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Claims  |
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We claim:
1. Apparatus for determining and reporting the present location of a
missing vehicle, the apparatus comprising:
a location determination (LD) unit, including an LD signal antenna and LD
receiver/processor, positioned on a vehicle to receive LD signals from at
least three distinguishable LD signal sources and to process these LD
signals so that the processed signals can be used to determine the present
location of the LD antenna;
a cellular phone unit positioned on the vehicle and comprising:
a cellular phone transceiver and antenna that receive incoming cellular
signals at a signal port on an incoming cellular channel and that transmit
outgoing cellular signals from the signal port on an outgoing cellular
channel at a selected frequency to a central station that is spaced apart
from the cellular phone transceiver, that receive incoming cellular
signals from the central station and that issue these signals as
electronic signals at the signal port, and that can generate and issue an
audibly perceptible or visually perceptible incoming call signal that
indicates when the transceiver and antenna are receiving an incoming
cellular signal intended for that transceiver, where the cellular phone
transceiver and antenna are capable of receiving and responding to an LD
interrogation signal from the central station that requests information on
the present location of the LD antenna; and
a cellular phone handset, having an on-hook state and an off-hook state,
that receives electronic signals from the cellular phone signal port and
converts these electronic signals to audio signals and that, in its
off-hook state, receives and converts audio signals to electronic signals
and delivers these electronic signals to the cellular signal port; and
a controller, positioned on the vehicle, connected to and selectively
controlling and acting as an interface between the LD unit and the
cellular phone unit, for passing signals between the LD unit and the
cellular phone unit, wherein (i) when the cellular phone unit receives an
incoming cellular call, the controller causes the cellular phone unit to
delay issuance of an incoming call signal for a selected initial time
interval of length .DELTA.td; (ii) when the cellular phone unit receives
an LD interrogation signal during an initial time interval of length
.DELTA.td as part of the incoming cellular call, the controller causes the
cellular phone unit not to issue an incoming cellular phone call signal
indicating receipt of an incoming phone call, causes the LD unit to
provide the cellular phone unit with information on the present location
of the LD antenna, and causes the cellular phone transceiver and antenna
to transmit this LD unit present location information to the central
station; and (iii) when the cellular phone unit does not receive an LD
interrogation signal during an initial time interval of length .DELTA.td
as part of the incoming cellular call, the controller causes the cellular
phone unit to operate as a normal cellular phone and to issue an incoming
cellular phone call signal that is perceptible by an occupant of the
vehicle.
2. The apparatus of claim 1, wherein said incoming cellular channel and
said outgoing channel are part of a first cellular channel.
3. The apparatus of claim 2, wherein said transceiver and antenna receive
said LD interrogation signal on said first cellular channel.
4. The apparatus of claim 2, wherein said transceiver and antenna receive
said LD interrogation signal on a second cellular channel.
5. The apparatus of claim 4, wherein said transceiver on said first
cellular channel and on said second cellular channel operate independently
of each other so that a vehicle occupant within said vehicle can use said
transceiver on said second cellular channel to communicate with another
person or facility at another location, at the same time said transceiver
is responding to said LD interrogation signal on said first cellular
channel.
6. The apparatus of claim 1, wherein, when said incoming cellular phone
unit does not receive an LD interrogation signal during an initial time
interval of length .DELTA.td as part of said incoming cellular phone call,
said controller causes said cellular phone unit to issue an incoming call
signal for said vehicle occupant, indicating receipt of an incoming
cellular phone call by said cellular phone unit, until said cellular
handset goes off-hook or the calling party disconnects or the incoming
cellular phone call signal is issued a selected number of times.
7. The apparatus of claim 1, further comprising a cellular unit cradle,
positioned on said vehicle and including a microprocessor, that accepts
and holds said cellular unit and said controller, wherein said cellular
unit is optionally detachable from the cellular unit cradle and can
receive said incoming cellular calls and said LD interrogation signals and
can transmit said outgoing cellular calls while said cellular unit is
detached from the cellular unit cradle and while said cellular unit is
attached to the cellular unit cradle.
8. The apparatus of claim 7, wherein said cellular unit cradle does not
hold said LD unit and said LD unit and said controller are electrically
connected when said cellular phone unit is accepted by and attached to
said cellular unit cradle.
9. The apparatus of claim 7, wherein said cellular cradle unit further
accepts and holds said LD unit.
10. The apparatus of claim 1, wherein at least one of said LD unit and said
controller is hidden from view on said vehicle.
11. The apparatus of claim 1, wherein, when a vehicle occupant within the
vehicle uses said cellular phone unit to communicate with an other person
or facility at another location, said cellular phone unit operates as a
normal cellular phone and allows the vehicle occupant to communicate with
that other person or facility, if said cellular phone unit is not
responding to said LD interrogation signal at the time the vehicle
occupant uses said cellular phone unit.
12. The apparatus of claim 1, further comprising activatable recording
means and a recording switch that activates and deactivates the recording
means, connected to said transceiver, for recording and storing at least
one of (i) a contact phone number for an incoming call or outgoing call
using said transceiver and (ii) a voice communication, which uses said
transceiver, between said vehicle occupant and said other person or
facility, when the recording means is activated.
13. The apparatus of claim 12, wherein said recording means in an activated
state causes said transceiver to transmit a recording advisory signal to
said central station, indicating that said transceiver has been used for
an incoming call or outgoing call, if at least one voice communication or
phone number has been recorded by said recording means.
14. The apparatus of claim 13, wherein said transceiver is capable of
receiving from said central station a recording interrogation signal, in
response to receipt by said central station of said recording advisory
signal, the apparatus further comprising stored message transmission
means, connected to said recording means and to said transceiver, for
obtaining information on at least one of (i) said contact phone number and
(ii) said voice communication, stored in said recording means, and for
transmitting this information to said central station when said
transceiver receives a recording response command signal from said central
station.
15. The apparatus of claim 1, further comprising a message storage memory,
connected to said controller, wherein, when a vehicle occupant uses said
transceiver to communicate with an other person or facility at another
location on said second cellular channel while said apparatus is receiving
or is responding to said LD interrogation signal on said first cellular
channel, said transceiver will abort its response to said LD interrogation
signal, will store said LD unit present location information in the
message storage memory, will operate as a normal cellular phone on said
second cellular channel and will allow the vehicle occupant to contact the
called person or facility.
16. The apparatus of claim 15, wherein said controller further comprises
stored message transmission means, for retrieving said LD unit present
location information from said message storage memory and for causing said
transceiver to transmit said LD antenna present location information to
said central station, after said cellular phone handset has returned to an
on-hook condition.
17. The apparatus of claim 1, wherein said transceiver transmits an abort
signal to said central station, if said transceiver's response to said LD
interrogation signal is aborted before this response is completed.
18. The apparatus of claim 1, wherein, when an occupant of the vehicle uses
said transceiver to communicate with an other person or facility at
another location on said second cellular channel while said transceiver is
receiving or is responding to said LD interrogation signal on said first
cellular channel, said transceiver will abort its response to said LD
interrogation signal, will operate as a normal cellular phone on said
second cellular channel and will allow the vehicle occupant to communicate
with the other person or facility.
19. The apparatus of claim 1, wherein, when an occupant of the vehicle uses
said transceiver to communicate with an other person or facility at
another location on said second cellular channel while said transceiver is
receiving or is responding to said LD interrogation signal on said first
cellular channel, said transceiver will complete the transmission of its
response to said LD interrogation signal, will then operate as a normal
cellular phone and will allow the vehicle occupant to communicate with the
other person or facility.
20. The apparatus of claim 1, wherein, when an occupant of the vehicle uses
said transceiver to communicate with an other person or facility at
another location on said second cellular channel while said transceiver is
receiving or is responding to said LD interrogation signal on said first
cellular channel, said transceiver will behave as if it is disabled so
that the vehicle occupant will be unable to complete a phone call
connection using said transceiver.
21. The apparatus of claim 1, wherein said time interval length .DELTA.td
lies in the range of about 0.2-30 sec.
22. The apparatus of claim 1, wherein said time interval length .DELTA.td
lies in the range of about 1-5 sec. |
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Claims |
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Description |
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FIELD OF THE INVENTION
This invention relates to clandestine use of location determination
systems, such as the Global Positioning System or Loran, to monitor and
report on the location of a missing vehicle, using cellular phone
channels.
BACKGROUND OF THE INVENTION
As used herein, the term "vehicle" refers to land vehicles, to marine
vehicles or vessels, and to aircraft. In the United States, about 1.7
million automotive vehicles and about 100,000 marine and aircraft vehicles
are reported missing (or stolen) each year. The probability that a land or
marine vehicle will be recovered drops dramatically after the vehicle or
vessel has been missing for 24 hours or more. Thus, time is of the essence
in locating and retrieving a missing vehicle.
Vehicle location and/or tracking systems are disclosed by Sheffer et al in
U.S. Pat. Nos. 4,891,650 and 5,218,367, by Darnell et al in U.S. Pat. No.
5,043,736, by Durboraw in U.S. Pat. No. 5,119,341, by Wortham in U.S. Pat.
Nos. 5,155,689 and 5,398,190, by Robinson et al in U.S. Pat. No.
5,159,344, by Bertiger et al in U.S. Pat. No. 5,187,805, by Song in U.S.
Pat. No. 5,208,756, by Mansell in U.S. Pat. No. 5,223,844, by Dennison in
U.S. Pat. No. 5,235,633, and by Simms et al in U.S. Pat. No. 5,334,974.
What is needed is a system including cellular telecommunication means that
allows determination and reporting of the present location of a missing
vehicle, using clandestine means on the vehicle itself and one or more
cellular phone channels. Preferably, the clandestine means permits normal
operation of the cellphone, regardless of who is using the vehicle or
phone, but can be used to determine and transmit a report on the present
location of the missing vehicle, if commanded to do so by a special
message sent via the cellular network. Preferably, the system will
optionally allow simultaneous use of the cellular phone system to report
vehicle location and to carry a normal cellular phone conversation.
Preferably, the system should allow recording of any telecommunications
made using the cellular phone while the vehicle is missing.
SUMMARY OF THE INVENTION
These needs are met by the invention, which provides a location
determination and reporting (LDR) system for clandestinely determining and
reporting on the present location of a missing vehicle. The vehicle may be
in motion or may be motionless when its location is determined and
reported, and the vehicle may be anywhere within reach of a cellular phone
station to which the vehicle location is reported. The clandestine
reporting system may be activated or disabled by appropriate command using
the cellphone keypad or remotely.
A vehicle is equipped with an operating cellular telephone (the term as
used herein includes a PDS telephone), with a location determination (LD)
unit, including an LD signal antenna and LD signal receiver/processor
(preferably hidden on the vehicle), that determines the present location
of the LD unit, with a call interceptor that may be part of the cellular
phone, and with a cellular telephone/LD unit controller and interface.
When the vehicle is reported missing, stolen or moved without
authorization from its last known resting place, the vehicle owner himself
from home, or from a service agency hired by the owner to track the
vehicle from an originating station, uses the cellular telephone facility
to place a call to the cellphone in the vehicle and transmit an
interrogation signal. The interrogation signal activates a reporting
procedure that reports the present location of the vehicle, even if the
vehicle is presently in motion. The owner, agent or other interested and
authorized person makes a phone call to the cellular phone unit in the
vehicle and transmits a location interrogation message that commands the
LD signal receiver/processor to provide information on the present
location of the LD unit for transmission by the vehicle cellular phone
unit to whoever placed the call, where the owner, tracking agent or police
are waiting to receive this location information.
When the vehicle cellular phone is contacted and the clandestine vehicle
tracking mode is activated, the phone will not immediately signal receipt
of an incoming call. The incoming call is first received by a call
interceptor, connected to the cellular phone, imposing an initial time
delay interval of selected length .DELTA.t.sub.d (.DELTA.t.sub.d
.apprxeq.0.2-30 sec, preferably .DELTA.t.sub.d .apprxeq.1-5 sec, and more
preferably .DELTA.t.sub.d .ltoreq.1 sec), and awaiting receipt of an
anticipated location interrogation signal from the originating station
that requests that the cellular phone unit provide present location
information for the vehicle.
If the call interceptor or cellular phone receives this location
interrogation signal within the initial time interval of length
.DELTA.t.sub.d, the call interceptor suppresses ringing by the cellular
phone in the usual sense; the cellular phone provides no indication to
occupants of the vehicle that the phone is communicating with the
designated station; and the cellular phone transmits information on the
vehicle's present location to the call originator.
However, if the anticipated location interrogation signal is not received
within the initial time interval of length .DELTA.t.sub.d, the call
interceptor allows the cellular phone to ring audibly or to signal
visually, after a time delay of length .DELTA.t.sub.d. The call
interceptor then enables normal operation of the cellphone.
When the system operates in a clandestine tracking mode, the controller and
cellular phone in the vehicle answer any incoming phone call with a
simulated ringing at the caller's end, to avoid alerting any caller to the
unusual nature of this phone system. If the incoming call is not a
location interrogation signal, the cellular phone handset produces a
standard audible ringing tone or equivalent visual signal (a "ringer"
signal) within the vehicle, and a vehicle occupant can respond to the
incoming phone in a normal manner. If the incoming phone call is not
answered, the controller and cellular phone will continue to transmit the
sounds of simulated ringing or actual ringing for the benefit of the
caller, until the caller disconnects, or until a selected large number of
rings, such as 10 or 20, has occurred.
The cellular phone channel used to contact and interrogate the vehicle
cellular phone and LD unit corresponds to a first mobile identification
number (MIN). The cellular phone may function normally, using the first
MIN channel or using an optional second MIN channel assigned to the
cellular phone, if a person in the vehicle attempts to use the cellular
phone. This "normal" use of the cellular phone will temporarily pre-empt
use of the cellular phone to respond to a location interrogation signal,
in one embodiment. Thus, an unauthorized user of the vehicle receives no
warning or indication that the innocuous cellular phone in the vehicle is
being used, or can be used, to track the present location of the vehicle.
If one or more phone calls is received by or made from the vehicle while
the vehicle is missing, the cellular phone unit and controller can record
the telephone number of the calling or called person and/or the voice
communication itself during this period, and can transmit this recorded
information upon receipt from the originating station of a voice
communication interrogation signal. Alternatively, location interrogation
and normal cellular phone use may occur on the same MIN channel. The
cellular phone may be permanently mounted or may be handheld or otherwise
portable. Where a handheld cellular unit is provided, the call interceptor
functionality is built into the phone.
Alternatively, the cellular phone can be disabled and rendered unusable
unless affirmative action is taken by the vehicle owner or authorized
operator, by toggling a concealed switch or entering a confidential
alphanumeric symbol sequence into a microprocessor associated with the
call interceptor and phone controller, using an on-board keypad.
Alternatively, the cellular phone may operate on the first MIN channel for
location interrogation (preferably initiatable only from the originating
station or the owner's home, if the owner is equipped to decode and make
use of the location information) and may operate on a second, separate MIN
channel for normal cellular phone activities.
In addition to tracking personal property like automobiles, this invention
is also well suited to tracking other types of high value cargo in
vehicles that may have been hijacked and must be tracked in some stealthy
manner so that the thieves are not aware that the vehicle is being
tracked. The cellular phone can be located in the cab just as it might be
in a personal vehicle, or it can be located in some less obvious and more
secure location, such as the trailer or cargo hold of the vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view illustrating use of one embodiment of the
invention for determining the location of a land vehicle, using an LD
system.
FIGS. 2 and 3 are schematic views illustrating use of an infrared or other
short distance electronic link to communicate LD information.
FIG. 4 is a schematic view illustrating use of one embodiment of the
invention for determining the location of a marine vehicle, using an LD
system.
FIG. 5 is a schematic view of apparatus that may be installed in a vehicle
for determining and reporting on the present location of the vehicle.
FIGS. 6A, 6B and 6C are a flow chart illustrating a procedure followed by
an LDR unit according to an embodiment of the invention.
DESCRIPTION OF BEST MODE OF THE INVENTION
FIG. 1 illustrates use of the invention to monitor and report on the
location of a land vehicle 11, using a satellite-based or ground-based LD
system. A cellular telephone unit 13, an LD unit 15 and a call interceptor
17 (including a specially programmed microprocessor) are installed in the
vehicle 11. The cellular phone unit 13 is placed in plain sight of, and
within the reach of, an operator of the vehicle 11, as a normal cellular
phone would be. The cellular phone 13 is connected to a power supply 19
and either operates normally or simulates operation as a normal cellular
phone (when in the clandestine mode) for most purposes. The LD unit 15,
preferably hidden from view on the vehicle 11, may include an LD signal
antenna 23 and associated LD signal receiver/processor 25 that receive LD
signals from three or more LD system signal sources 27, 29, 31, 33 and
determine the present location of the LD unit (usually, of the LD
antenna), either continuously or periodically or upon demand. The cellular
phone unit 13, LD unit 15 and call interceptor 17 (also preferably hidden
from view on the vehicle) together form a location determination and
reporting (LDR) unit that may be used to practice the invention in one
embodiment.
The cellular phone unit 13 receives incoming calls and places outgoing
calls through the call interceptor 17, which (1) receives cellular phone
messages through the cellular phone and (2) delays audible or visual
signaling of receipt of an incoming call to a vehicle occupant by the
cellular phone for a period of time .DELTA.t.sub.d, (.DELTA.t.sub.d
.apprxeq.0.2-30 sec, preferably .DELTA.t.sub.d .ltoreq.1 sec) to determine
whether the cellular phone message includes a location interrogation
signal or is a normal cellular phone signal. However, the call interceptor
17 and/or cellular phone unit 13 produces a simulated ringing at the
caller's end, for the benefit of the caller (only) on an incoming call, to
avoid alerting the caller that the cellular phone has another purpose. If
the incoming call is not a location interrogation signal, after the
time-out interval of length .DELTA.t.sub.d the cellular phone handset
receives a standard audible or visual ringer signal, and a vehicle
occupant can respond to the incoming phone call in a normal manner. If the
incoming phone call is not answered (i.e., if the cellular phone unit does
not go off-hook), the call interceptor 17 and/or cellular phone unit 13
will continue to transmit the sounds of simulated ringing or actual
ringing for the benefit of the caller, until the caller disconnects or a
specified number of rings occurs, after which the call interceptor
controller disconnects the phone, as if it were a dropped call, lost by
the cellular base station. This is referred to as a "spoofing" operation.
If the cellular phone message is a normal message, the call interceptor 17
(3A) allows the cellular phone unit 13 to ring and to function as a normal
cellular phone. If an occupant in the vehicle 11 answers the cellular
phone 13 as a result of receipt of an incoming call signal, the cellular
phone exhibits normal cellular phone behavior. If an occupant in the
vehicle 11 uses the cellular phone 13 to place an outgoing phone call, the
cellular phone will also exhibit normal cellular phone behavior in most
circumstances.
However, if the signal received on the cellular phone 13 includes a
location interrogation signal (sent from an originating station or some
other appropriately equipped central location), the call interceptor 17
will: (3B) suppress any production of an incoming call cellphone ringer
signal within the vehicle 11 by the cellular phone and send a location
determination command signal to the LD unit 15; (4B) receive present
location information allowing determination of the present location and/or
time of observation of the LD unit 15 from the LD unit; (5B) cause the
cellular phone 13 to transmit this present location information to the
originating station 37 (or to another designated information-receiving
facility) for analysis and (optionally) further signal processing; and
(6B) optionally sever the phone connection between the cellular phone 13
and the originating station 37 after the present location information is
received by the originating station. The present location information
transmitted by the cellular phone 13 can include the present location
coordinates of the vehicle 11, or the unprocessed signals received by the
LD unit 15 at the time the call interceptor 17 issues the location
determination command, or can include present location information that is
unprocessed or has been partly processed by the LD signal
receiver/processor 25.
If an occupant in the vehicle 11 picks up the handset 14 for the cellular
phone 13 and attempts to make a cellular phone call, while location
determination information is being received from the LD unit 15 and
transmitted to the originating station 37, the call interceptor 17 will:
(1) suppress transmission of the remainder of the location determination
information, immediately or after a selected time delay of no more than 1
sec (preferably, no more than 0.2 sec); (2) optionally transmit a
message-abort signal to the originating station 37; (3) optionally store
the remainder of the vehicle present location information in an associated
memory unit; (4A) optionally allow the person with the cellular phone
handset to place and conduct a normal cellular phone call; and (5A)
optionally cause the cellular phone to transmit the remainder of the
location determination information to the originating station 37, after
the vehicle occupant has completed that call, if the call interceptor 17
or cellular phone 13 supplies the cellular phone network number of the
originating station 37. As an alternative to step (5A), the call
interceptor 17 may (5B) issue another location determination command to
the LD unit 15 and cause the cellular phone 13 to transmit a new present
location message to the originating station 37, after the cellular phone
handset has been replaced on its cradle. As an alternative to step (4A),
the cellular phone handset may behave as if it is disabled so that the
vehicle occupant cannot initiate and complete an outgoing phone call using
the cellular phone 13.
Optionally, the call interceptor 17 can record and store any
telecommunications made by the cellular phone 13 either (1) after the LD
unit 15 receives a location interrogation signal or (2) at any time,
unless this recording capability is explicitly disabled (temporarily) by a
disable message (confidentially held by the vehicle owner) entered into
the call interceptor. If such telecommunication is recorded, the
originating station 37 is optionally notified by receipt of a voice or
electronic communication advisory signal from the cellular phone 13 (1)
that the cellular phone has been used to communicate with a phone other
than the originating station phone and (2) that the phone number of this
other phone and/or the voice communication itself has been recorded. The
originating station 37 optionally can then transmit a voice or electronic
communication interrogation signal to the cellular phone 13, and a
digital, analog or audio record of this recorded information can be
transmitted to the originating station by the cellular phone, after the
vehicle occupant has completed the call and is no longer using the
cellular phone. The originating station 37 can transmit a voice
communication interrogation signal to the cellular phone unit 13, whether
or not the originating station has received a voice communication advisory
signal.
Handheld devices for converting voice signals to digital form, or from
digital form to voice form, and storing these signals are now available
widely. For example, The Sharper Image Catalog, San Francisco, October
1996, pages 29, 41, 71 and 84 (back cover) displays and lists features
available for the Total Recall 23, the Voice Pager Organizer, the Memo
Manager and the Machina Cardcorder 6000 devices, respectively, all of
which perform such conversions and provide other features as well.
In an alternative embodiment, the LD signal antenna 23 is mounted in or on
the vehicle 11 and communicates with the LD signal receiver/processor 25,
using a short range, wireless communications link 42 that connects the LD
antenna 23 and the LD receiver/processor 25, as illustrated in FIG. 2. The
communications link 42 includes a receiver/transmitter 43, a modem 44
(optional) and a data bus 45 (optional) connected to the LD signal antenna
23, and includes a receiver 46, a modem 47 (optional) and a data bus 48
(optional) connected to the LD signal receiver/processor 25. The LD signal
information transmitted by the receiver/transmitter 43 and received by the
receiver 46 may be low intensity infrared or radiowave signals that need
not travel more than 1-20 feet (0.3-6 meters).
Optionally and alternatively, the communications link 42 may also include a
signal bus 49 that (1) is separated from the LD antenna 23 and from the LD
receiver/processor 25, (2) that receives LD signal information from the
receiver/transmitter 43 and (3) that provides this LDS signal information
for the receiver 46, as shown in FIG. 3.
Standards for signals transmitted by signal buses are set forth in the
Joint Society of Automotive Engineers and TMC (organization name unknown)
publications for J1587 (issued as 1988-01 and in revised form as
1994-01-10 and later revisions) and for J1708 (issued as 1986-01 and in
revised form as 1990-10-05 and later revisions), incorporated by reference
herein. The J1587 and J1708 publications recite standards and define
signal formats for use of microcomputer systems in heavy duty vehicle
applications, such as provision of electronic data on vehicle and
component performance, vehicle routing and scheduling, vehicle driver
information and vehicle cargo information. Each signal that is transmitted
using a signal bus complying with these standards includes (1) a message
identification (MID) no. (three digits, from 0-255), with MIDs 0-127 being
defined in J1708 and MIDs 128-255 being defined by J1587, (2) one or more
measured parameter values associated with and identified by the MID and
(3) a checksum. The current set of 256 MIDs, including MID numbers held in
reserve, are set forth in the J1587 document. Parameter update time
intervals and priorities for transmission of different groups of MIDs are
now being developed.
The cellular phone 13 may use a single channel, with one mobile
identification number (MIN) assigned to this channel in a conventional
manner. Alternatively, the cellular phone 13 may use two distinct MIN
channels: a first MIN channel for location interrogation, which is
preferably operable only from an originating station, not from the
vehicle; and a second MIN channel that receives and places telephone calls
in the vehicle, using the cellular phone in a conventional manner.
Provision and use of two MIN cellular phone channels is discussed in
EIA/TIA-553, published by Electronic Industries Association, Engineering
Department, 2001 Pennsylvania Avenue, N. W., Washington, D.C. 20008
(September 1989). The preceding discussion assumes that only one MIN
channel is available.
In a second approach, a first MIN channel is provided for location
interrogation and reporting, and a second, distinct MIN channel is
provided for normal cellular phone communications. The cellular phone does
not require use of the cellular handset to respond to a location
interrogation signal. In a first option using the second approach, the
first MIN channel and the second MIN channel operate independently:
receipt of and response to a location interrogation signal has no effect
on receipt or initiation of a cellular phone communication by a vehicle
occupant. In this first option to the second approach, the first and
second MIN cellular phone channels are preferably supplied by separate
power supplies so that use of one MIN channel will not diminish the power
available for use of the other MIN channel. Use of the first MIN channel
requires use of a first power supply 107 in FIG. 5, discussed below, and
the second MIN channel preferably uses a second power supply 109 in FIG.
5. In a second option to the second approach, the first and second MIN
channels are powered at the vehicle end by a single power supply 107 in
FIG. 5 that preferably has a larger maximum current drain so that use of
the two channels simultaneously will not noticeably reduce the power
available for operation on either channel.
FIG. 4 illustrates use of the invention in a second embodiment, wherein the
LD signals are provided by a plurality of LD signal sources (not shown)
and are received by an LD unit 54 that may include an LD signal antenna 55
and associated LD signal receiver/processor 56, carried in or on a marine
(or airborne) vehicle 51. The LD unit 54 in FIG. 4 replaces the LD unit 15
in FIG. 1, and the system in FIG. 4 otherwise operates as does the system
in FIG. 1. The LDR unit used to practice this embodiment includes a
cellular phone unit 53, the LD unit 54 and a call interceptor 57.
FIG. 5 illustrates an embodiment of an LDR unit 81 that can be used to
practice the invention as indicated in FIGS. 1 and 4. The system 81
includes a cellular phone handset 83, radio receiver and transmitter 85
and radio antenna 87. These three components may be part of a conventional
cellular phone, with other components shown in FIG. 5 being included in a
retrofitted unit that is positioned between the handset 83 and the radio
receiver and transmitter 85. Alternatively, all components of the LDR unit
81 can be integrated in a single compact package.
The LDR unit 81 also includes an LD unit 89 that may include an LD signal
antenna 91 connected to an LD signal receiver/processor 93. A call
interceptor 95 is connected to the handset 83 for audio signal exchange
and to a modem 101 (optional) for signal transmission. The call
interceptor 95 and the modem 101 are optionally configured to exchange
audio and digital signals, respectively, with the radio receiver and
transmitter 85.
The LDR unit 81 also includes an optional memory unit 103, for storing the
remainder of an aborted LD unit present location information message. The
LDR unit 81 also includes an optional voice recording module 105A, an
optional voice reformatting module 105B and an optional recording
activation switch 108, for recording any voice communication made over the
vehicle cellular phone unit and/or for reformatting this recorded
information in a form that can be transmitted as an analog or digital
communication message to the originating station 37. The LDR unit 81 also
includes an optional DTMF tone recording module 106 connected to the
recording activation switch 108, for recording a telephone number
contacted by a vehicle occupant in a normal outgoing phone call,
including, if desired, the phone number of the originating station 37. A
first power supply 107 and an optional second power supply 109 provide
electrical power for one or more of the other components of the LDR unit
81.
In future versions of a cellular phone, the handset 83 shown in FIG. 5 may
become a small, handheld, personal module to be carried around by an
individual user. A handheld handset will require an electrical power port
(unless the handset provides its own power) and a signal port to exchange
audio messages, or digital or analog signals that are converted from or to
audio signals within the handset itself. In this instance, a handheld
handset 83 would plug into the remainder of the LDR unit 81 shown in FIG.
5. This remainder of the LDR unit 81 can be provided as modules
retrofitted to a cellular phone radio receiver/transmitter 85; or this
remainder can be provided as an integrated package to which the handset 83
is attached. Thus, the embodiment shown in FIG. 5 will accommodate
handheld, carry-around cellular phone handsets as well as the familiar
cellular phone handset, radio receiver, radio antenna combinations that
are attached to one another.
The call interceptor 95 may include a timeout mechanism 111 that, in
response to an incoming cellphone call, changes from an inactive state to
an active state. An associated clock or other time delay mechanism 113
begins a countdown over an initial time interval of length .DELTA.t.sub.d.
The call interceptor 95 receives a signal indicating which state the
timeout mechanism 111 is in. If the timeout mechanism 111 is in an active
state, a cellphone tip-and-ring suppressor 115 suppresses a cellphone
tip-and-ring mechanism 117 and the cellphone handset 83 does not (yet)
audibly "ring" to indicate that the cellphone unit is receiving an
incoming call. During this initial time interval of length .DELTA.t.sub.d,
the incoming cellphone call is received and controlled by the call
interceptor 95. The call interceptor 95 performs in this mode when the
cellphone timeout mechanism 111 is activated and determines whether an
incoming phone call includes an LD interrogation signal. The call
interceptor thus incorporates an "auto answer" function, similar to what
is used in | | |
