ORPG Build 5.0 brings many new enhancements for the meteorological community. Of the many enhancements, two in particular are the two new Volume Coverage Patterns (VCPs): VCP 12 and VCP 121.

- VCP 12 has a 4.1 minute duration and improved vertical resolution at low angles. The Antenna will rotate at speeds ranging from 3.5rpm - 5rpm completing 17 slices in a span of 4.1 minutes per Volume scan.

- VCP 121 is used with the Multiple Pulse Repetition Frequency Dealiasing Algorithm(MPDA). MPDA combines velocity data from up to three Doppler sweeps (at the same elevation angle) with differing Pulse Repetition Frequencies (PRFs) to mitigate range and velocity aliasing problems. The Antenna will rotate at speeds ranging from 2.72rpm - 5rpm completing 20 slices in a span of 5 minutes per Volume scan.

During Beta testing at seven radar sites there were two systems that generated pedestal alarms during VCP 121. What we found was the Pedestal Electronics required alignments. The procedures accomplished were:

• NWS 6-514 (paragraph 3-6.5.2 through 3-6-5.2.4)
• AFTO 31P1-4-108-201 (paragraph 3-6.5.2 through 3-6-5.2.4)
• FAA TI 6345.1 V22 (paragraph 3-6.5.2 through 3-6-5.2.4)

Note VCP 12 and VCP 121 turn the Pedestal/Antenna faster than before. Faster rotational speeds will require the pedestal system to be properly aligned. Proper performance of the Pedestal Electronics is critical to the operation of the new VCPs. Please continue to perform the Pedestal PMIs as scheduled and take actions to service the system when required. If you require further assistance, feel free to contact the WSR-88D Hotline.