DQR ID | Subject | Data Streams Affected |
---|---|---|
D050714.4 | SGP/MMCR/C1 - Poor cross polar isolation | sgpmmcrmomC1.b1 |
D080324.1 | SGP/MMCR/C1 - Sensitivity Shift | sgpmmcrmomC1.b1 |
D080421.2 | SGP/MMCR/C1 - Polarization Mode Problem | sgpmmcrmomC1.b1, sgpmmcrspecmomC1.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 |
---|---|---|---|
02/21/2008 | 1930 | 02/26/2008 | 1500 |
Subject: | SGP/MMCR/C1 - Sensitivity Shift |
DataStreams: | sgpmmcrmomC1.b1 |
Description: | There was a sensitivity shift on the MMCR during this period of time. Cycling the power cleared the problem. Do not use data. |
Measurements: | sgpmmcrmomC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
04/17/2008 | 1400 | 04/23/2008 | 1445 |
Subject: | SGP/MMCR/C1 - Polarization Mode Problem |
DataStreams: | sgpmmcrmomC1.b1, sgpmmcrspecmomC1.a0 |
Description: | The cross-polarization and co-polarization modes (6 and 5) were measuring cross-polarization only. This means that one of the control signals was not hooked up correctly. The signals were rerouted on 4/23/2008. The General Mode (mode 3) is a co-polarization channel and worked during this time period. The reason why we don't use the general mode all of the time is that the co-pol and cross-pol modes are temporally closer and make a better estimation of linear depolarization ratio. |
Measurements: | sgpmmcrmomC1.b1:
sgpmmcrspecmomC1.a0:
|