The P-band radar has been re-installed on the JSC G-III for campaigns in the East Coast and California during the second half of May.  The radar’s Differential GPS (DGPS) experienced difficulty tracking satellite broadcast of real-time GPS correctors (NAVCOM service) reliably and we have had to replace the problematic unit (FM4) with a brand new spare (FM5) which works well on the ground but has not been flight-tested.  We flew a calibration flight over Rosamond corner reflector array on Monday with FM5 and continued to have trouble with reliable DGPS solution.  There are a couple of hypotheses that we need to investigate with FM5 (and FM4), but in the interest of time, we have re-installed an older unit (FM3) that worked well on both AirMOSS and UAVSAR flights before, but its satellite mask is about to expire on June 1.  With FM3, we will be able to complete the May campaigns.