SNR issues: Definitions, theory and practice

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SNR issues Definitions, theory and practice

• Emmitt and OHandley
• Simpson Weather Associates
• Working Group on Space-based Lidar Winds
• June 28- July 1, 2005
• Welches, Oregon

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Issues

• What is the correct figure of merit for obtaining
  the correct LOS wind speed from a coherent DWL?
• Which SNR should we use?
• CNR, wideband, narrow band
• Peak, FWHM, power under spectral feature
• Complex returns due to shear and velocity
  variation

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Peak detection

• Perform complex FFT on each shot and account for
  variation of transmitted frequency and start of
  digitization
• Accumulate the spectrum of N shots
• Level noise floor
• Pick the spectral peak within the search window
  (10 m/s)

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1000 shot accumulation
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Questions?

• How does feature broadening lower threshold of
  signal detection?
• How can we get independent measure of beta on
  experiment days?

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Backup slides
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