Analytical performance evaluation of association of active and passive tracks for airborne sensors
Section snippets
Problem formulation
In recent years, the association of active and passive tracks has been an active research area in multisensor data fusion and has been widely studied [2], [3], [5], [6], [7], [10], [11], [12], [13], [14], [16]. The association logic should decide whether the active and passive tracks have been generated by the same target or pertain to different objects. This paper studies the association performance evaluation for deterministic target trajectories. Let us consider the scenarios presented in [6]
Simplified formula of PFAS for given PC
Assume that Q is a non-central chi-square variable with four degrees of freedom and non-centrality parameter s, and its PDF, denoted as p(q), isAssume λ(PC) is the threshold for a fixed value of PC. Then, we have the following lemma:
Lemma For given PC, PFAS in Eq. (5) is equivalent to
Proof Assume that the characteristic function of Q is φ(μ). Then we haveand
Simplified formula of PC for given PFAS
In some applications, the threshold may be determined such that the false association probability is below a certain value, i.e., the correct association probability for a fixed value of false association probability is required. In this case, the threshold is not only dependent on PFAS but also on s.
Since PFAS<0.5 is a reasonable requirement in this case, referring to [15], the inverse transformation of (12) can be written aswhere
Test of goodness of fit for the approximations
In this section, the Kolmogorov test method is used to explain the reasonableness of the approximations. The first approximation is taken for example. The first approximation consists of two steps: first, approximating the non-central chi-square variable Q into , and then approximating the cumulative distribution function of Z1 aswith K is similar to K1 in Eq. (14b) with z replacing t1.
Assuming that FQ(x) and FX(x) are the
Results and comparisons
In order to verify the effectiveness of the presented methods, the calculation of PFAS for a prescribed PC and the calculation of PC for a prescribed PFAS have been done. For notational convenience of comparisons, some notations are introduced. ΔPFAS is assumed to be the absolute differences of PFAS between the exact values obtained by using Eq. (5) and the approximate values obtained by using either Eq. (14) or Eq. (19). ΔPC is assumed to be the absolute differences of PC between the exact
Conclusions
The main contribution of this work is to derive the simplified closed-form formula of false association probability for a prescribed correct association probability and those of correct association probability for a prescribed false association probability in active and passive track association. The main results are represented by , , , . It should be emphasized, however, that the discussion in this paper is confined to deterministic target trajectories. The advantage of the work is that the
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