Exam B-IQFILT

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Exam 6.0.3[edit]

B-IQFILT.jpg

B-Mode Imaging[edit]

The RF data is low-pass filtered in the base band after down mixing. The order of filter (number of taps) is proportional to IQ Window Factor (see here). The Cutoff Frequency is in percent of the sampling frequency/2.

  • IQ Window Factor
  • Cutoff Frequency

To account for the downshifting of the center frequency of the RF signal as a function of depth, the carrier frequency used in the IQ demodulation is not constant but is sliding. More accurately it changes linearly with depth. The frequency used at the top of the image (depth zero) is Top Frequency. The frequency used at the Bottom Frequency Depth is Bottom Frequency.

  • Top Frequency
  • Bottom Frequency
  • Bottom Frequency Depth

Harmonic Imaging[edit]

When doing PIH imaging, the carrier frequency is double the frequency of the transmitted pulses. Therefore another set of values are needed for harmonic imaging:

  • Top Frequency Base
  • Bottom Frequency Base
  • Bottom Frequency Depth Base

The harmonic signals are typically weaker than the original signals, specially for deeper tissue. Therefore the harmonic images are always blended into the b-mode images. Percentage of blending is determined by Blend Percent Base where 0 mean no blending and 100 means full blending. The depth to start the blending for harmonic and B-mode images is determined by Blend Depth Base 1. The depth to maximize the blending for harmonic and B-mode images is determined by Blend Depth Base 2.

  • Blend Depth Base 1
  • Blend Depth Base 2
  • Blend Percent Base

TODO[edit]

  • B-iq Fast Processing