On Sat, 04 May 2013 22:00:36 -0700
Hal Murray hmur...@megapathdsl.net wrote:
mspencer12...@yahoo.ca said:
Hi, while skimming some articles I found re GPS satellites, I found some
references to certain buffer gasses in Rb cells working much better with
optical filters than others. As far
On Sat, 4 May 2013 12:36:20 -0700
Tom Van Baak (lab) t...@leapsecond.com wrote:
Rule of thumb: quartz is best short term, Rb or H-maser mid-term,
and Cs by far the best long-term.
Ah.. so it's a fundamental limitation. And i was looking for something
GPS specific.
Any references i could read
On Sat, 4 May 2013 16:31:42 -0700 (PDT)
Mark Spencer mspencer12...@yahoo.ca wrote:
The article available for download via this URL contains some history
about development issues with Rb and Cs Clocks for GPS. It seems at
one point after the GPS system was placed into service a development
On Sat, 04 May 2013 21:53:00 -0700
Hal Murray hmur...@megapathdsl.net wrote:
Radio astronomers use H-masers. Can I assume that they are mid-term and that
H-masers are better than Rb (at mid-term)?
Disclaimer: I'm not into astronomy. What i write below is solely based
on what i've stumbled
On 05/05/2013 10:05 AM, Attila Kinali wrote:
On Sat, 4 May 2013 12:36:20 -0700
Tom Van Baak (lab)t...@leapsecond.com wrote:
Rule of thumb: quartz is best short term, Rb or H-maser mid-term,
and Cs by far the best long-term.
Ah.. so it's a fundamental limitation. And i was looking for
Hi fellow time nuts!
I've recently bought a Trimble Acutime gold that will be used as a
reference clock for a NTP server.
This receiver has the possibility of averaging it's position before
entering what Trimble calls the overdetermined clock state. The
default is to average the position with
In message 8311230247672528820@unknownmsgid, =?ISO-8859-1?Q?Miguel_Barbosa_Go
n=E7alves?= writes:
This receiver has the possibility of averaging it's position before
entering what Trimble calls the overdetermined clock state. The
default is to average the position with 2000 fixes.
What do you
On 5 May 2013 11:51, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message 8311230247672528820@unknownmsgid,
=?ISO-8859-1?Q?Miguel_Barbosa_Go
n=E7alves?= writes:
This receiver has the possibility of averaging it's position before
entering what Trimble calls the overdetermined clock state.
Hi
All the data is in an adev plot. In this case short is 100 seconds, and long
is 10,000 seconds. Those are rough numbers, since a really good Rb (like
Corby's) may cross over a bit earlier. A really crummy Cs (low beam current)
might not cross over for a couple of days against a well
Hi
Something like 48 hours is a good idea *if* you have the time to do them.
Bob
On May 5, 2013, at 7:34 AM, Miguel Barbosa Gonçalves m...@mbg.pt wrote:
On 5 May 2013 11:51, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message 8311230247672528820@unknownmsgid,
On 5/5/13 1:48 AM, Magnus Danielson wrote:
On 05/05/2013 10:05 AM, Attila Kinali wrote:
On Sat, 4 May 2013 12:36:20 -0700
Tom Van Baak (lab)t...@leapsecond.com wrote:
Rule of thumb: quartz is best short term, Rb or H-maser mid-term,
and Cs by far the best long-term.
Ah.. so it's a
What is the relationship between the T'Bolt survey fixes number (e.g. 2000)
and number of hours duration of the survey? Is it one fix per second or
something? What number of fixes should be input to accomplish a 24 hour or a
48 hour survey?
Second question: how is the survey duration set on
Hi
Mercury was tried very early on as a vapor standard. They had some significant
problems with it in the 1950's. It's not surprising that after 60 years
somebody might want to take another swing at it.
Bob
On May 5, 2013, at 9:59 AM, Jim Lux jim...@earthlink.net wrote:
On 5/5/13 1:48 AM,
Hi
I believe it's one fix per second on the TBolt. LH is your friend when it comes
to long surveys on the TBolt. Being able to see what's going on is *very*
useful.
Bob
On May 5, 2013, at 10:15 AM, James Robbins jsrobb...@earthlink.net wrote:
What is the relationship between the T'Bolt
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
When people say rubidium is inferior to cesium, they
Usually the survey is accomplished by one fix per second so for a 24hour
survey you need 86400 fixes.
About the second question, you'll have to read the manual but I think that
the position hold can be stored to be retained after power cycles. Usually
the survey length can be set.
On Sun, May 5,
If the only use of the GPS receiver is to drive NTP, then 2,000
seconds is long enough NTP runs at the microsecond level and the tiny
remaining error after 2000 seconds will never be noticed by NTP.
However if you are really nuts and want to do the best you can then
let it run for 12 hours.
All the data is in an adev plot... The cross overs will happen... you have
to measure them.
True, but then what do you do?
It is not quite as simple or easy as it may sound.
Although it is a good place to start,
for best results in a GPSDO you can not just compare the ADEV crossover
points of
On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
When
Hi Jim,
On 05/05/2013 03:59 PM, Jim Lux wrote:
On 5/5/13 1:48 AM, Magnus Danielson wrote:
The above is a summary of things collected from a variety of sources,
but I think this coarse walk-through of issues gives some insight as to
what issues pops up where and the milage vary a lot within
On 05/05/2013 06:50 PM, Jim Lux wrote:
On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is important to understand that
the architecture is the key
On 5/5/13 10:05 AM, Magnus Danielson wrote:
On 05/05/2013 06:50 PM, Jim Lux wrote:
On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is important
On 5/5/13 10:01 AM, Magnus Danielson wrote:
Hi Jim,
On 05/05/2013 03:59 PM, Jim Lux wrote:
On 5/5/13 1:48 AM, Magnus Danielson wrote:
The above is a summary of things collected from a variety of sources,
but I think this coarse walk-through of issues gives some insight as to
what issues pops
On 05/05/2013 04:15 PM, James Robbins wrote:
What is the relationship between the T'Bolt survey fixes number (e.g. 2000) and number
of hours duration of the survey? Is it one fix per second or something? What number
of fixes should be input to accomplish a 24 hour or a 48 hour survey?
If
On Sun, 5 May 2013 09:53:31 +0200
Attila Kinali att...@kinali.ch wrote:
[1] I know i have some papers which anylse different buffer gasses, but
i cannot find them. I also have never seen anyone mention non-elementary
gasses like CO2.
Correction. I just remembered reading somewhere, someone
In message caedntmsjwt0suxbzdrnz3enyw6xhuvlhvmfw_cmq5r8etay...@mail.gmail.com
, =?ISO-8859-1?Q?Miguel_Barbosa_Gon=E7alves?= writes:
So you think a full day of position survey will be better?
I don't know if it is as sensitive on your lattitude as mine (56N)
but here N*12 hours works best, for as
In message 51867df4.4010...@karlquist.com, Richard (Rick) Karlquist writes:
BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
Well, somewhat.
Some flavours of atoms don't work with some architectures, so for
most of the stuff in reach for us,
Hi Jim,
On 05/05/2013 07:33 PM, Jim Lux wrote:
On 5/5/13 10:05 AM, Magnus Danielson wrote:
They have been targeting this goal for a very long time. Several
interesting papers is to be found at PTTI, NIST etc.
Yeah.. some years (6 or 7?) ago, John Prestage had a prototype of the
physics
On Sun, 05 May 2013 18:29:53 +
Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message 51867df4.4010...@karlquist.com, Richard (Rick) Karlquist
writes:
BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
Well, somewhat.
Some
When doing a position survey, does Lady Heather have to be running?
Or does the Thunderbolt do it by itself?
--
Chuck Forsberg WA7KGX c...@omen.com www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
Omen Technology Inc The High Reliability Software
10255 NW
On 5 May 2013 20:18, Chuck Forsberg WA7KGX N2469R c...@omen.com wrote:
When doing a position survey, does Lady Heather have to be running?
Or does the Thunderbolt do it by itself?
I don't know about Thunderbolt but on my Acutime Gold the Windows
software sends the restart survey command to the
In message 20130505205257.8497f166abb1e49186953...@kinali.ch, Attila Kinali w
rites:
I also have never seen a H gas cell standard, probably for the same reason
of needing UV light.
Hydrogen is very hard to contain.
The way you *filter* hydrogen is to press it through a palladium film,
and that
i only know about the fury: the scpi command GPS:POS:SURV:STAT ONCE
starts an auto-survey and lasts about three hours as 10,000 acquisition
points are needed. if reception is bad this may take longer. you can
specify the maximal number of points with GPS:POS:SURV:MAXP [0,1].
10,000 is the
Hi Poul-Henning,
On 05/05/2013 08:29 PM, Poul-Henning Kamp wrote:
In message51867df4.4010...@karlquist.com, Richard (Rick) Karlquist writes:
BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
Well, somewhat.
Some flavours of atoms don't work
On 05/05/2013 09:28 PM, Poul-Henning Kamp wrote:
In message20130505205257.8497f166abb1e49186953...@kinali.ch, Attila Kinali w
rites:
I also have never seen a H gas cell standard, probably for the same reason
of needing UV light.
Hydrogen is very hard to contain.
The way you *filter*
On 5/5/13 11:45 AM, Magnus Danielson wrote:
Hi Jim,
On 05/05/2013 07:33 PM, Jim Lux wrote:
On 5/5/13 10:05 AM, Magnus Danielson wrote:
They have been targeting this goal for a very long time. Several
interesting papers is to be found at PTTI, NIST etc.
Yeah.. some years (6 or 7?) ago, John
On 05/05/2013 11:14 PM, Jim Lux wrote:
On 5/5/13 11:45 AM, Magnus Danielson wrote:
Hi Jim,
On 05/05/2013 07:33 PM, Jim Lux wrote:
On 5/5/13 10:05 AM, Magnus Danielson wrote:
They have been targeting this goal for a very long time. Several
interesting papers is to be found at PTTI, NIST etc.
The idea of a Mercury Ion clocks started about 2000 and from about 2005 until
recently has held the title of worlds most accurate clock.
Approx 1 sec per 1.6 billion years the last I heard. At the heart is a single
trapped mercury atom. Jim Bergquist at NIST was one of those that lead the
Hi Tom,
On 05/05/2013 11:33 PM, Tom Knox wrote:
The idea of a Mercury Ion clocks started about 2000 and from about 2005 until
recently has held the title of worlds most accurate clock.
Approx 1 sec per 1.6 billion years the last I heard. At the heart is a single
trapped mercury atom. Jim
On 5/5/2013 6:35 AM, Miguel Barbosa Gonçalves wrote:
Hi fellow time nuts!
I've recently bought a Trimble Acutime gold that will be used as a
reference clock for a NTP server.
This receiver has the possibility of averaging it's position before
entering what Trimble calls the overdetermined
Le 5 mai 2013 à 21:18, Chuck Forsberg WA7KGX N2469R a écrit :
When doing a position survey, does Lady Heather have to be running?
Or does the Thunderbolt do it by itself?
Good question. I would have thought that once started, the survey would
complete even though LH was stopped/started,
On 5/5/13 2:49 PM, Magnus Danielson wrote:
I have all the Hg-199 and Hg-202 I need for a few clocks, but in it's
natural mixture. Don't feel like building a separation facility...
Use the quadrupole system you're using as a trap as a mass-spec to do
the separation.
Hi
There were a number of trapped ion papers back in the 70's and 80's. The NIST
effort to transition from Cs to an ion standard was well underway by the mid
1980's.
Bob
On May 5, 2013, at 5:49 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote:
Hi Tom,
On 05/05/2013 11:33 PM, Tom
On 27 April 2013 14:17, Mark C. Stephens ma...@non-stop.com.au wrote:
Hi All, I am trying to get my head around building a nanobsd for some HP
thinclients to run as stratum 1 servers.
If you have the time, please send me an example conf file for sh nanobsd.sh
-c myconf.nano
I am unsure of
On 5 May 2013 12:28, Sarah White kuze...@gmail.com wrote:
I myself did a sampling over a period of 1 million samples
(actually, it was a value of 2^20, not exactly 1 million)
quickest it could have completed such a survey is 12+ days
... However, I had masks set for elevation, signal, etc.
If you are talking about using this with NTP. I don't know if you
have a choice. The Trimble receiver is going to do whatever it is
going to do when you power it up.Software running on a PC can
perform a 24 hour survey and report the location but the Type 29
driver in NTP has no way to tell
Hi
The sawtooth issues of most GPS receivers are much greater than the position
errors a short / long survey will produce. Unless you have a very fancy self
correcting receiver or a driver that does sawtooth correction, don't' worry
about it.
Bob
On May 5, 2013, at 5:33 PM, Tom Knox
On 5/4/2013 2:40 PM, Attila Kinali wrote:
Can anyone shed some light on why the GPS Cs beams have a worse stability
than the Rb vapor clocks?
I don't know, but it makes me wonder about things like
1) How sensitive is each to C-field tuning - i.e. for the same change in
C-field, by how much
There are multiple variables that effect the minimum number of fixes that
will yield a particular position accuracy (and hence a time accuracy when
using that position as truth).
(1) The ability of the antenna to see the entire sky. If a mountain, tall
building or tree is between you and a
Bing birdseye tech uses Pictometry. They have a few papers on their position
accuracy. Perhaps conflicting papers. One shows the RMS error of 0.6ft. Another
shows a 95% confidence level at 2.8ft. This is on 4 inch resolution imagery.
In any event, if your city uses the service, you possibly
After you get the position, how does the OP (or anyone else) put the
location data into the Trimble GPS receiver so that it can be used in
the time solution. This is for NTP remember.
Assuming there is some way, will the Trimble GPS receiver remember
the location over a power cycle?
In other
Hi Chris!
On 06/05/2013, at 01:21, Chris Albertson albertson.ch...@gmail.com wrote:
If you are talking about using this with NTP. I don't know if you
have a choice. The Trimble receiver is going to do whatever it is
going to do when you power it up.Software running on a PC can
perform
Eh, I just recalled the original question a day or so ago and was curious if
any of the imagery services had statistics on their position accuracy. It was
an interesting question.
This is the server with the marker data.
http://www.ngs.noaa.gov/cgi-bin/ds_radius.prl
--Original
So this is different from the Thunderbolt, even if they both use the
same serial protocol or can the t-bolt also have it's flash rom
programmed from a PC?
The bottle neck in the system in the uncertainty in the interrupt
latency on the PC where NTP runs. After all this I doubt you can
captures
albertson.ch...@gmail.com said:
After you get the position, how does the OP (or anyone else) put the
location data into the Trimble GPS receiver so that it can be used in the
time solution. This is for NTP remember.
Assuming there is some way, will the Trimble GPS receiver remember the
Isn't the other half of the question how useful the information is to the OS?
That is how is the time integrated with the application using it. Even if the
RTCs had perfect sync, would two apps attempting to read the clock get the same
time value in a multitasking system?
I've been looking for
On 05/06/2013 02:29 AM, Mike S wrote:
On 5/4/2013 2:40 PM, Attila Kinali wrote:
Can anyone shed some light on why the GPS Cs beams have a worse stability
than the Rb vapor clocks?
I don't know, but it makes me wonder about things like
1) How sensitive is each to C-field tuning - i.e. for the
The 48-hour precision survey in Lady Heather uses a statistical weighted median
filter to arrive at its final location instead of a simple average of fixes.
It processes data of one minute, hour, and overlapping 24 hour intervals to
calculate the final position. It can produce a location
On 5/6/2013 12:29 AM, Mark Sims wrote:
The 48-hour precision survey in Lady Heather uses a statistical weighted
median filter to arrive at its final location instead of a simple average of
fixes. It processes data of one minute, hour, and overlapping 24 hour
intervals to calculate the
Oh... 24 bit mantissa should give 1.25 m resolution if my headcounting is about
right. Thats about 4 ns.
Royal kludge indeed.
Cheers
Magnus
Originalmeddelande
Från: Mark Sims hol...@hotmail.com
Datum:
Till: time-nuts@febo.com
Rubrik: [time-nuts] GPS position survey
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