[sdiy] I suck at halfband filters and maths...

Gordonjcp gordonjcp at gjcp.net
Sun May 27 00:10:24 CEST 2018


On Thu, May 17, 2018 at 03:45:51PM +0100, rburnett at richieburnett.co.uk wrote:
> Is this just a thought exercise or is it required for a particular
> application?
> 
> This isn't how *I* personally would make a half-band filter.  They
> are usually done with FIR filters if the ultimate aim of the game is
> to drop the sample rate down (decimation.)
> 
> FIR has a number of advantages here over IIR here:  It is inherently
> stable (even with coefficient rounding on your low-end micro,) it
> has linear phase response, and you don't need to calculate the
> output samples that you will be throwing away later in the
> decimating process.

Right, but for FIR you'd need a multiplier and a whole bunch of
registers for the taps, which I'm keen to avoid.

-- 
Gordonjcp



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