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Claims  |
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We claim:
1. A communications system for communicating with operators of motor
vehicles travelling along roadways, said system comprising:
at least one transmitter disposed along a roadway for intermittently
transmitting short bursts of signals within a band of frequencies to
reduce the duty cycle and to permit operation of a plurality of
transmitters within the same band of frequencies, said signals, being
transmitted according to a predetermined cycle;
said transmitter having an antenna, a first microprocessor and a first
storage means coupled thereto for storing program instructions used by
said first microprocessor to control encoding and modulation of a carrier
frequency which is transmitted through the antenna as said short bursts of
signals, said program instructions also controlling said predetermined
cycle;
a plurality of receivers including sweep tuning means for sweeping across
said band of frequencies until said short bursts of signals are received,
each of said receivers mounted in one of said motor vehicles for receiving
said signals from said transmitter;
each of said plurality of receivers having a second microprocessor and mass
storage means coupled thereto, said second microprocessor functioning to
decode said short bursts of signals to form a decoded message, said
decoder message being used by said second microprocessor as an address for
retrieving a group of messages from said mass storage means, said group of
messages being comprised of a plurality of selected messages;
input means coupled to said second microprocessor for allowing a vehicle
operator to designate a message option parameter, said message option
parameter being used by said second microprocessor to select at least one
of said selected messages from said group of messages for presentation to
said vehicle operator as a displayed message; and
display means coupled to each of said receivers for presenting said
displayed message to said vehicle operator.
2. A communications system as in claim 1 wherein the sweep tuning means
comprises a voltage controlled oscillator and a clock oscillator for
producing a control voltage for controlling said voltage controlled
oscillator.
3. A communications system as in claim 1 wherein said carrier frequency is
in the microwave range (10 GHz to 35 GHz).
4. A communications system as in claim 1 wherein said short bursts of
signals include codes identifying commercial messages contained in said
mass storage means.
5. A communications system as in claim 1 wherein said short bursts of
signals include codes identifying traffic hazard information contained in
said mass storage means.
6. A communication system as in claim 3 wherein said transmitter antenna is
a directional horn antenna.
7. A communications system as in claim 1 wherein said transmitter includes
interface means suitable for communicating with remote communications
means.
8. A transmitter as in claim 7 wherein said remote communications means
comprises a telephone.
9. A transmitter as in claim 8 wherein said remote communications means
comprises a cellular telephone.
10. A transmitter as in claim 7 wherein said remote communication means
comprises a radio.
11. A communications system as in claim 1 wherein said mass storage means
contains messages in more than one language.
12. A communication system as in claim 1 wherein said transmitter are
coupled to at least one real-time sensor.
13. A communications system for providing occupants of vehicles with
information, the system comprising:
a first transmitter for intermittently transmitting short bursts of signals
within a band of frequencies to reduce the duty of cycle and to permit a
plurality of transmitters to operate within the same band of frequencies,
said signals including a transmitter identification code that
distinguishes the first transmitter from a second transmitter;
a receiver positioned in at least one of the vehicles receiving the
information and including sweep tuning means for sweeping across said band
of frequencies until said short bursts of signals are received;
storage means coupled to the receiver for storing a data base comprised of
a plurality of messages grouped into a plurality of types of messages;
input means coupled to the receiver for allowing an occupant of the vehicle
containing the receiver to specify a message code that identifies one of
the types of messages included in the data base;
processing means for searching said data base for a first message that
satisfies the message code and the transmitter identification code; and
display means for displaying the first message.
14. A communication system as in claim 13 wherein the bandwidth is
approximately 150 MHz.
15. A communication system as in claim 13 wherein the sweep tuning means
comprises a voltage controlled oscillator and a clock oscillator for
producing a control voltage for controlling said voltage controlled
oscillator.
16. A communications system as in claim 13 wherein the first transmitter
operates in the microwave range of frequencies (10 GHz to 35 GHz).
17. A communications system as in claim 13 wherein the first transmitter
includes a Gunn diode oscillator.
18. A method for conveying information to a vehicle comprising the steps
of:
a) having a vehicle occupant specify a message type that identifies a type
of message to be displayed by a display means located in a vehicle and
coupled to a receiver;
b) transmitting short bursts of signals within a band of frequencies
intermittently at predetermined intervals from a first transmitter to
reduce the duty cycle and to permit a plurality of transmitters to operate
within the same band of frequencies, said signals including a transmitter
identification information that distinguishes the first transmitter from a
second transmitter, the first transmitter including a microprocessor for
controlling the encoding of the signals and for controlling the
predetermined intervals;
c) sweeping the band of frequencies and receiving and decoding the message
at the receiver as a received message, the received message including the
transmitter identification information;
d) using the transmitter identification information contained in the
received message in a microprocessor to scan a plurality of stored
messages and generate a group of one or more messages based on the
transmitter identification information and the message type specified by
the vehicle occupant; and
e) displaying the group of one or more messages to the vehicle occupant.
19. A method for conveying information as in claim 18 wherein the short
bursts of signals are transmitted in the microwave frequency range.
20. A communications system as in claim 1 wherein said short bursts of
signals include message information and information uniquely identifying
said transmitter.
21. A system for communicating to vehicles on a highway, said system
comprising:
A plurality of transmitters disposed adjacent a highway, each of said
transmitters comprising an antenna, an oscillator, a modulator, a
controller and a power supply, said transmitters for intermittently
transmitting short bursts of signals within a band of frequencies to
reduce the duty cycle of said transmitters and to permit said plurality of
transmitters to operate in the same band of frequencies without causing
mutual interference, said short bursts of signals transmitted in
accordance with a predetermined cycle, said controller provided with
resident pre-programmed information for transmission in said short bursts
of signals; and
a plurality of receivers disposed in vehicles located on said highway, each
of said receivers comprising an antenna, a demodulator, a replaceable
database, a microprocessor and a display, said receivers including sweep
tuning means for sweeping across said band of frequencies until said short
bursts of signals are received; messages resident in said replaceable
database are displayed which correspond to the short bursts of signals
transmitted by said transmitters, said microprocessors synthesizing
complete messages from brief message fragments.
22. The system of claim 21 in which said transmitters further comprise a
remote interface having an emergency vehicle interface, a central control
interface and real-time sensors.
23. The system of claim 22 in which said transmitters comprise cavity-tuned
Gunn diode oscillators that are allowed to drift with temperature within a
predetermined band of frequencies to provide random frequency diversity.
24. The system of claim 23 in which said transmitters are further
characterized in that they operate in a band of frequencies from 10 GHz to
35 GHz and are allowed to drift with temperature within a band 150 MHz
wide.
25. The system of claim 23 which further comprises an interface with a
voice play menu system, a cellular telephone, a telephone automatic
answering circuit, a digital modem, a DTMF decoder and a PC/PW
demodulator.
26. The system of claim 23 in which said power supply comprises a battery
and a battery charger.
27. The system of claim 23 in which said modulator comprises a transistor
arranged to controllably short circuit a resistor which interrupts power
supplied to said oscillator.
28. The system of claim 23 in which said receivers further include means
for permitting the user to select the type of information to be displayed.
29. The system of claim 23 in which said receivers are further
characterized in that said replaceable database stores full messages and
provides reconstruction of new messages from the short bursts of signals,
the messages being linked together and displayed at said receivers.
30. The system of claim 29 in which said replaceable database may provide
messages in any selected language.
31. The system of claim 23 further characterized in that said system
includes means for storage of received signals and for computing direction
of travel, thereby permitting prediction of transmitter codes and display
of information relevant to future location of said vehicle.
32. The system of claim 24 in which said sweep tuning means sweeps
approximately 150 MHz around the expected center frequency of said
transmitters.
33. A system for communicating on a highway, said system comprising:
a plurality of transmitters disposed adjacent to a highway, each of said
transmitters comprising an antenna, an oscillator, a modulator, a
controller and a power supply, said transmitters for intermittently
transmitting short bursts of signals within a band of frequencies to
reduce the duty cycle of said transmitters and to permit said plurality of
transmitters to operate in the same band of frequencies without causing
mutual interference, said short bursts of signals transmitted in
accordance with a predetermined cycle, said controller provided with
resident pre-programmed information comprising instructions for traffic
advisories, emergency messages, warnings of upcoming exits from the
highway and driving instructions; and
a plurality of receivers disposed in vehicles located on said highway, each
of said receivers comprising an antenna, a demodulator, a replaceable
database, a microprocessor and a display, said receivers including sweep
tuning means for sweeping across said band of frequencies until said short
bursts of signals are received; messages resident in said replaceable
database are displayed which correspond to the short bursts of signals
transmitted by said transmitters, said microprocessors synthesizing
complete messages from brief message fragments. |
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Claims |
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Description |
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TECHNICAL FIELD
The present invention relates to a low cost communication system to
communicate information to the drivers of vehicles while traveling along
roadways. More particularly, the system relates to information transfer by
means of short bursts of microwave pulses from independent transmitters
placed in selected locations along roadways. The transmitted signals are
coded prior to transmission and decoded after being received by receivers
installed in the vehicles. After decoding the pulses, the receivers
retrieve complete messages from a data base included as part of the
in-vehicle receiver system. Depending on selection criteria specified by
the driver, the messages are displayed or replayed audibly. The messages
may be decoded and displayed or replayed in whatever language the driver
selected for the onboard database.
BACKGROUND ART
Americans spend up to ten percent or more of their waking hours travelling
between home, work, school and shopping facilities. In addition, they
spend many more hours on the highways travelling for pleasure. This
represents a substantial opportunity for advertisers to reach their
potential customers with roadside advertisements. In the past, such
advertisements were communicated by way of billboards which were placed
along the highways. This advertising occurs at a time when the motorists
are most likely to respond. Often the response to this advertising is
immediate in that the driver leaves the highway and patronizes the
establishment which placed the advertisement. The ability to communicate a
message at the precise time the receptor is willing to respond is the goal
of virtually all commercial communications. If the advertiser has direct
control over the timing of the advertisement transmission, the
effectiveness of the advertisement may be more directly observed and
correlated.
In many locations, however, billboard advertisement along the national
highways is forbidden and is likely to be banned in many more locations
owing to present day environmental and aesthetic considerations. Therefore
an inexpensive and convenient method of communicating service information
is extremely desirable to replace the locality-specific billboards.
Perhaps more importantly, the motorist needs roadway regulatory and
advisory information to safely and efficiently travel to his or her
destination. A system for communicating current roadway safety
information, such as speed limits, road conditions, traffic density,
accidents, and other obstructions to the flow of traffic, in an easily
assimilated format, would assist the driver to safely adjust to potential
problems. For this type of information to be useful it must be both
accurate and timely. It is not uncommon for highway advisory signs to be
missed by drivers due to their being obscured by other traffic,
obstructions to vision such as rain, snow or fog, or the driver's
attention being directed elsewhere at the time the sign is readable.
Similarly, navigational information such as the proximity of desired exits
from controlled-access highways or turns off of the current roadway, would
assist the driver to prepare for and make directional turns both
efficiently and safely. Thus, on-board navigational systems which would
automatically determine the present location of the vehicle and provide
directions to a desired destination to assist the driver when traveling in
unfamiliar areas is also desirable.
Improvement in the art of communicating traffic and commercial information
to drivers has been the subject of numerous efforts in the past. U.S. Pat.
No. 3,899,671 (Stover) discloses an automobile communication system which
consists of radio broadcast stations located along highways and receiving
devices located in the vehicles so that the driver can receive information
pertinent to the location of the transmitter. Stover further discloses
that the driver may instruct a device in the vehicle system as to which
highway the driver desires to travel or to select certain types of
information from that broadcast.
The system disclosed by Stover utilizes a transmitting means which
broadcasts signals which contain detailed information pertinent to the
location of the transmitter. Such information may concern traffic control
signals, intersections and exits, or highway identification messages. This
information is stored in a memory device associated with the transmitter
and broadcast on a cyclic schedule.
This information is received by vehicle-mounted receiving means and
selectively edited in accordance with the instructions provided by the
operator. The desired information is then presented to the driver in
either audible or visual format. The data processor in the vehicle must
wait for the desired information to be transmitted to it before the
information is selected and presented. This limits the time available for
the transmitter to complete an information cycle. As the broadcast cycle
becomes extended, the transmitter power must be increased and the
broadcast time extended to insure that the information is reliably
received before the vehicle passes the transmitter. The broadcast
transmitters also must be separated in either space, time or frequency to
avoid interfering with one another.
Stover teaches that the information transmitted by the system may be
altered in real time by connecting remote sensors to the transmitter
input. An application suggested by Stover is the addition of sensors which
detect the status of traffic signals which affect traffic beyond the
location of the transmitter. This information is then used to access
appropriate messages in the transmitter database. Stover does not suggest,
however, that non-routine information such as changing highway conditions
or traffic patterns could be incorporated into the broadcast signal in an
interactive, real-time manner. Neither does Stover suggest the
incorporation of commercial messages into the system.
U.S. Pat. No. 4,481,584 (Holland) discloses a method and apparatus for
providing highway information by means of a microprocessor and a plug-in
data cartridge. The plug-in cartridge permanently stores in digital form a
multitude of data related to services and other pertinent information
available along a selected roadway. Each of these data is indexed
according to distance or mile marker indicators along the roadway. A
keyboard serves as a data entry means for the motorist to manually input
the required location information necessary to indicate the section of
highway for which he or she desires roadway information. In use, the
driver must manually provide to the computer the vehicle present location
relative to a highway mile marker and the present direction of travel. If
the driver, for whatever reason, is unable to determine the present
vehicle location, he must wait until he sees the next mile marker, thereby
losing possibly relevant desired information. The system may also allow
the selection of type of information desired. However, Holland does not
teach that the driver may preselect the type of information desired for
each location; rather, a complete set of different instructions must be
provided for each location.
The computer in Holland combines this information with the data in storage
and provides the programmed response. The system retrieves all stored
information related to the data input by the driver and provides a visual
display and/or audible speech synthesis means for conveying the
information to the driver.
The data storage module described by Holland may be a plug-in magnetic
disk, tape or laser disk which has been programmed with the available or
desired information on a highway or system of highways. Holland suggests
arranging the data modules by state or interstate highway systems. The
information contained in storage is current as of the time the module is
programmed. Holland does not suggest any method of providing real-time
update or rapid revision to the information available to the motorist, nor
does he suggest that complete messages may be synthesized from information
existing in the database.
U.S. Pat. No. 4,816,827 (Baloutch et al.) discloses a system of
broadcasting signals to activate audible messages associated with traffic
signs. Baloutch describes an infrared transmitter which transmits an
encoded signal peculiar to the type of traffic sign. The transmitter is
triggered by a sound detector which detects the approach of a vehicle. A
receiver in the vehicle receives and translates the code into an audible
signal peculiar to the type of traffic sign. Baloutch further discloses
that an additional coded signal may be activated remotely as required to
provide warning of traffic conditions ahead. Among other disadvantages,
since infrared signals are dispersed by rain, snow, heavy fog or other
high humidity atmospheric conditions, this system would work well only
during relatively clear atmospheric conditions.
U.S. Pat. No. 4,023,017 (Ceseri) discloses a complex traffic control system
utilizing groups of detectors to determine traffic conditions, a central
controlling computer, and a communications system to communicate encoded
and clear messages between detectors, traffic warning signs along the
roadway, and to receivers in vehicles. Ceseri describes a system wherein
the detectors are grouped on posts along a highway and determine vehicle
movement and ambient environment information. Information such as vehicle
speed, traffic density, precipitation, and temperature are collected by
the detectors and transmitted over cable or by radio broadcast to a
central computing system. The central computer determines if these
parameters, along with highway design information such as grade, number of
lanes, and road surface, are within expected ranges. Combinations of these
factors which are not within the predetermined parameters are used by the
central computer to activate warning signs and to alert human controllers
that problems may exist. The human controllers then take appropriate
action such as turning on warning signs or broadcasting warnings to
vehicle-mounted receivers. Audio or visual devices associated with the
receivers alert the drivers to the abnormal conditions.
U.S. Pat. Nos. 4,527,155 (Yamaki et al.) and 4,937,570 (Matsukawa et al.)
address the presentation of data from vehicle-mounted navigational systems
to the driver. Yamaki utilizes a computer provided with coordinate data
and a direction of travel sensor to rotate visual data for presentation to
the operator. Yamaki discloses a method of rotating diagrammatical
displays, i.e. a "map", so that the direction of travel is always
presented in one direction, while simultaneously presenting the map labels
in an upright, easily read format.
Matsukawa discloses a route guidance display device which receives signals
from an on-board computer which utilizes an external memory programmed
with map data, an input device which indicates starting and destination
points, and direction and distance sensors. The display provides in a
three dimensional diagram visual indication of the appropriate direction
of travel at intersections between the starting point and the destination.
U.S. Pat. No. 3,105,119 (Cory, Jr., et al.) discloses a highway
communications system which utilizes a dual transmitter system to first
enable a receiver with a trigger signal in one frequency band followed by
a message signal in a different band. The communications system transmits
entire messages to the in-vehicle receiver. Cory neither teaches nor
suggests how to increase the number of messages conveyed to the driver.
U.S. Pat. No. 3,105,120 (Hanysz) discloses a highway communications system
which broadcasts messages to vehicles traveling along a roadway by use of
a dual transmitter arrangement. Hanysz describes how a first transmitter
provides a signal which enables an in-vehicle receiver which is thereby
prepared to receive the information transmitted by a second transmitter.
Hanysz does not suggest, however, how a single transmitter could provide
unidirectional signals to a receiver.
U.S. Pat. No. 4,630,209 (Saito et al.) discloses a vehicle-based system to
electronically present to the driver a map of the area in which the driver
is operating. This provides the driver with information on where streets,
intersections etc. are located relative to each other. Saito does not
however suggest how the driver can ascertain where he is relative to any
particular point on the electronic map.
U.S. Pat. No. 4,190,819 (Burgyan) discloses a programmable automobile
information system utilizing a tape recorder to deliver sequential
prerecorded messages. The recorder receives start and stop signals from a
microprocessor which translates distance traveled information from the
vehicle odometer into appropriately timed signals to operate the recorder.
The recorded message may be routing directions to a preselected
destination or information about the area through which the vehicle is
passing. Burgyan further discloses a means for the operator to
resynchronize the tape with a landmark described on the tape. Burgyan does
not however suggest how the system could be automated with location
information for a randomly moving vehicle.
U.S. Pat. No. 4,350,970 (von Tomkewitsch) describes a system for
determining traffic situations and providing route guidance and other
information to vehicles on a highway system. This system utilizes
unspecified transmitting and receiving devices to communicate data carried
from one roadside site to another by the vehicle itself, along with a time
measurement for completing one part of a preplanned route. That
information would then be used to provide route information to assist the
driver in travelling to the next roadside site. Since von Tomkewitsch does
not specify a recommended communications system for the transmission of
such information, it is not clear how the system communicates with a large
number of vehicles simultaneously at each location. This patent also does
not address the immense amount of computational time needed to recommend
optimum routes to each passing vehicle.
In addition to prior art patents, there have been a number of studies
conducted by state and federal transportation agencies which provide
insight into the types of displays that are most effective in
communicating with drivers in moving vehicles. These studies provide
analyses of the requirements of safety and hazard warning systems. A study
completed by Commonwealth Research Corporation in April, 1982, provides an
analysis of the requirements that must be met in order to successfully
build a dedicated safety and hazard warning communications system for
vehicles. This study specifically rules out receivers operating in
anything but standard broadcast bands because of the cost of installing a
different receiver and a separate antenna in vehicles.
The U.S. Department of Transportation (DOT) has started to develop the
concept of the Intelligent Vehicle Highway System (IVHS) wherein dynamic
roadway information could be provided to the driver. Early DOT concepts
envisioned using sensors to collect and feed roadway information to
central computers for analysis. The results would be retransmitted back to
the driver via satellite communication networks, AM/FM radio networks or
other sophisticated and expensive technologies. This concept was
formalized in the DOT Policy Statement in 1989 and published in the 1990
annual report.
The International Congress on Transportation Electronics, sponsored by the
Society of Automotive Engineers and held in Detroit, Mich. in October,
1990, provided a forum for most of the international projects that are
concerned with roadway communication systems, vehicle navigation, and
traffic management systems. Several papers published in "Vehicle
Electronics in the 90's: Proceedings of the International Congress on
Transportation Electronics", outline systems under development by
governments and companies in Asia, Europe, and the United States. None of
these papers describe systems under development that would meet the low
cost requirement for wide spread utilization by non-business users.
The electronic communications art is rapidly becoming the primary
communications method by which an individual receives information. Modern
day society relies on the electronic communication of information by
either radio or television. Communication of vehicle-specific information
to motorists, however, is not well developed. The adaptation of this
medium to real-time vehicle operations depends on the ability to present
pertinent information to the driver in a timely manner without greatly
distracting him or her from the driving task.
DISCLOSURE OF INVENTION
The Electronic Billboard and Vehicle Traffic Control Communication System
(hereinafter called "Billboard System") provides a means to simultaneously
satisfy the demands of advertisers, consumers and current social pressures
which support the removal of billboards along the highways. The present
invention replaces large unsightly billboards and signs and provides the
motorist with more and timely information without distracting him or her
from safely operating the vehicle. The system of the present invention
allows the driver to select the desired type of message at the time it is
needed. This represents true "point-of-decision" advertising. Application
of the Billboard System to nonvehicular uses is also possible. While the
present invention is described for use by vehicle operators, other
applications are briefly described as well.
The Billboard System also provides motorists with a display of highway
regulatory and traffic advisory and other public service messages within
their vehicle as they travel the highway. Safety and regulatory messages
are communicated on a priority basis. With the use of appropriate
programming, the Billboard System allows the motorist to preselect the
type of message desired at a time convenient to him. For example, a
motorist desiring directions on how to reach a destination would be
interested in highway identification and direction information. A motorist
requiring fuel, food or lodging may select the desired type of
information. No other form of advertising is capable of communicating this
immediate, location-specific knowledge to consumers and providing timely
feedback to the advertiser as to the effectiveness of the advertisement.
This form of advertising is cost efficient and effective for the
advertiser, and provides a needed service to the motorist-consumer.
The Billboard System comprises small, simple, low cost, low power,
directional microwave transmitters mounted along the highway right-of-way
or aimed at the highway from private property near the roadway. Currently
available low cost technology allows the use of a multitude of
transmitters in the system. These transmitters transmit a short encoded
message for providing locality-specific information which corresponds to
the location of the transmitter. In addition, individually coded keys for
advertisers may be transmitted. The use of coded messages reduces the duty
cycle of the transmitters and allows multiple transmitters to use the same
frequency band without interference with each other.
Microwave communications systems have nearly ideal characteristics for use
in roadway applications because the transmitted signals can be aimed. This
efficient directional capability allows low-power transmitters to send
signals over relatively long distances. This advantage has not been
exploited in the past for highway communications, however, because of the
high cost of conventional microwave transmitters and receivers precluded
their use where a very large number of them were required.
Most of the complexity and associated cost of conventional microwave
systems is avoided in the present invention by eliminating the need for
strict frequency control of the communication signal.
The encoded messages transmitted by the Billboard System transmitters are
received by an inexpensive in-vehicle intelligent receiver which permits
the driver to select the desired type of information and allows the
information to be formatted and communicated in the most efficient manner.
The use of encoded messages allows one transmitter network to support
multiple users simultaneously. The transmission of coded messages allows
multiple transmitters to use the same carrier frequency without
interfering with each other.
The information processing program and the database resident in the
replaceable memory module in the in-vehicle smart receiver determines how
the transmitted encoded message is used. The program provides for decoding
of the encoded signal, selection of messages resident in the database
which correspond to the encoded signal, and synthesizing of complete
messages from message fragments in the database in response to directions
contained in the coded signal. The program also responds to specific
instructions from the driver to display only selected messages. The range
of messages possible may be updated or changed by use of plug-in modular
memory devices for the database. The smart database in each vehicle
receiver stores full messages and permits construction of new messages
from the transmitted codes which are linked together by the receiver.
Program instructions in the database permit the receiver to perform
different functions such as navigation, commercial message display and
safety information presentation.
The driver determines the preferred language for data presentation by
selecting the appropriate system function and database. This negates the
need for the transmitted signal to contain specific language references
and allows one transmitter to simultaneously communicate in any number of
languages via encoded messages.
The system provides storage for the last several, usually two or three,
transmitted signals received. By simple logic circuitry, the system then
determines the direction of travel and average speed. This information
allows the system to predict subsequent transmitter codes and to present
the information desired relevant to the future location of the vehicle.
This capability provides specific directions to drivers regardless of the
direction of approach to an intersection or location. The information for
previous locations may also be recalled if desired.
The use of encoded message transmitters also allows portable transmitters
to be installed in emergency vehicles. These portable transmitters are
capable of providing information to drivers about the movement or
direction of approach of emergency vehicles and the location of emergency
situations.
BRIEF DESCRIPTION OF THE DRAWING
For fuller understanding of the present invention, reference is made to the
accompanying drawing in the following detailed Description Of The
Preferred Embodiment of the invention. In the drawing:
FIG. 1 is a block diagram of the complete Electronic Billboard and Vehicle
Traffic Control Communications System constructed according to the
principles of the present invention.
FIG. 2 is a block diagram of the transmitter of the system of FIG. 1.
FIG. 3 is a simplified schematic of the transmitter of FIG. 2.
FIG. 4A is a simplified block diagram of the receiver of the system of FIG.
1.
FIG. 4B is a detailed block diagram of the receiver of FIG. 4A.
FIG. 5 is a block diagram of a remote interface for use with the
transmitter of FIG. 2.
FIG. 6 is a diagram of a typical installation configuration of the system
of FIG. 1.
FIGS. 7A and 7B are a logic flow diagram of the main program for control of
the receiver in the system of FIG. 1.
FIGS. 8A and 8B are a logic flow diagram for the main interrupt handler
program utilized by the main program of FIG. 7.
FIG. 9 is a logic flow diagram for the secondary interrupt handler program
utilized by the main program of FIG. 7.
FIG. 10 is a typical encoded transmitted message sequence of the system in
FIG. 1.
FIG. 11 is a diagram of an installation configuration for the emergency
vehicle warning feature of the system of FIG. 1.
FIG. 12 is a block diagram of the system of FIG. 1 for applications
involving a two-way radio communications link.
Reference numbers refer to the same or equivalent parts of the present
invention throughout the several figures of the drawing.
BEST MODE OF CARRYING OUT THE INVENTION
Referring now to FIG. 1, a simplified block diagram of Billboard System 100
is shown. Transmitter 10 is installed at known locations alongside or near
highways as described hereinbelow. Preprogrammed instructions 14 are
utilized by transmitter 10 to modulate transmitted signal 12 in a manner
unique to each transmitter. Preprogrammed instructions 14 consist of a
specific location identifier, codes appropriate for each subscriber who
wishes their message to be accessed for that location, and any unchanging
location-specific safety or warning information for each transmitter
installation.
Additional instructions to transmitter 10 may be received through remote
interface 30. These additional instructions may consist of emergency
vehicle instructions 31, central control instructions 37 or real-time
sensor instructions 39 as described hereinbelow.
On a predetermined cycle transmitter 10 transmits a low powered microwave
signal 12. Signal 12 consists of encoded information dictated by
preprogrammed instructions 14 and any additional instructions provided
through remote interface 30 from emergency vehicle interface 31, central
control interface 37 and real-time sensors 39. Signal 12 is received and
decoded by receiver 40 and microprocessor 80.
Receiver 40 receives encoded signal 12 with antenna 41 and processes signal
12 in a manner well known in the microwave communications art. Antenna 41
may be a directional antenna such as a standard gain horn antenna tuned to
the appropriate carrier frequency band. Alternative, it may be a
substantially omnidirectional antenna such as a quarter-wave length dipole
or stub antenna. Signal 12 is decoded by microprocessor 80 and temporarily
stored. Microprocessor 80 utilizes driver instructions 90 to retrieve the
appropriate information related to decoded signal 12 from replaceable data
base 95 which will satisfy driver instructions 90. Microprocessor 80 then
displays the desired information at driver display and interface 99.
Driver display and interface 99 may be any device common in the
communications art such as an audio speaker, cathode ray tube or liquid
crystal display, or a combination of these, or any other means capable of
readily conveying information.
Signal 12 comprises a modulated carrier frequency in the microwave range,
approximately 10 GHz to 35 GHz. Other frequencies may be used if necessary
due to frequency allocation decisions by authorities. The frequency of the
transmitters will be allowed to drift with oscillator temperature within a
band approximately 150 MHz wide. This allows low-cost, cavity-tuned, Gunn
diode oscillator technology to be used for the transmitters. This drift
also provides random frequency diversity for different transmitters as
each oscillator drifts in a manner unique to itself.
Emergency vehicle interface 31 provides signals which allow emergency
vehicle operators to assume local control of traffic management based on
local emergency situations. Central control interface 37 provides traffic
control management information from an appropriate governmental or other
regulatory agency which may be based on information received from
real-time sensors 39 via remote interface 30. Real-time sensors 39 sends
location specific traffic and other environmental conditions such as
temperature, fog, water, high winds and the like.
Referring now to FIGS. 2 and 3, the essential details of low power
microwave transmitter 10 are shown. Transmitter 10 consists of a
microprocessor 15 which utilizes preprogrammed instructions 14 and, if
present, instructions from remote interface 30 to drive modulator 20 and
oscillator 25 to form microwave signal 12 which is transmitted through
antenna 11.
Operating under simple program control instructions, when microprocessor 15
determines that the preprogrammed time has elapsed between transmissions,
it initiates the transmission sequence by providing an input to modulator
20. This input consists of a coded series of pulses which turn modulator
20 on and off as described hereinbelow. Modulator 20 consequently applies
power and removes power alternately to oscillator 25. Oscillator 25
generates the appropriate microwave frequency when power is applied. This
modulated microwave frequency, signal 12, is then transferred by
appropriate wave guide as is well known in the art to antenna 11. Antenna
11 is typically a directional horn antenna as is well known in the
microwave communications art, but may also be designed to more broadly
transmit signal 12 if desired for specific applications. The instructions
for controlling microprocessor 15 are of a simple format, readily
recreated by one skilled in computer programming.
Transmitter 10 may be powered by battery 32 or directly by a source of
commercial power (not shown). Battery power is preferred so that the
Electronic Billboard may operate independently of commercial power.
Battery 32 must have sufficient capacity to operate the system through the
longest expected period when external power for recharging will be
unavailable. Battery 32 may be recharged by any convenient battery
charging device 34. Solar power cells are the preferred source to make
Billboard System 100 power-independent, but commercial power may be used
to recharge battery 32. If commercial power is utilized directly, it would
be necessary to add to the transmitter an appropriate alternating current
(AC) to direct current (DC) power converter as is also well known in the
art.
With continuing reference to FIGS. 2 and 3, battery 32 powers
microprocessor 15 and single-board control | | |
