> Thanks downloaded the paper. I assume the hyper fine transition happened to
> be the one nearest that frequency? You can tune to either side of the peak
> and get a lock on the next transition.
> Regards
> Paul.
Hi Paul,
The definition is the second specifies which hyperfine transition to use;
In message <4EBB3F0321D24025B6BA3F4AA81B5134@pc52>, "Tom Van Baak" writes:
>As long as you're playing with @@Hn messages, Kalman filters,
>and software sawtooth correction, you might want to consider
>looking at the per-SV "fractional GPS local time estimates" in the
>Hn message. It's the mean of
In message , "Eric Lemmon" wri
tes:
>No, leap seconds have to do with the gradual slowing of the Earth's
>rotation, and nothing to do with Cesium.
Not quite true.
When they decided the 9,192,631,770 they did so with astronomical
observations which were half a century old. If they had used a
mor
Hello.
Would not be very useful to create a list of what interesting ideas have
been implemented on what instrument (sometimes in a perfect way,
sometimes
maybe not), so everyone could study the service manuals, schematics, and
learn?
I think it will become a reference of the "state of the art"
On Tue, May 08, 2012 at 09:28:33PM -0400, David McGaw wrote:
> It is my understanding that they actually got it a bit wrong, which
> is why we seem to have a lot of leap seconds.
The atom is a much better timekeeper than the Earth. They
could have chosen differently for convenience, but t
I had a failure of my -12 V supply that interrupted communications that was
resolved by fixing the -12 V supply. You might want to make sure you are
getting the -12 V supply in the unit. I suspect your 24 V supply provides
power to an internal supply that generates +12, +5 and -12 V.
Might want
No, leap seconds have to do with the gradual slowing of the Earth's
rotation, and nothing to do with Cesium.
73, Eric Lemmon WB6FLY
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of David McGaw
Sent: Tuesday, May 08, 2012 6:29 PM
To: Di
It is my understanding that they actually got it a bit wrong, which is
why we seem to have a lot of leap seconds.
David
On 5/8/12 9:19 PM, paul swed wrote:
Thanks downloaded the paper. I assume the hyper fine transition happened to
be the one nearest that frequency? You can tune to either side
Thanks downloaded the paper. I assume the hyper fine transition happened to
be the one nearest that frequency? You can tune to either side of the peak
and get a lock on the next transition.
Regards
Paul.
On Tue, May 8, 2012 at 9:14 PM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:
>
It's unlikely you'll ever see a negative leap second - the earth's rotation is
slowing down, not speeding up.
Dave
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of Jerry Mulchin
Sent: 09 May 2012 01:56
To: j...@quikus.com; Discussion o
Yes, but eventually the time must be corrected with leap seconds because of all
the
randomness that accumulates. It is interesting that the leap seconds correction
is
always a positive number. We never seem to gain time that I'm aware of. argh
Jerry
At 05:35 PM 5/8/2012, you wrote:
>Becaus
Tom,
So I'm thinking that as long as I'm putting in sawtooth correction, and I'm
using a
0.25ns/step delay device (DS1123L part), then it seems to me that at some point
in the kalman filtering algorithm I should be able to decide that instead of
delaying
1ns all the time, that I should be able t
Because the length of the second is essentially arbitrary. There is
nothing 'fundamental' or 'universal' about it. It is essentially derived
from the average rotational period of the earth, which is a random number.
When the number of cycles was defined, they picked the nearest whole
number to an
Who decided 9,192,631,770 cycles of 'light' constitute one second? I don't
mean who the person was, or which company or institution or when.
I ask, why not ...771 cycles ...or ...669 cycles
Hi Don,
It was the result of 4 astronomical measurements made over several years.
9,192,631,76
I've gotten myself confused ...easily done when you're not a physicist (just
a lowly EE.) :-)
I am studying cesium clock design and trying to learn how these complex
instruments actually work. I seem to be getting the understanding on the
'workings' of the clock ...the tube, the counters, discip
Tom,
very interesting. The Kalman filtering, as long as I know, requires a
model: you apply the model, make the measurements, compute the delta
between the model and the measurements and then the new gain to take the
next step. Let me ask: is this model to be determined? From your message it
seems
Andrea,
See www.leapsecond.com/time-nuts.htm for an intro to the
group and list of resources.
While it would be nice to have one central place for all this
information it works out pretty well to have multiple web sites
each with their own particular slant. You'll see a list of sites
on the intr
Jerry,
It depends on what your goal is. Hardware sawtooth correction is
good at improving the short-term jitter of the 1PPS output.
But if you're using the M12+T with a TIC simply to measure the
performance of some time/frequency standard, then software
correction is easier and gives slightly be
On 05/09/2012 12:49 AM, Azelio Boriani wrote:
Here in Europe the time now is late night, anyway there is also U15: a
LinearTechnolgy LT2105 or LTC2105 but I can't find nothing... maybe it a
marking code and not the actual part number. Maybe a linear regulator,
google says LT2105-5.0 but on the Li
Hi,
I recently picked up a Measurement Computing USB-1208 Series card. There
is some TracerDAQ SW available for download from the company's site.
I've got it running with 1 D/A channel, but not the second. Does anybody
know if the SW is crippled?
If anybody is familiar with this unit, can you pl
No, it is an LT1021DCS8-5 5V precision voltage reference. Not a voltage
regulator, should be the refernce for the OCXO DAC.
On Wed, May 9, 2012 at 12:49 AM, Azelio Boriani wrote:
> Here in Europe the time now is late night, anyway there is also U15: a
> LinearTechnolgy LT2105 or LTC2105 but I can
On 05/09/2012 12:25 AM, Azelio Boriani wrote:
That is the very reason to follow the time-nuts group. Yes, not the only
one, of course. You can learn, for example, that the Tek 7L series and
2240 'scopes have interesting analog time interpolators, Wavecrest has a
patent on the same item, it is us
Here in Europe the time now is late night, anyway there is also U15: a
LinearTechnolgy LT2105 or LTC2105 but I can't find nothing... maybe it a
marking code and not the actual part number. Maybe a linear regulator,
google says LT2105-5.0 but on the Linear site it doesn't exist.
On Wed, May 9, 2012
On 05/09/2012 12:33 AM, b...@lysator.liu.se wrote:
Hi Magnus,
On 05/08/2012 11:58 PM, Bob Camp wrote:
Hi
The first thing to check is the soldering job on the DB-9 connector.
Second thing to check is the RS-232 level translator IC. (RS-232 in
should create TTL etc)
Does not explain why the O
> Agreed, the CPU is not working... check the 3.6864MHz crystal under the
> CPU. If it is possible to locate the reset signal...
Time to get some sleep... I found the crystal. It is not easily probeable
when mounted on the PSU board. Also the power rail has to short pins to
accept the external 3 v
On 05/09/2012 12:23 AM, b...@lysator.liu.se wrote:
Hi Bob,
The DB-9 looks fine even with magnifying glass.
The good one has a MAX232EWE IC, the faulty has a TC232EOE. I see
RS232-level coming in at pin 13 and going inside the Tbolt at pin 12 (ttl
level).So there should be no problem there.
Have
To use the Kalman filtering technique you need a model of the sawtooth
error... the model of the error is simply the quantization of the UTC PPS
done by the M12 clock, so I think that in the sawtooth correction output by
the M12 you have already all you need.
On Wed, May 9, 2012 at 12:20 AM, Jerry
Hi Magnus,
> On 05/08/2012 11:58 PM, Bob Camp wrote:
>> Hi
>>
>> The first thing to check is the soldering job on the DB-9 connector.
>> Second thing to check is the RS-232 level translator IC. (RS-232 in
>> should create TTL etc)
>
> Does not explain why the OCXO remains stuck as if it was untrai
Agreed, the CPU is not working... check the 3.6864MHz crystal under the
CPU. If it is possible to locate the reset signal...
On Wed, May 9, 2012 at 12:23 AM, wrote:
> Hi Bob,
>
> The DB-9 looks fine even with magnifying glass.
> The good one has a MAX232EWE IC, the faulty has a TC232EOE. I see
>
That is the very reason to follow the time-nuts group. Yes, not the only
one, of course. You can learn, for example, that the Tek 7L series and
2240 'scopes have interesting analog time interpolators, Wavecrest has a
patent on the same item, it is useful to get and study the PRS10 manual and
schem
Hi Bob,
The DB-9 looks fine even with magnifying glass.
The good one has a MAX232EWE IC, the faulty has a TC232EOE. I see
RS232-level coming in at pin 13 and going inside the Tbolt at pin 12 (ttl
level).So there should be no problem there.
Have also swapped PSU board, so the problem is inside th
OK, so before I commit to my Sawtooth correction design, I had a thought about
adding
additional filtering to the sawtooth corrections using a Kalman filter.
The Kalman filter would be driven using the @@Hn data coming from the M12+T
reciever.
Is this something worth doing or am I expecting to
On 05/08/2012 11:58 PM, Bob Camp wrote:
Hi
The first thing to check is the soldering job on the DB-9 connector. Second
thing to check is the RS-232 level translator IC. (RS-232 in should create TTL
etc)
Does not explain why the OCXO remains stuck as if it was untrained.
I suspect that the C
Hi
The first thing to check is the soldering job on the DB-9 connector. Second
thing to check is the RS-232 level translator IC. (RS-232 in should create TTL
etc)
Bob
On May 8, 2012, at 5:52 PM, b...@lysator.liu.se wrote:
> Hi group!
>
> Just got a few Thunderbolts. It is a few PN 39448-61 a
Hi group!
Just got a few Thunderbolts. It is a few PN 39448-61 and one PN 38223-61.
Date codes from 9932 to 0025. This is the "normal" version with a 24VDC
power board and Tbolt board integrated in a small AL box with red
markings. One of the receivers is having a problem. Measuring from the
outsi
Hello.
Would not be very useful to create a list of what interesting ideas have
been implemented on what instrument (sometimes in a perfect way, sometimes
maybe not), so everyone could study the service manuals, schematics, and learn?
I think it will become a reference of the "state of the art" of
Mark,
Does that mean that there might be yet another version of LH forthcoming?
The latest one works well with my NTGS50AA, and doesn't seem to miss much,
although it has crashed occasionally when I change the screen resolution.
Probably due to insufficient PC performance. I now have it running
They will not be using a null steering antenna because of ITAR but IF
notching is still a possibility. I suspect the easiest change is to
use a superhetrodyne design so that all of the out of band rejection
does not depend on the RF filter but it will cost the power and space
of the local oscillat
“Receivers which cannot tolerate LightSquared will get in
trouble in North Korea!” commented one well-known GPS
manufacturer. “Today's receivers don't have protection. We just
completed our ad [for the June issue of GPS World] which
somewhat covers this.”
An interesting half-truth. So, wil
I have poked and prodded the Nortel 8F-AE packet some more. Here is what seems
to be in it:
u08 subcode; // packet ID subcode
u16 zero; // ??? always zero
u08 leds; // led status
u08 ffom; // frequency figure of merit
u08 tfom; // time figure of merit
u08 ho
What I found funny was that the Audiophlie and light thread drew such attacks
when it hit home to me as exactly what the Time-Nuts mission is about. The
Audio thread touched on some real world time and freq research I am helping a
friend with in the near future. Why do I believe it is relevant
Just read in GPSWorld magazine.
http://www.gpsworld.com/gnss-system/news/massive-gps-jamming-attack-north-korea-12948?utm_source=GPS&utm_medium=email&utm_campaign=navigate_05_08_2012&utm_content=massive-gps-jamming-attack-north-korea-12948
73 - Marco IK1ODO
___
Hal,
Excellent comment!
"In some sense, success is related to the number of people signed up."
Yes, in the same sense that happiness is related to the money you have.
It is possible to have too many or too much.
Human nature includes "Look at me, Ma. Look at me!" Most pros can
stifle that. Peopl
Thanks had not seen it before.
Now thats a real C reference. You can refill the Cs it seems as simple as
dumping new Cs stuff in the oven and bolting it in. ;-) Well maybe not.
All that said pretty amazing how small they ended up making them.
Regards
Paul
On Tue, May 8, 2012 at 6:52 AM, Rob Kimber
Mike,
Thanks for posting that. A wonderful film, and a great insight into early Cs
development.
I was lucky to see one of their Cs fountains a few years ago when attending
an NPL T&F Club meeting. They also gave us a view of the work being done on
optical clocks.
Louis Essen would have been mo
I've always been fascinated with science history. If you all haven't seen
this already, here is a video from 1955 about the first "accurate" cesium
atomic clock designed by Louis Essen and made in the UK's National Physical
Laboratory. Interesting that the one made after the prototype was 17 feet
Hal, others,
There were two things that are interesting about this. There was a
special about Hawkings theories and a recent turn of heart and theory he
had, which hits at the center of the quantum theory involved here.
The other is the current groups experience with Rb oscillators and those
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