a typical gain around 53 dB using a center-fed parabolic antenna. The pulse repetition frequency (PRF) varies from 318 to 1300 Hz with a maximum power output of 700 kW at Klystron output, although dependent on the volume coverage pattern (VCP) selected by the operator. All NEXRADs have a dish diameter of 9.1 m (30 ft) and an aperture diameter of 8.5 m (28 ft). Using the predetermined VCPs, NEXRADs have a traditional elevation minimum and maximum ranging from 0.1 to 19.5 degrees, although the non-operational minimum and maximum spans from −1 to +45 degrees. Unlike its predecessor, the WSR-74, the antenna can not be manually steered by the operator. WSR-88D Level I data is the recorded output of the digital receiver. Spatial resolution varies with data type and scan angle – level III data has a resolution of 1 km x 1 degree in azimuth, while super-res level II, (implemented in 2008 nationwide), has a resolution of 250m by 0.5 degrees in azimuth below 2.4 degrees in elevation. Scan strategies The NEXRAD radar system continually refreshes its three-dimensional database via one of several predetermined scan patterns. These patterns have differing PRFs to fit the respective use, but all have a constant resolution. Since the system samples the atmosphere in three dimensions, there are many variables that can be changed, depending on the desired output. With all traditional VCPs, the antenna scans at a maximum of 19.5 degrees in elevation, and a minimum of .5, with some coastal sites scanning as low as .2 or lower. Due to the incomplete elevation coverage, a phenomenon known as "The Cone of Silence" is present with all NEXRAD radars. The term describes the lack of coverage directly above the radar sites. There are currently seven Volume Coverage Patterns (VCP) available to NWS meteorologists, with an eighth in the process of replacing one of the existing seven. Each VCP is a predefined set of instructions that control antenna rotation speed, elevation angle, transmitter pulse repetition frequency and pulse width. The radar operator chooses from the VCPs based on the type of weather occurring: Clear Air or Light Precipitation: VCP 31, 32, and 35 Shallow Precipitation: VCP 35, 112, and 215 Non-Tropical Convection: VCP 12, 212, and 215 Tropical System Convection: VCP 212, 215, 112, and 121 The specific VCP currently in use at each NEXRAD site is available. Enhancements Super resolution Deployed from March