The WSR-88D Radar Operations Center is charged with evaluating the new signal processor, digital receiver, and software algorithms under development by the Office of Science and Technology. The ROC is responsible for ensuring that ORDA signal processing, including base moment estimators and clutter filters, meets NEXRAD program functional requirements. Additionally, operations center team members will evaluate the capability of the ORDA system to support enhancements identified by the user community as important for advancing the utility of the radar network. The team is focusing on several near term enhancements. These improved techniques include higher resolution base products, range-velocity ambiguity mitigation, range over sampling, and full power spectral analysis.

The ROC team plans to use several evaluation methods. Engineers will use a digital signal simulation utility to characterize the signal processor algorithms, initially focusing on spectrum width. The spectrum width estimators are of interest because the ORDA allows use of the poly-pulse or lag 2-covariance estimator in addition to the basic estimator deployed with the WSR-88D. This evaluation project addresses performance differences in the two estimators and will review ORDA design and selection criteria. The commercial signal processor supplier, SIGMET, Inc., will provide improvements to the clutter filter design and these functions will also be evaluated.

In addition to simulated data, the engineering team plans to use time series data during the evaluation. The ROC team has access to a number of time series data sets recorded from several legacy WSR-88D systems. Through use of a software utility, this data can be inserted into the ORDA processing chain for analysis. The results can then be compared to base moment outputs generated by the legacy systems. Additionally, ROC engineers have developed a time series recording capability for the ORDA. Recorded data sets can then be processed by off line spectral analysis programs. The output of the spectral analysis processes will then be regressed with the results from the ORDA moment estimators. The engineering team will pay particular attention to differences such as increased variance and estimator bias. The analysis will be conducted with a variety of weather parameters, including selected ranges of signal spectrum widths.

This paper will review the engineering process, including theory, simulation results, and live data analysis. Preliminary results of the base moment evaluations will be presented.