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Lim IGARSS2011 Reduced.ppt
 

Lim IGARSS2011 Reduced.ppt

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  • 4 distributed thermisors Ambient targets maximum rate of change ~20C over 3 hours, 7C per hour Heated targets very stable Improvements with dithering of the dac
  • Approx 10C separation in the targets Will also automatically flag if there is a ‘broken’ channel – connection loose, thermal breaks, motor scanning, other mechanical issues
  • No discernable difference when Using the Hot or Ambient Counts. Future processing would take a better average of it.
  • The gain now actually represents the physical change in the system Receiver temperature does not change on small time scales
  • Instantaneous reaction to changes in the system, represented by the change in the counts. Note the thickness in the trace of the ‘smoothed’ gain Actually in the receiver
  • Even in failure situations, the calibration is robust and does not incorrectly flag data
  • Noise statistics, STD vs percentage Imperative that the flagged pixels are actually what ‘marginal’ and is not flagging good data
  • Noise statistics, STD vs percentage Imperative that the flagged pixels are actually what ‘marginal’ and is not flagging good data
  • Integrated Multispectral Atmospheric Sounders (IMAS) – NASA Code Y Technology Development Funds JPL, TRW, UMASS develop InP MMICs 55/118 downconverter units CAMEX-4 Convection And Moisture Experiment (Jacksonville, Florida) TCSP Tropical Cloud Systems and Processes (Costa Rica) NAMMA NASA African Monsoon Multidisciplinary Analyses (Cape Verde)
  • 4 distributed thermisors Ambient targets maximum rate of change ~20C over 3 hours, 7C per hour Heated targets very stable Improvements with dithering of the dac
  • 0.52 dwell time on each target Lines indicated the maximum time from the other target and the maximum time from a single ended calibration

Lim IGARSS2011 Reduced.ppt Lim IGARSS2011 Reduced.ppt Presentation Transcript

  • CALIBRATION AND PERFORMANCE OF THE HAMSR INSTRUMENT DURING THE NASA GRIP CAMPAIGN Boon Lim*, Shannon Brown, Richard Denning, Pekka Kangaslahti, Bjorn Lambrigtsen, Jordan Tanabe, and Alan Tanner Jet Propulsion Laboratory *Contact : Boon.H.Lim@jpl.nasa.gov
  • Outline
    • HAMSR Overview
    • Genesis and Rapid Intensification Processes (GRIP) Campaign
    • Data System
    • Thermal Environment
    • External target – Stability, Gradients, Reflection
    • Nominal Calibration (V0)
    • Receiver Temperature Calibration (V1)
    • Calibration Comparison (V0 vs V1)
    • HAMSR Performance
    • Summary
    7/29/2011 IGARSS 2011
  • HAMSR Overview
    • High Altitude MMIC Sounding Radiometer (HAMSR)
    • 3 Sounding Bands (55, 118 and 183 GHz)
    • 25 total channels
    • Oxygen and Water Vapor Bands for Profiling
    • Cross-Track Scanner with Ambient/Hot External Calibration Targets
    • Product of ESTO (IIP, ACT and AITT)
      • Entering 15 th Year
      • Participated in 5 Campaigns
      • Integrated on 3 Aircraft
    7/29/2011 IGARSS 2011
  • GRIP Campaign
    • Genesis and Rapid Intensification Processes Campaign
      • 5 th Coordinated Hurricane Field Campaign Since 1998
      • NOAA, NSF and the AF
    • From August to September 2010
    • DC-8 (9), Global Hawk (4) and WB-57 (2)
      • Approximately 300 flight hours
    • Hurricane Frank (Pacific), Tropical Storm Matthew (Atlantic), Hurricanes Earl and AL-92/Karl (Atlantic)
      • Global Hawk Stationed at Dryden
      • Over 120 Flight Hours for the Global Hawk
      • 20 Eye Overpasses Hurricane Karl (~13 Hours)
      • Typical flight duration 24 Hours
    7/29/2011 IGARSS 2011
  • GRIP Flights 7/29/2011 IGARSS 2011 Frank 08/28/2010 Earl 09/02/2010 Matthew 09/23/2010 AL92 09/12/2010 Karl 09/16/2010
  • HAMSR Imagery During GRIP Hurricane Earl 2010
  • Hurricane Matthew Platform Report – Scott Braun 7/29/2011 IGARSS 2011
  • HAMSR GRIP Ground Data System HAMSR ground data processor netCDF L1B files JPL Hurricane Portal HAMSR website quick look images RTMM Commanding Data downlink GHOC
  • HAMSR software upgraded after GRIP to provide real-time imagery over Iridium Successfully tested during 2011 WISPAR campaign HAMSR RTMM Display for GRIP
  • Thermal Environment
    • HAMSR Sits in an Unpressurized Pod
    • RF Section is Thermally Insulated with Styrofoam
    • Temperature Controlled Heaters on the RF Plates
      • Thermistors Available Across the Instrument
      • RF Components (RF/IF LNAs, Mixers), RF Plate Temperatures, Motor, Power Supply, Digital System, Computer, Etc
    • Fans for Circulation of Air
      • On Runway if Temperatures Exceed a Threshold
    • At Flight Altitude (~17 km)
      • Temperature Typically -15 0 C
    7/29/2011 IGARSS 2011
  • WISPAR 2011- Thermal Environment 7/29/2011 IGARSS 2011
  • External Target - Stability
    • Thermistors Embedded in Targets
    • Ambient Target Drifts Freely
      • Rate of Change 6-7 o C/Hour
    • Hot Target Held at ~68 o C
      • Oscillation at 120 Second Period, 0.01K<
    7/29/2011 IGARSS 2011
  • External Target - Gradients
    • Gradients Across the Target Pixels
      • Typically Monotonic
      • Magnitude Under 0.3K
      • Easily Mitigated with Averaging
    7/29/2011 IGARSS 2011
  • External Target - Reflections
    • Standing Waves Setup in the Middle of the Target
      • Despite Low Return Loss Material (~35 dB)
      • Only in Several Frequencies
      • Remove Central Pixels
    7/29/2011 IGARSS 2011
  • Initial Processing
    • Moving Average of the Hot and Ambient Counts
      • Period of the Heating Oscillation (~110 Seconds)
    • Time ‘Shift’ in Ambient Counts
      • Account for linear time drifts
    • Calculate Per-Scan Gain
      • Gain = (C Hot – C Amb )/(T Hot – T Amb ) [C/K]
    • Flag Unusable Pixels (-2)
      • Insufficient Separation of the Hot and Ambient Targets
      • Differential Temperatures on Targets, 5xNEDT
      • Differential Gain, Threshold (empirical)
    7/29/2011 IGARSS 2011
  • Nominal Processing
    • Moving Average of Gain
    • Calculate Antenna Temperature
      • T A = (Ct – C Amb )/Gain + T Amb
    • Standard Calibration Stratagy
    • Gain Drifts/Jumps Distributed in the Averaging
    • Incorrectly Processes ‘Good’ Data
    7/29/2011 IGARSS 2011
  • Receiver Temperature Calibration
    • Calculate Receiver Temperature
      • T Rx = C Amb /Gain - T Amb
    • Smooth Receiver Temperature
    • Calculate Gain (from Hot Target)
      • G Hot = C Hot /(T Rx +C Hot )
    • Calculate Gain (from Ambient Target)
      • G Amb = C Amb /(T Rx +C Amb )
    • Average Gain
      • Gain = (G Hot +G Amb )/2
    • Calculate Ta
      • T A = (Ct – C Amb )/Gain + T Amb
    7/29/2011 IGARSS 2011
  • Comparison – Gain Smoothing 7/29/2011 IGARSS 2011
  • Comparison – Spikes 7/29/2011 IGARSS 2011
  • Comparison – Robustness 7/29/2011 IGARSS 2011
  • Flag Marginal Pixels
    • Pixels that Exhibit Larger than Expected Noise
      • Temperature is Over 3.5x NEDT
      • Empirical Value for Each Channel
      • For End-Product Users
    7/29/2011 IGARSS 2011
  • Marginal Pixels 7/29/2011 IGARSS 2011
  • Flag Marginal Pixels Second Check
    • Receiver Temperature Calibration
    • Close to the Theoretical Values for Noise
    7/29/2011 IGARSS 2011
  • Instrument Performance
    • As Derived from the Data
      • Hurricane Karl
    • 55 GHz Performs the Poorest
      • Legacy Hardware
      • Upgrade in Progress (~4dB)
    • 118 GHz and 183 GHz Upgraded During AITT
    • Performance is as Expected from the Receiver Temperatures
    • 99.9% Up-Time
      • 1 Channel Dropped Out for 3 Hours
    7/29/2011 IGARSS 2011
  • Summary
    • External Targets Well Characterized
    • HAMSR Successfully Participated in GRIP Campaign
      • Data System Utilized High Bandwidth Link (‘Real-Time’)
      • Utility was Immediate in Directing the GH Flight Path
    • Calibration Methodology Relies on Stability of Receivers
      • Front End LNAs vs Entire Gain Chain
    • HAMSR Receivers as a System Perform to Measured Receiver Temperatures
    • WISPAR Campaign Had Coincident Dropsondes
      • Absolute Calibration Comparison Pending
    • Instrument calibration and characterization (Brown et al., TGRS, in press)
    7/29/2011 IGARSS 2011
  • Backup Slides
    • HAMSR Timeline
    • HAMSR Block Diagram
    • External Target Construction
    • Pre-Flight Evaluation
    • Allan Variance LN2 Stare
    • GRIP – Agency Coordination
    • Danielle, Earl and Fiona
    7/29/2011 IGARSS 2011
  • HAMSR Timeline 7/29/2011 IGARSS 2010=1
  • HAMSR Block Diagram 7/29/2011 IGARSS 2011
  • External Target - Construction
    • Pyramidal Blackbody Calibration Targets
      • Ambient and ~68 0 C
    • Commercial Product with -50dB Return Loss Spec
      • Heavy Aluminium Coated with a Ferrite Loaded Epoxy Absorbing Material
      • 16x12 cm Area, 4 cm Long Pyramids, 1 cm Apart at Tips
    • 4 Thermistors Embedded in Targets at the Tips
    • Insulated in Styrofoam
      • ~35dB Return Loss
    7/29/2011 IGARSS 2011
  • Pre-Flight Evaluation – Scan Bias
    • Within the field of view, minimal bias in the various channels
    • 50 GHz channels:
      • Bias < 0.5 K for -45 o < θ < 45 o
    • 118/183 GHz channels:
      • Bias < 0.25 K for -45 o < θ < 45 o
    7/29/2011 IGARSS 2011
  • Allan Variance LN2 Stare 7/29/2011 IGARSS 2011
  • GRIP – Agency Coordination 7/29/2011 IGARSS 2011
  • Danielle, Earl and Fiona 7/29/2011 IGARSS 2011