Design FIR filters by number of taps


#1

In looking at the tools for designing FIR filters, I see that you can do
it
by selecting cutoff frequencies and transition bandwidths. Is there a
block
already in existence that allows you to design an FIR filter based on
cutoff
frequency and maximum number of taps where the transition bandwidth
would be
variable based on the taps? I didn’t notice one, but this would be very
helpful to me. Thanks.

John

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#2

On Tue, Apr 18, 2006 at 08:37:55AM -0700, jjw wrote:

In looking at the tools for designing FIR filters, I see that you can do it
by selecting cutoff frequencies and transition bandwidths. Is there a block
already in existence that allows you to design an FIR filter based on cutoff
frequency and maximum number of taps where the transition bandwidth would be
variable based on the taps? I didn’t notice one, but this would be very
helpful to me. Thanks.

John

There are lots of ways to design filters.

We provide two: gr.firdes.* (windowed design) and optfir.* (Parks
McClellan)

In both of them, you specify the characteristics that you want, and
the code figures out the number of taps that it takes to get what you
asked for. This approach seemed to make the most sense.

If you want to specify the number of taps, you’re on your own.
The guts of the windowed design code may be useful.

Eric