An interrogation transmission method of a secondary surveillance radar compares prediction angle ranges for transmitting interrogations with a beam-width of an antenna, and transmits the interrogations at every roll-call period if the prediction angle ranges for transmitting interrogations are narrower than the beam-width of the antenna. In contrast, if the prediction angle ranges for transmitting the interrogations are wider than the beam-width of the antenna, the radar respectively sets a period to transmit the interrogations and a period not to transmit the interrogations until responses can be received, and transmits interrogations at every roll-call period after the responses can be received (even if a receiving error or downlink occurs).

An improved system and methods for correlating an interrogation-based air traffic surveillance intruder, such as an Traffic alert and Collision Avoidance System (TCAS) intruder, and a GPS-based air traffic surveillance target, such as an Automatic Dependent Surveillance Broadcast (ADS-B) target to minimize or eliminate the display of two symbols for the same intruder/target on the CDTI of an aircraft. The method comprises the steps of receiving ADS-B data at a processing unit and calculating select component deltas for the ADS-B data versus an entry in a TCAS intruder file. Progressive weights are assigned to the deltas and the progressive weights are summed, resulting in a total confidence score. Total confidence scores of ADS-B target and TCAS intruder pairs are compared to determine correlation between the ADS-B target and the TCAS intruders.

Systems and methods are provided for filtering detected events to determine events of interest. A sensor data analysis system identifies a plurality of detected events from provided sensor data and evaluates the sensor data to determine at least one characteristic associated with each event. The sensor data analysis system reports the plurality of detected events and their associated characteristics. At least one affiliated event generator is operative to generate at least one affiliated event and produce at least one event report. A given event report provides at least one characteristic associated with an affiliated event. An event filtering system compares the at least one event report to the detected events to identify at least one affiliated event amongst the plurality of detected events.

An improved method for correlating between targets in an air traffic control system. A methods or systems according to the invention compare selected components of a first target report to the components of a second target report, produce a confidence level on each component comparison, and determine whether to declare the targets similar based on the confidence level on each component compared. The first and second target reports may include ADS-B target reports and TIS target reports. The individual components of the reports may be range, bearing, track angle, and relative altitude. The methods or systems may use a fuzzy logic probability model to produce a continuous confidence level on each component comparison.

An improved method for correlating between targets in an air traffic control system. A methods or systems according to the invention compare selected components of a first target report to the components of a second target report, produce a confidence level on each component comparison, and determine whether to declare the targets similar based on the confidence level on each component compared. The first and second target reports may include ADS-B target reports and TIS target reports. The individual components of the reports may be range, bearing, track angle, and relative altitude. The methods or systems may use a fuzzy logic probability model to produce a continuous confidence level on each component comparison.