Empirical spectral processes for stationary state space models

In this paper, we consider function-indexed normalized weighted integrated periodograms for equidistantly sampled multivariate continuous-time state space models which are multivariate continuous -time ARMA processes. Thereby, the sampling distance is fixed and the driving Levy process has at least a finite fourth moment. Under different assumptions on the function space and the moments of the driving Levy process we derive a central limit theorem for the function-indexed normalized weighted integrated periodogram. Either the assumption on the function space or the assumption on the existence of moments of the Levy process is weaker. Furthermore, we show the weak convergence in both the space of continuous functions and in the dual space to a Gaussian process and give an explicit representation of the covariance function. The results can be used to derive the asymptotic behavior of the Whittle estimator and to construct goodness-of-fit test statistics as the Grenander-Rosenblatt statistic and the Cramer-von Mises statistic. We present the exact limit distributions of both statistics and show their performance through a simulation study.(c) 2022 Elsevier B.V. All rights reserved.