SAEVO EVUS 8, Руководство пользователя

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6 Acquiring Images
Basic User Manual 73
■ High Pulse Repetition Frequency
Once HPRF is enabled, besides the original sample volume gate, one or more sample volume gates appear at
shallower positions on the 2D image.
The unnecessary low frequency signal or the disturbances made by non-flow movements, such as breath, heart beat
or sweeps of the probe will be filtered.
To enable the High Pulse Repetition Frequency:
Flip the
PRF
switch upwards to increase the value continuously, HPRF is automatically enabled when a certain
value is reached.
■ Baseline
Baseline represents the position of zero velocity or frequency. The velocity range in one direction can be increased
or decreased by adjusting the baseline.
Baseline is used to eliminate the alias during color flow imaging, and display higher velocities without reversal of
colors.
To adjust the baseline:
1. Select the
Menu
key in the real time PW/CW mode. A menu pops up on the screen.
2. Select Baseline by using the trackball or the ↑ or ↓ key.
3. Rotate the Menu key or select the ← or → key to move the baseline towards the positive or negative direction.
4. The speed scale on the y-axis at the bottom right of the screen varies with the baseline.
You can also flip the BASELINE switch to change the position of the baseline.
■ Wall Filter
Wall filter is used to filter the low frequency noise from tissues, such as the vascular wall.
To adjust the wall filter:
1. Select WF by pressing the corresponding function key.
2. Rotate it to adjust the value.
■ Frequency
The probe is capable of generating a broadband signal with a certain frequency and bandwidth. The frequency
optimizes the edges when scanning deeper locations with Doppler imaging.
To adjust the frequency:
1. Select
Frequency by pressing the corresponding function key.
2. Rotate it to adjust the value.
■ Sweep Speed
Sweep speed is used to set the sweep speed of the Doppler trace. The refresh speeds of the time scale and the
frequency scale vary with the sweep speed.
To adjust the sweep speed:
1. Select
Sweep Speed by pressing the corresponding function key.
2. Rotate it to adjust the value.