[time-nuts] Z3801A predicted holdover phase drift convergence

Magnus Danielson cfmd at bredband.net
Tue Aug 2 08:04:11 UTC 2005


From: "Tom Van Baak" <tvb at leapsecond.com>
Subject: Re: [time-nuts] Z3801A predicted holdover phase drift convergence
Date: Mon, 1 Aug 2005 17:52:00 -0700
Message-ID: <002901c596fc$6529f260$3918f204 at computer>

> Is that a typo: 100-200 us?

I am sorry to say no, it is not a typo. This is why I started to wonder.

> Check out:
> 
> http://www.realhamradio.com/GPS_websites_list.htm
> 
> 10 us to 1 us or even sub-us is ok. But if it's
> really over 100 us something for sure is not
> working right.

Which I assumed.

> Send me a some plots and we can work it out. Antenna type; feed cable,
> obstructed sky view, signal level, number of sats in view, surveyed position,
> etc.

All in due time. Also, I have yeat to move the antenna.

Currently I have the antenna with its 6 meter long cable hooked directly to the
Z3801A using only the necessary BNC to N adapter. The antenna is not the most
phase-stable one around, a no-namer really. My signal levels is usually in the
80-100 range for a few satellites (1-3) and then about 1-3 reaching the other
span (20-79). Usually have something like 4-5 satellites. Antenna position is
not optimal, but at least some consideration of unobstructed skyview. A real
scetch is however a little hard to acheive.

Cheers,
Magnus

> /tvb
> 
> ----- Original Message -----
> From: "Magnus Danielson" <cfmd at bredband.net>
> To: <time-nuts at febo.com>
> Sent: Monday, August 01, 2005 14:48
> Subject: [time-nuts] Z3801A predicted holdover phase drift convergence
> 
> 
> > Hi!
> >
> > I have been monitoring my Z3801A and noticed that the predicted hold over
> > time/phase drift (i.e. frequency error) is fluctuating in the 100-200 us
> per
> > day range. Am I expecting too much, or should I really expect this to be
> an
> > acceptable level?
> >
> > Recalculating it to frequency error it would be an initial fractional
> frequency
> > error of 1,157E-9 to 2,315E-9. That is not bad, but I would assumed a
> little
> > better without thinking things thru. If somebody done the thinking, please
> > enlighten me on the details, I am sure it will make sense.
> >
> > Cheers,
> > Magnus
> >
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> 
> 
> 
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