[time-nuts] GPS: ADEV or MDEV?

Magnus Danielson cfmd at bredband.net
Sat Apr 14 09:08:39 EDT 2007


From: bg at lysator.liu.se
Subject: Re: [time-nuts] GPS: ADEV or MDEV?
Date: Sat, 14 Apr 2007 14:46:42 +0200 (CEST)
Message-ID: <1678.125.24.131.37.1176554802.squirrel at webmail.lysator.liu.se>

> On Sat, April 14, 2007 13:32, Magnus Danielson said:
> > From: Peter Schmelcher <nebula at telus.net>
> > Subject: Re: [time-nuts] GPS: ADEV or MDEV?
> > Date: Sat, 14 Apr 2007 02:40:57 -0700
> > Message-ID: <5.2.1.1.2.20070414001036.02afa7d0 at pop.telus.net>
> >
> >>
> >> >Surely its better to detect the pseudorange instability in software (if
> >> >one has access)  rather than attenuating the signal from all SVs.
> >> >Another option is to use multiple GPS antennae operating as a phased
> >> array.
> >> >
> >> >Bruce
> >>
> >> Of course but I think that approach is part of sub nanosecond time
> >> transfer
> >> accuracy. Attenuation is simple and the results are descent. The signal
> >> is
> >> less than 6dB above the receiver noise floor to acquire SV.
> >> Unfortunately
> >> the SV do not have matched output power so they are acquired and
> >> weighted
> >> unequally.
> >
> > The difference in path-length and thus space attenuation is compensated by
> > the
> > antenna pattern such that it emits stronger to the rimb of its earth view
> > than
> > central. That evens out power-shifts due to space attenuation for the
> > viewer.
> > Otherwise we would have yeat another problem to deal with.
> 
> Do the HP GPSDOs not have a tuneable maskangle?

Maskangle is indeed setable.

Cheers,
Magnus




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