DQR ID | Subject | Data Streams Affected |
---|---|---|
D050714.4 | SGP/MMCR/C1 - Poor cross polar isolation | sgpmmcrmomC1.b1 |
D070717.1 | SGP/RL/C1 - Invalid liquid water channel data | sgprlC1.a0 |
Start Date | Start Time | End Date | End Time |
---|---|---|---|
08/15/2004 | 0000 | 08/27/2010 | 2100 |
Subject: | SGP/MMCR/C1 - Poor cross polar isolation |
DataStreams: | sgpmmcrmomC1.b1 |
Description: | This last spring, Sergey Matrosov pointed out that the Circular Depolarization Ratio measurements on the SGP radar indicated the isolation between the co and cross channels was only about 15 dB. Typically isolation of 25-30 dB is expected for polarization measurements to be useful. We set about to see if we could identify the source of the poor isolation. Kevin Widener had purchased a custom built orthomode transducer and polarizer that hadn't gone through any previous testing and we decided to swap it out with an ETL unit that had shown good isolation in the past. Kevin performed the swap a couple of weeks back and this week the latest archive data was available to compare results between the OMTs. Results from two precipitating cloud conditions, where we looked below the melting layer, where we expect to find domination of spherical water droplets and therefore maximum values for cdr - the maximum isolation (CDR) appears to be about 17 dB. The results showed that the poor isolation is probably not due to the OMTs but rather to the antenna itself. |
Measurements: | sgpmmcrmomC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
09/06/2006 | 1920 | 03/05/2008 | 0000 |
Subject: | SGP/RL/C1 - Invalid liquid water channel data |
DataStreams: | sgprlC1.a0 |
Description: | On 20060906, the liquid water channel (LWC) was disabled due to the removal of its photomultiplier tube (PMT). Consequently, the signals recorded for the LWC contain either zero or pure noise after that date. Also, starting on 20070522, the LWC was populated with data from the T2 channel as a result of a slight reconfiguration of the data acquisition system. On 4 March 2008 The LW channel photomultiplier tube was reinstalled in the Raman lidar. Effective 0000 UTC on 5 March 2008 the LW channel began producing valid liquid water data once again. |
Measurements: | sgprlC1.a0:
|