32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Sunday, 10 August 2003: 4:00 PM
Range-Velocity Mitigation via SZ Phase Coding with Experimental S-band Radar Data
J.C. Hubbert, NCAR, Boulder, CO; and G. Meymaris and R. J. Keeler
Poster PDF (2.4 MB)
The fundamental range and velocity measurement limitation of pulsed radar systems is expressed by the following equation


where ra, va are the unambiguous range and velocity, respectively, for wavelength L and where c is the speed of light.Since the product rava is a constant for a particular wavelength, increasing either one (ra or va) necessarily decreases the other. For L=10 cm (S-band) and a typical pulse repetition time (PRT) of 1ms, ra=150km and va=25m/s. Weather phenomena routinely exceed both of these limits. Phase coding of the transmit pulses for single polarization radars has been shown to be an effective method for the separation of range overlaid echoes thus extending ra without compromising va. NCAR has been funded by the Radar Operations Center (ROC) of Norman, OK to investigate and implement phase coding for real time operation on NCAR's S-Pol. The goal is to develop and verify a phase coding algorithm for the NWS (National Weather Service) WSR-88D radars. To date phase coding statistical performance has only been shown for simulated Gaussian shaped weather spectra. It is well know that weather spectra shapes can deviate significantly from Gaussian. In this paper examples of data quality improvement via SZ phase coding of experimental S-band radar data are given. Statistical performance plots are shown and compared to numerical simulations.

Installation of the new Sigmet RVP8 radar signal processor into S-Pol (due to take place in May 2003) will make real time phase coding for S-Pol possible. Results are given.

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