Digital Signal Processing Reference
In-Depth Information
bandpass filter design using a Hamming window, and with low and high cut-
off frequencies of 500 and 1000 Hz, respectively. Select Operate
Run. In
Figure 9.23, the upper graphs show both the input sine wave generated with
LabVIEW and the output of the filter implemented on the DSK. The theo-
retical frequency response of the designed filter is also plotted showing a
center frequency at 750 Hz. Vary the input signal frequency between 300 and
1200 Hz and verify that the filter's output amplitude starts with zero, reaches
a maximum at 750 Hz, and then decreases again towards zero.
Change the filter settings for a lowpass with a bandwidth (low cutoff
frequency) of 1500 Hz. Vary the frequency of the input signal between 0 and
1600 Hz. Verify that the amplitude and frequency of the filtered output signal
are the same as those of the input signal for frequencies between 0 and 1300
Hz. The output signal's amplitude decreases towards zero for input frequen-
cies beyond 1300 Hz.
Various windows for the filter design are available, such as Hamming,
Hanning, Blackman, and so on. Experiment with different filter characteristics.
2.
From Figure 9.23, select Window
Æ
Show Block Diagram. The LabVIEW
tools are required to view the block diagram (the source). Figure 9.24 shows
a section of the block diagram that contains various components (smaller
Æ
FIGURE 9.24.
LabVIEW block diagram for FIR filter design through RTDX for the project
rtdx_lv_filter
.
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