The CORI system has been deployed since June 2009 on the east coast of Limnos Island, measuring surface currents in front of Dardanelles Straits every 30 minutes. It comprises by two sub-systems (units) deployed ~23 km apart in order to get the full 2D near surface currents field (figure 1). Each sub-system has four transmit and four receive antenna elements (a 4-element square array of receiving antennas can be used if only surface currents are to be measured) and makes independent measurements of current speeds along radials emanating from its phased-array antenna system. The system working frequency is at 13.544 MHz for which the Bragg frequency is at 0.375 Hz in deep water, corresponding to a 11.08m wavelength. The Bragg scattering effect in the absence of surface currents results in two well defined spectral peaks (Bragg peaks) at ±0.375 Hz which in the case of surface current with radial component V are displaced from Bragg frequency by an amount Δf=(2/22.16)*V. The system emits a chirped continuous wave with a repetition frequency of 3.85 Hz and a 50 kHz bandwidth which gives a radial resolution of 3 km.