DQRID : D070716.4
Start DateStart TimeEnd DateEnd Time Data Quality Metric
01/01/2006000010/17/20070200Incorrect
more
Subject:
NSA/MMCR/C1 - Antenna Feed Corrosion
DataStreams:nsammcrspecmomC1.a0, nsammcrmomC1.b1
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.
Suggestions: 
Use the reflectivity data for geometric cloud boundary detection only.  Beware that 

we may not be seeing all of the clouds.
Measurements:nsammcrmomC1.b1:
  • Power
  • Reflectivity
  • RadarConstant
  • RangeCorrectedPower
more
nsammcrspecmomC1.a0:
  • RangeCorrectedPower
  • SignalToNoiseRatio
  • RadarConstant
  • Reflectivity
  • Power
more

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