Asymptotic Cramér–Rao bounds for two closely spaced damped cisoids

Simple closed-form expressions are presented for the Cramér–Rao bounds (CRBs) for estimating the parameters of two closely spaced damped cisoids in complex additive white Gaussian noise in the case of low damping and a sufficiently large number of data samples. The expressions provide useful insight into the behaviour of the CRBs with the frequency separation and the damping factors of the cisoids.