🚀 go-pugleaf

jefft@phred.UUCP (Jeff Taylor) writes:

>: 30

>All the postings on 180 deg phase shifts reminds me of standard questions I
>ask when interviewing for positions which require some knowledge of DSP.

>	"WHEN WOULD YOU USE A FIR FILTER?"

>	"If I wanted a linear phase linear phase characteristics."

>	"HOW DO YOU GET A LINEAR PHASE CHARACTERISTIC? "

>	"Have a symeterical time response."

>	"WHERE ARE THE ZEROS?

>	"On the unit circle."

>	"DOESN'T THAT GIVE PHASE SHIFTS OF 180 DEG'S?

>(it's kind of fun watching people sort through the dichotomy - everyone KNOWS
> symeterical fir filters have linear phase, but the zeros are on the unit
> circle - which does give a 180 deg phase shift)

>I suppose it depends on how one wants to interperate signal inversion.

"... but the zeros are on the unit circle" ??????

O.K. smartass, I'll play your game:

    H(z) = (1+0.5 z^-1)(1+2z^-1)
         = 1 + 2.5z^-1 + z^-2

Looks symmetric, looks too me like either you are wrong or
0.5/1 = 2/1 = 1.


Nothing like interviewing someone, trying to screw them up, and
being completely wrong, eh ??

The zeros are not on the unit circle.

>-- 
>-----------------------------------------------------------------------------
> Jeff Taylor
> Physio Control Corp.
>-----------------------------------------------------------------------------
--
Wilf LeBlanc, Carleton University, Systems & Comp. Eng. Ottawa, Canada, K1S 5B6
Internet: wilf@sce.carleton.ca   UUCP: ...!uunet!mitel!cunews!sce!wilf
                Oh, cruel fate! Why do you mock me so! (H. Simpson)