Chapter 16 Dynamic Range

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Chapter 16Dynamic Range
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Dynamic Range

• A method of reporting the extent to which a
  signal can vary and still be accurately measured
• A relative measurement, ratio, between the
  largest smallest signals
• Ratio of the largest power to smallest power that
  a system can handle
• Ratio of the largest to the smallest intensity of
  a group of echoes
• Units
• Decibels (dB)

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Dynamic Range

• The ultrasound systems individual components
  have different dynamic ranges
• The dynamic range of information decreases the
  more it is processed

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Calculating Dynamic Range

• Divide the bigger voltage by the smaller voltage
• Result will be a factor of ten, e.g. 10, 100,
  1000, etc.
• Count the number of zeros in the number
• For each 0, there is 20 dB more of dynamic
  range

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Compression of Dynamic Range

• A technique which reduces the dynamic range of a
  signal without introducing errors
• The largest signal remains the largest
• The smallest signal remains the smallest
• The range of signals is reduced
• Sonographer adjustable
• Dynamic range of the human eye is narrower than
  that of the systems display
• Mathematics of Compression
• Decibels add or subtract
• Review and understand the examples on pg. 261

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Dynamic Range - of Choices

• Dynamic range can report the number of possible
  gray shades
• Narrow dynamic range
• Fewer gray shades
• High contrast
• Wide dynamic range
• Many shades of gray
• Low contrast

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Dynamic Range - of Choices