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Description  |
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TECHNICAL FIELD
The invention relates to personnel locating systems, travel reservation
systems, airport security systems, radio frequency identification devices.
BACKGROUND OF THE INVENTION
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. Pat. Nos. relate to reservation systems and are
incorporated herein by reference: 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.
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.
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.
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.
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.
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.
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.
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,
issued Nov. 24, 1998. Antenna switching for this application is performed
for diversity purposes.
SUMMARY OF THE INVENTION
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
Preferred embodiments of the invention are described below with reference
to the following accompanying drawings.
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.
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.
FIG. 3 is a perspective view showing a monitor included in the system of
FIG. 2.
FIG. 4 is a front view of a card used in the system of FIG. 1 or 2.
FIG. 5 is a circuit schematic of an interrogator included in the system of
FIG. 1 or 2.
FIG. 6 is a circuit schematic of circuitry included in card of FIG. 4.
FIG. 7 is a block diagram of an interrogator included in the system of FIG.
1 or 2.
FIG. 8 is a circuit schematic of DPSK circuitry included in the
interrogator of FIG. 7.
FIG. 9 is a circuit schematic of RF circuitry included in the interrogator
of FIG. 7.
FIG. 10 is a plan view of a card in accordance with an alternative
embodiment of the invention.
FIG. 11 is a block diagram illustrating assembly of the card of FIG. 10.
FIG. 12 is a flow chart illustrating a routine run by the system of FIG. 1
or 2 to log locations of individuals.
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.
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
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).
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.
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
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.
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.
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,
issued Jul. 11, 1995; 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, issued
Feb. 27, 1996; 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, now abandoned. 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.
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.
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.
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.
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 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.
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.
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.
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.
Various U.S. patent applications, which are incorporated herein by
reference, disclose features that are employed in various alternative
embodiments of the invention: 08/092,147, filed Jul. 15, 1993, "Wake Up
Device for a Communications System", now abandoned and continuation
application 08/424,827, filed Apr. 19, 1995, "Wake Up Device for a
Communications System", now U.S. Pat. No. 5,568,512; 08/281,384, filed
Jul. 27, 1994, "Communication System Having Transmitter Frequency
Control", now U.S. Pat. No. 5,568,512; 07/990,918, filed Dec. 15, 1992,
now U.S. Pat. No. 5,365,551, "Data Communication Transceiver Using
Identification Protocol"; 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;
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,";
08/168,909, 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 08/032,384, filed on Mar.
17, 1993, "Modulated Spread Spectrum in RF Identification Systems Method,"
now U.S. Pat. No. 5,539,775.
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.
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.
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.
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.
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
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.
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.
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.
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
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