Detecting roadway targets across beams

At a computer system, a method for filtering computed target positions across a plurality of beams of a multiple beam radar system in a roadway, the method comprising:

• an act of dividing returns from the multiple beam radar system for a first detection period into a grid of range bins, dividing returns into a grid of range bins including dividing each beam in the plurality of beams into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;
• an act of creating a comprehensive image from the returns for each beam in the first detection period;
• an act of dividing returns from the multiple beam radar system for a second detection period into the grid of range bins;
• an act of creating a comprehensive image form the returns for each beam in the second detection period;
• an act of filtering the comprehensive image from the second detection period using the comprehensive image from the first detection period;
• and
• an act of detecting targets using the filtered comprehensive image.

At a computer system, a method updating track files for targets within a roadway intersection, the method comprising:

• an act of accessing a target list for the roadway intersection, the target list including currently computed positions for one or more targets in the roadway intersection, the grid of range bins dividing returns form a plurality of beams of a multiple beam radar into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;
• an act of maintaining a track file for each target in the roadway intersection, each track file including target data for a target that is within the roadway intersection, the target data including target position data for a target, the target position data including at least one of:
• a last known position for the target and a predicted future position for the target, maintaining track files including:
• an act of accessing a currently computed position from the target list;
• an act of accessing a specified track file for an existing target, the specified track file having target position data that may correspond to the currently computed position;
• an act of determining if the currently computed position is a position of the existing target by comparing the currently computed position to the target position data in the accessed track file;
• an act of updating the specified track file for the existing target when the currently computed position is determined to correspond to the position of the existing target;
• and
• an act of creating a new track file for a new target when the currently computed position is determined not to correspond to the position of the existing target.

A traffic sensor for monitoring a roadway intersection, the traffic sensor comprising:

• a multiple beam radar system, including:
• transmit antennas for transmitting frequency a plurality of beams of modulated continuous wave (FMCW) radio frequency (RF) signals into the roadway intersection;
• receive antennas for receiving reflections of the frequency modulated continuous wave (FMCW) radio frequency (RF) signals reflected off of objects within the plurality of beams in the roadway intersection, the reflections corresponding to two dimensional image data for the roadway intersection;
• system memory;
• one or more processors;
• and
• one or more computer storage media having stored thereon computer-executable instructions representing one or more modules for identifying targets in a roadway intersection and representing a track file maintenance module for maintaining track files for the roadway intersection, the one or more modules for identifying targets in a roadway intersection configured to:
• divide received reflections into a grid of range bins, dividing received reflections into a grid of range bins including dividing each beam in the plurality of beams into a plurality of range bins of uniform varied distances from the multiple beam radar system, each beam divided into a plurality of range bins in accordance with the uniform varied distances;
• detecting a multi-beam image within the two-dimensional image data, the multi-beam image representing a target within the roadway intersection, the multi-beam image spanning a sub-plurality of the plurality of beams, the multi-beam image also spanning a plurality of range bins within the grid of range bins;
• identify an energy peak within the multi-beam image, including:
• for a specified range bin in one of the beams of the sub-plurality of beams:
• determine that the magnitude of the radio frequency (RF) energy in the specified range bin is above a specified threshold;
• and
• determine that the magnitude of the radio frequency (RF) energy in the specified range bin is greater than the magnitude of the radio frequency (RF) energy in any of the surrounding adjacent range bins within the grid of range bins;
• compute the position of the target;
• and
• add the position of the target to the target list for the roadway intersection;
• and
• wherein the track file maintenance module is configured to:
• access the target list for the roadway intersection
• maintain a track file for each target in the roadway intersection, each track file including target data for a target that is within the roadway intersection, the target data including target position data for a target, the target position data including at least one of:
• a last known position for the target and a predicted future position for the target, maintaining track files including:
• access a currently computed position from the target list;
• access a specified track file for an existing target, the specified track file having target position data corresponding to the currently computed position;
• determine if the currently computed position is a position of the existing target by comparing the currently computed position to the target position data in the accessed track file;
• update the specified track file for the existing target when the currently computed position is determined to be the position of the existing target;
• and
• create a new track file for a new target when the currently computed position is determined not to be the position of the existing target.