An architecture for a real-time signal correlation based on optical joint transform correlation is proposed. Two parallel on-plane acousto-optic (AO) cells and square-law converter are employed to produce cross correlation of two electrical signals. Arrangement of the two AO cells on the same plane permits this architecture to be implemented in a compact form. The proposed architecture has a capability of performing parallel multiple cross correlations by addition of AO cells on the input plane. The theoretical analysis and preliminary experimental results are presented.