UP-SAMPLING AND CROSS-CORRELATION FOR TIME OF ARRIVAL DETERMINATIONS IN PASSIVE ENTRY/PASSIVE START SYSTEMS

A system is provided and includes a receiver and an access module. The receiver is configured to receive a signal transmitted from a portable access device to a vehicle. The access module is configured to generate a differentiated signal based on the received signal, up-sample the differentiated signal to generate a first up-sampled signal, up-sample an expected signal to generate a second up-sampled signal, cross-correlate the first up-sampled signal and the second up-sampled signal to generate a cross-correlation signal, determine, based on the cross-correlation signal, a phase difference between the first up-sampled signal and the second up-sampled signal, determine a round trip time of the signal received by the receiver based on the phase difference, and permit access to the vehicle based on the round trip time.