On Sat, 17 Mar 2012 10:15:17 +0000
"Poul-Henning Kamp" <p...@phk.freebsd.dk> wrote:
> In message <20120317111119.9536107ebf82050fe14ee...@kinali.ch>, Attila Kinali
> w
> rites:
> >On Sat, 17 Mar 2012 10:01:13 +0000
>
> >Could you explain why? Yes, you need a higher BW for Loran-C,
> >but the phase(f) function will give you only a distortion of
> >the signal and a constant time delay in your signal recovery.
> >But that shouldnt degrade the usefullness of the system.
> >What am i missing here?
>
> 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.
>
> The more you disturb a Loran-C pulse, the more it just looks like
> a bit of a sine-function, and the harder it is to lock on the right
> zero-crossing.
Ah.. so it is because Loran-C uses the third zero crossing as specified
measurement point, which you thus have to capture with the greates
possible resolution.
Am i right that for DCF77, WWVB and the like, where there is no such
requirement on the zero crossing of a pulse, one can just lock to the
carrier and the distortions from filters are not so relevant?
Attila Kinali
--
Why does it take years to find the answers to
the questions one should have asked long ago?
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