The system operates at 449 MHz, and is unique in that the antenna uses a Yagi element array rather than a coaxial-collinear array. By using Yagi elements, each with their own phase-shifter, the antenna can point anywhere within a cone above the radar, +/- 25 degrees. Additionally, this allows the antenna to have very good sidelobe performance. The ability to continuously and actively steer the antenna beam is used to enable the radar to avoid pointing its main beam at the aerostatthus preventing any illumination of the aerostat payload, and greatly reducing interfering backscatter to the wind profiler. The antenna array is composed of 192 elements, but the antenna and transmitter systems were both designed for scaled use, so that other sizes of antennas and transmit power levels are available depending on data requirements.
Other important features of the system are the use a digital intermediate-frequency (IF) receiver and Advanced Signal Detection (ASD) algorithms. With the digital IF, the receiver is greatly simplified and is very reliable. The ASD software utilizes multiple peak-picking and identification routines, and time-height continuity analysis to screen out radio frequency interference, aerostat caused or other interfering clutter, birds, and other non-atmospheric backscatter signatures. The ASD routines also allow for shorter averaging times and higher data update rates than traditional processing.
The first two systems have been installed in India, with a third system scheduled for installation in Kuwait in Fall 2005. The systems were fully tested in Colorado, before shipment. A full system description will presented along with data products and comparisons.
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