
420 VisualSonics Vevo 2100 Imaging System Operator Manual Rev 1.1
Appendix C: Descriptions of control panel controls
Velocity
Adjusts the PRF (pulse repetition frequency). The higher you set the PRF, the
lower the signal resolution.
In PW Doppler Mode: Adjust the range of the scale of the Y axis on the Power
Doppler Mode image window by adjusting the pulse rate frequency of the
ultrasound signal. Use this control when the spectral waveform is either too
compressed or too expanded for your purposes.
Note: In the General tab of the Preferences window you can set the PW Doppler Scale
(Y axis) to display either velocity or frequency.
Turn the dial clockwise to compress the waveform by increasing the range of the
scale. Turn counterclockwise to expand the waveform by decreasing the range of
the scale.
Volume
Adjusts the speaker volume for the PW Doppler Mode and PW Tissue Doppler
Mode audio data that the system acquires along with the spectral data.
To use this dial control:
Turn clockwise to increase the volume.
Turn counterclockwise to decrease the volume.
Active during: PW Doppler Mode and PW Tissue Doppler Mode image
acquisition and review sessions.
Wall Filter
Filters out signals that correspond to low velocity axial motion. Typically these
include vessel wall movement, cardiac wall movement and tissue movement
caused by respiration. Push up to filter out more. Pull down to filter out less.
In PW Doppler Mode: Use this control to filter out the display of low velocity
signal artifacting that appears as a horizontal black band along either side of the
white baseline. Push up to reduce the lower velocity signals and bring the
waveform of the spectral data closer to the baseline. Pull down to display more
low velocity signals.
In Color Doppler Mode and Power Doppler Mode: Set as low as you can so that
you don't lose any flow, but higher than any motion that creates low frequency
artifacting.
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