DQR ID | Subject | Data Streams Affected |
---|---|---|
D050714.4 | SGP/MMCR/C1 - Poor cross polar isolation | sgpmmcrmomC1.b1 |
D100826.1 | SGP/MMCR/C1 - Dual polarization modes discontinued | sgpmmcrmomC1.b1 |
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 |
---|---|---|---|
08/25/2010 | 1453 | 01/04/2011 | 1400 |
Subject: | SGP/MMCR/C1 - Dual polarization modes discontinued |
DataStreams: | sgpmmcrmomC1.b1 |
Description: | During a heat spell, the MMCR shelter internal temperature approached 100 F after the air conditioner failed. Either the heat, or a UPS failure, caused a failure of the MMCR radar computer hard disk. I had a spare computer shipped from Barrow and installed it on 8.24.2010. I was unable to get the dual polarization modes working. With help from Coy Chanders (the software developer) and Ken Moran (the hardware developer), we were able to determine the problem was the spare was running an older version of Lap-XM. Since the MMCR will be upgraded in two months and the antenna (to be replaced in September and its cross-polarization isolation makes cross-polarization essentially worthless), I decided to eliminate the dual-polarization modes. Dual polarization will return with the MMCR upgrade in October. The MMCR was removed from service 20110104 to be replaced by the KAZR instrument. |
Measurements: | sgpmmcrmomC1.b1:
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