United States Patent (19)
`Hanchett
`
`56
`
`54) TRAFFICCONDITION INFORMATION
`SYSTEM
`76 Inventor: Byron L. Hanchett, 7112D Calabria
`Ct., San Diego, Calif. 92122
`21 Appl. No.: 906,827
`22 Filed:
`Jun. 30, 1992
`5) Int. Cl......................... G08G 1/01; G08G 1/052
`52 U.S.C. .................................... 364/436; 364/438:
`348/149; 340/910; 340/937
`58) Field of Search ............... 364/436, 437, 438, 444,
`364/449, 460, 462; 340/990,993, 937, 910;
`342/454, 456, 463; 358/103, 108, 109, 139
`References Cited
`U.S. PATENT DOCUMENTS
`2,710,390 6/1955 Forse ..................................... 340/40
`4023,017 5/1977 Ceseri........
`235/150.24
`4,258,351 3/1981 Shigeta et al. .................... 340/38 P
`4,398,171 8/1983 Dahan et al. ......................... 340/22
`4,819,174 4/1989 Furuno et al. ...........
`a P
`4,847,772 7/1989 Michalopoulos et al.
`... 364/436
`5,061,996 10/1991 Schiffman ........................... 358/103
`5,115,398 5/1992 De Jong ...
`... 364/443
`5, 182,555 1/1993 Sumner .....
`... 340/905
`5,214,793 5/1993 Conway et al..................... 455/49.
`5,289,183 2/1994 Hassett ................................ 340/905
`OTHER PUBLICATIONS
`Jurgen; Smart Cars and Highway Go Global; IEEE
`Spectrum; May 1991; pp. 26–37.
`J. E. Ferrell; The Big Fix, Los Angeles Time Magazine;
`Apr. 14, 1991; pp. 14, 16, 18 & Others.
`S. Goldstein; Getting Around Gridlock is Goal of High
`
`
`
`US005396.429A
`Patent Number:
`11
`45) Date of Patent:
`
`5,396,429
`Mar. 7, 1995
`
`(way)-tech Research Teams, The San Diego Union; Sep.
`30, 1990; pp. F-58 & Other.
`E. Schine; Here Comes the Thinking Car, Business
`Week; May 25, 1992; pp. 84, 87.
`M. Schrage; Smart Highways-Too Clever to Succeed?In
`novation; Jun. 6, 1991; pp. Other & D12.
`Primary Examiner-Michael Zanelli
`Attorney, Agent, or Firm-Joseph F. McLellan
`57
`ABSTRACT
`A series of image sensors is spaced along a roadway at
`particular intervals to provide images of the traffic and
`an identification signal associating those images with
`the location of the particular sensor providing the im
`ages. A main station receives the images from all can
`eras and broadcasts an information signal comprising
`segments of those images and the identifications in a
`particular sequence in accordance with the predomi
`nant direction of travel on the roadway. User units
`include a receiver which displays the images so that the
`user may preview the roadway ahead to make route
`choices. In systems covering multiple roadways, the
`user may select images of the particular roadway to
`view. The receiver is also responsive to a local broad
`cast of the camera's identification signal to thereby
`determine the geographical location of the user and
`alert the user when particularly pertinent images are
`being displayed and when decision points are reached
`where the user must make a route change choice. In
`another aspect, speed data is also provided by each
`camera station along the roadway.
`
`24 Claims, 5 Drawing Sheets
`
`yeaw
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`Google Ex. 1008, p. 1
`
`

`

`U.S. Patent
`
`Mar. 7, 1995
`
`Sheet 1 of 5
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`5,396,429
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`Google Ex. 1008, p. 2
`
`

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`U.S. Patent
`
`Mar. 7, 1995
`
`Sheet 2 of 5
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`5,396,429
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`Google Ex. 1008, p. 3
`
`

`

`U.S. Patent
`
`. Mar. 7, 1995
`
`Sheet 3 of 5
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`5,396,429
`
`
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`
`
`Google Ex. 1008, p. 4
`
`

`

`U.S. Patent
`
`Mar. 7, 1995
`
`Sheet 4 of 5
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`5,396,429
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`Google Ex. 1008, p. 5
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`

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`U.S. Patent
`
`Mar. 7, 1995
`
`Sheet 5 of 5
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`5,396,429
`
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`Google Ex. 1008, p. 6
`
`Google Ex. 1008, p. 6
`
`

`

`1
`
`TRAFFIC CONDITION INFORMATION SYSTEM
`
`BACKGROUND
`The invention relates generally to information sys
`tems and more particularly, to systems for monitoring
`traffic conditions and providing information about
`those conditions.
`On roadways where a significant proportion of the
`traffic is attributable to commuters, traffic congestion is
`a routine problem. In some particularly crowded areas,
`such as metropolitan areas of the country, traffic during
`commuter hours slows to a stop. While stopped, vehi
`cles are not transporting their drivers, passengers and
`15
`cargoes to their destinations. The California South
`Coast Air Quality Management District estimates that
`Californians alone waste over 400,000 hours a day on
`the way to work. A by-product of these conditions is
`that stopped vehicles continue to expel hydrocarbons
`20
`into the environment.
`In addition to the adverse impact on the environment,
`there is typically an adverse impact on the work force.
`Many drivers of motor vehicles spend an enormous
`amount of time getting to and from their workplaces,
`25
`homes and destinations. These same conditions are ex
`perienced during non-commuter times as the result of
`accidents, maintenance and construction, and unex
`pected other causes. Additionally, the large amount of
`time spent on crowded freeways with the inevitable
`traffic accidents, disabled vehicles, confrontations with
`other drivers, short tempers, poor drivers, and reckless
`and dangerous drivers accelerates tension and anger
`and results in increased stress levels and decreased job
`35
`performance. By the time many drivers arrive at work,
`they have had at least one hour of high intensity traffic
`interaction sometimes including actions taken to avoid
`damage to property and harm to life and limb.
`Many drivers have the option of selecting more than
`one route to reach their destinations. In many cases,
`certain routes are congested while others have little
`traffic. Communicating such traffic information visually
`on a route-by-route basis to drivers so that they may
`take the less congested routes would result in a more
`45
`efficient and balanced use of the roadway system.
`Certain locations along the routes offer decision
`points at which time the driver must decide to take one
`or another route. At these points, the driver must decide
`whether to continue ahead on the same route or change
`50
`routes to get to the destination. After that decision
`point, the driver is committed unless another decision
`point lies ahead. In cases where the driver knows before
`a decision point that slow traffic conditions exist ahead
`on the present route but an alternate route is less con
`55
`gested, the driver can take the alternate route, thereby
`relieving traffic congestion, reducing the driver's travel
`time and reducing hydrocarbon emissions. Receiving
`timely, accurate, and sufficient information before
`reaching decision points is essential to the driver's deci
`sion process.
`In some cases, drivers have flexible work schedules
`and can decide to arrive at their destinations at a later
`time if traffic conditions are presently unfavorable.
`However, sufficient accurate information is needed for
`the driver to make an informed decision. Delaying their
`entry onto the roadways will also result in a more bal
`anced use of the roadways. This approach was ex
`
`5,396,429
`2
`tremely successful during the 1984 Summer Olympics
`in Los Angeles.
`Several systems for monitoring traffic and informing
`motorists of traffic conditions have been used. In cities
`such as New York and Los Angeles for example, certain
`roadways are monitored by television cameras and sen
`sors embedded in the pavement. These sensors relay
`information to a central control center where traffic
`problems are identified. Information can be sent to one
`or more message boards located on the roadway to
`inform drivers of problems, and in certain cases, access
`to particular segments of roadways can be controlled
`from the central control center by activating traffic
`control devices.
`However in the case of Los Angeles, the message
`boards are few and give limited information. Although
`some can recommend an alternate route, a common
`complaint is that the information on the board is not
`accurate, current or sufficient to make an informed
`decision. Additionally, because there are so few mes
`sage boards, decision points are often missed before the
`relevant message board is encountered.
`In another example of traffic information systems, a
`series of low power radio transmitters were installed
`along a roadway in northern San Diego County, Cali
`fornia which is heavily traversed by commuter traffic.
`These transmitters broadcast information on traffic
`conditions along the roadway on an AM frequency.
`Complaints from motorists that the information broad
`cast is not current enough to be helpful and that recep
`tion of the radio signal at points along the route is so
`poor that information could not be received are indica
`tive of the drawbacks of such a system.
`An additional consideration with the above systems is
`that someone other than the driver (the person tasked
`with making the decision) analyzes the traffic data and
`draws the conclusions (makes the decision for the
`driver) which are then communicated to drivers. An
`alternate system is one where the driver evaluates the
`information in light of his or her particular situation and
`draws the conclusion. For example, an operator in a
`central station may review the images provided by the
`roadway cameras and determine that a particular road
`way is "clogged' and so indicate by the roadway mes
`sage board along with a recommended alternate route.
`However, a driver examining the images reflecting
`conditions on the primary and alternate routes may
`determine that although the roadway is presently
`clogged, the pattern of traffic indicates that the road
`way will become less congested shortly, or that staying
`on the primary route will result in the shortest travel
`time.
`Hence, those skilled in the art have recognized the
`desirability of a traffic condition information system
`which provides a sufficient amount of current and accu
`rate information concerning traffic conditions prior to
`decision points and decision times. It has also been rec
`ognized that it would be desirable to alert drivers of an
`upcoming decision point. The present invention fulfills
`these needs.
`SUMMARY OF THE INVENTION
`Briefly and in general terms, the traffic condition
`information system of the present invention comprises a
`plurality of monitor stations placed at intervals along a
`roadway of interest. Each monitor station includes an
`image sensor for sensing visual images of the traffic on
`that roadway and providing image signals representa
`
`10
`
`65
`
`Google Ex. 1008, p. 7
`
`

`

`5,396,429
`4.
`3
`broadcasts image data for more than one roadway; e.g.,
`tive of the sensed traffic image. Also provided is an
`other primary routes or alternative routes, on the same
`identification means which associates that monitor sta
`frequency such that a waiting period exists between
`tion with the image signals provided. The identification
`updates of images of the same roadway. The user unit's
`means is used to determine the geographical position of
`processor may store images of the roadway of interest
`the origin of the images. A controller receives the iden- 5
`and repeatedly display those stored images until the
`tified image signals and provides an information signal
`main station once again transmits new images of the
`which comprises a sequence of image signal segments,
`roadway of interest. At this time, the receiver displays
`each segment being images from a single monitor sta
`and stores the new images.
`tion. The information signal therefore comprises signals
`Other aspects and advantages of the invention will
`from a plurality of monitor stations. A user display unit 10
`become apparent from the following detailed descrip
`displays images corresponding to the image signals in
`tion and accompanying drawings, illustrating by way of
`the segments along with the identification code so that
`example the features of the invention.
`a user can correlate the images displayed with the geo
`graphical position at which they were created.
`BRIEF DESCRIPTION OF THE DRAWINGS
`In yet another aspect of the invention, each monitor 15
`FIG. 1 is a schematic representation of a traffic condi
`station includes a speed sensor or sensors for providing
`tion information system in accordance with the princi
`data regarding the speed of the traffic at the position of
`ples of the present invention showing eight traffic moni
`the monitor station. The speed sensor signals are also
`tor stations disposed along a roadway of interest, a main
`communicated to the controller which then provides
`station, a mobile user unit and a non-mobile user unit;
`the speed data from all monitor stations to users along 20
`FIG. 2 is a schematic representation of a monitor
`with the images and identification code. A speed com
`station of FIG. 1 showing the component parts in more
`parator compares the speeds between sequential moni
`detail;
`tor stations and if the difference exceeds a threshold, a
`FIG. 3 is a block diagram of an embodiment of a main
`speed alert signal is provided the user.
`In one aspect of the invention, the image signals pro- 25
`station;
`FIG. 4 is a schematic representation of a user unit of
`vided by the monitor stations represent actual images of
`FIG. 1 showing component parts in more detail;
`traffic existing at the monitor station. The user display
`FIG. 5 is a representation of a possible video display
`unit translates the image signals back into the images of
`format of the traffic information signal of the present
`the traffic and displays these actual images. In another
`aspect, the monitor station provides image signals 30
`invention; and
`which are only representative of one of a plurality of
`FIG. 6 is a flow chart of an embodiment of a method
`predetermined and prerecorded traffic images. Images
`for providing traffic condition information in accor
`dance with the principles of the invention.
`corresponding to such predetermined traffic conditions
`are stored at the display unit and upon receipt, the pro
`DESCRIPTION OF THE PREFERRED
`cessor of the display unit retrieves the appropriate 35
`EMBODIMENTS
`image from memory which corresponds to the image
`Referring now to the drawings with more particular
`signal, and that retrieved image is displayed.
`ity wherein like reference numerals indicate like or
`In a further aspect in accordance with the invention,
`corresponding elements among the several views, in
`a mobile monitor station, such as a helicopter, may be
`FIG. 1 there is shown schematically a traffic informa
`selectively positioned along the route. This mobile sta- 40
`tion system 10 according to the present invention,
`tion provides image signals which may be given a prior
`which generally comprises a network 12 of traffic moni
`ity and displayed immediately or may be included in the
`tor stations 14 spaced apart from each other by approxi
`proper sequence of segments in the information signal
`mately one mile, or at some other informative interval,
`and may be given an extended dwell time.
`a main station 16 which may be a land based transmitter
`A position location means determines the position of 45
`or satellite, user units, which in this embodiment are
`the display unit, compares that position with the identi
`fication of the images being displayed, the identification
`shown as a mobile user unit 18 and a non-mobile user
`unit 20. FIG. 1 also presents an intermediate station 13
`being correlated with the geographic position of the
`which receives signals from some of the monitor sta
`monitor station providing those images, and a look
`tions and forwards those signals to the main station 16.
`ahead alert signal is provided to the user when the im- 50
`The monitor stations 14 are located along a roadway 22
`ages displayed are of a portion of the route which is a
`of interest, such as an interstate freeway which in FIG.
`predetermined distance behind the display unit. In one
`1 is shown as proceeding in a north/south direction.
`case, the location means comprises an identification
`Referring now also to FIG.2, each monitor station 14
`signal broadcast locally by each monitor station and
`includes an image sensor 24, such as a video camera, and
`received by the user unit. The broadcast identification 55
`a data processor 26. The data processor 26 receives the
`signal is used to determine the geographic or relative
`image signals from the image sensor 24, adds an identifi
`position of the user unit to the images being displayed
`cation code to them which is unique to this particular
`and the look-ahead alert signal is provided at the appro
`monitor station 14 and provides these combined signals
`priate time.
`to a transmitter 28. The identification code may be
`In yet another aspect, a decision means is provided 60
`stored in a mass storage unit 36 or stored in a dedicated
`for indicating to the user a location on the route at
`identification code storage unit 25. In another embodi
`which a decision must be made as to continuing on the
`ment, the identification code that is unique to the moni
`present route or changing to another route.
`toring station may be added at the main station before
`In a further aspect, a storage unit is included with the
`the visual image is broadcast by the main station to
`display unit which stores parts of the information signal. 65
`users. As used herein, a mass storage unit is meant to
`This stored data may be redisplayed at the user's selec
`refer to devices such as magnetic disks, compact disks,
`tion instead of received information signals. Such a
`magnetic tape and other such devices which provide
`feature is beneficial in the case where the main station
`
`Google Ex. 1008, p. 8
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`

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`10
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`25
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`5,396,429
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`5
`storage of data and programs. Typically, memory chips
`The image, speed and identification signals are pro
`are not used as power-off storage devices but in some
`vided to the processor 26 which either combines them
`cases they have been designed for just that purpose.
`or separately communicates them to the interim trans
`Thus, they may also qualify as mass storage units in
`mitter 31 or directly to the main station 16 as the case
`may be. Associating the identification code with the
`SO3 C3SS
`image and speed signals may be done by adding a cer
`The transmitter 28 provides the signal to a communi
`tain number of bits at a certain position in the data
`cation link30 which may be an antenna for broadcast, a
`stream. To identify the particular monitor station to the
`line, a fiber optic cable, or a combination of methods.
`user, a video image comprising words or symbols de
`The means or combination of means will depend on the
`scribing the geographical location of the monitor sta
`topography and distances involved between the indi
`tion may be overlaid by the processor 26 on the image
`vidual monitor stations and the main station 16. For
`example, in one case, all monitor stations 14 may be
`signals received from the image sensor and then the
`connected together by land line and this land line is
`combined signals may be transmitted to the main station
`16. Other techniques for identifying the monitor station
`connected to the intermediate station 13 which then
`14 as having provided the image and speed signals may
`broadcasts to the main station 16. In another case, the
`15
`be used. For example, the particular broadcast fre
`common land line between all monitor stations 14 may
`quency used by the monitor station 14 may be the iden
`be directly connected to the main station 16 and no
`tifying factor. The individual image, speed and identi
`intermediate station 13 is used. In the example shown in
`fier signals can be impressed on a carrier signal through
`FIG. 1, the intermediate transmitter 13 receives the data
`multiplexing and the individual signals can be retrieved
`signals from monitor stations SD1 through SD3 and a
`from the transmitted signal at the main station 16.
`mobile station MD1. The mobile monitor unit MD117
`may comprise a helicopter or other vehicle. The mobile
`As an alternative, the speed and identifier data can be
`monitor 17 may supply image and speed signals as do
`broadcast by the monitor stations 14 during the times
`that the image signal is not needed at the main station
`the other monitor stations 14 or may simply supply
`image signals.
`16. Image signals typically require more processing
`time than speed and identification signals, thus during
`The monitor station 14 may also apply the identifica
`the time that image signals are not needed, efficiency
`tion code 25 to a carrier signal and broadcast the signal
`can be improved by transmitting other data. As will be
`by means of a low-power transmitter 32 and an antenna
`34. Further details of this feature are provided below.
`discussed below in more detail, the data from the moni
`tor stations are interspaced with data from other moni
`The monitor station 14 in the embodiment of FIG. 2
`also includes a speed sensor 37, which may be a Dop
`tor stations, thus there is "down time' for each monitor
`pler RADAR unit, for detecting the speed of vehicles
`station. This "down time' may be substantial depending
`on the roadway 22 adjacent the particular monitor sta
`on the length of the route and the number of monitor
`tion 14. The signals from the speed sensor 37 are also
`stations along the route.
`provided to the processor 26 for communication to the
`The monitor stations 14 may provide other informa
`tion such as average vehicle speed and traffic density in
`main station 16.
`cars per unit time. The speed sensor signals may be
`In the embodiment shown in FIG. 2, the monitor
`processed to provide an average speed reading which
`station 14 includes a first sensor group 38 of a camera
`and speed sensor facing in one direction on the roadway
`can also be communicated to the main station 16 by the
`processor 26. In more elaborate monitor stations 14, a
`22 and a second sensor group 40 of a camera 42 and
`speed sensor 44 facing the opposite direction on the
`speed sensor device for each lane of traffic may be
`roadway 22. Alternatively, a single sensor group may
`installed to provide a lane-by-lane speed reading. Aver
`age speeds on a lane-by-lane basis could also be pro
`be used which is mechanically moved to sense one or
`vided. Traffic density in cars per unit time could be
`the other directions of the roadway as desired. On road
`provided by sensors in the pavement of the type cur
`ways having a configuration which would not accom
`45
`rently in use in the Los Angeles freeway system and in
`modate a monitor station 14 with two sensor groups 38
`and 40 or a single sensor group for monitoring both
`more elaborate monitor stations, traffic density data per
`lane may be provided.
`roadway directions, a separate monitor station on the
`Alternatively, raw data may be forwarded to the
`other side of the roadway may be necessary.
`Although a video camera is mentioned as an image
`main station 16 by the monitor stations 14 and the main
`50
`station would calculate average speed and traffic den
`sensor, this is only one example of an image sensor
`sity.
`which may be used. Other sensors, such as charge cou
`pled devices and infrared devices may be used.
`Each monitor station 14 in the embodiment of FIG.2
`transmits its identification signal at low power to the
`The image sensor 24 of each monitor station 14 is
`preferably pointed in the same direction as the flow of 55
`roadway local to it. As is described in more detail be
`the traffic being monitored to give the user of the infor
`low, the receivers of the .mobile user units 18 can re
`ceive this separately broadcast identification signal,
`mation system a feeling of looking ahead. This makes it
`possible to have a sequential presentation of video im
`compare it to the identification signal associated with
`the images presently being received, and alert the user
`ages that simulates traveling the roadway 22 in the same
`when an opportunity to look ahead is upcoming. The
`direction as the mobile user 18 is traveling. To a user in
`low power identification signal may be broadcast by
`a vehicle traveling on the monitored roadway 22, the
`numerous techniques, such as a digital code impressed
`effect will be that of observing the roadway coming up
`on a carrier which may be deciphered by the mobile
`from behind the user's vehicle and then passing the
`user receiver unit 18. Alternatively, location of the user
`user's vehicle. The effect might be likened to traveling
`the roadway at great speed to preview the traffic condi
`unit may occur by other techniques, such as by satellite
`65
`tions. The image sensors 24 and 42 of each monitoring
`location.
`station 38 and 40 alternatively is directed opposite the
`The main station 16 acting as a controller receives the
`image and the speed signals representative of sensed
`direction of traffic monitored.
`
`35
`
`Google Ex. 1008, p. 9
`
`

`

`O
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`5
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`5,396,429
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`7
`Referring now to FIG. 3, an example of a main sta
`traffic conditions and the identification code from each
`tion 16 is presented. A receiving antenna 46 is shown
`of the monitor stations 14 and broadcasts those signals
`receiving the signals from monitor stations SD1
`in a selected order and for a selected amount of time per
`through SD4. Although only one antenna is shown in
`each monitor station 14 to user units 18 and 20. At the
`main station 16, individual signals from the respective
`FIG. 4, there may be additional antennas used to re
`ceive signals from other monitor stations. Alternatively,
`monitor stations 14 are combined to produce a signal
`that comprises a predetermined sequential presentation
`one antenna may be used to receive all signals from the
`of video images of the monitored roadway 22. This
`monitor stations. In another case, there may be direct
`sequence is selected so as to offer relevant traffic condi
`connection to monitor stations or to an intermediate
`station as discussed above. From the receiving antenna
`tion information to the user and is generally selected to
`46, the signal is demodulated 48 and the individual
`present images from the monitor stations 14 in the same
`video and data signals are input to a first switch 50. The
`order as the driver would encounter those images. For
`first switch 50 is controlled by a processor 52 to select
`example, if the commuting direction in FIG. 1 is from
`south to north, the sequence of images will comprise
`which monitor station video and data will be switched
`through to the second switch 54 which functions as a
`images first from monitor station SD8, and then from
`SD7 and so on to images from SD1. The sequence
`switch and a demodulator. The second switch is also
`controlled by the processor 52 to choose which input
`would then be repeated starting with images from SD8.
`line is processed. The second switch selects the input
`The amount of time that the main station broadcasts
`images from each monitor station in the sequence de
`line in accordance with the processor 52 command and
`pends upon the desired update frequency, the amount
`demodulates the signal to separate the data, such as
`20
`speed data. The speed data, for example, is provided to
`and significance of information to be assimilated by the
`the processor 52 which provides the data to a character
`user. For example, if an update to the information from
`generator 56 which in turn provides characters repre
`each station is desired every five minutes, and there are
`fifty monitor stations 14, the main station 16 will only
`sentative of the speed to a mixer 58. The mixer 58 com
`bines the video with the characters representative of the
`show images from each monitor station for approxi
`25
`data and provides the combined signal to output stages.
`mately six seconds. In the case where equal time is not
`In the case shown in FIG. 3 the output stages comprise
`given to each monitor station 14, an average of six sec
`a first set of a carrier signal generator 60 and a modula
`onds would be given. For example, in some particularly
`tor 62 and a second set of a carrier signal generator 64
`congested areas, more time may be given to the local
`monitor station than to stations experiencing little or no
`and a modulator 66. Each of the modulated output
`congestion.
`signals is amplified 68 and 70 respectively, and is pro
`vided to an output device, such as a transmitting an
`In another embodiment, multiple roadways may be
`tenna 72 and a cable TV output 74.
`monitored and the main station 16 would receive image
`Sequential video switches and microprocessor based
`and speed signals from the monitor stations 14 on those
`switcher and control systems are well known in the art
`roadways also. In the case where the main station 16
`35
`broadcasts to users on only one frequency, the images of
`and are available; for example, from Burle. Video com
`pression devices, encoding and decoding devices are
`all roadways would be included in the broadcast. In this
`available from Compression. Labs, Inc.
`case, the total number of monitor stations along all
`roadways monitored must be considered when planning
`In addition, the main station 16 of FIG. 3 includes
`twenty-four television monitors referred to collectively
`for the update frequency. Where the number of monitor
`by the numeral 76 for viewing the video output of each
`stations is large, the amount of dwell time per each
`monitor station in the system. Also included are twenty
`monitor station may need to be reduced. The roadway
`four monitors referred to collectively by numeral 78 for
`information signals from monitor stations on different
`roadways may be interleaved and the signals of interest
`viewing the data from each of the monitor stations. By
`are separated by the processor of the user unit.
`means of these monitors 76 and 78, the signals provided
`In an additional feature, the data processor of the
`by each of the monitor stations 14 can be observed at
`the main station 16 simultaneously. In another embodi
`main station 16 can compare traffic speed data between
`ment, processors may be provided to superimpose the
`consecutive monitor stations and if the change in speed
`exceeds a predetermined threshold, a speed alert signal
`data of each monitor station on the video so that only
`twenty-four television monitors are needed. Addition
`is provided which would be communicated to the user.
`ally, monitors other than television monitors may be
`For example, where the speed at a first monitor station
`used, such as microcomputers with accompanying dis
`is fifty-five mph but the rate of speed at the next monitor
`plays.
`station which is located one mile from the first station is
`only fifteen mph, a speed alert signal would be given to
`Turning now to the user units, and in particular, re
`ferring first to a mobile user unit, FIG. 4 includes a
`the user who is at the first monitor station. This warning
`55
`block diagram of an exemplary mobile user unit 18. The
`may be an audio signal or a visual signal or both. This
`mobile user unit 18 comprises three main blocks; a tele
`capability can be of extreme value in areas of airborne
`dust, fog or other visual impairment. In an alternate
`vision receiver block 80, an FM radio receiver block 82,
`and a personal computer block 84. The television re
`embodiment, the user unit 18 and 20 may perform the
`comparison of speeds between sequential monitor sta
`ceiver block 80 includes an antenna 86, a VHF/UHF
`tions and provide the speed alert signal.
`tuner 88, an IF amplifier 90, a video detector 92 and a
`video amplifier 94. The video amplifier 94 provides the
`The ability to measure speeds along the route enables
`video signal to a video display device 96. A sound/data
`the user unit to calculate an approximate time of travel
`IF circuit 98 is connected to the video amplifier 94 and
`between selected points on the route. The user would
`provide