| Subject: | NSA/MMCR/C1 - Sensitivity Loss, Calibration Wrong |
| DataStreams: | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0
|
| Description: | Jay Mace compared data from CLOUDSAT to the MMCR and found significant discrepancies. It
appears that the MMCR has a sensitivity problem and is underreporting reflectivity by ~20
dBZ. A comparison with the MPL shows that this might be a gradual degradation, i.e.
there are no apparent shifts identifying when this might have occured. |
| Measurements: | nsammcrmomC1.b1: - TimeAvg
- DataQualityStatus
- StartGateDelay
- NumSpectralAverages
- SkyNoiseLevel
- RangeCorrectedPower
- base_time
- time_offset
- RadarConstant
- InterPulsePeriod
- lat
- alt
- MMCR Mean Doppler Velocity(MeanDopplerVelocity)
- NumCodeBits
- PeakTransmittedPowerAvg
- NyquistVelocity
- ReceiverNumber
- MMCR Spectral Width(SpectralWidth)
- Cloud, reflectivity, at altitude(Reflectivity)
- NumHeights
- heights
- TWTStatusCode
- Power
- NumFFT
- ReceiverMode
- AvgNoiseLevel
- RxGain
- NoiseLevel
- SignalToNoiseRatio
- Rx290KLevel
- ClutterHeight
- DCFilterONOFF
- CalCheckTime
- WindowingONOFF
- lon
- ModeDescription
- time
- RxCalTimeStamp
- CalCheckLevel
- NumReceivers
- CircularDepolarizationRatio
- NumCoherentIntegrations
- ModeNum
- PulseWidth
- MinimumDetectableReflectivity
- GateSpacing
nsammcrspecmomC1.a0: - NumSpectralAverages
- MMCR Mean Doppler Velocity(MeanDopplerVelocity)
- StartGateDelay
- Elevation
- CircularDepolarizationRatio
- InterPulsePeriod
- NumFFT
- NumCodeBits
- MinimumDetectableReflectivity
- time_offset
- Power
- Heights
- NumReceivers
- NoiseLevel
- ModeDescription
- SkyNoiseLevel
- ModeNum
- lon
- RxCalTimeStamp
- Rx290KLevel
- CalCheckLevel
- DataQualityStatus
- alt
- base_time
- CalibrationConstant
- RadarConstant
- SignalToNoiseRatio
- ReceiverNumber
- CalCheckTime
- NumHeights
- ReceiverMode
- NyquistVelocity
- AvgNoiseLevel
- MMCR Spectral Width(SpectralWidth)
- Azimuth
- WindowingONOFF
- ClutterHeight
- PulseWidth
- Cloud, doppler spectrum, at altitude, 8-mm radar(Spectra)
- NumCoherentIntegrations
- RxGain
- RangeCorrectedPower
- Cloud, reflectivity, at altitude(Reflectivity)
- DCFilterONOFF
- GateSpacing
- lat
nsammcrmomC1.00: - AVHRR satellite images for Darwin from BOM (RAW)(raw)
|
| Subject: | NSA/MMCR/C1 - MMCR TWTA Failure |
| DataStreams: | nsammcrmomC1.00, nsammcrmomC1.b1, nsammcrspecmomC1.a0
|
| Description: | The TWTA is no longer transmitting. |
| Measurements: | nsammcrmomC1.b1: - TimeAvg
- DataQualityStatus
- StartGateDelay
- NumSpectralAverages
- SkyNoiseLevel
- RangeCorrectedPower
- base_time
- time_offset
- RadarConstant
- InterPulsePeriod
- lat
- alt
- MMCR Mean Doppler Velocity(MeanDopplerVelocity)
- NumCodeBits
- PeakTransmittedPowerAvg
- NyquistVelocity
- ReceiverNumber
- MMCR Spectral Width(SpectralWidth)
- Cloud, reflectivity, at altitude(Reflectivity)
- NumHeights
- heights
- TWTStatusCode
- Power
- NumFFT
- ReceiverMode
- AvgNoiseLevel
- RxGain
- NoiseLevel
- SignalToNoiseRatio
- Rx290KLevel
- ClutterHeight
- DCFilterONOFF
- CalCheckTime
- WindowingONOFF
- lon
- ModeDescription
- time
- RxCalTimeStamp
- CalCheckLevel
- NumReceivers
- CircularDepolarizationRatio
- NumCoherentIntegrations
- ModeNum
- PulseWidth
- MinimumDetectableReflectivity
- GateSpacing
nsammcrspecmomC1.a0: - NumSpectralAverages
- MMCR Mean Doppler Velocity(MeanDopplerVelocity)
- StartGateDelay
- Elevation
- CircularDepolarizationRatio
- InterPulsePeriod
- NumFFT
- NumCodeBits
- MinimumDetectableReflectivity
- time_offset
- Power
- Heights
- NumReceivers
- NoiseLevel
- ModeDescription
- SkyNoiseLevel
- ModeNum
- lon
- RxCalTimeStamp
- Rx290KLevel
- CalCheckLevel
- DataQualityStatus
- alt
- base_time
- CalibrationConstant
- RadarConstant
- SignalToNoiseRatio
- ReceiverNumber
- CalCheckTime
- NumHeights
- ReceiverMode
- NyquistVelocity
- AvgNoiseLevel
- MMCR Spectral Width(SpectralWidth)
- Azimuth
- WindowingONOFF
- ClutterHeight
- PulseWidth
- Cloud, doppler spectrum, at altitude, 8-mm radar(Spectra)
- NumCoherentIntegrations
- RxGain
- RangeCorrectedPower
- Cloud, reflectivity, at altitude(Reflectivity)
- DCFilterONOFF
- GateSpacing
- lat
nsammcrmomC1.00: - AVHRR satellite images for Darwin from BOM (RAW)(raw)
|
| 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: | nsammcrmomC1.b1: - Power
- RadarConstant
- Cloud, reflectivity, at altitude(Reflectivity)
- RangeCorrectedPower
nsammcrspecmomC1.a0: - RangeCorrectedPower
- Cloud, reflectivity, at altitude(Reflectivity)
- RadarConstant
- SignalToNoiseRatio
- Power
|