TRMM/PR suffered a lose of its original (A-side) electronics interface. Fortunately JAXA/NICT had designed and built the TRMM PR with redundancy (B-side). On May 29, the A-side began to be a problem and the process of switching to the B-side electronics was begun. This changeover including investigation took about 2 weeks.

NASA/PPS have been operating PR with the B-side since June 17. B-side electronics have slightly different characteristics than the A-side and JAXA has been carefully investigating the best way to calibrate the PR so as to maintain continuity with the A-side driven measurements. This has required not only internal calibration information but also several external calibrations. It has also required looking at a longer period of data using B-side to ensure it is fully understood. These re-calibration of B-side took about 5 months.

Please refer to a report of the PR V6 1B21 B-side calibration coefficients and retrieved level 1, 2, 3, statistical results (pdf ).