9-4
IM DLM6054-01EN
Setting an IIR Filter (IIR Low Pass/IIR High Pass)
Press the IIR Low Pass or IIR High Pass soft key to display the following menu.
Set the filter order (1, 2).
Set the cutoff frequency.
Explanation
You can apply a phase-shift, moving-average, or IIR filter to the source waveform.
Filter Type (Setup)
Set the filter type to one of the settings listed below.
• Delay: Displays a phase-shifted waveform.
• Moving Avg: Displays a waveform whose noise has been eliminated through
moving averaging.
• IIR Lowpass or IIR Highpass:
Displays a waveform whose noise has been eliminated through an
IIR filter.
IIR Filter (Low Pass IIR/High Pass IIR)
You can use a first-order low-pass filter and a differentiator to apply low-pass and high-pass filters.
Computation Source Waveform
You can select a waveform from CH1 to CH4 or M1.
*
* You can select M1 when the selected trace number (Select Trace) is one of the numbers from
M2 to M4.
Cutoff Frequency Setting (Cut off)
You can set the cutoff frequency to a value up to 1 GHz.
Filter Order Selection (Filter Order)
This setting varies depending on the selected filter type.
Filter Type Order Phase Change
High Pass 1 The phase advances.
Low Pass 1 The phase lags.
High Pass/Low Pass 2 The phase does not change.
Note
IIR filter calculation cannot be performed correctly immediately after the start of calculation, because the
initial value is indeterminate. This why with a first-order filter, the left end of the waveform is not shown, and
with a second-order filter, both ends of the waveform are not shown.
Smoothing (Moving Avg)
The DL6000/DLM6000 averages waveform values according to the following equation.
xn=(Σ xi + Σ xi)/(2N×2)
i=n-N
i=n-N+1
(when the weight is set to 2N)
Weighted Points
Set the number of points to use for moving averaging to a value from 2 to 128.
Phase Shift (Delay)
You can set the delay to a value within the range of time corresponding to ±5 divisions.
9.3 Performing Filter Computations
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