| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D070716.4 | NSA/MMCR/C1 - Antenna Feed Corrosion | nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| D071205.1 | NSA/MMCR/C1 - Antenna rotation | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| D071214.2 | NSA/MMCR/C1 - Reprocess: Antenna Gain Error | nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| D080218.2 | NSA/MMCR/C1/C2 - Wrong Polarization | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2006 | 0000 | 10/17/2007 | 0200 |
| Subject: | NSA/MMCR/C1 - Antenna Feed Corrosion |
| DataStreams: | nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| Description: | During a trip to Barrow, I inspected the feed under the antenna and noticed an extreme amount of corrosion that has resulted in the flexible waveguide connected to the feed to be pushed off at an angle with corrosion in between. I attempted to remove and clean but the corrosion has effectively welded the two pieces together. This didn't happen overnight and the start date is a guess. The last inspection of the antenna probably took place in April 2004 when we did the C40 DSP upgrade. I don't know how much the reflectivity is affected by this corrosion. It may be possible to get an idea once we replace the antenna by making some intercomparison measurements. The feed was temporarily repaired on 10/16/2007 until the new antenna was installed. The measured loss before and after the repair was 5.1 dB. This means that the MMCR was under-reporting reflectivity by 10.2 dB just before it was repaired. That said, there is no way of ascertaining what the rate of corrosion was and how the loss changed during the period of this DQR. One can assume that the 5.1 dB loss was the worst that it was. |
| Measurements: | nsammcrspecmomC1.a0:
nsammcrmomC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/01/2007 | 0000 | 12/01/2007 | 2359 |
| Subject: | NSA/MMCR/C1 - Antenna rotation |
| DataStreams: | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| Description: | A new antenna was installed and the orientation of the antenna feed caused a rotation of the polarization by 90 degrees. Since this is a zenith pointing radar, the polarization orientation is arbitrary and should have no appreciable effects. |
| Measurements: | nsammcrmomC1.00:
nsammcrspecmomC1.a0:
nsammcrmomC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/01/2007 | 0000 | 12/14/2007 | 2156 |
| Subject: | NSA/MMCR/C1 - Reprocess: Antenna Gain Error |
| DataStreams: | nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| Description: | The antenna gain used in the calibration table was for the old antenna (54.3 dBi). The new gain figure was received today and it is 52 dBi. The antenna designer stated that the gain has an unexpected and unexplained minimum at the design frequency (34.86 GHz.) |
| Measurements: | nsammcrspecmomC1.a0:
nsammcrmomC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/01/2007 | 0100 | 02/14/2008 | 0200 |
| Subject: | NSA/MMCR/C1/C2 - Wrong Polarization |
| DataStreams: | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0 |
| Description: | The new antenna was mistakingly set to transmit/receive in circular polarization instead of linear polarization. The result is that reflectivities are much lower than they should be. Since we only measure on polarization channel, there is no way to apply a correction to go from circular to linear polarization. |
| Measurements: | nsammcrmomC1.00:
nsammcrspecmomC1.a0:
nsammcrmomC1.b1:
|