[time-nuts] GPS Phase locked Local Oscillator experiment

[Magnus Danielson]

From: bg at lysator.liu.se
Subject: Re: [time-nuts] GPS Phase locked Local Oscillator experiment
Date: Thu, 8 Mar 2007 17:13:04 +0100 (CET)
Message-ID: <50126.125.24.152.4.1173370384.squirrel at webmail.lysator.liu.se>

Björn,

> On Thu, March 8, 2007 12:53, Magnus Danielson said:
> 
> >> Is this not pretty much the setup that HP was refering to in the paper
> >> and patent that Magnus dug out some weeks ago.
> >
> > The big difference is that Peter used another GPS clock as reference. By
> > that
> > he is actually doing a delta measurement between the receivers. Hooking
> > the 3325 up to a Cesium would be a much more interesting measurement.
> 
> Hmmm... do you mean that the 1-pps from the GPSDO is "raw" 1pps from its
> internal receiver?

No.

> I really do not understand. Please elaborate.
> 
> Its kind of a duality in the receivers. The GPSDO receiver is using a
> lousy internal crystal producing relatively noisy 1pps-pulses being
> cleaned up by a very good oven crystal. The modified receiver takes a very
> good clock to drive it, then using the relatively noisy 1pps circutry of
> the GPS-receiver.

My point was rather that the frequency of the crystal and thus the generated
19.something MHz clock of the VP is already in GPS time (so to say) so then
looking at the data and PPS comming out of it measures only the receiver
degradation. It doesn't really show the stability of the timing acheived.
Not that it is not interesting, the 74 second ticks are, but one should not
confuse the findings, that's all what I want to imply.

> >> Its good news that the atmosphere is well behaved!
> >
> > Wait for the sunspot high-season before anouncing something like that! ;)
> 
> Lets rephrase. Its good news that the atmosphere can be well behaved at a
> randomly chosen spot.

The common view from the same antenna or possibly from two antennas separated
with only a handfull of meters away should give such result. The atmosphere is
relatively smooth in this regard.

Cheers,
Magnus