John,
Thanks for the reply. I expected to hear from someone besides me who was
also experiencing problems trying to run the link. I wonder if anyone
can confirm that they are able to use the page successfully from an XP
machine (or other MS OS), using the Firefox browser. Perhaps someone can
No such thing as a siderial second.
Le 15/01/2010 05:04, Neville Michie a écrit :
It is an interesting question, we are so used to WWV and GPS with
regular time signals to synchronise clocks to mean solar time.
One method is to get a pocket calculator to identify a time in the
future when a s
If you are going to do that computation, HP has a Digital Display (59304A)
for the GPIB in the very same family of instruments.
-John
==
> Sidereal Time is another form of Earth Orientation angle based time
> where the orientation angle reference is the "fixed stars" instead of
>
Sidereal Time is another form of Earth Orientation angle based time
where the orientation angle reference is the "fixed stars" instead of
the mean sun.
You need to take such effects as precession, nutation and polar motion
into account.
The rate isn't uniform with respect to atomic time.
The
The 59309A is a GPIB interfaced clock unit and can be set to a specific
time via the GPIB interface. It also puts out the time and date via the
GPIB.
So it can be set to a specific siderial time from an external UTC clock w/
the appropriate SW to compute Siderial Time from UTC.
-John
===
Hi Rex, sorry to hear that. Apparently the page uses a new Google Earth
plugin (For Firefox). Google Earth is known for it's demands on hardware,
particularly Graphics memory and possibly Main Memory.
Please let us know if you find out what is going on.
John Allen K1AE
-Original Message---
It is an interesting question, we are so used to WWV and GPS with
regular time signals to synchronise clocks to mean solar time.
One method is to get a pocket calculator to identify a time in the
future when a siderial second nearly corresponds to a UTC second
and use the PPS pulse from GPS to
Hi
Depending on exactly how the 59309 works, you might do better by chopping into
it and feeding it with a micro that added an extra pulse every so often. That
would allow you to stick some math in-between a UTC pps source and your clock.
Let the micro go get all the magic numbers from USNO and
Wait 'till EXACTLY the Spring Equinox?
-John
==
> Brian Kirby wrote:
>> I would like to have an electronic clock to keep sidereal time. I am
>> planning on using a HP 59309A, which can except an external clock of
>> 1/5/10 Mhz.
>>
>> According to Wikipedia sidereal time is 23 ho
Brian Kirby wrote:
I would like to have an electronic clock to keep sidereal time. I am
planning on using a HP 59309A, which can except an external clock of
1/5/10 Mhz.
According to Wikipedia sidereal time is 23 hours 56 minutes and 4.091
seconds - a total of 86,164.091 seconds
So 86,400 s
oops I omitted an important phrase.
Bruce
Bruce Griffiths wrote:
There are 4 principal sources of noise
1) The GPS receiver
2) The 4046 Phase detector
3) The opamp
4) The OCXO
In the short term the GPS receiver noise will dominate.
The GPS receiver noise will dominate the sort term phase d
I would like to have an electronic clock to keep sidereal time. I am
planning on using a HP 59309A, which can except an external clock of
1/5/10 Mhz.
According to Wikipedia sidereal time is 23 hours 56 minutes and 4.091
seconds - a total of 86,164.091 seconds
So 86,400 seconds for a normal
I was on the engineering team for the Rockwell Collins Navcore I GPS
receiver back in the late 80s here in Cedar Rapids. The Navcore I was a
single channel sequencing GPS receiver. It was available both in timing and
navigation versions. It had the following cards, power supply, memory, CPU,
and a
Hi
A lot depends on exactly how old the TBolt is. If it's a unit from 2000 it's a
different beast than one from 2005.
Bob
On Jan 14, 2010, at 7:19 PM, Mitchell Janoff wrote:
> My z3816a no longer locks to GPS. While it still outputs 1 PPS and 10MHz, it
> doesn't track any satellites. I've che
Mike -
On the thunderbolt, what datum do you have selected in Setup > Packet Masks
and Options? The default of 0 is the WGS-84 ellipsoid.
Looking at the 2003 geoid, Most of Florida is -25 to -30m hae.
Try datum 2, it looks like it may approximate NAD-27. Any better?
Ed, k1ggi
-Original Mes
iov...@inwind.it wrote:
Hi Magnus,
temperature data will be welcome, of course. I didn't ask for them in order to keep my request simple, with the hope to get more answers.
Anyway I would be pleased to see as many traces as possible, even in the lack of temperature data, and without the claim t
puter has surreal ports..."
> >>
> >>
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >>
No,
one is reporting in MSL, the other in GPS height.
There is about a 30m difference between the two here in Santa Clara
county, CA, similar to what you are seeing.
bye,
Said
In a message dated 1/14/2010 15:23:09 Pacific Standard Time,
r...@timing-consultants.com writes:
Depends on
Hi Mike,
the model is Extech 380950
It shows up on a Google search. It has a resolution of 1mA DC LSB.
That is the low-cost version, with lot's of features, about $130. The
high-end version costs about $350.
bye,
Said
In a message dated 1/13/2010 14:37:25 Pacific Standard Time,
mp..
My z3816a no longer locks to GPS. While it still outputs 1 PPS and 10MHz, it
doesn't track any satellites. I've checked the GPS card and it locks outside
the unit, so I don't think that's the problem. I've decided to replace it
and was wondering if I should get another z3816a or T-Bolt. They would
Just how significant is opamp flicker noise?
If the opamp ficker noise can be modeled as
en = k/SQRT(f)
for a typical JFET opamp K ~ 100nV/rtHz
Then the noise of interest is
~ k*SQRT(ln(f2/f1))
where
f1 is the PLL noise bandwidth
f2 is the noise bandwidth of the low pass filter at the EFC in
Yep
Everything is a trade off. If you want to make a simple, cheap, good GPSDO,
including some manual tuning has several benefits.
Shorter time constants and smaller caps for the same response TC is the one
I was pointing out.
And yes, there are all kinds of ways to do it wrong.
IF YOU have a
/www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>
>
>
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Depends on satellite geometry. Where they both tracking same satellites?
Rob K
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of John Green
Sent: 14 January 2010 9:36 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Tbolt altitude erro
Have you checked to power supplies for ripple or bad C's?
-John
===
> Fellow time-techs,
>
> Nothing lasts forever, and my faithful Odetics 425 is doing its best to
> demonstrate that fact. Before I put "Fix or Replace the thing" on my
> project list for the new year, I thoug
Fellow time-techs,
Nothing lasts forever, and my faithful Odetics 425 is doing its best to
demonstrate that fact. Before I put "Fix or Replace the thing" on my
project list for the new year, I thought I'd check to see if any other
owners of the beasties have run into the symptoms I'm getti
OCXO aging may actually prevent a lock ever occurring with too small a
tuning range, unless some form of acquisition aid is used.
One simple method of reducing the initial phase error is to initially
reset the PPS divider using the PPS output of the GPS receiver.
This will reduce the initial
Hi
If you fire up a conventional 1 pps loop with 10 ppb tune range, it's going
to take it a while to track out any initial error. The most it can move by
is +/-5 ns per second. You probably don't want to wait a year for it to
catch up with a 158 ms initial error.
Lots of fun little details to wor
If one attenuates the amplifier output by a factor of 1000 (effective
EFC range is then ~1E-10) or so then a 10811A with an aging rate of
5E-10/day will require manual retuning every few hours.
Typical aging may be better than this but this would still require
manual tuning every few days.
Bru
Oops wrong thread.
Bruce
Bruce Griffiths wrote:
Eventually the flicker noise of most amplifiers (apart from chopper
stabilised and related amplifiers) will exceed the noise of a resistor.
The internal zener noise will in most cases be much larger than
amplifier noise.
The output noise (due to
Eventually the flicker noise of most amplifiers (apart from chopper
stabilised and related amplifiers) will exceed the noise of a resistor.
The internal zener noise will in most cases be much larger than
amplifier noise.
The output noise (due to the filter components) of an RC low pass filter
John ask
>Translating nV/sqrt(Hz) to something
>practical is basically the assistance I'm looking for here.
>I would appreciate anyone being able to teach me a bit more about this.
If that is ALL you want to know, That's easy and quick.
For this application sounds like you already know ALL you n
Björn
In the case of the Thunderbolt with the default WGS84 datum the height
is calculated with respect to the MSL geoid.
If another datum is selected the height is calculated with respect to
the ellipsoid.
The attached snapshot from the Thunderbolt book makes this clear.
The MSL goeid doesnt
Hi
Back when the Z3801 was new, some GPS's would let you pick a specific geoid
model to use for altitude. Apparently it's a receiver side choice of what
model to use.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of John Green
Sent:
Hi
A couple other interesting component issues:
If the tuning diode in the OCXO is decoupled with "typical" value resistors,
the KTB noise in the resistors will be greater than the voltage noise of a
good op amp.
If you go the active filter route and use a 1 meg ohm resistor in the time
constant
I had a Tbolt and a Z3801 both fed from the same antenna and they indicated
26 meters differenence in altitude. The 3801 seemed closer to right. If
geoid error were the cause, it seems that both would indicate about the
same.
___
time-nuts mailing list --
Yes, the error is almost certainly due to the difference between the true
earth surface and the value calculated by the GPS model of the earth surface.
The difference is Dallas, Texas is around 26 meters (and John Miles actually
does live in a pineapple under the sea, so his altitude is ne
The noise of the internal zener used to bias the OCXO EFC varicap is
likely to exceed the output noise of any amplifier unless the filter
series resistance is sufficiently large that noise due to amplifier bias
current is excessive or the amplifier gain is very large.
Bruce
Dick Moore wrote:
Hi Bruce,
> The GPS altitude is calculated with respect to the geoid.
No, the GPS calculates altitude wrt the ellipsoid. Then its a conversion
with lots of coefficients or a lookup table to add the geoid separation.
Altitude wrt to the geoid is the same as Mean Sea level, which is what
normal map
I wonder if this is a HAE vs. MSL issue? What is the
elevation delta for your location in FL? It's about 18
meters for me in Seattle.
Mark, do you know?
/tvb
Hello, TimeNutters--
While we are on a thread about Trimble T-bolts,
perhaps someone might expand on why my T-bolt
does not ever come
John, I wouldn't bother with amplitude scaling, just unity gain with a DC
offset to center the control range to the 10811A to zero volts or thereabout,
and choose inverting or non-inverting to suit the characteristics of the
control voltage slope vis-avis the 10811A's slope, which is negative if
The GPS altitude is calculated with respect to the geoid.
The geoid surface may have a vertical separation from the actual surface
by several meters.
This correction varies with location on the Earth's surface.
Bruce
Michael Baker wrote:
Hello, TimeNutters--
While we are on a thread about Tr
To tell you how far above ground you are, the GPS has to know where the ground
is. For that, it is using a model that is not perfect. That is why John Miles'
GPS tells him he should get his scuba gear immediately...
If you google "geoid" you will find more than you wanted to know about it.
Didi
The time constant for a passive loop filter followed by an amplifier is
tau = Ko*Kd*A/(2+PI*fn)^2
where
Ko is the phase detector gain (radian/volt)
Kd is the VCO gain (rad/sec/volt)
A is the amplifier gain
For a CMOS exclusive OR phase detector with a 5V supply
Ko = 0.79 volt/rad
For a 10811A
Hello, TimeNutters--
While we are on a thread about Trimble T-bolts,
perhaps someone might expand on why my T-bolt
does not ever come up with altitude readings that
are even close. After a long fix, the Lat-Lon
coordinates are pretty close, but the altitude
is always given as around 2 meters. W
There are 4 principal sources of noise
1) The GPS receiver
2) The 4046 Phase detector
3) The opamp
4) The OCXO
In the short term the GPS receiver noise will dominate.
In the long term the 4046 phase detector noise and drift together with
the OCXO noise and drift will dominate.
Unless you m
Sounds good.
Remember it's the position of the antenna
Rob K
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Dan Rae
Sent: 14 January 2010 5:19 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Accu
Hi Dan,
you should be aware that Google Earth does not give an "accurate" location.
It give a "precise" location, but not particularly accurate (a distinction
particularly relevant to this forum).
ian
> Date: Thu, 14 Jan 2010 09:18:40 -0800
> From: Dan Rae
> Subject: [time-nuts] Accurate Posi
Hi Pete, it would be nice to have a couple, I've got a couple old HP's 5261A
that use them and I know of at least on bad
chip. A typical useless counter but like most I just can't get rid of it.
Would be fun to convert one to a clock !
what r u asking ?
-pete
On Thu, Jan 14, 2010 at 10:46 AM,
Greetings,
If anybody needs a few of the proprietary hp 1820-0092 Nixie driver
chips, please contact me off list.
Regards,
Peter
___
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Or use the beta realase of Lady Heather to do a 48 hour accurate survey.
Dave
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Ken Winterling
Sent: 14 January 2010 17:53
To: Discussion of precise time and frequency measurement
Subject: R
To All,
The following procedure is taken from notes I made years ago when setting up
my TBOLT using TBOLTMON. I have never had to enter the information again and
the unit recovers automatically even after extended power failures that
exhausted its UPS.
Click Setup -> Self-Survey,
Click the "Enabl
Hi
Your OCXO is going to have phase noise. It might be easier to think of the
added op-amp noise in the frequency domain. Phase modulation from the noise
voltage is a direct calculation, unlike short term stability from the noise
voltage. As long as the noise from the op amp is more than 10 db bel
I just found out that Google Earth now gives a seemingly quite accurate
position at the mouse pointer which I don't remember seeing before.
This would seem like a good way to start for a T-bolt survey for example.
Dan
___
time-nuts mailing list -
Starting without good saved coordinates will put you into search
mode, and it may take around 45 minutes to an hour to establish a
position, after which you will see SVs and AMUs.
Once you get a good position, either from self-survey by the Tbolt or
by a different GPS, you can enter these as f
Thanks to those who replied, all is now "Green".
73, Dick, W1KSZ
-Original Message-
>From: Jim Mandaville
>Sent: Jan 13, 2010 8:12 PM
>To: "Richard W. Solomon" , Discussion of precise time and
>frequency measurement
>Subject: Re: [time-nuts] T-Bolt Question
>
>And after typing them in
HI Dick,
I have the same problem and nothing works to enter the coordonates.
More, i don't see the SV nor AMUs.
73
Alain
F4GBC
- Original Message -
From: "Richard W. Solomon"
To:
Sent: Thursday, January 14, 2010 3:50 AM
Subject: Re: [time-nuts] T-Bolt Question
Perhaps I posted thi
that sure is a antique.
What size weight and power I would guess.
And all for $198.
On Thu, Jan 14, 2010 at 2:51 AM, Robert Atkinson wrote:
> Hi,
> If anyone is interested in historic GPS receivers (or old junk?) Mike
> Murphy has a Rockwell Collins Navcore I up for sale, see:-
> http://www.murph
Hi Magnus,
temperature data will be welcome, of course. I didn't ask for them in order to
keep my request simple, with the hope to get more answers.
Anyway I would be pleased to see as many traces as possible, even in the lack
of temperature data, and without the claim to draw any conclusion, b
I should point out that I was planning on using a passive loop filter
after the 4096 phase comparator with a long time constant and then
simply using an opamp to scale my EFC voltage after the passive filter
accordingly. However I assume I could make an active lowpass filter
with a good opamp that
G3RUH used an LT1006 with good results for the IsoTemp OCXO.
http://www.jrmiller.demon.co.uk/projects/ministd/dcamp.gif
cheers,
ian
> Date: Thu, 14 Jan 2010 06:57:39 -0500
> From: John Foege
> Subject: [time-nuts] GPSDO Design
> To: time-nuts@febo.com
> Message-ID:
> <888d55281001140357s6
> -Original Message-
> From: time-nuts-boun...@febo.com
> [mailto:time-nuts-boun...@febo.com] On Behalf Of John Foege
> Sent: Thursday, January 14, 2010 5:58 AM
> To: time-nuts@febo.com
> Subject: [time-nuts] GPSDO Design
>
> Hi All,
>
> Quick question for the more experienced members
Hi
If you are doing a GPSDO, your input to the 4096 is at 1 pps / 1 Hz. The PLL
loop filter would be part of the circuitry around the op-amp you are talking
about. That filter is going to have time constants around 300 to 10,000 seconds
associated with it. What ever noise you have will be atten
Works OK here in Windoze explorer running on XP.
Nic
Sydney
Australia
The link doesn't play nice on my machine.
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and follow
Hi All,
Quick question for the more experienced members here with GPSDO
design/operation. Let's assume I'm using a 4096 phase comparator chip
followed by some kind of long time constant lowpass loop filter,
whether it be analog or digital, is not of concern for the following
question.
Obviously u
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