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From: jefft@phred.UUCP (Jeff Taylor)
Newsgroups: comp.dsp,sci.electronics
Subject: Re: 180 deg phase shift
Message-ID: <3404@phred.UUCP>
Date: 20 May 91 20:25:27 GMT
References: <1991May8.222501.19572@syd.dms.CSIRO.AU> <1991May10.003817.5593@milton.u.washington.edu> <625@fudd.dataco.UUCP> <1991May15.055011.5823@milton.u.washington.edu>
Reply-To: jefft@phred.UUCP (Jeff Taylor)
Organization: <1991May15.055011.5823@milton.u.washington.edu>o
Lines: 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.



-- 
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 Jeff Taylor
 Physio Control Corp.
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