Abstract: A light emitter for a traffic control preemption system. The emitter includes a plurality of groups of infrared (IR) LEDs and a power source coupled to the groups of LEDs. A plurality of controlled current sources is coupled to the plurality of groups of LEDs, respectively. A controller is configured to trigger an IR light pulse pattern from the groups of LEDs and maintain a first level of IR radiant power from the groups of LEDs using individual control of respective current levels to the groups of LEDs in response to current sense levels from the groups of LEDs. The pulse pattern and first level of IR radiant power activate preemption in the traffic control preemption system.

Abstract: Various approaches for a traffic control preemption system that includes a receiver, a light emitter, and control circuitry. The receiver includes a photodetector and circuitry that produces a number of electrical pulses in response to each detected light pulse. For each detected light pulse the number of electrical pulses represents a level of radiant power of the light pulse, and a threshold number of electrical pulses and an activation frequency at which the threshold number of electrical pulses is repeated activates preemption. The control circuitry is coupled to the light emitter and controls the light emitter to emit bursts of light pulses. Each burst includes at least two light pulses and a frequency of light pulses in each burst and a frequency of the bursts cause the receiver to produce at least the threshold number of electrical pulses at the activation frequency and activate the preemption.

Abstract: Various approaches for activating a traffic control preemption system. The traffic control preemption system has a receiver with a photodetector and circuitry that produces a number of electrical pulses in response to each detected light pulse. For each detected light pulse the number of electrical pulses represents a level of radiant power of the light pulse. A threshold number of electrical pulses and an activation frequency at which the threshold number of electrical pulses is repeated activates preemption. Control circuitry is coupled to a light emitter and controls the light emitter to emit bursts of light pulses. Each burst includes at least two light pulses and the control circuitry controls the frequency of light pulses in each burst and the frequency of the bursts to cause the receiver to produce at least the threshold number of electrical pulses at the activation frequency and activate the preemption.

Abstract: An arrangement for requesting preemption from a vehicle is used in a traffic control system. The arrangement for requesting preemption includes a protocol circuit, a signal control generation circuit, and an optical source. The protocol circuit is adapted to provide a plurality of communication protocols, wherein a plurality of the communication protocols communicate encoded data. The signal control generation circuit is adapted to generate an output signal in accordance with at least one of the plurality of communication protocols. The optical source is adapted to transmit light pulses from the vehicle, wherein the light pulses are generated from the output signal and include the encoded data for said at least one of the plurality of communication protocols.

Abstract: A remotely-activated vehicle priority system includes a control center, a vehicle-priority communication device, at least one receiver, and a phase selector. The control center transmits an activation message. The vehicle-priority communication device is mounted to a vehicle and is communicatively coupled to the control center. In response to the activation message, the vehicle-priority communication device transmits a priority preemption request. Transmission of the priority preemption request in response to the activation message prevents improper activation, either intentional or unintentional, of the vehicle priority system by an operator of the vehicle. The receiver is situated at a traffic signal and receives the priority preemption request. The phase selector issues, responsive to the priority preemption request, a command to a controller of the traffic signal. The command selects a phase for the traffic signal.

Abstract: A traffic-preemption system and method that communicates an identification code from vehicles to a traffic location. Traffic light control equipment, such as a receiver and traffic light circuit at each intersection of a controlled area, is used to manage headway in mass-transit systems as well as to provide traffic light pre-emption for emergency vehicles. Each traffic light circuit in the controlled area has a receiver located at a traffic location and adapted to receive an identification code from a mass-transit vehicle. A decoding circuit responds to the received identification code by attempting to identify the mass-transit vehicle and determine the timing on the identified route that improves an identified vehicle's headway and/or route timing. In response to determining the timing, a traffic-preemption command is generated for a traffic light on the identified route.

Abstract: A traffic light control system includes at least one parameter and a signal decoding circuit. The parameter or parameters are useful for assisting in differentiating between multiple communication modes. The signal decoding circuit has a front-end circuit and a back-end circuit. The front-end circuit is adapted to receive respective signals transmitted in multiple communication modes. The front-end circuit is adapted to produce data representative of at least a portion of the respective signals. The back-end circuit is adapted to interpret and process the produced data according to at least one of multiple traffic light control protocols respectively associated with the multiple communication modes. The signal decoding circuit is adapted to access said at least one parameter and associate the produced data with one of the multiple communication modes.

Abstract: A remotely-controlled traffic-preemption system and method includes an encoder circuit, an optical source, an optical detector, and a decoder circuit. The encoder circuit is adapted to generate a set of signal pulses. At least one bit of a data word is encoded as a function of amplitude modulation of a first subset of the set of signal pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of signal pulses. The optical source is adapted to transmit a set of light pulses having a respective light pulse for each signal pulse of the set of signal pulses. The optical detector is adapted to receive the set of light pulses. The decoder circuit is adapted to generate the data word from the set of light pulses received at the optical detector.

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.