CONFIRMATION OF ADS-B DATA IN THE AERODROME TRAFFIC ZONE BY GATING METHOD

Abstract

The low cost of ADS-B stations in comparison with radars and multi-position surveillance systems allows to consider them as promising means, including for the airfield zone. However, at present, the ICAO does not recommend the use of the ADS-B as the main means of observation, since confirmation of the accuracy of the received coordinate information is required. The article presents a method of algorithmic confirmation of the ADS-B data, while providing flights in the aerodrome traffic zone. It is suggested to use method of the gating to estimate the fidelity of the ADS-B data by selecting the area of space around he extrapolated coordinate of the aircraft. According to the required flight procedure, request of the enhanced surveillance a Mode S is transmitted to the aircraft. On the coordinates of assigned track, according to the maneuvering scheme, aircraft trajectory is built, relative to which the calculation of location errors is performed. Estimation of the mathematical expectation and the mean square deviation of the location error is performed for different levels of reliability. Based on the size of the gate area, a check is performed for compliance of the obtained interval estimates with the data validity condition. The check is performed sequentially for reliability levels 0.9, 0.95, and 0.999. On exit the values of estimate of the error beyond the limit of tolerance for a target level of reliability, information about the unreliability of the received data is displayed, which allows to detect large deviations of the measured coordinates for a smaller number of observations. When performing imitation modelling for the obtained data were set various inaccuracy values: the mathematical expectation from 10 to 48 m and the mean square deviation from 20 to 100 m. The error estimation for the reliability level of 0.999 required from 5 to 22 observations, which corresponds to a time interval of 3 to 11 s real time. At values systematic error of 10 m and mean square deviation of 70 m, the accepted coordinates will be identified as untrusted and will display the information on prohibiting the use of ADS-B and necessary to use other surveillance equipment.