Extended Abstract (128K)9B.3
Digital IF receiver—capabilities, tests and evaluation
Igor Ivic, CIMMS/University of Oklahoma, Norman, OK; and A. Zahrai and D. Zrnic
A commercial digital receiver has been integrated into the Research WSR-88D Doppler weather radar system in Norman, OK. The receiver was originally built for the cellular phone market but it has suitable characteristics for radar use. It has a 14 bit A/D converter and can operate at 100 MHz sampling rate. The chosen sampling frequency equals 5/3 (about 95 MHz) of the intermediate frequency. In this manner an integer number of samples at the output coincides exactly with the prescribed gate spacing in range (250 m) for the WSR-88D system. Moreover, as the receiver clock is derived from the intermediate frequency it is completely synchronous with the gate spacing and pulse repetition times. The receiver has two programmable Finite Impulse Response (FIR) filters. The weights are designed for two modes of operation. One is the standard digital matched filter mode which is equivalent to the analogue matched filter. The second mode is for generating oversampled signals; oversampling by a factor of 10 or 5 is almost automatic for the sampling frequency we have in the system. Other oversampling factors can be programmed into the receiver. Measured dynamic range is over 90 dB and spectral artifacts are below measurable values of the system. Examples of the dynamic range for the two modes of operation will be shown as well as select spectra from meteorological and ground scatterers.
Session 9B, Signal processing
Sunday, 10 August 2003, 4:00 PM-6:00 PM
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