identification device applications or functions. Most of the
functions communicate with the interrogator 50. These functions
effect radio frequency communication between the interrogator 50
and the card 32. In one embodiment, the controller 54 and the
interrogator 50 are combined together (e.g., in a common housing),
or functions of the host computer are implemented in hard wired
digital logic circuitry.
[0036] In the illustrated embodiment, the communications system 10
includes multiple selectable transmit antennas X1, X2, X3 etc., and
multiple receive antennas R1, R2, R3 etc. connected to the
interrogator 50. Each antenna pair X1, R1, X2, R2, etc. defines an
antenna 52 of the antenna array for purposes of the discussion
below. In one embodiment, the communications system 10 includes
combined antennas that are used both for transmitting and receiving
by the interrogator 50. Generally, the interrogator 50 transmits an
interrogation signal or command, such as an "Identify" command,
("forward link") via one of the antennas 52. The card 32 receives
the incoming interrogation signal via its antenna, if it is within
receiving range of the particular antenna 52 used to transmit. Upon
receiving the signal, the card 32 responds by generating and
transmitting a responsive signal or reply ("return link"). The
interrogator 50 is described in greater detail below.
[0037] In the illustrated embodiment, the responsive signal is
encoded with information that uniquely identifies, or labels the
particular card 32 that is transmitting, so as to identify any
object or person with which the card 32 is associated.
[0038] In the embodiment illustrated in FIG. 2, multiple cards 32
are employed; however, there is no communication between the cards
32. Instead, the multiple cards 32 communicate with the
interrogator 50. Multiple cards 32 can be used in the same range of
an antenna 52.
[0039] Various U.S. patent applications, which are incorporated
herein by reference, disclose features that are employed in various
alternative embodiments of the invention: Ser. No. 08/092,147,
filed Jul. 15, 1993, "Wake Up Device for a Communications System"
and continuation application Ser. No. 08/424,827, filed Apr. 19,
1995, "Wake Up Device for a Communications System"; Ser. No.
08/281,384, filed Jul. 27, 1994, "Communication System Having
Transmitter Frequency Control"; Ser. No. 07/990,918, filed Dec. 15,
1992, now U.S. Pat. No. 5,365,551, "Data Communication Transceiver
Using Identification Protocol"; Ser. No. 07/899,777, filed Jun. 17,
1992, "Radio Frequency Identification Device (RFID) and Method of
Manufacture, Including an Electrical Operating System and Method,"
now abandoned; Ser. No. 07/151,599, filed Nov. 12, 1993, now U.S.
Pat. No. 5,406,263, "Anti-Theft Method for Detecting The
Unauthorized Opening of Containers and Baggage,"; Ser. No.
07/168,909, filed Dec. 17, 1993, now U.S. Pat. No. 5,497,140,
"Electrically Powered Postage Stamp or Mailing or Shipping Label
Operative with Radio Frequency (RF) Communication,"; and Ser. No.
08/032,384, filed on Mar. 17, 1993, "Modulated Spread Spectrum in
RF Identification Systems Method," now allowed.
[0040] The integrated circuit 34 is advantageous over prior art
devices that utilize magnetic field effect systems because, with
the circuit 34, a greater range can be achieved, and more
information can be obtained (instead of just an identification
number). As a result, the circuit 34 can be used for the
application of the present invention, where transmission over a
large range is required. In one embodiment, the sensitivity of the
cards 32 is adjustable so that only devices within an adjustable
range of an antenna 52 will respond. In another embodiment, the
power of the interrogator 50 is adjustable so that only devices
within a certain range of an antenna 52 will respond.
[0041] A power conservation problem is posed by such
implementations where batteries are used to supply power to the
integrated circuits 34. If the integrated circuit 34 operates
continuously at full power, battery life will be short, and card 32
will have to be frequently replaced. If the battery 42 is
permanently sealed in a housing, replacement of the battery will be
difficult or impossible. For example, one reason for sealing the
battery with the integrated circuit 34 and antenna(s) in a housing
is to simplify the design and construction, to reduce the cost of
production, and protect the electrical interconnections between
devices. Another reason is protection of the battery and integrated
circuit 34 from moisture and contaminants. A third reason is to
enhance the cosmetic appeal of the card 32 by eliminating the need
for an access port or door otherwise necessary to insert and remove
the battery. When the battery is discharged, the entire badge or
stamp is then discarded. It is therefore desirable to incorporate
power conservation techniques into the integrated circuit 32 in
order to extend useful life.
[0042] FIG. 6 is a circuit schematic of the integrated circuit 34
utilized in the devices of FIG. 4 or 5. In the embodiment shown in
FIG. 6, the circuit 34 is a monolithic integrated circuit. In the
illustrated embodiment, the integrated circuit 34 comprises a
single die, having a size of 209.times.116 mils.sup.2. The
integrated circuit 34 includes a receiver 56, a transmitter 58, a
micro controller or microprocessor 60, a wake up timer and logic
circuit 62, a clock recovery and data recovery circuit 64, and a
bias voltage and current generator 66.
[0043] In one embodiment, the circuit 34 switches between a "sleep"
mode of operation, and higher power modes to conserve energy and
extend battery life during periods of time where no interrogation
signal is received by the circuit 34. The wake up timer and logic
circuitry 62 provides this switching.
[0044] In one embodiment, a spread spectrum processing circuit 68
is also included in the circuit 34. In this embodiment, signals
transmitted and received by the interrogator 50, and signals
transmitted and received by the circuit 34 are modulated spread
spectrum signals. Spread spectrum modulation is described below. In
one illustrated embodiment, the modulation scheme for replies sent
by the transmitter 58 is selectable. One of the available
selections for replies sent by the transmitter 58 is modulated
spread spectrum.
Spread Spectrum Modulation
[0045] Many modulation techniques minimize required transmission
bandwidth. However, the spread spectrum modulation technique
employed in the illustrated embodiment requires a transmission
bandwidth that is up to several orders of magnitude greater than
the minimum required signal bandwidth. Although spread spectrum
modulation techniques are bandwidth inefficient in single user
applications, they are advantageous where there are multiple users,
as is the case with the instant circuit 34. The spread spectrum
modulation technique of the illustrated embodiment is advantageous
because the interrogator signal can be distinguished from other
signals (e.g., radar, microwave ovens, etc.) operating at the same
frequency. The spread spectrum signals transmitted by the circuit
34 and by the interrogator 50 are pseudo random and have noise-like
properties when compared with the digital command or reply. The
spreading waveform is controlled by a pseudo-noise or pseudo random
number (PN) sequence or code. The PN code is a binary sequence that
appears random but can be reproduced in a predetermined manner by
the circuit 34. More particularly, incoming spread spectrum signals
are demodulated by the circuit 34 or by the interrogator 50 through
cross correlation with a version of the pseudo random carrier that
is generated by the circuit 34 itself or the interrogator 50
itself, respectfully. Cross correlation with the correct PN
sequence unspreads the spread spectrum signal and restores the
modulated message in the same narrow band as the original data.
[0046] A pseudo-noise or pseudo random sequence (PN sequence) is a
binary sequence with an autocorrelation that resembles, over a
period, the autocorrelation of a random binary sequence. The
autocorrelation of a pseudo-noise sequence also roughly resembles
the autocorrelation of band-limited white noise. A pseudo-noise
sequence has many characteristics that are similar to those of
random binary sequences. For example, a pseudo-noise sequence has a
nearly equal number of zeros and ones, very low correlation between
shifted versions of the sequence, and very low cross correlation
between any two sequences. A pseudo-noise sequence is usually
generated using sequential logic circuits. For example, a
pseudo-noise sequence can be generated using a feedback shift
register.
[0047] A feedback shift register comprises consecutive stages of
two state memory devices, and feedback logic. Binary sequences are
shifted through the shift registers in response to clock pulses,
and the output of the various stages are logically combined and fed
back as the input to the first stage. The initial contents of the
memory stages and the feedback logic circuit determine the
successive contents of the memory.
[0048] The illustrated embodiment employs direct sequence spread
spectrum modulation. A direct sequence spread spectrum (DSSS)
system spreads the baseband data by directly multiplying the
baseband data pulses with a pseudo-noise sequence that is produced
by a pseudo-noise generator. A single pulse or symbol of the PN
waveform is called a "chip." Synchronized data symbols, which may
be information bits or binary channel code symbols, are added in
modulo-2 fashion to the chips before being modulated. The receiver
performs demodulation. For example, in one embodiment the data is
phase modulated, and the receiver performs coherent or
differentially coherent phase-shift keying (PSK) demodulation. In
another embodiment, the data is amplitude modulated. Assuming that
code synchronization has been achieved at the receiver, the
received signal passes through a wideband filter and is multiplied
by a local replica of the PN code sequence. This multiplication
yields the unspread signal.
[0049] A pseudo-noise sequence is usually an odd number of chips
long. In the illustrated embodiment, one bit of data is represented
by a thirty-one chip sequence. A zero bit of data is represented by
inverting the pseudo-noise sequence.
[0050] Spread spectrum techniques are also disclosed in the
following patent applications and patent, which are incorporated
herein by reference: U.S. patent application Ser. No. 08/092,147;
U.S. patent application Ser. No. 08/424,827, filed Apr. 19, 1995,
now U.S. Pat. No. 5,790,946; and U.S. Pat. No. 5,121,407 to Partyka
et al. They are also disclosed, for example, in "Spread Spectrum
Systems," by R. C. Dixon, published by John Wiley and Sons,
Inc.
Backscatter and Frequency Hopping
[0051] The interrogator 50 sends out a command that is spread
around a certain center frequency (e.g., 2.44 GHz). After the
interrogator transmits the command, and is expecting a response,
the interrogator switches to a CW mode (continuous wave mode). In
the continuous wave mode, the interrogator does not transmit any
information. Instead, the interrogator just transmits 2.44 GHz
radiation. In other words, the signal transmitted by the
interrogator is not modulated. After the circuit 34 receives the
command from the interrogator, the circuit 34 processes the
command. If the circuit 34 is in a backscatter mode it alternately
reflects or does not reflect the signal from the interrogator to
send its reply. For example, in the illustrated embodiment, two
halves of a dipole antenna are either shorted together or isolated
from each other to send a reply.
[0052] Frequency hopping is employed in one embodiment. In the
illustrated embodiment, frequency hopping does not occur when the
interrogator transmits a command, but occurs when the interrogator
is in the continuous wave mode. The interrogator, in the continuous
wave mode, hops between various frequencies close to the 2.44 GHz
frequency. These various frequencies are sufficiently close to the
2.44 GHz frequency that backscatter antenna reflection
characteristics of the circuit 34 are not appreciably altered.
Because the interrogator is hopping between frequencies, the
interrogator knows what frequency backscatter reflections to expect
back from the circuit 34. By hopping between various frequencies,
the amount of time the interrogator continuously uses a single
frequency is reduced. This is advantageous in view of FCC
regulatory requirements.
[0053] In one illustrated embodiment, no attempt is made to
frequency hop at the interrogator to a pseudo-random sequence and
then correlate to that at the receiver. However, in alternative
embodiments, such correlation takes place.
[0054] In one embodiment, the transmitter 58 is switchable between
operating in a modulated backscatter transmitter mode, and
operating in an active mode. The transmitter 58 switches between
the backscatter mode and the active mode in response to a radio
frequency command, instructing the transmitter to switch, sent by
the interrogator 50 and received by the receiver 56. In the active
mode, a carrier for the transmitter 58 is extracted from a signal
received by the receiver 56.
[0055] Active transmitters are known in the art. See, for example,
U.S. patent application Ser. No. 08/281,384; U.S. patent
application Ser. No. 08/281,384 also discloses how transmit
frequency for the transmitter 58 is recovered from a message
received via radio frequency from the interrogator 50.
[0056] In one embodiment, the transmitter 58 is capable of
transmitting using different modulation schemes, and the modulation
scheme is selectable by the interrogator. More particularly, if it
is desired to change the modulation scheme, the interrogator sends
an appropriate command via radio frequency. In this embodiment, the
transmitter can switch between multiple available modulation
schemes such as Binary Phase Shift Keying (BPSK), Direct Sequence
Spread Spectrum, On-Off Keying (OOK), and Modulated Backscatter
(MBS).
[0057] In one embodiment, the clock for the entire integrated
circuit 16 is extracted from the incoming message itself by clock
recovery and data recovery circuitry 64. This clock is recovered
from the incoming message, and used for timing for the micro
controller 60 and all the other clock circuitry on the chip, and
also for deriving the transmitter carrier or the subcarrier,
depending on whether the transmitter is operating in active mode or
backscatter mode.
[0058] In addition to recovering a clock, the clock recovery and
data recovery circuit 64 also performs data recovery on valid
incoming signals. The valid spread spectrum incoming signal is
passed through the spread spectrum processing circuit 68, and the
spread spectrum processing circuit 68 extracts the actual ones and
zeros of data from the incoming signal. More particularly, the
spread spectrum processing circuit 68 takes the chips from the
spread spectrum signal, and reduces each thirty-one chip section
down to a bit of one or zero, which is passed to the micro
controller 60.
[0059] The micro controller 60 includes a serial processor, or I/O
facility that received the bits from the spread spectrum processing
circuit 68. The micro controller 60 performs further error
correction. More particularly, a modified hamming code is employed,
where each eight bits of data is accompanied by five check bits
used by the micro controller 60 for error correction. The micro
controller 60 further includes a memory, and after performing the
data correction, the micro controller 60 stores bytes of the data
bits in memory. These bytes contain a command sent by the
interrogator 50. The micro controller 60 responds to the
command.
[0060] For example, the interrogator 50 may send a command over one
of the antennas 52 requesting that any integrated circuit 34 in
communications range of that antenna 52 respond with the integrated
circuit's identification number. Status information is also
returned to the interrogator 50 from the integrated circuit 34 when
the circuit 34 responds.
[0061] The transmitted replies have a format similar to the format
of incoming messages. More particularly, a reply starts with a
preamble (e.g., all zeros in active mode, or alternating double
zeros and double ones in backscatter mode), followed by a Barker or
start code which is thirteen bits long, followed by actual
data.
[0062] No stop bits are included in the incoming message or reply,
in the preferred embodiment. Instead, part of the incoming message
describes how many bytes are included, so the integrated circuit 34
knows how much information is included. Similarly, part of the
outgoing reply describes how many bytes are included, so the
interrogator 50 knows how much information is included. The
incoming message and outgoing reply preferably also include a check
sum or redundancy code so that the integrated circuit 34 or the
interrogator 50 can confirm receipt of the entire message or
reply.
[0063] After the reply is sent, the integrated circuit 34 returns
to the sleep mode, and the wake up timer and logic circuit 62
starts timing again for the next wake up (e.g., in 16 milliseconds,
or whatever period is selected).
[0064] The interrogator 50 provides a communication link between
the controller 54 and the integrated circuit 34. In one embodiment,
the interrogator 50 connects to the controller 54 via an IEEE-1284
enhanced parallel port (EPP). The interrogator communicates with
the circuit 34 via a selected RF (microwave) antenna 52.
[0065] In one embodiment, communications from the interrogator 50
to the circuit 34, and communications from the circuit 34 to the
interrogator 50 use different physical protocols.
[0066] The physical communications protocol for communications from
the interrogator 50 to the circuit 34 is referred to as the
"forward link" protocol. The forward link data is sent in the
following order:
[0067] Preamble
[0068] Barker Code
[0069] Command Packet
[0070] Check Sum
[0071] A Maximal Length Pseudo Noise (PN) Sequence is used in the
Direct Sequence Spread Spectrum (DSSS) communications scheme in the
forward link. In one embodiment, the sequence is generated by a
linear feedback shift register of the form [5,2]. That is, there
are five registers, the output of the second register is X-ORed
with the output of the fifth register, and the result is fed into
the input of the first register one. This produces a repeating 31
"chip" sequence. The sequence ends with all registers set to one.
The sequence is taken from the output of the first register. This
code is synchronous with the data in that each data bit comprises
one and only one full PN sequence. The chip sequence for each bit
is:
001 1010 0100 0010 1011 1011 0001 1111.
[0072] Other embodiments are, of course, possible. For example,
other forms of linear feedback shift registers can be employed.
[0073] In one embodiment, a zero bit is transmitted as one inverted
full cycle of the PN sequence. A one bit is transmitted as one full
non-inverted cycle of the PN sequence.
[0074] In the illustrated embodiment, the data is not
differentially encoded.
[0075] In one embodiment, there are at least two available
"chipping" rates. One rate is 9.5375 Mchips/sec (high band) and
another rate is 4.768750 Mchips/sec (low band).
[0076] The preamble precedes the data. In one embodiment, the
preamble includes a series of zeros, followed by a start or Barker
code. In embodiments where the transponder 16 includes wake up
timer and logic circuitry 36, the preamble includes a series of
zeros for a duration equal to the wakeup interval (e.g., 5, 16, 64,
or 256 ms) plus 2 milliseconds, followed by a start or Barker
code.
[0077] In one embodiment, the Barker code is defined by the
following bit string:
1111 1001 1010 1. Other embodiments are possible.
[0078] Command data is grouped into 13-bit words. Each word
includes eight data bits (D7, D6, D5, D4, D3, D2, D1, D0) and five
ECC (Error Correction Code) bits (P4, P3, P2, P1, and P0). In one
embodiment, the bit transmission order is (with D7 transmitted
first):
D7, D6, D5, D4, D3, D2, D1, D0, P4, P3, P2, P1, P0 . . .
[0079] In one embodiment, the ECC bits (P4-P0) are generated using
the following equations: P0=(D1+D2+D5+D7)modulo 2
P1=[(D1+D3+D4+D6)modulo 2]Complement P2=(D0+D2+D3+D6+D7)modulo 2
P3=[(D0+D4+D5+D6+D7)modulo 2]Complement
P4=(D0+D1+D2+D3+D4+D5)modulo 2.
[0080] Data rates depend on which data band is being used. A high
data band has an effective data rate (adjusting for PN and ECC) of
189.3 Kbps. A low data band has an effective data rate of 94.68
Kbps.
[0081] In the illustrated embodiment, a 16-bit check sum is
provided to detect bit errors on the packet level. A circuit 34 can
be programmed to either return a reply if a bad check sum is found
in the forward link, or to simply halt execution and send no
replies. In one embodiment, a 16 bit CRC is employed in the forward
link, the return link, or both, instead of or in addition to the
check sum.
[0082] The physical communications protocol for communications from
the circuit 34 to the interrogator 50 is referred to as the "return
link" protocol. In the illustrated embodiment, the return link
messages are sent in the following order:
[0083] Preamble
[0084] Barker Code
[0085] Reply Packet
[0086] Check Sum
[0087] After sending a command, the interrogator sends a continuous
unmodulated RF signal with a frequency of 2.44175; Ghz. Return link
data is Differential Phase Shift Key (DPSK) modulated onto a square
wave subcarrier with a frequency of 596.1 Khz. A data 0 corresponds
to one phase and data 1 corresponds to another, shifted 180 degrees
from the first phase. The subcarrier is used to modulate antenna
impedance of a card 32. For a simple dipole, a switch between the
two halves of the dipole antenna is opened and closed. When the
switch is closed, the antenna becomes the electrical equivalent of
a single half-wavelength antenna that reflects a portion of the
power being transmitted by the interrogator. When the switch is
open, the antenna becomes the electrical equivalent of two
quarter-wavelength antennas that reflect very little of the power
transmitted by the interrogator. The switch driving a printed half
wavelength dipole antenna gives a typical range of 15 feet when the
interrogator 50 transmits at 30 dBm into a 6 dB gain antenna.
Therefore, antennas 52 are located no more than 15 feet apart in
areas of the facility 10 where it is desirable to locate people or
objects.
[0088] The preamble for the return link includes 2000 bits,
alternating 2 zeros then 2 ones, etc., and a 13-bit start (Barker)
code. Alternative preambles are possible.
[0089] In the illustrated embodiment, the start code or Barker Code
is defined by the following bit string: 1111 1001 1010 1.
[0090] The reply link data is grouped in 13 bit words. Each word is
composed of 8 data bits (D7, D6, D5, D4, D3, D2, D1, D0) and 5 ECC
bits (P4, P3, P2, P1, P0).
[0091] The Block Encoded Sequence is D7, D6, D5, D4, D3, D2, D1,
D0, P4, P3, P2, P1, P0.
[0092] The Block ECC Bits (P4-P0) are generated using the following
equations: P0=(D1+D2+D5+D7)modulo 2 P1=[(D1+D3+D4+D6)modulo
2]Complement P2=(D0+D2+D3+D6+D7)modulo 2 P3=[(D0+D4+D5+D6+D7)modulo
2]Complement P4=(D0+D1+D2+D3+D4+D5)modulo 2.
[0093] In the illustrated embodiment, the bit duration is 6.71
.mu.s making the effective data rate 91.75 Kbps for the return
link.
[0094] In the illustrated embodiment, a 16-bit check sum is
provided to detect bit errors on the packet level. In one
embodiment, a 16 bit CRC is employed in addition to or instead of
the check sum.
[0095] Each pair of data words is interleaved, starting with the
Barker code and the first data word. The transmitted bit order for
two sequential words, A and B, is D7A, D7B, D6A, D6B, D5A, D5B,
D4A, D4B, D3A, D3B, D2A, D2B, D1A, D1B, D0A, D0B, P4A, P4B, P3A,
P3B, P2A, P2B, P1A, P1B, P0A, P0B.
[0096] D7A is the first transmitted bit. In the illustrated
embodiment, DPSK is applied to the interleaved data.
[0097] In one embodiment (see FIG. 7), the interrogator 50 includes
enhanced parallel port (EPP) circuitry 70, DPSK (differential phase
shift keyed) circuitry 72, and RF (radio frequency) circuitry 74,
as well as a power supply (not shown) and a housing or chassis (not
shown). In the illustrated embodiment, the enhanced parallel port
circuitry 70, the DPSK circuitry 72, and the RF circuitry 74
respectively define circuit card assemblies (CCAs). The
interrogator uses an IEEE-1284 compatible port in EPP mode to
communicate with the controller 54. The EPP circuitry 70 provides
all the digital logic required to coordinate sending and receiving
a message to and from a circuit 34. The EPP circuitry 70 buffers
data to transmit from the controller 54, converts the data to
serial data, and encodes it. The EPP circuitry 70 then waits for
data from the circuit 34, converts it to parallel data, and
transfers it to the controller 54. In one embodiment, messages
include up to 64 bytes of data.
[0098] The EPP mode interface provides an asynchronous,
interlocked, byte wide, bidirectional channel controlled by the
controller 54. The EPP mode allows the controller 54 to transfer,
at high speed, a data byte to/from the interrogator within a single
host computer CPU I/O cycle (typically 0.5 microseconds per
byte).
[0099] The DPSK circuitry 72 (see FIG. 8) receives signals I and Q
from the RF circuitry 74 (described below), which signals contain
the DPSK modulated sub-carrier. The DPSK circuitry 72 includes
anti-aliasing filters 76 and 78 filtering the I and Q signals,
respectively, and analog to digital (A/D) converters 80 and 82
respectively coupled to the filters 76 and 78 and respectively
converting the filtered signals from analog to digital signals. The
DPSK circuitry 72 further includes a combiner 84, coupled to the
A/D converters 80 and 82, combining the digital signals. The DPSK
circuitry 72 further includes a FIR matched filter 86, coupled to
the combiner 84, which filters the combined signals. The DPSK
circuitry 72 further includes delay circuitry 88 and multiplier
circuitry 90 coupled to the FIR matched filter 86 for delaying the
signal and multiplying the signal with the delayed signal to remove
the sub-carrier. The DPSK circuitry 72 further includes low pass
filter circuitry 92, coupled to the multiplier 90, filtering the
output of the multiplier 90 to remove the X2 component. The DPSK
circuitry 72 further includes a bit synchronizer 94 coupled to the
filter 92 for regeneration of the data clock. The DPSK circuitry 72
further includes lock detect circuitry 96 coupled to the low pass
filter 92 and generating a lock detect signal. The data, clock, and
lock detect signal are sent to the EPP circuitry 70.
[0100] The RF circuitry 74 (see FIG. 9) interfaces with the
transmit and receive antennas X1, X2, X3, etc., and R1, R2, R3, etc
defining antennas 52. The RF circuitry modulates the data for
transmission to a circuit 34, provides a continuous wave (CW)
carrier for backscatter communications with a circuit 34 (if
backscatter communications are employed), and receives and
downconverts the signal received from the transponder unit (which
is a backscatter signal in one embodiment).
[0101] The RF circuitry 74 also includes a power divider 98, and a
frequency synthesizer 100 coupled to the power divider 98. The
frequency synthesizer 100 tunes the RF continuous waver carrier for
frequency hopping and band selection. The RF circuitry defines a
transmitter, and receives data from the EPP circuitry 70. The RF
circuitry 74 includes an amplitude modulation (AM) switch 102 that
receives the data from the EPP circuitry 70 and amplitude modulates
the data onto a carrier. More particularly, the AM switch 102 turns
the RF on and off (ON OFF KEY). The RF circuitry 74 further
includes a power amplifier 104, coupled to the AM switch 102, to
amplify the signal. The RF circuitry 74 further includes a switch
106, coupled to the power amplifier 104, for transmission of the
amplified signal through a selected one of the transmit antennas
X1, X2, X3, etc.
[0102] During continuous wave (CW) transmission for the backscatter
mode, the AM switch 102 is left in a closed position. When the
interrogator 50 is transmitting in the CW mode, the circuit 34
backscatters the signal with a DPSK modulated sub carrier. This
signal is received via one of the receive antennas R1, R2, R3, etc.
More particularly, the RF circuitry 74 further includes a switch
108 coupled to the receive antennas R1, R2, R3, etc. In another
alternative embodiment, such as when backscatter communications are
not employed, the RF circuitry uses common antennas for both
transmission and reception, and alternates use of antennas from
multiple available send/receive antennas. The RF circuitry 74
further includes a low noise amplifier (LNA) 110 coupled to the
switch 108 and amplifying the received signal. The RF circuitry 74
further includes a quadrature downconverter 112, coupled to the LNA
110, coherently downconverting the received signal. The RF
circuitry 74 further includes automatic gain controls (AGCs) 114
and 116 coupled to the quadrature down converter 112. The amplitude
of the signals are set using the automatic gain controls 114 and
116 to provide the signals I and Q. The I and Q signals, which
contain the DPSK modulated sub-carrier, are passed on to the DPSK
circuitry 72 (FIG. 8) for demodulation.
[0103] Although one interrogator 50 has been described, it may be
desirable to provide multiple interrogators depending on the size
and layout of a facility, in which case the multiple interrogators
will preferably share information.
[0104] The interrogator or interrogators 50 are respectively
selectively connected to the antennas 52 of an array of antennas
distributed in at least the passenger areas of the facility, such
as in the main terminal 14, the baggage check in area 16, the
terminal concourse area 18, and the security check area 20. An
interrogator connected to any of the antennas 52 has a range
covering less than the area of the entire facility 10. More
particularly, the more antennas 52 that are provided, the more
precisely the location of an individual can be determined (the
transmission and reception range of the interrogator can be
decreased appropriately). Preferably, some antennas 52 are located
in non-passenger areas, such as outdoor areas, to assist in
locating individuals or equipment instead of passengers. The
antennas 52 are designed for transmission and reception at
microwave frequencies (e.g., 2.44 GHz). As described above, the
antennas 52 can either comprise combined send/receive antennas, or
separate antennas for sending (transmitting) and receiving. If
separate antennas are used for sending and receiving, they will be
referred to as a single antenna for purposes of the following
discussion and claims.
[0105] Preferably, the antennas 52 are distributed fairly evenly
throughout monitored areas of the facility 10. In one embodiment,
an area of communication is defined by the interrogator 50
connected to an antenna 52, and the area of communication of the
interrogator using one of the antennas 52 overlaps with the area of
communication of the interrogator using another one of the antennas
52 so that there are no gaps in the areas of the facility desired
to be covered by the system.
[0106] In operation, the interrogator 52 repeatedly transmits a
wireless command to the portable wireless transponder device using
alternating ones of the antennas 52. In one embodiment, the
interrogator is sequentially connected to respective antennas 52,
and makes at least one communication attempt using each antenna 52.
The device 32 owned by an individual or supported by an object or
checked or carry-on luggage transmits data identifying the device
32 (and thus the bearer or possessor of the device 32) in response
to an interrogator command if the device 32 is within
communications range of the antenna 52 sending the command. Thus,
the individual or object is located by determining with which
antenna the interrogator 50 was able to establish communications
with the portable wireless transponder device.
[0107] FIGS. 12 and 13 illustrate routines executed by the
controller 54 to locate individuals, equipment, or checked or
carry-on baggage in the facility 10. Note that it may be useful for
an airline to determine the location of checked baggage, using the
system of the invention, for various reasons. For example, it may
be useful to locate a piece of baggage that has been misplaced, or
that is destined for a flight that is about to leave, or a piece of
baggage that is in transit to a plane, but must be re-routed to a
different plane. It may be useful to locate a piece of carry on
baggage using the system of the invention for various reasons. For
example, if a piece of carry on baggage becomes separated from its
owner for a predetermined time, an assumption can be made that it
is either lost or else creates a possible bomb risk that should be
investigated. Also, the system can be used to locate a passenger's
lost carry on or checked baggage.
[0108] The routine of FIG. 12 is continuously run (during hours of
operation of the facility) and includes a step 118 of causing the
interrogator to send an "identify" command, which requests that all
devices 32 (within communication range) reply with their respective
identification numbers. After performing step 118, the controller
54 proceeds to step 120.
[0109] In step 120, the controller 54 deletes old entries and logs
identification numbers of devices 32 within the range of the
antenna 52 being used. After performing step 120, the controller 54
proceeds to step 122.
[0110] In step 122, the controller switches the antenna 52 (or
antenna pair) being used by the interrogator. After performing step
122, the controller 54 proceeds to step 118.
[0111] The routine of FIG. 13 is run when it is desired to locate a
specific individual, item of equipment, piece of carry-on baggage,
or piece of checked baggage (by inputting an identification number
of a device 32).
[0112] The routine of FIG. 13 includes a step 124 of receiving
(inputting) an inquiry as to the location of a particular
individual. After performing step 124, the controller 54 proceeds
to step 126.
[0113] In step 126, the controller determines if the individual (or
item of equipment, or piece of carry-on baggage, or piece of
checked baggage) is on the carrier (plane) by checking the logs for
antennas at controlled access points (e.g., the gate for the flight
the individual was scheduled to take). After performing step 126,
the system proceeds to step 128.
[0114] In step 128, a determination is made as to whether the
individual (or item of equipment, or piece of carry-on baggage, or
piece of checked baggage) is on the carrier. If so, the controller
proceeds to step 130. If not, the controller proceeds to step
132.
[0115] In step 130, the location of the individual (or item of
equipment, or piece of carry-on baggage, or piece of checked
baggage) is displayed as being on board the carrier (e.g. the
airplane). After performing step 130, execution terminates.
[0116] In steps 132 and 134 (which can be combined), current (most
recent) logs are read for all other antennas, and the controller
searches for the particular individual (or item of equipment, or
piece of carry-on baggage, or piece of checked baggage) in these
logs. After performing steps 132 and 134, the controller proceeds
to step 136.
[0117] In step 136, a determination is made as to whether the
particular individual (or item of equipment, or piece of carry-on
baggage, or piece of checked baggage) was located in any of these
logs. If so, the controller proceeds to step 140. If not, the
controller proceeds to step 138.
[0118] In step 138, the controller causes a display to be generated
that the search failed or the individual (or item of equipment, or
piece of carry-on baggage, or piece of checked baggage) was not
located on the premises. After performing step 138, execution
terminates.
[0119] In step 140, a determination is made as to whether the
individual (or item of equipment, or piece of carry-on baggage, or
piece of checked baggage) was located in more than one log in logs
associated with more than one antenna). If so, the controller
proceeds to step 142. If not, the controller proceeds to step
144.
[0120] In step 142, the location is displayed of the antenna where
the logged communication with the device of the particular
individual (or item of equipment, or piece of carry-on baggage, or
piece of checked baggage) took place. This is presumably where the
individual (or item of equipment, or piece of carry-on baggage, or
piece of checked baggage) is presently located. After performing
step 142, execution terminates.
[0121] In step 144, because the individual has been logged in more
than one antenna location, all antenna locations can be displayed
or, in the illustrated embodiment, triangulation or telemetry are
used, and/or relative signal strengths measured by the multiple
antennas for the last logged reply by the card are used, to locate
with particularity the particular individual's location (or the
location of the item of equipment, or piece of carry-on baggage, or
piece of checked baggage). Optionally, the direction of travel is
also determined by determining change in triangulated location with
respect to time. After performing step 144, the controller proceeds
to step 146.
[0122] In step 146 the controller causes the location of the
particular individual (or item of equipment, or piece of carry-on
baggage, or piece of checked baggage) to be displayed. After
performing step 146, the controller proceeds to step 148.
[0123] This system and routine can be used to track the location of
equipment bearing the circuit 34, carry-on baggage bearing the
equipment, or checked baggage bearing the equipment.
[0124] In one embodiment of the invention, the system 12 further
comprises a carrier (e.g., airline) reservation and baggage
tracking system 152 (FIG. 2). Any presently used reservation system
can be employed. For example, a system such as the systems
described in incorporated U.S. Pat. Nos. 5,401,944; 5,151,692;
5,051,565; 5,010,240; 4,984,156; 4,931,932; 4,449,186; 4,247,795;
and 3,750,103 can be employed for the carrier reservation and
baggage tracking system 152. The reservation and baggage tracking
system 152 includes a computer having a database storing
information identifying passengers who have purchased tickets for
passage (e.g., a flight), information about scheduled departures
(e.g., for flights), information identifying passengers who have
checked in (e.g., for a flight), etc. The system 12 further
includes a network 154 connecting the interrogator 50 to the
carrier reservation and baggage tracking system 152. Any
appropriate network, such as a local area network, wide area
network, Intranet network, Internet network, etc. can be employed.
If multiple airlines or carriers in the facility have separate
reservation systems, the network 154 preferably connects all
participating reservation systems to the interrogator 50.
[0125] In this embodiment, the card 32 is used to automatically
check in a passenger who enters the facility or a designated area
of the facility (e.g., a gate area), as desired.
[0126] More particularly, the interrogator 50 defines a wireless
transponder in communication with the computer of the carrier
reservation and baggage tracking system 152. The interrogator
periodically sends wireless commands requesting responses from
portable identification devices (e.g., the cards 32). The cards 32
transmitting identifying data (e.g., a serial number that is
associated with the bearer, a Social Security Number, a frequent
flyer number, a confirmation number, etc.) in response to receiving
a command from the interrogator. The interrogator has a desired
coverage area (e.g., in the airport, or in the gate area), and
communicates only with cards 32 within the desired area. The
computer of the carrier reservation and baggage tracking system 152
modifies the reservation database to indicate that a passenger has
checked in, in response to the interrogator 50 receiving a response
from a card 32 in the desired coverage area. Thus, the card 32 acts
as an electronic boarding pass, saving the passenger from having to
stand in line to check in, and reducing labor required by the
carrier.
[0127] Conditions can be imposed before the electronic boarding
pass is accepted. For example, in one embodiment, the electronic
boarding pass (card 32) is accepted to check in a passenger only
within a predetermined time period before a scheduled departure.
Thus, if a passenger is in the airport the day before a flight
(e.g., to greet an arriving passenger, or for an unrelated flight),
the passenger is not considered to be checked in. In one
embodiment, the electronic boarding pass is only accepted if the
response from the card 32 includes identifying data for a passenger
for whom the database in the carrier reservation and baggage
tracking system 152 indicates that a ticket for a flight has been
purchased. A routine for execution by the system 152 to this effect
is provided in FIG. 14, and includes a first step 156 in which the
system 152 retrieves a list of passengers having reservations for
flights scheduled to leave in the next predetermined time period
(e.g., flights scheduled to leave in the next two hours, or next
one hour). After performing step 156, the system proceeds to step
158.
[0128] In step 158, a determination is made as to whether
identification data (e.g., Social Security Number, frequent flier
number, serial number, etc.) logged using designated antennas 52
(e.g., in the airport, or in the gate area for the particular
flight, etc.) match the identification data of any passengers on
the reservation list for flights scheduled to leave in the next
predetermined time period. If so, the system proceeds to step 160.
If not, the system proceeds to step 162.
[0129] In step 160, the system checks in the qualifying passengers
(those logged using designated antennas and matching the
identification data of passengers on the reservation list for
flights scheduled to leave in the next predetermined time period).
The system further assigns seats (this may be based on known
customer preferences, such as preferences stored for frequent
fliers), and moves the checked in passengers from the reservation
list to the checked in list. This is so that there is no need to
search for passengers who have already checked in, next time step
156 is executed. After performing step 160, the system proceeds to
step 166.
[0130] In step 162, a time delay is imposed so that the system is
freed up to perform other tasks. After performing step 162, the
system proceeds to step 164.
[0131] In step 164, the time is updated. In other words, the system
time is retrieved for purposes of defining the predetermined time
period of step 156. After performing step 164, the system proceeds
to step 156.
[0132] In step 166, a time delay is imposed so that the system is
freed up to perform other tasks. After performing step 166, the
system proceeds to step 168.
[0133] In step 168, the time is updated. In other words, the system
time is retrieved for purposes of defining the predetermined time
period of step 156. After performing step 168, the system proceeds
to step 156.
[0134] In one embodiment, the transponder device 32 is manufactured
using techniques such as those described in a commonly assigned
U.S. patent application (attorney docket MI40-048) titled "Tamper
Resistant Smart Card and Method of Protecting Data In a Smart
Card", filed Feb. 13, 1997, listing as inventor John R. Tuttle et
al., now U.S. Pat. No. 5,988,510, and incorporated herein by
reference. In one embodiment, the device 32 includes a magnetic
stripe which the carrier (e.g., airline) can use for various
purposes instead of or in addition to using the antennas 42. For
example, an airline may use the antennas 42 to check in a
passenger, but may use the magnetic stripe with a card reader at a
gate 22 (such as the card reader described in U.S. Pat. No.
5,010,240) in place of a boarding card when a passenger passes
through the gate 22 to board a plane, or vice versa.
[0135] In one embodiment, the system gives an indication to a
passenger that the passenger has been successfully checked in, such
as by displaying a message on a monitor, on a display on the card
32 (described elsewhere herein), by making an announcement on a
speaker, or by other means.
[0136] In one embodiment, a similar method and routine is used to
check in luggage bearing a card 32 (or a miniature tag housing the
integrated circuit 34) which is configured to transmit data
indicating the card is associated with checked baggage (instead of
carry-on baggage or other equipment) in response to a command from
the interrogator. The luggage can be checked in instead of or,
preferably, in addition to the passenger. This way, the passenger
can just leave the luggage in a designated area instead of waiting
in a line. Airline personnel can determine the destination by
interrogating the card 32 or tag on the baggage. Thus, the card 32
or tag becomes an electronic (recyclable) baggage tag. In one
embodiment, the card 32 or tag on the checked baggage includes a
display (as described elsewhere herein), which displays the
destination of the baggage (and/or transfer points).
[0137] In one embodiment of the invention (see FIGS. 1-3), the
system 12 communicates custom travel (e.g. flight) information to a
passenger. The system 12 uses the computer of the previously
described carrier reservation and baggage tracking system 152. The
system further includes monitors 170 and/or speakers 172, and
appropriate converters 174 and 176 connecting the monitors and
speakers to the network. The converters 174, for example, may
convert from EGA, VGA, or super VGA to a standard television
signal, and the converters 176, for example, may be sound cards or
equivalent circuitry. Whenever a passenger is in proximity to an
antenna located near a monitor or speaker, the interrogator 50
determines this in the same way that the interrogator 50 locates
passengers, by communicating with a card 32 possessed by the
passenger. The system accesses the reservation and baggage tracking
system 152, retrieves the departure information for that passenger,
and displays the information on the monitor as shown in FIG. 3.
More particularly, the system uses the existing reservation
database of the system 152, including information identifying
passengers who have purchased tickets for a flight, and information
about scheduled departures. The information includes existing
information such as a flight, bus or train number 178, destination
180, a gate, bay, or track number 182, scheduled departure time
184, and status information 186 (e.g., boarding, on time, delayed,
gate change, see agent, cancelled, etc.).
[0138] If multiple passengers are in communications range of the
antenna near the monitor 170, information will appear tailored for
each of these passengers, as shown in FIG. 3. The information
displayed therefore preferably includes the passenger's name 188
(or an identifying code or number known by the passenger), as well.
The information may be sorted (arranged) by passenger name in
alphabetical order, by scheduled departure time, or by order of
detection of the passengers by the interrogator 50.
[0139] In one embodiment, shown in FIGS. 10 and 11, an alternative
card 32B is provided which is similar to the card 32, but further
includes a display 190 coupled to the integrated circuit 34. The
display 190 can be a liquid crystal display, LED display, or other
type of display. In this embodiment, the customized information for
the passenger bearing the card 32B appears on the display 190. The
display 190 can be activated by bringing the card 32B in
communication range with a designated antenna 52 in the facility
(which may be arranged to have a small range requiring close
proximity, so the display is not continuously activated while the
passenger travels through the facility). Alternatively, the card
32B is further include an actuator 192 coupled to the integrated
circuit 34, actuation of which causes display of the information.
The information can be similar to the information displayed on the
monitor 170, if a monitor 170 is used, except that the name of the
passenger may be omitted because the bearer of the card 32B is
obviously the passenger. On the other hand, it may be desirable to
display the passenger name to avoid mistaken swapping of the cards
32B or to avoid theft. The actuator 192 may be connected to an
analog or digital input pin of the integrated circuit.
[0140] In the embodiment of FIGS. 10 and 11, the card further
includes a buffer memory 194 coupled to a serial input/output port
of the integrated circuit 34, a controller 196, and a display
driver 198. The serial input output port is used to load the buffer
memory 194, and then the controller 196 and display driver 198
drive the display 190.
[0141] Although the system of the invention has been described in
connection with an airport and airline reservation system, it will
be apparent that the system also has application to other travel
depots and reservation systems, for those traveling by train, boat,
bus, etc.
[0142] In one embodiment, systems of multiple facilities (airports)
are connected together, such as by using a telephone link, wide
area network, Internet, Intranet, etc., so that data can be shared
among various systems. In this embodiment, the location of checked
luggage, carry-on luggage, equipment, or individuals can be
determined if the location is within communications range of an
interrogator in any of the connected facilities (airports).
[0143] Various other applications for the system 10 will readily be
apparent to those of ordinary skill in the art.
[0144] In compliance with the statute, the invention has been
described in language more or less specific as to structural and
methodical features. It is to be understood, however, that the
invention is not limited to the specific features shown and
described, since the means herein disclosed comprise preferred
forms of putting the invention into effect. The invention is,
therefore, claimed in any of its forms or modifications within the
proper scope of the appended claims appropriately interpreted in
accordance with the doctrine of equivalents.
* * * * *