The blind separation of multiple co-channel binary digital signals using an antenna array involves finding a factorization of a data matrix X into X=AS, where all entries of S are +1 or -1. It is shown that this problem can be solved exactly and non-iteratively, via a certain generalized eigenvalue decomposition. As indicated by simulations, the algorithm is robust in the presence of noise. An interesting implication is that certain cluster segmentation problems can be solved using eigenvalue techniques.