Abstract: An emergency vehicle traffic light preemption system for preemption of traffic lights at an intersection to allow safe passage of emergency vehicles. The system includes a real-time status monitor of an intersection which is relayed to a control module for transmission to emergency vehicles as well as to a central dispatch office. The system also provides for audio warnings at an intersection to protect pedestrians who may not be in a position to see visual warnings or for various reasons cannot hear the approach of emergency vehicles. A transponder mounted on an emergency vehicle provides autonomous control so the vehicle operator can attend to getting to an emergency and not be concerned with the operation of the system. Activation of a priority-code (i.e. Code-3) situation provides communications with each intersection being approached by an emergency vehicle and indicates whether the intersection is preempted or if there is any conflict with other approaching emergency vehicles.

Abstract: An improved apparatus for controlling a traffic signal at an intersection includes a signal controller having an artificial intelligence based situational analyzer. The signal controller receives vehicle data related to the speed and position of vehicles approaching the intersection, and optionally time and ambient condition data. If the artificial intelligence based situational analyzer predicts a signal violation, operation of the traffic signal is modified to reduce the probability of a vehicular collision.

Abstract: A secure optical-communication traffic-preemption system and method is provided that securely communicates an identification code from an optical emitter to a traffic location. The optical emitter transmits light pulses that represent an encrypted code that is an encryption using a time-varying encryption key of at least an identification code. An optical detector situated at a traffic location receives the transmitted light pulses. Validation, including decryption using a time-varying decryption key, is attempted for the encrypted identification code represented within the received light pulses. In response to validating the included identification code, a traffic-preemption command is generated for a traffic light at the traffic location.

Abstract: This invention relates to a method and apparatus for secure traffic light interruption. A purpose of this invention is to allow for the use of a secure system to allow the interruption of the traffic light signals by emergency (and other authorized) vehicles. An objective of this invention is to allow for the use of a more secure system than the currently installed strobe only traffic light interruption (changing) systems. This invention integrates additional wireless technologies to assure that only authorized users trigger the traffic light changes that typically make it safer for emergency vehicles when they approach a traffic light.

Abstract: Disclosed herein is a traveler information monitoring and dissemination system. The system disclosed herein provides real time information to a traveler, wherein the real time information may be pre-selected by the traveler. The system ensures consistent and quality data are produced and issued to the traveler.

Abstract: A simple region-specific broadcasting system for broadcasting information pertinent to motor vehicles in sequential regions of a roadway or highway directly to such vehicles when the vehicles are passing through such sequential regions. Existing cellular facilities and resources may be advantageously used in the implementation of the system. A system for broadcasting short range RF real-time information to motor vehicles traveling along a roadway implemented through a sequence of transceiving short range broadcast stations along said highway, the stations spaced so that the broadcast ranges of said stations tangentially overlap each other. Each of the sequence of motor vehicles moving along this roadway should include a transceiver for the short range RF signals.

Abstract: Methods and systems use a programmable sign display located in proximity to a traffic light to provide information to motorists upon the motorists directing their attention toward the traffic light. The programmable sign display may receive programming for content to be displayed in various ways, such as through an interface to a telephone network accessible by a cell phone that sends programming information to the sign. The programmable sign may be used to inform motorists of a radio frequency upon which relevant information such as advertising or traffic reports is being broadcast. The programmable sign may be used to provide textual or graphical information, such as an instruction to motorists that relates to avoiding an approaching emergency vehicle. Additionally, management of the sign is provided to coordinate programming and control of the content being displayed.

Abstract: Disclosed herein is a traveler information monitoring and dissemination system. The system disclosed herein provides real time information to a traveler, wherein the real time information may be pre-selected by the traveler. The system ensures consistent and quality data are produced and issued to the traveler.

Abstract: An emergency vehicle intersection preemption beacon/heading system and method that relies on the use of highly localized, low-power communication system. The system can be implemented in a “car-active” mode or a “car-passive” mode. In the “car-active” mode, the system includes a low-power transmitter providing a beacon channel for all emergency vehicles that allow them to separately communicate with each intersection for a very short period of time and within very close proximity. The localized low-power transmitter continuously transmits the emergency vehicle ID and heading every second. When within range, receivers at each intersection are able to lock the signal and begin receiving ID and heading data. In the “car-passive” system, each intersection will have a low-power, highly localized transmitter. In this embodiment, the intersection constantly sends out pulses of data.

Abstract: An emergency vehicle traffic signal preemption system using existing inductive traffic loops that is either “car-active” or “car-passive”. In the “car-active” system, a passive element having position information transmits an ID tag and the position information to a transceiver in the vehicle when an emergency vehicle is detected by the existing inductive traffic loop. In the “car-passive” system, a transceiver at the intersection is activated to send an excitation signal to a transponder on the emergency vehicle. The transponder responds with the emergency vehicle ID. The transceiver in the vehicle in the “car-active” system or the transceiver at the intersection in the “car-passive” system, transmit position information to the traffic controller to preempt operation of the traffic signals.

Abstract: A traffic preemption system is described that includes onboard equipment located on a vehicle and a fleet management center in communication with the onboard equipment. The fleet management center is also in communication with a traffic management center that is in communication with at least one intersection controller, which controls the signals displayed at a traffic intersection. In one embodiment, the invention includes a vehicle equipped with an onboard computer system capable of capturing diagnostic information, estimating the location of the emergency vehicle using information provided by a GPS receiver connected to the onboard computer system and transmitting the captured diagnostic information and estimated location using a wireless transmitter connected to the onboard computer system via a first wireless network.

Abstract: A pedestrian trail signaling device for warning users of the trail or path when an emergency vehicle is approaching the intersection. Emergency vehicles 14 have an actuatable transceiver that transmits a signal to the trail posted signaling device causing warning lights to flash and generation of a response signal informing the emergency vehicle operator that the trail posted signaling device has received the emergency vehicle transmission. A user transmitter having an on/off switch that broadcasts a signal to the trail signaling device causing the signaling device blinking yellow LED displays to blink A passive detector is provided whereby an emergency vehicle strobe light can trigger both flashing warning signals when the passive detector(s) is triggered. A motion detector 44 located on the trail user 16 warning light whereby either or both systems will flash their respective predetermined warning signals when the motion detector(s) is triggered.

Abstract: A method and arrangement for controlling a system of multiple traffic signals for regulating the traffic of vehicles is described. Traffic data is transmitted by wireless transmission to traffic data processing units assigned individually to a locally limited group of traffic signals, and each traffic data processing unit performs an analysis of the local traffic situation for the environment of the locally limited group of traffic signals up to, at the maximum, the neighboring locally limited groups of traffic signals.

Abstract: A warning light system for a traffic intersection for alerting pedestrians and operators of passenger vehicles to the approach of an emergency vehicle. The warning light system is activated only by sounds in the range of frequencies which are emitted by the siren of an emergency vehicle. The warning light system has a warning light assembly having a control unit, and also has an audio sensor unit. The warning light assembly has a blue light and a white light, which flash alternately and repeatedly, after receipt of an audio signal by the audio sensor unit from the siren of an emergency vehicle, and processing of that signal by the control unit. The lights of the warning light assembly continuously flash until the sound emitted from the siren is no longer detectable by the audio sensor.

Abstract: A method and system for providing travel guidance for transportation vehicles traveling on a highway system that comprises highway transceivers (HTs) with limited range placed at selected intervals along the highway. Each transportation vehicle has an automobile transceiver (AT) for receiving and transmitting information using a communication protocol. The HTs have a limited transmission range. The AT may be programmed to selectively present information received from the HTs to a passenger in an automobile. The ATs may also receive information from other transportation vehicles equipped with an AT. The HTs may receive information from all of the transceivers or other transmitters, for example, a GPS satellite transmitter. The HTs may also transmit information to traffic signal units about numbers of vehicles in its transmission pattern.

Abstract: An emergency vehicle traffic light preemption system for preemption of traffic lights at an intersection to allow safe passage of emergency vehicles. The system includes a real-time status monitor of an intersection which is relayed to a communications controller for transmission to emergency vehicles as well as to a central dispatch office. The system also provides for audio warnings at an intersection to protect pedestrians who may not be in a position to see visual warnings or for various reasons cannot hear the approach of emergency vehicles. A transponder mounted on an emergency vehicle provides autonomous control so the vehicle operator can attend to getting to an emergency and not be concerned with the operation of the system. Activation of a Code 3 situation provides communications with each intersection being approached by an emergency vehicle and indicates whether the intersection is preempted or if there is any conflict with other approaching emergency vehicles.

Abstract: A radio linked vehicle communication system for text messaging, traffic light control, resource management and traffic monitoring, designed to establish the location of emergency vehicles and related privately owned vehicles within their vicinity and have this information relayed to a third party using conventional electronic devices. Specifically to notify the privately owned vehicle or vehicles in close proximity of an emergency vehicle of their presence, so as to avoid possible accidents and to relay this information to a third party to be recorded and verified. Additional benefits of the system would be the ability of having interrogators, either mobile, aircraft of in a fixed location that could identify and personalize specific vehicles for investigation purposes and to provide a mobile repeater system.

Abstract: A system and method of centralizing traffic signal preemption for roadway emergency operations provides for increased accuracy and coordination of emergency response vehicles along an emergency route. A centralized preemption system receives status and location information, e.g., GPS, from emergency vehicles via fleet management systems or dispatch centers. As an emergency route is determined and projected in real-time, predetermined policies are applied to create an overall preemption plan of traffic lights at intersections along an anticipated route. The preemption plan results in preemption directives being transmitted to traffic management systems that are controlling traffic signal controllers at intersections along the route. The centralized preemption system may coordinate among many traffic management systems that provides for a much larger preemption service area including multiple jurisdictions.

Abstract: The invention relates to a method for outputting traffic information in a motor vehicle. In order to present the driver with traffic information in such a way that he can adapt his driving behaviour and/or his selection of a route for his journey to the respective current traffic situation in time, there is a provision that traffic messages are stored together with the respective position of the route section to which they relate. The positions of the traffic messages are then compared with the respective position of a motor vehicle in which the traffic information is to be output in order to detect the distances between the respective position of the traffic messages and the position of this motor vehicle. The traffic messages are then output sorted according to distances, starting with the smallest distance.

Abstract: An emergency traffic signal device comprising a plurality of elongated display units that are affixed to the traffic signal around the three traffic lights thereon and comprise arrays of LEDs capable of displaying graphic directional instructions in the form of moving chevrons or arrows that indicate the need to move laterally to the side of the road in response to preemptive signals detected by a controller. The display units are mounted on channel-shaped bodies to be retrofitted to the signal, or are installed as original equipment on new signals, preferably in a continuous band around the traffic lights. Alternatively, message display panels, also responsive to the controller, are applied to one or both of the upper and lower sides of the traffic signal, and additional arrays of LEDs are provided in the positions of two of the traffic lights to emit standard color lights during normal operation and to display graphic directional symbols in response to emergency signals.

Abstract: An attachment for a traffic signal having a housing for fitting over one of the normal lights, herein the green light, of the signal and overriding the normal sequence in response to preemptive emergency signals, and a electro-optically responsive data display panel on the housing to provide clear and direct instructional messages to motorists as to the appropriate actions to be taken. A first embodiment overrides the normal green light with a reflective electro-optically responsive panel overlying the normal green light to become opaque in response to the emergency signals, with a red light source outside the panel that is activated to produce red reflected light. A second embodiment replaces the normal green (or alternatively yellow or red) signal with a panel of light-emitting elements (LEDs) that have one group capable of providing the normal green signals and a second group that are capable of providing graphic instructions in response to emergency signals.

Abstract: Vehicle security systems comprise at least one addressable transponder for communication with at least one base station. Each transponder and base station comprises a steerable directional antenna having an antenna azimuth sensor. Transponder and base station antenna azimuths assist in locating a vehicle carrying a transponder and allow near real-time estimation of vehicle heading. Base station networks facilitate location, tracking and/or interception of vehicles within a network geographic area. Use of multiple effective transmission ranges for transponders and/or base stations improves the accuracy of vehicle location.

Abstract: A system and method of centralizing traffic signal preemption for roadway emergency operations provides for increased accuracy and coordination of emergency response vehicles along an emergency route. A centralized preemption system receives status and location information, e.g., GPS, from emergency vehicles via fleet management systems or dispatch centers. As an emergency route is determined and projected in real-time, predetermined policies are applied to create an overall preemption plan of traffic lights at intersections along an anticipated route. The preemption plan results in preemption directives being transmitted to traffic management systems that are controlling traffic signal controllers at intersections along the route. The centralized preemption system may coordinate among many traffic management systems that provides for a much larger preemption service area including multiple jurisdictions.

Abstract: A traffic priority defining system implemented by emergency vehicles at an intersection. A signal, designated the second electronic signal, post emanation, is electronically verified as to source and sent to the controller for a traffic control device, such as a tricolor traffic light, to override the primary signal operating the traffic light for opposing traffic. One of the colored lights, usually yellow, is actuated to a second operational mode, to display an icon of an emergency situation. The specified color light's incandescent bulb resumes normal full to yield a yellow glow at the proper time.

Abstract: There is provided a system and method for controlling at least one traffic light having a vehicle having a transmitter and a receiver for transmitting and receiving traffic control signals, and a control unit for processing traffic control signals; and a traffic control module having a transmitter and a receiver for transmitting and receiving traffic control signals, a control unit for processing traffic control signals, traffic light control logic for controlling the at least one traffic light, and means to connect to the at least one traffic light; wherein the traffic control signals control the flow of traffic about the at least one traffic light enabling a vehicle to travel from a present location to a destination passing through intersections at which traffic flow is controlled by the at least one traffic light; and also including means for controlling at least one traffic light on a selected optimal route in response to the traffic control signals.

Abstract: An apparatus and method for supplementing automotive safety includes a transmitter associated with the traffic safety concerns or conditions such as traffic signals, traffic barricades, or pedestrians. The transmitter is adapted to transmit a signal conveying information indicative of a type or class of traffic safety concern or condition. A receiver is adapted to receive and distinguish the type or class of traffic safety concern or condition. Some type of alarm or display can be connected to the receiver to convey information about the traffic safety concern or condition to a driver. The apparatus and method could also be applied to search and/or rescue missions for persons, animals or objects.

Abstract: An emergency traffic signal device comprising a plurality of elongated display units that are affixed to the traffic signal around the three traffic lights thereon and comprise arrays of LEDs capable of displaying graphic directional instructions in the form of moving chevrons or arrows that indicate the need to move laterally to the side of the road in response to preemptive signals detected by a controller. The display units are mounted on channel-shaped bodies to be retrofitted to the signal, or are installed as original equipment on new signals, preferably in a continuous band around the traffic lights. Alternatively, message display panels, also responsive to the controller, are applied to one or both of the upper and lower sides of the traffic signal, and additional arrays of LEDs are provided in the positions of two of the traffic lights to emit standard color lights during normal operation and to display graphic directional symbols in response to emergency signals.

Abstract: A parking control system is disclosed. The parking control system comprises a plurality of vehicles. A portion of the plurality of vehicles occupies parking spaces in a parking lot. At least one of the vehicles is attempting to park in a parking space of the parking lot. At least one of the plurality of vehicles is capable of a two-way communication. The parking control system also includes a parking controller. The parking controller receives and provides information to the plurality of vehicles. The parking controller can communicate the most appropriate parking space to the vehicle that is attempting to park. In a method and system in accordance with the present invention, a parking controller monitors a parking lot and can be in direct contact with the vehicles. The parking controller receives and transmits information to and from the vehicles and allows for an overall view of the parking lot to be understood.

Abstract: A system and method for controlling traffic and traffic lights and selectively distributing warning messages to motorists includes a controller to determine appropriate action based on traffic congestion parameters. Fuzzy logic is used to determine optimum traffic light phase split based on the traffic information from the traffic information units. Global Positioning System technology is used by the system and method in order to track moving vehicles and signs and be able to communicate with them.

Abstract: A vehicle detection apparatus using existing traffic preemption technologies to include automatic vehicle location, remote traffic preemption, and central decision support system for transit, congestion and emergency vehicle control. The apparatus includes emitters mounted on emergency or transit vehicles to activate and preempt existing intersection control systems, automatic vehicle location protocol, real time mapping of intersections within the system, and interconnecting communications means for transferring the system output data to the respective control or data receiving center. The preferred embodiment of the present invention uses a wireless modem with embedded software protocol connected to the preemption card installed at a typical traffic intersection controller cabinet. As vehicles approach the intersection, the wireless modem reports the location and preemption information to the control center.

Abstract: A wire-loop vehicle detector is configured with a vertically oriented blade aligned at an angle to the direction of traffic-flow with each end of the blade extending laterally beyond the normal limits of vehicle presence over the blade. The extended blade configuration of the wire-loop constrains over-passing vehicles to present repeatable inductive signatures while electromagnetic noise and thermal-drift are selectively canceled using a secondary coil to increase the signal-to-noise ratio of inductance measurements. Inductive signatures of vehicles are recorded using a high-speed and high-precision method of making multiple successive measurements of the inductance of a wire-loop as vehicles pass over. Inductive signatures of automotive vehicles are useful for parking-lot revenue control, car-bomb detection, passive security of isolated communities, and other traffic-flow monitoring and control applications.

Abstract: A traffic control system is described. The traffic control system comprises a primary controller. The primary controller receives information about traffic in an area. The traffic control system further includes a plurality of subsidiary controllers providing information to and receiving information from the primary controller. Each of the plurality of subsidiary controllers is associated with a cell within the area. Each of the subsidiary controllers receives and provides information to at least one vehicle concerning traffic conditions within its associated cell. The primary controller and each of the subsidiary controllers are capable of negotiating a change in the flow of traffic based upon traffic conditions. The at least one vehicle is granted a permission based upon its role.

Abstract: A fixed station and an on-board apparatus are constructed to carry out a short range communication. The on-board apparatus specifies an application from a command included in reception data received from the fixed station and starts a corresponding processing, when an acquired command is a menu selection command. A menu including commodities and charges are displayed. When a selected item is determined, the determined content is displayed. When an IC card unit receives an IC card for settling the charge, the charge is settled by rewriting the IC card by data exchange via wireless communication. A short range wireless unit is used to ensure individuality of the communication. This short range communication may also be used at a vehicle repair shop, at a curved corner on a travel path or the like.

Abstract: An apparatus and method for remotely controlling a traffic control device, including an input device for inputting at least one of a control code and a command code corresponding to a control operation to be performed on a traffic control device, a processor for processing the at least one of a control code and a command code, wherein the processor generates a first control signal for performing a control operation on the traffic control device, and a transmitter for transmitting the first control signal to the traffic control device. The traffic control device receives the first control signal and generates a second control signal effectuating the control operation.

Abstract: The SafeLight is comprised of a photo eye that emanates a signal that is received by a photo eye placed to receive the aforementioned signal, thereby altering the targeted traffic light accordingly. The signal is sent by pressing a button on the handheld or mounted apparatus manually or the signal is sent via an automatic setting. The handheld or mounted device may be placed on a simple mounting bracket to be placed in a convenient location in an emergency or official vehicle.

Abstract: An emergency flashing light mechanism includes one or more emergency flashing lights, a processor, a transmitter, and a receiver. The emergency light flashing mechanisms can exchange information with the vehicles, pedestrians and other components of a traffic complex via their respective transmitters and receivers. The emergency flashing light mechanisms can process such information and override control lights having red, yellow and green lights. The emergency flashing lights can selectively respond to emergency vehicles.

Abstract: There is provided a system and method for controlling at least one traffic light having a vehicle having a transmitter and a receiver for transmitting and receiving traffic control signals, and a control unit for processing said traffic control signals; and a traffic control module having a transmitter and a receiver for transmitting and receiving said traffic control signals, a control unit for processing said traffic control signals, traffic light control logic for controlling said at least one traffic light, and means to connect to said at least one traffic light; wherein said traffic control signals control the flow of traffic about said at least one traffic light enabling said vehicle to travel from a present location to a destination passing through intersections at which traffic flow is controlled by said at least one traffic light.

Abstract: An adaptive navigation system for a land vehicle is provided that incorporates learned segments of preferred routes into adaptive calculated routes. The navigation system preferably includes a global positioning system or other sources of locator system data and a data processor that may be programmed with destination data and current location data. The data storage apparatus is capable of recording current location data as the vehicle travels to a destination. The system automatically develops a database of a plurality of segments of preferred routes where those segments are different from the route normally calculated by the data processor. On future occasions when the navigation system is used, the data processor is able to incorporate segments of preferred routes in an adaptive calculated route determination when the segments are within a predetermined degree of similarity to the calculated route.

Abstract: An clear-cross crossing system for use by emergency vehicles that includes a traffic light attachable strobe light/receiver unit that is attachable to and existing traffic signal and a transmitter unit mounted to the dash board of an emergency vehicle which transmits an activation signal to the strobe light/receiver unit to activate the unit and to cause the unit to override the existing traffic signal to generate a green light signal in the direction of the oncoming emergency vehicle.

Abstract: An electronic warning signal device that includes a receive/warning light unit attached to an existing traffic signal and a transmitter carried by an emergency vehicle that is tuned to and transmits an activating signal to activate the warning light to assist the emergency vehicle in passing safely through an intersection. The receiver further includes a reset circuit having a timer element that is triggered by a reset signal sent from the transmitter once the emergency unit has traveled through the intersection.

Abstract: A wire-loop vehicle detector is configured with a vertically oriented blade aligned at an angle to the direction of traffic-flow with each end of the blade extending laterally beyond the normal limits of vehicle presence over the blade. The extended blade configuration of the wire-loop constrains over-passing vehicles to present repeatable inductive signatures while electromagnetic noise and thermal-drift are selectively canceled using a secondary coil to increase the signal-to-noise ratio of inductance measurements. Inductive signatures of vehicles are recorded using a high-speed and high-precision method of making multiple successive measurements of the inductance of a wire-loop as vehicles pass over. Inductive signatures of automotive vehicles are useful for parking-lot revenue control, car-bomb detection, passive security of isolated communities, and other traffic-flow monitoring and control applications.

Abstract: A speed limit indicator for, for example, a four-lane highway (1) having left lanes (3) and right lanes (4), the direction of travel indicated by the arrows. Road markings (11, 12 and 13) of different colors are used to provide an indication of the speed limit for the particular speed zone. The invention also provides a transmitter which is sited usually at the entrance to a speed zone and a receiver in a vehicle which are used to signal the speed limit to a driver.

Abstract: A system and method for controlling traffic and traffic lights and selectively distributing warning messages to motorists is described. Traffic information is obtained from various traffic information units. The traffic information units have intelligent controllers. The traffic information is transmitted to at least one central controller. The central controller is used to determine congestion parameters and warning information. The congestion parameters and the warning information are transmitted from the central controller to the intelligent controllers. The intelligent controllers are used to determine appropriate action based on the congestion parameters and the warning information. Fuzzy logic is used to determine optimum traffic light phase split based on the traffic information from the traffic information units. The optimum traffic light phase split is determined for each of the intelligent controllers.

Abstract: A vehicle follow-up control apparatus includes a distance sensor sensing an actual vehicle-to-vehicle distance from a controlled vehicle to a preceding vehicle, a vehicle speed sensor sensing an actual vehicle speed of the controlled vehicle, and a controller for calculating a desired vehicle speed to be achieved in the controlled vehicle. The desired vehicle speed is calculated in accordance with the actual vehicle-to-vehicle distance, the relative speed and a control gain which is adjusted in accordance with the relative speed.

Abstract: The invention relates to a method of signalling traffic-relevant status information (5), in particular warning signals, to road users. In order to convey warning signals in a simple and reliable manner to road users when these are distracted by terminal equipment, it is provided that the terminal equipment, in particular mobile telephone, audio device, computer, is used for acoustic and/or optical and/or mechanical signalling, during which time the normal function of the terminal is suppressed.

Abstract: A method for controlling automobile traffic lights uses global positioning systems installed at each vehicle. Each vehicle determines a location of the vehicle via a global positioning system calculation. Each vehicle determines a cell corresponding to the determined location. Each vehicle broadcasts a message at a time slice allocated for the cell. A traffic light computer system receives broadcasted messages from a plurality of vehicles which are approaching the traffic light. The system uses the received broadcasted messages to determine an optimal traffic signal sequence.

Abstract: For qualification for traffic preemption an area is defined and if the vehicle is in the area it can obtain preemption. The vehicle's position is determined, in one embodiment, by use of differential GPS.

Abstract: A traffic information warning system for conveying first and second messages regarding a traffic situation from a traffic advisory site is disclosed. The system comprises a transmitter adapted for placement at the advisory site and a receiver. The transmitter includes an oscillator for transmitting a first carrier signal and a second carrier signal. The first carrier signal has a first discrete carrier frequency and the second carrier signal has a second discrete carrier frequency. The first and second discrete carrier signal frequencies are located at a frequency location. The first message of a traffic situation is reflective of the specific frequency locations of the first and second discrete frequencies. A modulator modulates the first carrier signal with a modulating signal reflective of the second message regarding the traffic situation. The second carrier signal comprises an unmodulated signal.

Abstract: A system and method is provided for preempting the signal lights of an intersection. A magnetic heading of an emergency or other vehicle is measured using a mobile unit and adjusted to account for the magnetic interference of the vehicle. The magnetic heading is transmitted to a base unit installed at the intersection. Upon receiving a verified magnetic heading from a vehicle, the base unit preempts the normal operation of the signal lights to present a green light or other preferred display to the emergency vehicle Additionally the vehicle has a transmitter operating at a high frequency, which limits the range of the transmission. Thus, only the intersection to be preempted receives the transmission from the mobile unit. Also, a tester is provided to evaluate the function of the base unit and the mobile unit without interfering with the normal operation of the traffic signal. Also, the location, type and direction of other vehicles can be tracked even if the signal lights are not preempted.

Abstract: A coded siren sound generator and a corresponding detector module are provided which allow uniquely coded tone patterns generated by the coded siren to be detected and processed such that only specific sirens will activate the detector module. In one embodiment, only a few codewords are sent by the transmitter. The receiver looks for the occurrence of one or more of these selected codewords and takes a predetermined action based on programming of the detector. The system may operate at audible or ultrasonic frequencies. In accordance with a further embodiment, audio (either audible or ultrasonic) "packets" are sent by the transmitter These packets contain sufficient information to uniquely identify the vehicle sending the packet and allow the vehicle to send commands and data to the detector. The commands and data may be for purposes such as requesting emergency pre-emption for a left turn at an intersection, requesting straight ahead pre-emption, etc.