Select +/- on the [Smooth Fall] key to select the fall filter.
FALL: This filter leads to prolongation of the displayed flow. Usage with quick
pulses (short "color flashes") prolongates them for better evaluation on the
monitor.
Select +/- on the [Smooth Rise] key to select the rise filter.
RISE: Filtering of the rise velocity leads to noise suppression. To be used with
small laminar flows. Avoid quick movements of the probe, because the flow is
"built up" slowly. When displaying pulses the Rise-Filter must be set low.
8.7.20 Sweep Speed
PW CW CF PD HD-Flow TD
X - - - - -
The “Speed” control allows selection of variable sweep speeds. The faster sweep speed may
be useful to analyze flow curves. For example, to calculate a mean pressure gradient then it
will be much easier to do this on a fast speed trace than on a low speed trace.
By Selecting - or + three different sweep speeds can be selected.
3,5 cm/s 5,0 cm/s 7,5 cm/s 10,0 cm/s (in relation to the system’s monitor)
8.7.21 Threshold
PW CW CF PD HD-Flow TD
- - X - - -
After [Freeze]
you can adjust the Color Threshold. This function eliminates small color noise or
motion artefact signals in the Color image or alternatively can be viewed as similar to the gain
control in scan mode.
Switch on/off this mode by Selecting the [2D+2D/C] key.
A small number cuts off fewer signals than a higher number.
8.7.22 Velocity Range (PRF)
PW CW CF PD HD-Flow TD
- - X X X X
The displayed velocity range is governed by the pulse repetition frequency (PRF). As you
increase PRF the velocity range increases. As the display scale increases, the maximum
Doppler shift information that can be displayed without aliasing also increases. Aliasing is
where the blood velocity exceeds the maximum measurable velocity, causing the displayed
Doppler Modes
8-40
Voluson® S6/S8 Basic User Manual
5433669-100 Revision 4
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