A couple weeks ago (check the archives around 26 July 2009) I posted some
plots of the PPS/OSC error estimates when the receiver's position was
intentionally offset from its true position. The results were rather
dramatic... And the quality of the data scaled with the position error. It
ce
On Fri, Aug 14, 2009 at 07:30, wrote:
>
>
> Magnetic flux could have an effect on atomic standards,
> but they normally have magnetic shielding to mitigate
> this effect. Orientation (or at least acceleration)
> can affect cesium beam standards because the atoms
> are flying. Len Cutler put in
Hi Tom - how about the Trimble NTPX26AB-06 made for Nortel Z3801 clone -
where does this rank compared to the T-Bolt? It seems to run the same
software.
Regards, John, K1AE, Bolton, MA, USA, newbie time-nut.
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@fe
With a good (geodetic/survey) quality antenna I get my location to
within a few inches. With a conical timing antenna, I get around
8 inches of error. With a cheap patch antenna, around a foot.
HI Mark,
A couple more thoughts.
I still question the value of all this for a cheap receiver suc
Rick is right.
The effect you see when turning your GPSDO upside down will be
predominantly the direct gravitational effect on the OCXO crystal and
its mountings. You see this with any OCXO, and the good ones will have a
'2G turnover' or other G rating quoted.
For example, the well known HP 10811
I have developed some code that processes a 24-48 hour survey
to calculate a precise position. With a good (geodetic/survey)
quality antenna I get my location to within a few inches. With a
conical timing antenna, I get around 8 inches of error. With a
cheap patch antenna, around a foot.
Ni
Hi there,
there are special low-g OCXO's out there. We offer one that has better than
3E-010 per g per axis, which is about 10x better than your "standard"
OCXO.
This is also important for stationary applications where the unit is not
tilted, for vibration-induced phase-noise is also that
>
> Date: Thu, 13 Aug 2009 15:34:43 -0700 (PDT)
> From: "Rick Karlquist"
> Subject: Re: [time-nuts] OCXO sensitive to gravity
> To: "Discussion of precise time and frequency measurement"
>
> Message-ID:
>
> Content-Type: text/plain;charset=iso-8859-1
>
> Tom Duckworth wrote:
> > The or
Date: Thu, 13 Aug 2009 15:34:43 -0700 (PDT)
From: "Rick Karlquist"
Subject: Re: [time-nuts] OCXO sensitive to gravity
To: "Discussion of precise time and frequency measurement"
Message-ID:
Content-Type: text/plain;charset=iso-8859-1
Tom Duckworth wrote:
> The orientation change is
Rick Karlquist wrote:
> Len Cutler put in a fix to mitigate against this in the 5071A CBT.
How so? Is there a 3-axis accelerometer in the 5071A?
-ch
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> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Lux, Jim (337C)
> Sent: Thursday, August 13, 2009 4:01 PM
> To: rich...@karlquist.com; Discussion of precise time and frequency
> measurement
> Subject: Re: [time-nuts] OCXO sensitive
Some caution is in order as some ferrites used in RF transformer coils
may be permanently altered by application of a strong magnetic filed.
Testing at lower fields first would be safer.
Setupo a pair of Helmholtz coils and excite them with low frequency AC
and look for associated sidebands in the
once again, a simple experiment would suffice. Got a refrigerator magnet
handy?
Don
Lux, Jim (337C)
>> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of Rick Karlquist
>> Sent: Thursday, August 13, 2009 3:35 PM
>> To: Discussion of p
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Rick Karlquist
> Sent: Thursday, August 13, 2009 3:35 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] OCXO sensitive to gravity
>
> Tom Duckwo
No, no. It's the rho mesons. See Mark Alpert's "Final Theory."
Excuse me, please.
Bill Hawkins
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Tom Duckworth
Sent: Thursday, August 13, 2009 4:53 PM
To: Discussion of precise time and f
Tom Duckworth wrote:
> The orientation change is due more to the earth's magnetic flux effect on
> the oscillator, and less so from gravity.
>
> Tom
> Tom Duckworth
> tomd...@comcast.net
Sorry, this is simply incorrect. Magnetic flux from the
earth has no effect on quartz oscillators. There is n
Tom
Really?
What mechanism do you have in mind?
In practice the same effect is observed when the Earths magnetic field
is cancelled using a set (3 pairs) of Helmholtz coils (or equivalent) or
in a magnetically sheilded enclosure?
Bruce
Tom Duckworth wrote:
> The orientation change is due more t
The orientation change is due more to the earth's magnetic flux effect on
the oscillator, and less so from gravity.
Tom
Tom Duckworth
tomd...@comcast.net
- Original Message -
From: "John Green"
To:
Sent: Thursday, August 13, 2009 11:02 AM
Subject: [time-nuts] OCXO sensitive to gravit
A while back there was some discussion about crystal oscillator's changing
frequency due to the effects of gravity. Since I got my Z3801 up and running
full time, I have been trying to characterize some OCXOs I had picked off
eBay but had no specifications for. I was trying to fine tune one to the
Does anyone know if support for this is still available to those who
bought it through TAPR? TAPR refer inquiries to CNS who do not answer
my emails.
It's not a big problem, simply that I upgraded to the latest version
(2.7.8) only to find that I didn't have the password, and could not
reve
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/39389/1/05-2893.pdf tells you
what JPL is up to at the deep space network, where we do things that are
similar to, if not the same as, you'd be doing at a radio observatory.
http://trs-new.jpl.nasa.gov/dspace/handle/2014/38025 has more details
W
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