Function "lowpass()" Behavior Dependent on Sampling Rate?
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Hi folks,
I'm trying to determing the bandwidth of amplifier I'll need, as part of control system.
So I wrote up a simulator script and got this waveform:
Fig.1: Waveform from simulator output
Then I tried to apply a lowpass filter to the waveform, and see how the signal will be warped by the limited bandwidth.
I tried to use the "lowpass()" function provided in the signal processing toolbox:
Fig.2: Call of the lowpass function
Here comes the wierd part, the output do not change when I changed the variable "bnd_f", which should be the cut-off frequency. But when I changed the simulator time resolution (i.e. 1/sampling rate), the output from "lowpass()" changed.
Fig.3: The changed value res_t is highlighted
Fig.4: Resolution = 1ns
Fig.5: Resolution = 5ns
Fig.6 Resolution = 10ns
I'm so confused by what's going on. Any suggestion is highly appreciated!
Many Thanks,
Anyu
1 个评论
Anyu
2024-9-20
Seems like I posted the wrong picture for Resolution = 5ns, here's the correct one:
Replace Fig.5: Resolution = 5ns
回答（1 个）
Rishav
2024-9-20
0 个投票
Hi Anyu,
Yes, the 'lowpass' function in MATLAB is dependent on the sampling rate of the input signal.
Please refer to the following documentation to know more about the 'lowpass' function:
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