Siemens SITRANS F - Cursor Use on the Spectra Graph

7-6
1010ENFM-3BSection 7
7.11 HOW TO USE SPECTRA GRAPH DATA AND CONTROLS
When you first access the Spectra Graph, the data shown on the top highlighted line shows Velocity in
feet-per-second (F/S) on the left side and the volumetric Flow Rate in the current rate units on the right
side. You can scroll the data shown using the <Up and Down> Arrows.
Pressing the <Up Arrow> changes the data in the highlight to [Diagnostic Data] containing, from left to
right: (Hz) Doppler shift frequency in Hertz, (mV) Signal Amplitude in millivolts, (FFT Pk) Peak FFT mag-
nitude and (%D) FFT Percent Deviation. Carefully inspect the data for Signal Amplitude and Percent
Deviation. Refer to the “Available Adjustments to Spectra Graph” table in paragraph 7.12 and the “Reflexor
Diagnostic Data” table found in paragraph 7.13. Press the <Down Arrow> to return to Velocity.
Press the <Down Arrow> from Flow Velocity in feet per second (F/S) to advance to the Noise Level Set
cursor control. A numeric indication of the Noise Level Cursor position is provided in the highlighted area.
Refer to the “Available Adjustments To Spectra Graph” table found in paragraph 7.12.
Adjust the Noise Level cursor, if required, by pressing the <+> key to increase or <-> key to decrease.
NOTE: A delay in response to all keys will occur. This is due to the longer periodic sampling of
the keyboard by the processor while performing FFT’s.
Press the <Down Arrow> from Noise Level to advance to the High Limit cursor control. The <+> and <->
key are active in this position. Refer to the “Available Adjustments To Spectra Graph” table found in
paragraph 7.12.
7.10 CURSOR USE ON THE SPECTRA GRAPH
CURSOR USAGE TIPS
High Limit Cursor
This cursor appears as a vertical line on the right side of the Spectra
Graph. All signals to the right of this line will be excluded from the flow
calculation. Use this adjustment if the right side of the Spectra Graph has
noise that is larger in amplitude than the signal that is produced by flow.
The cursor may be arbitrarily placed at two times the maximum flow
expected.
Low Limit Cursor
This cursor appears as a vertical line on the left side of the Spectra Graph.
All signals to the left of this line will be excluded from the flow calculation.
Use this adjustment if the left side of the Spectra Graph has noise that is
larger in amplitude than the signal that is produced by flow. The cursor
may be arbitrarily placed at one half the minimum flow expected.
Noise Level Set Cursor
This cursor appears as a horizontal line on the Spectra Graph. All signals
below this line will be excluded from the flow calculation. Position the
cursor approximately one quarter the height of the FFT peak.