Forums

Soft and hard filter length

Started by manlightman September 18, 2015
Hi guys,

I'm currently working with an AD ADSP-21489 processor. This generation has
3 destict hardware accelerators which can perform fft fir and iir
computations.

Skipping through the manual, I came across the terms "soft" and "hard"
filter length in the FIR chapter.

Can someone enlighten me? Is this basic knowlege?

greets
Pete


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manlightman <103114@DSPRelated> wrote:

>Hi guys,
>I'm currently working with an AD ADSP-21489 processor. This generation has >3 destict hardware accelerators which can perform fft fir and iir >computations.
>Skipping through the manual, I came across the terms "soft" and "hard" >filter length in the FIR chapter. > >Can someone enlighten me? Is this basic knowlege?
Never heard of it before. Steve
On 9/18/15 12:26 PM, Steve Pope wrote:
> manlightman<103114@DSPRelated> wrote: > >> Hi guys, > >> I'm currently working with an AD ADSP-21489 processor. This generation has >> 3 destict hardware accelerators which can perform fft fir and iir >> computations. > >> Skipping through the manual,
which manual? and what page?
>> I came across the terms "soft" and "hard" >> filter length in the FIR chapter. >> >> Can someone enlighten me? Is this basic knowledge? > > Never heard of it before.
the only think i can imagine is a time-variant or modifiable FIR in which, at instantiation time certain amount of memory for the circular buffer is allocated. that might be the "hard" length. but the FIR could be modified in such a way that the impulse response has length of an integer no longer than the hard filter length. that might be the "soft" length. i dunno. -- r b-j rbj@audioimagination.com "Imagination is more important than knowledge."
On Fri, 18 Sep 2015 09:19:10 -0500, "manlightman" <103114@DSPRelated>
wrote:

>Skipping through the manual, I came across the terms "soft" and "hard" >filter length in the FIR chapter. > >Can someone enlighten me? Is this basic knowlege?
I suspect that "soft" refers to filters implemented purely in software, while "hard" refers to filters executed in the hardware FIR accelerator. Otherwise, a quick Google search of the AD literature this morning produced nothing. Greg
Greg Berchin <gjberchin@chatter.net.invalid> wrote:
> On Fri, 18 Sep 2015 09:19:10 -0500, "manlightman" <103114@DSPRelated> > wrote:
>>Skipping through the manual, I came across the terms "soft" and "hard" >>filter length in the FIR chapter.
(snip)
> I suspect that "soft" refers to filters implemented purely in software, > while "hard" refers to filters executed in the hardware FIR accelerator. > Otherwise, a quick Google search of the AD literature this morning > produced nothing.
I was thinking hard (fixed), vs soft (variable), but then that almost means hardware vs. software. With FPGAs, you might still have some possibility for variable length. Then again, firm. -- glen