[time-nuts] WWVB BPSK Receiver Project? (fwd)

[Attila Kinali]

On Sat, 17 Mar 2012 06:13:28 -0700
gary <lists at lazygranch.com> wrote:

> On 3/17/2012 5:44 AM, Attila Kinali wrote:
> > On Sat, 17 Mar 2012 10:15:17 +0000
> > "Poul-Henning Kamp"<phk at phk.freebsd.dk>  wrote:
> >
> >> Either you need to characterize the exact behaviour of your filter
> >> and build the necessary compensation for its phase/frequency behaviour
> >> into your receiver, or you need a very flat filter (both freq+phase)
> >> in order to reliably recognize the proper zero-crossing to track.
> >
> > BTW: how do you compensate for the filter characteristics of your
> > magnetic loop antenna?

> Any filter's group delay can be equalized by all pass filters.
> 
> Delay builds up at the filter corner. Since everything in the real world 
> is causal, you add delay outside that corner frequency but in the 
> passband to equalize it. This is to say, you can't remove delay, but 
> just add it to flatten out the group delay.

Sorry, i asked in a misleading way. I didnt mean to ask what technique
to use to flaten the phase delay, but rather how does phk know how the
compensating filter should look like? For this, one needs to exactly
characterize the antenna-amplifier chain...AFAIK

			Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?