Standard digital correlators, which rely on the acquisition of signals and their processing, are intrinsically limited by the clock jitter of the analog-to-digital converters, and by the processing capabilities in real time of digital electronics. Here, we demonstrate a novel analog correlator architecture based on a simple photonic platform, suitable for wideband RF signal processing. The system gives access in real time to the entire correlation function of two signals by computing the cross correlation coefficients for 200 values of their relative delay simultaneously. The time-delay step can be adjusted from a few ns down to a few ps, enabling us to process signals with MHz to multi-GHz bandwidth. The system, based on a frequency shifting loop, can find applications in radar, electronic warfare, imaging, and radio-astronomy.