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C H A P T E R
4 :
G E T T I N G
F R A M E W O R K
τ
static
Figure 4.35: Block diagram of the complete functionality of the delay compensation
If Static Gain Compensation is checked, OPERA™ tries to determine the overall
attenuation between the two input signals and compensates for it. This option
should always be checked, if not otherwise stated in the description of the
active measurement algorithm. The total range that can be compensated for is
±
60 dB.
If Invert Test Signal is checked, the test signal is always inverted (multiplied by
–1.0).
If Auto Invert Test Signal is checked, the test signal is automatically inverted if
the system detects that reference and test signals are of different polarity.
Enabling this function also has an influence on the Automatic Delay
Compensation. The Delay compensation does not accept delays with a 180º
phase shift, unless Auto Invert Test Signal is selected.
If Remove DC From Signals is checked, a DC filter is applied to all input
signals, before they are processed by the measurement algorithm. If the signals
show a DC bias, the filters will need approximately 2000 samples to settle. DC
filtering may be used safely for signals containing no DC bias. The only side
effect may be that applying the DC filter requires additional computational
power.
Actual Measurement
After confirming the last wizard step by pressing "Finish", the actual
measurement starts. If automatic delay compensation was selected, there may
be some seconds delay before any action becomes visible. After that the
process of the measurement is visible, since the diagram panes will be updated
on a regular basis. After the measurement is completed, a small message box
will appear confirming successful termination, consequently, confirm. Use the
scrollbar at the bottom of the screen to scroll through the history buffer to view
the measurement results of past frames. The number of frames stored in the
history buffer depends on the algorithm you actually selected. The values
shown in the diagrams will be explained in the chapters describing the
algorithms.
T O
K N O W
τ
auto
.
τ
fixed
67
T H E
O P E R A ™
τ
tracking
Static Gain
Compensation
Invert Test Signal
Auto Invert Test
signal
Remove DC from
signals
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