A system for detecting railroad cars in a moving train. The cars are assumed to be of the type having two wheel trucks, each with at least two axles arranged adjacent to each other such that the maximum distance between the axles of a single truck is less than the center distance between facing axles of two trucks of a single car. The system includes a device for measuring the distance between successive axles as a train of cars moves in one direction along a track, a device for comparing each measured distance with the maximum axle distance for a truck, and a device for determining whether the axle spacing of a first truck equals the axle spacing of a second truck after the maximum axle distance for a truck has been exceeded. In this way, an individual car is detected upon identification of two identical truck assemblies which are separated by an axle spacing that is greater than the maximum permissible axle distance in a truck.

An apparatus for use in determining the weight and the location of the center of gravity of a vehicle, particularly an aircraft prior to its taking off, comprising in combination at least one load-measuring device secured in a roadway and adapted for contacting load-supporting members of the vehicle when such is moved thereover; computer means linked to the load-measuring devices and adapted to receive data therefrom; means for relaying to the operator of the vehicle data computed by the computer means, and sensor means linked to the computer means, the sensor means adapted to read characteristics of the vehicle as it observes the same and alert the computer, programmed for such characteristics. Also disclosed are methods based on use of the disclosed apparatus.

In accordance with the present invention there is provided a monitoring system that monitors and locates objects such as airplanes and other vehicles on runways, taxiways, or other preprogrammed areas. The invention utilizes a minimum of three transmitters for generating a diffusion field and two receivers which detect displacements in a diffusion field. The receivers are coupled with a computer which calculates the position of the object causing the displacement in the diffusion field. The area to be monitored is divided into grids which are programmed onto the computer, and objects moving in the monitored area cause changes in the signal received by the receivers which are conveyed to the computer and compared by the computer to the programmed grid to indicate the location of the object causing the changes.

A method and apparatus for acoustically monitoring a highway is disclosed which is inexpensive to maintain and install and does not require that the roadway be closed, torn-up or repaved. These results are obtained in an illustrative embodiment of the present invention which comprises a Mill's Cross acoustic array mounted proximate to a highway, spatial discrimination circuitry, frequency discrimination circuitry and interface circuitry that generates a binary signal which indicates when a motor vehicle is, or is not, within a detection zone on the roadway.

Apparatus and method are provided for detecting vehicles which are moving through a predetermined zone. The apparatus includes a plurality of acousto-electric transducers trained on the zone. A bandpass filter is provided for processing electrical signals from the plurality of acousto-electric transducers. A correlator having at least two inputs and an output is provided for correlating filtered versions of the electrical signals originating from at least two of the plurality of acousto-electric transducers. An integrator is provided for integrating the output of the correlator means over time. Finally, a comparator is provided for indicating detection of a vehicle when the integrated output exceeds a predetermined threshold.