Wet and moist sandy soils enhance the ground wave propagation, whereas dry and rocky grounds reduce signal strengths. A single CODAR system can measure only the component of surface current travelling toward or away from the radar so, to determine the total surface current vectors, it is necessary to use at least a two-system setup. An array of CODAR sites can be employed to obtain regional coverage. In a multiple radar configuration, spacing between two radar systems should be approximately 15 to 40 km for long-range open ocean mode and 8 to 20 km for “higher frequency, higher resolution, shorter range” mode. Typically, CODAR data are averaged over one hour to reduce the noisiness of the sea echo. Therefore, current maps can be produced every hour. This period can be reduced to approximately 20 minutes, however the data may become noisy over such a short period. CODAR’s measurements are interesting for both military and civil purposes. Main applications are for example coastal engineering and public safety projects, planning of navigational seaways, mitigation of ocean pollution, search and rescue operations, oil-spill mitigation in real time and larval population connectivity assessment. Also, data obtained by using CODAR are used as inputs for global resource monitoring and weather forecasting models and are particularly helpful for tidal and storm-surge measurements. Moreover, from the measurements can be extracted the direction of propagation of wave energy and the period of the most energetic waves, which are important data for many practical applications in design and operation of coastal and offshore structures. CODAR operates using sky transmission of waves in the high frequency (HF) band (3–30 MHz), as electromagnetic waves in this band have wavelengths that are commensurate with wind-driven gravity waves on the ocean surface. According as the customer necessities, it can be used in single or multi-frequency mode. As the ocean has a rough surface, when a high frequency signal reaches the ocean surface, a portion of the incident energy is scattered back towards the source and the receiver measures the reflected signal. This backscattering (or reflection) produces an energy spectrum at the receiver, even if the energy source is single-frequency, because of the shape and motion of the sea surface. Interpreting the spectral returns for various transmit frequencies is the key to extracting information about the ocean  and, specifically, to measure surface currents. As a consequence of Bragg’s Scattering Law; the strongest received return comes from ocean waves traveling directly toward or away from the radar source and whose physical wavelength is exactly one-half as long as the transmitted radar wave.