Cyclostationary processes are an important class of nonstationary proc
esses. In this correspondence we consider nonparametric estimation of
the cyclic cross-spectrum. A smoothed periodogram-based estimator is s
tudied and its asymptotic behavior characterized, extending recent uni
variate work to the multivariate case. Application to cyclic coherence
measurements is discussed, The results are useful in a variety of mul
tisensor cyclostationary signal processing scenarios such as time dela
y and bearing estimation.