A sunny day although windy at times. We worked at all three ISS sites today, the main issue was the ISS3 profiler
ISS1 (Santa Barbara county offices): Connected and powered up the CL61 ceilometer, although the data ingest on the DM computer isn't up yet.
ISS2 (Rancho Alegre): John hooked up the ISS3 wind profiler front-end to the ISS2 profiler and made some diagnostic measurements. The ISS2 profiler worked well with the ISS3 front-end which suggests a problem with the antenna at ISS3. Also we installed the NR01 solar radiation sensor and Gary did DM and DSM work in preparation for the training sounding tomorrow.
ISS3 (Sedgwick): More diagnosing of the problems with the wind profiler. John did some return loss and frequency response measurements on the antenna and some of its elements. He found that the peak response of the antenna was around the 905 - 909 MHz range instead of the 915 MHz that is should be. It appears to have drifted over time for some reason, perhaps the antenna substrate has degraded. It may be that this is causing the more significant return loss seen on this antenna as compared to the ISS2 antenna (something around 30% as compared to around 5% at ISS2). The stronger signals being reflected in the antenna may be bouncing back into the front-end receiver chain showing up as clutter like signals. He added a second circulator and limiter to try to suppress it, but that doesn't seem to help.