Abstract: A detector system filters the effects of periodic noise such as magnetic flux from nearby power lines or other periodic sources. The detector system further adapts in the case that the system incorporates microloops for the inductive sensors. The detector system further counts multiple vehicles while in presence mode. The detector system also logging of vehicle data and system faults.

Abstract: A method for determining the speed of a vehicle using a camera. The method automatically compensates an apparent speed determination for inaccuracies due to the position of the camera with respect to the vehicle. The invention also includes a method for calibrating a camera to compensate for inaccuracies due to the position of the camera.

Abstract: A self-propelled remotely controlled pilot vehicle adapted for use on raiad tracks to monitor hazardous conditions and obstacles on the railroad tracks. The pilot vehicle precedes a train along the railroad tracks at a distance which will allow the train to come to a complete stop in the event the pilot vehicle encounters a hazardous condition on the track. The pilot vehicle is equipped with a sensor array which measures a variety of different parameters such as the presence of noxious gases, moisture in the atmosphere or at ground level, breakage in one or both rails of the track and orientation with respect to the force of gravity as well as the yaw, pitch and roll of the tracks upon which the pilot vehicle is riding. The pilot vehicle is also equipped with a television camera which provides a visual image of the railroad track ahead of the pilot vehicle to the engineer of the train. An infrared camera which is mounted on the front of the pilot vehicle generates an infrared image of the tracks.

Abstract: The present invention is a system and method for identifying a vehicle for the purpose of displaying diagnostic information to the driver. Each vehicle includes a transponder that transmits an encoded character sequence that is unique to that vehicle. In this way vehicle diagnostic measurements made at the establishment entrance can be associated with the vehicle, and displayed to the customer when the vehicle is recognized again at a service area.

Abstract: Apparatus for determining the position of a mobile vehicle relative to a fixed location marker device which comprises a coil energized to emit a magnetic field composed of lines of magnetic flux extending radially and arcuately from the ends of the coil's longitudinal axis. A sensor unit mounted on the mobile vehicle comprises four identical sensing coils each responsive to the frequency of the magnetic field of the marker device and each having a major axis. These sensor coils are supported in two pairs with the major axes of the sensor coils of each pair disposed on either side of a common central plane and extending parallel thereto, this common central plane extending transversely to the longitudinal axis of the marker device coil. Each pair of sensor coils is arranged in an X pattern in which their major axes cross each other medially and perpendicularly to define a center for the coil pair.

Abstract: An oscillator which produces a continuous wave output signal on an antenna having a preset frequency. A detection circuit detects changes in the preset frequency resulting from proximity between the antenna and an object and when such an object is detected, the detection circuit generates an output signal. A compensation circuit is also provided for compensating for changes of the preset frequency which are caused by factors other than proximity of the antenna with an object. Such other factors include radio frequency interference, long term component degradation, temperature, and the like.

Abstract: A fast acting sensing circuit for use in a warning system to indicate relative movement between an object and a sensor when the movement exceeds a predetermined rate of speed. The circuit only provides an output if the rate of speed exceeds the predetermined level.

Abstract: In a vehicle presence detection system in which an inductive sensor loop is the frequency-determining element of the tuned circuit of a loop oscillator, discrimination against variations in inductance due to environmental changes is achieved by comparing detect and tracking reference numbers with a sample number that is a function of the oscillator frequency and updating each reference number repeatedly at real time intervals independent of loop oscillator frequency. The current sample number is compared with either the tracking reference or the detect reference according to whether or not the system is indicating the presence of a vehicle.

Abstract: A railroad train moving along an approach to a grade crossing (or other location of interest) is detected by apparatus that is responsive to the change in effective track impedance caused by the moving shunt. A constant current AC signal is applied to the track adjacent the crossing, and the resulting voltage changed in amplitude and phase is picked off by a receiver on the opposite side of the crossing. Voltage and current information derived from these signals is inputted to a microcomputer which calculates the track impedance and determines whether or not a warning device or devices at the crossing should be activated. Such determination is made on a repetitive basis in accordance with a repeating program loop and stored in memory.