  Co-prime arrays with compressed inter-element spacing (CACIS) is one of the
generalizations of the co-prime array. The inter-element spacing can be varied
in this case. The prototype co-prime arrays and nested arrays are a special
case of the CACIS scheme. The problems that were not addressed previously are
considered in this paper. The fundamentals of the difference set for the CACIS
configuration are developed for low latency. In addition, the closed-form
expressions for the weight function (number of samples that contribute to
estimate the autocorrelation) and bias window of the correlogram estimate,
which were previously unknown, are derived. Ideally, the bias window should be
an impulse. Several examples are provided along with simulations to verify the
claims made. All possible sample pairs are used for estimation, which provides
for low latency. As an application, temporal spectrum is considered for
simulations.
