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Scanning Modes
Vivid i User’s Manual
95
2378958-100 Rev. 02
PW and CW Doppler controls
PW and CW Doppler assignable controls
Horizontal sweep
Adjusts the horizontal refresh rate of the Doppler area of the
display. Horizontal sweep is available in live and cine replay.
Baseline
Enables the Doppler baseline to be shifted up and down. The
default Doppler baseline is set at the center of the vertical
aspect of the Doppler display, dividing evenly the flow toward
and away from the probe. By adjusting the baseline a larger
portion of the analysis is assigned to the flow direction present.
Baseline is available in live and cine replay.
Maximum velocity
depends on sample
volume size, sample
volume position and
frequency settings.
Velocity range
Enables the vertical scale of the Doppler spectrum and the
maximal detectable velocity to be modified. Velocity range
directly controls the pulse repetition frequency, which is
responsible for the setting of the Nyquist limit (the ability to
detect maximum velocity without aliasing).
Scale
Enables the low velocity portions of the spectrum to be filtered,
since the Doppler spectrum and audio may contain strong
wall-motion signals. The amount of Low Velocity Reject. is
indicated by the green vertical bar at the right end of the
baseline.
If the Doppler mode
is combined with
Color mode, the
color map will be
also inverted.
Invert
Enables the Doppler spectrum to be flipped 180 degrees, so
that negative velocities are displayed above the baseline and
positive velocities below the baseline. Invert is available in live
and cine replay.
LPRF (PW mode)
Sets the pulse repetition frequency for the PW Doppler
acquisition of flow data. Enables toggling between high and low
Pulse Repetition Frequency (PRF). When the Doppler PRF is
raised beyond a certain limit, more than one Doppler gate is
displayed on the screen.