Trajectory Filtering Algorithm in Multi-Position Passive Radars with Additional Flight Altitude Observation

This work is devoted to developing an algorithm for trajectory filtering in multi-position passive radar systems. The peculiarity of such systems is to find radio radiation sources in areas with a high value of dilution of precision, which leads to a sharp deterioration in the accuracy of coordinate estimation. Another negative factor is the presence of incomplete marks in the observations, which can lead to a failure of tracking and a sharp deterioration in the accuracy of determining the coordinates of radio radiation sources. This paper presents an algorithm that uses the flight altitude in the geodetic coordinate system as an additional observation. In practice, this information can be known if the radio radiation source uses an onboard IFF responder in A/C mode. In this case, the flight altitude can be decoded and used as an additional observation. In this paper, a simulation was performed to compare the effectiveness of the proposed algorithm with the standard one based on the Extended Kalman filter without using additional observation. Comparison of the algorithms was also carried out on experimental data. It is shown that the use of a priori information about the geodetic altitude of the flight as additional observations of the algorithm allows not only to increase the accuracy of two-dimensional coordinate estimation (up to 2.5 times), but also to increase the stability of trajectory tracking in comparison with the algorithm that does not take this information into account.