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I have this problem where I have to design a low pass filter with a slope of -6dB/octave. Now I don't know what this means and How to get it done? I would be glad if anybody could help me out understanding the concept behind it and how it is related with the performance of the filter?

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  • $\begingroup$ To give you a hint, an "octave" is a doubling in frequency, and magnitude quantities in dB are 20*log10(magnitude). -6 dB/octave means a rolloff of 1/f (you should confirm that). So how can you make a filter that rolls off at the rate of 1/f? $\endgroup$ – Dan Boschen Mar 17 '17 at 20:42
  • $\begingroup$ Analog or digital filter? $\endgroup$ – MBaz Mar 17 '17 at 21:25
  • $\begingroup$ @DanBoschen I just made a regular low pass filter using remez() and at the end of it i found that it had -6dB/octave roll off in the stop band. How is it related with the performance of the filter? A couple of things I can think of are that it makes the transition band narrower, and makes faster roll off possible. I hope I am right. $\endgroup$ – Copernicus Mar 20 '17 at 17:59
  • $\begingroup$ @MBaz it is digital. $\endgroup$ – Copernicus Mar 20 '17 at 17:59
  • $\begingroup$ How is -6dB/Octave roll-off related with the performance of the filter? It is the performance of the filter, so not really sure what you are asking? Faster roll-off means something more than -6 dB/Octave, which can be achieved at the expense of longer filters, longer delay. $\endgroup$ – Dan Boschen Mar 20 '17 at 18:31