Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Chris Erickson]

Don't overlook the fact that it also puts out a square wave signal. Great
for a digital clock pulse, but for a clean radio reference you also have to
remember the nature of a square wave - it is an infinite number of odd
harmonics. There's a lot of built in jitter. You'd need to filter the heck
out of it to get it down to a 10 MHz sine wave. The level may then need to
be boosted back up to a usable level.

 

Really neat device though.

 

Chris Erickson

 

 

>Hi Tom,

 

   >Well, the phase noise is not as good as other Rb sources that can be

   >had for around $100 that are not much bigger in size.  For example the

   >FE-5650A or even the FE5680A Rb's.

 

   >Would it be useful ?  That depends upon your operating requirements.

   >For wide band FM at 10 GHz it would be ok, but for narrow SSB I would

   >think it is lacking.  Perhaps John Miles, KE5FX, who has experience

   >with that sort of stuff will chime in.

 

   >This CSAC device will shine in those areas where power and size really

   >matter.  If you read the supporting literature, a lot of

   >computerization in the form of algorithms were required to tame the

   >beast.  All of that will improve over time.  So this first to market

   >item is interesting but let the big boys pay for it and down the road

   >we mere commoners will reap the benefits.

 

   >BillWB6BNQ

 

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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[J. L. Trantham]

I am only using LH with the TBolt.  I also run a Z3816A simultaneously to
cross check frequencies to make sure I am not using a 'dead' reference.  I
monitor both on the same computer that has two serial ports and runs
Win2KPro.  I had previously used TBoltMon but decided to give LH a try.
Quite the amazing display.  It is going to take me weeks to get a handle on
all that it can do.

The problem I had was downloading and installing the program while the TBolt
was operating and connected to COM 2.  The only way I could get the program
to respond was to move the TBolt to COM 1.  After that, everything worked.
I have not tried telling LH to switch to COM 2 then moving the TBolt back to
COM 2 to see if that would work.  My Symmetricom SatStat program is doing
fine with the Z3816A on COM 2 so no need as best I can tell.

The confusion is probably that I asked two unrelated questions in the same
posting.

Joe

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of paul swed
Sent: Tuesday, January 18, 2011 4:18 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question


A quick question
I thought lady heather was a Tbolt program only.
Does it work with other GPSDP like the hp 3801 etc???
Thanks

On Tue, Jan 18, 2011 at 9:20 AM, J. L. Trantham  wrote:

> The Z3816A responded to the command nicely.  I was also able to use 
> the
> command:
>*tst?
> to reboot the receiver without having to turn off the Z3816A.  This was
> using Symmetricom SatStat v5.0.  I have not tried with HP SatStat v4.2.
>
> Initially, the time was off by what appeared to be the leap second 
> value with a TFOM of 6.  Now it is back to a TFOM of 3 and the time 
> appears correct.
>
> Thanks,
>
> Joe
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> Behalf Of J. L. Trantham
> Sent: Tuesday, January 18, 2011 6:36 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
>
>
> Michael,
>
> Thanks for the hint.  I've looked at that site a thousand times but 
> never found that hint until now.  I'll give it a try.
>
> Thanks again.
>
> Joe
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] 
> On Behalf Of cook michael
> Sent: Tuesday, January 18, 2011 2:20 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
>
>
> Le 18/01/2011 05:07, J. L. Trantham a écrit :
> > An unrelated question.  My Z3816A reports GPS time.  I have looked 
> > but have not found a command to make it switch to UTC.  Does such a 
> > command exist? If so, what is it?
> >
> The command to do the same on the Z3801A might work with this box 
> aswell.
>
> Using info from K8CU; 
> http://www.realhamradio.com/GPS_Frequency_Standard.htm
>
> Issue the command:
>
>:diag:gps:utc?
>
> If it returns 0 you are in GPS mode; if 1 you are in UTC
>
> Use the command:
>
>:diag:gps:utc 1
>
> followed by
>
>:syst:pon
>
> to set it to UTC mode.  Some units have to be powered off to actually 
> reset to UTC depending on software version.
>
>
>
>
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Re: [time-nuts] Sure Electronics GPS

[Tom Van Baak]

Thanks for all the info.
I wasn't aware that leapsecond did any testing on the unit.
Now I gotta play more with it.

Rix Seacord K2AVP


Right, I ordered one too when the thread started in November.
I just updated the "lab report" page to include 1PPS risetime
and TTL/RS232 NMEA latency/jitter measurements:
   http://www.leapsecond.com/pages/MG1613S/

If there are any other questions about the unit, let me know
off-line and I'll see what I can do while I still have it on the
bench.

/tvb


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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Bob Camp]

Hi

Using this directly at microwave - not a real good idea. Using it to drive a 
100 MHz phase locked low noise VCXO through a very narrow loop and then taking 
that on up to microwave - should work pretty well. The only gotcha would be if 
they are into PSK-32 at 24 GHz and don't like to tune around. Then indeed the 
GPSDO might do a bit better. 

The degree of advantage will depend on just how much power they are already 
hauling along. If the rest of the gear runs a hundred watts, then there's no 
significant savings over the alternatives. If they have everything else down to 
under ten watts, then indeed there will be a real advantage to the low power / 
small size. 

Bob


On Jan 18, 2011, at 7:43 PM, Tom Holmes wrote:

> OK, so aside from the price of this toy, are there any performance reasons
> why this itty bitty gizmo wouldn't be quite useful to my ham friends who do
> portable/mobile microwave operation, as opposed to dragging along a GPSDO or
> OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even higher.
> 
> Tom Holmes, N8ZM
> Tipp City, OH
> EM79
> 
> 
>> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of Bob Camp
>> Sent: Tuesday, January 18, 2011 5:55 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>> 
>> Hi
>> 
>> In this case, it's an itty bitty gizmo that has some significant
> compromises in
>> performance compared to it's bigger cousins.
>> 
>> Bob
>> 
>> 
>> On Jan 18, 2011, at 5:47 PM, William H. Fite wrote:
>> 
>>> Oh gosh, it would never, EVER do to find a li'l bitty product that
> performs
>>> as well as our big ole spare rooms full of costly, bulky, heavy, mostly
>>> antiquated equipment.  [?]
>>> 
>>> 
>>> 
>>> On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp  wrote:
>>> 
 Hi
 
 Simply having cesium in it does not make it a primary standard. Since
> it's
 more like a rubidium than anything else, it's a lot easier to think of
> it
 as
 a "really small low power rubidium". One other advantage it may have is
 that
 the LED may have a longer life than a normal "light bulb" source. I
> suspect
 it's a little early to forecast 20 year (or not) life on these yet.
 
 Bob
 
 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of WB6BNQ
 Sent: Tuesday, January 18, 2011 5:03 PM
 To: Discussion of precise time and frequency measurement
 Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
 
 To the list,
 
 If you listen carefully to the Symmetricom slide show, particularly
> page 3,
 it will tell you all you need to
 know:
 
 
 
>> http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pau
>> se=1&
 
>> appKey=77> &dm=5&pause=1&%0AappKey=77>
 
 You will discover that that it is indeed a Cesium operated device.
> HOWEVER
 !  It is operated in the same manner
 as a Rubidium device.  Doing such does NOT make it a primary standard.
 
 In a Cesium Primary standard, a beam of Cesium atoms are energized to a
 higher state whose decay give off a
 photon of light such that being on frequecy produces more light to the
 detector.  In the Rb system, the Rb cell
 acts simply as a light filter such that when on frequency the light
> level
 is
 reduced as seen by the detector.
 
 This Symmetricom CSAC device uses the same process as the Rb method
>> above.
 It uses a laser to push light through
 a chamber of Cesium gas.  This Cesium gas is acting as a simple light
 filter.  So in its current state it will
 not rival it superior cousins except in size and power comsumption and
 possibly price for performance in some
 applications.
 
 BillWB6BNQ
 
 
 
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 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
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>>> ___
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Re: [time-nuts] Sure Electronics GPS

[Rix Seacord]

Thanks for all the info.
I wasn't aware that leapsecond did any testing on the unit.
Now I gotta play more with it.

Rix Seacord K2AVP
eseac...@verizon.net

845-628-0892
914-262-9186


On 1/17/2011 11:50 AM, Scott Burris wrote:

http://www.sureelectronics.net/goods.php?id=99

Scott

On 1/17/2011 8:27 AM, paul swed wrote:

This particular link does not seem to offer the gps board

On Mon, Jan 17, 2011 at 10:02 AM, Scott Burris  
wrote:



On 1/16/2011 9:49 PM, Rix Seacord wrote:


Dick and Tom
The gps is sold on ebay in several different versions.
The don't have a web site under their name. The manual, virtual 
drivers

and software are down loadable via their ebay offer. There is a
www.sure-electronics.com site but it takes you to ebay.


Their web site is http://www.sureelectronics.net/

I used to buy from them on ebay, but mostly just direct now.  I've 
never

had a
problem with them.

Scott



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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[John Miles]

> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> Behalf Of Tom Holmes
> Sent: Tuesday, January 18, 2011 4:43 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>
>
> OK, so aside from the price of this toy, are there any performance reasons
> why this itty bitty gizmo wouldn't be quite useful to my ham
> friends who do
> portable/mobile microwave operation, as opposed to dragging along
> a GPSDO or
> OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even higher.

Bragging rights!  What else is needed?

Apart from that, until we see some PN and ADEV/MDEV plots, there's no way to
say if it would be better than an eBay-special rubidium standard in any
corner of the performance envelope.  This thing might sound like so much
white noise if you multiplied it to 10 GHz+... or it might work well.

Unless Symmetricom is positioning it as some kind of loss leader, I'd guess
that the $1500 price point means that they are following the usual Rb recipe
of dragging a cheap crystal oscillator around with a relatively fast loop.

Warmup time and low power consumption shouldn't be dismissed as selling
points, though.  Conventional Rb standards lock quickly enough, but they
don't live up to their full performance potential until they've been on for
several hours.  If the only major heat source is the cesium oven, the VCSEL
illumination scheme might offer the best overall time-to-stability
performance of any source ever produced.

And you can always use it to discipline another OCXO if you don't like the
one it comes with.

-- john, KE5FX



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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[WB6BNQ]

   Hi Tom,

   Well, the phase noise is not as good as other Rb sources that can be
   had for around $100 that are not much bigger in size.  For example the
   FE-5650A or even the FE5680A Rb's.

   Would it be useful ?  That depends upon your operating requirements.
   For wide band FM at 10 GHz it would be ok, but for narrow SSB I would
   think it is lacking.  Perhaps John Miles, KE5FX, who has experience
   with that sort of stuff will chime in.

   This CSAC device will shine in those areas where power and size really
   matter.  If you read the supporting literature, a lot of
   computerization in the form of algorithms were required to tame the
   beast.  All of that will improve over time.  So this first to market
   item is interesting but let the big boys pay for it and down the road
   we mere commoners will reap the benefits.

   BillWB6BNQ

   Tom Holmes wrote:

 OK, so aside from the price of this toy, are there any performance
 reasons
 why this itty bitty gizmo wouldn't be quite useful to my ham friends
 who do
 portable/mobile microwave operation, as opposed to dragging along a
 GPSDO or
 OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even
 higher.

 Tom Holmes, N8ZM
 Tipp City, OH
 EM79

 > -Original Message-
 > From: time-nuts-boun...@febo.com
 [[1]mailto:time-nuts-boun...@febo.com] On
 > Behalf Of Bob Camp
 > Sent: Tuesday, January 18, 2011 5:55 PM
 > To: Discussion of precise time and frequency measurement
 > Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb
 unit
 >
 > Hi
 >
 > In this case, it's an itty bitty gizmo that has some significant
 compromises in
 > performance compared to it's bigger cousins.
 >
 > Bob
 >
 >
 > On Jan 18, 2011, at 5:47 PM, William H. Fite wrote:
 >
 > > Oh gosh, it would never, EVER do to find a li'l bitty product
 that
 performs
 > > as well as our big ole spare rooms full of costly, bulky, heavy,
 mostly
 > > antiquated equipment.  [?]
 > >
 > >
 > >
 > > On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp  wrote:
 > >
 > >> Hi
 > >>
 > >> Simply having cesium in it does not make it a primary standard.
 Since
 it's
 > >> more like a rubidium than anything else, it's a lot easier to
 think of
 it
 > >> as
 > >> a "really small low power rubidium". One other advantage it may
 have is
 > >> that
 > >> the LED may have a longer life than a normal "light bulb"
 source. I
 suspect
 > >> it's a little early to forecast 20 year (or not) life on these
 yet.
 > >>
 > >> Bob
 > >>
 > >> -Original Message-
 > >> From: time-nuts-boun...@febo.com
 [[2]mailto:time-nuts-boun...@febo.com] On
 > >> Behalf Of WB6BNQ
 > >> Sent: Tuesday, January 18, 2011 5:03 PM
 > >> To: Discussion of precise time and frequency measurement
 > >> Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb
 unit
 > >>
 > >> To the list,
 > >>
 > >> If you listen carefully to the Symmetricom slide show,
 particularly
 page 3,
 > >> it will tell you all you need to
 > >> know:
 > >>
 > >>
 > >>
 >
 [3]http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm
 =5&pau
 > se=1&
 > >>
 >
 appKey=77<[4]http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=69
 1826191
 > &dm=5&pause=1&%0AappKey=77>
 > >>
 > >> You will discover that that it is indeed a Cesium operated
 device.
 HOWEVER
 > >> !  It is operated in the same manner
 > >> as a Rubidium device.  Doing such does NOT make it a primary
 standard.
 > >>
 > >> In a Cesium Primary standard, a beam of Cesium atoms are
 energized to a
 > >> higher state whose decay give off a
 > >> photon of light such that being on frequecy produces more light
 to the
 > >> detector.  In the Rb system, the Rb cell
 > >> acts simply as a light filter such that when on frequency the
 light
 level
 > >> is
 > >> reduced as seen by the detector.
 > >>
 > >> This Symmetricom CSAC device uses the same process as the Rb
 method
 > above.
 > >> It uses a laser to push light through
 > >> a chamber of Cesium gas.  This Cesium gas is acting as a simple
 light
 > >> filter.  So in its current state it will
 > >> not rival it superior cousins except in size and power
 comsumption and
 > >> possibly price for performance in some
 > >> applications.
 > >>
 > >> BillWB6BNQ
 > >>
 > >>
 > >>
 > >> ___
 > >> time-nuts mailing list -- time-nuts@febo.com
 > >> To unsubscribe, go to
 > >> [5]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 > >> and follow the instru

Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Tom Holmes]

OK, so aside from the price of this toy, are there any performance reasons
why this itty bitty gizmo wouldn't be quite useful to my ham friends who do
portable/mobile microwave operation, as opposed to dragging along a GPSDO or
OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even higher.

Tom Holmes, N8ZM
Tipp City, OH
EM79


> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Bob Camp
> Sent: Tuesday, January 18, 2011 5:55 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
> 
> Hi
> 
> In this case, it's an itty bitty gizmo that has some significant
compromises in
> performance compared to it's bigger cousins.
> 
> Bob
> 
> 
> On Jan 18, 2011, at 5:47 PM, William H. Fite wrote:
> 
> > Oh gosh, it would never, EVER do to find a li'l bitty product that
performs
> > as well as our big ole spare rooms full of costly, bulky, heavy, mostly
> > antiquated equipment.  [?]
> >
> >
> >
> > On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp  wrote:
> >
> >> Hi
> >>
> >> Simply having cesium in it does not make it a primary standard. Since
it's
> >> more like a rubidium than anything else, it's a lot easier to think of
it
> >> as
> >> a "really small low power rubidium". One other advantage it may have is
> >> that
> >> the LED may have a longer life than a normal "light bulb" source. I
suspect
> >> it's a little early to forecast 20 year (or not) life on these yet.
> >>
> >> Bob
> >>
> >> -Original Message-
> >> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> >> Behalf Of WB6BNQ
> >> Sent: Tuesday, January 18, 2011 5:03 PM
> >> To: Discussion of precise time and frequency measurement
> >> Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
> >>
> >> To the list,
> >>
> >> If you listen carefully to the Symmetricom slide show, particularly
page 3,
> >> it will tell you all you need to
> >> know:
> >>
> >>
> >>
> http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pau
> se=1&
> >>
> appKey=77 &dm=5&pause=1&%0AappKey=77>
> >>
> >> You will discover that that it is indeed a Cesium operated device.
HOWEVER
> >> !  It is operated in the same manner
> >> as a Rubidium device.  Doing such does NOT make it a primary standard.
> >>
> >> In a Cesium Primary standard, a beam of Cesium atoms are energized to a
> >> higher state whose decay give off a
> >> photon of light such that being on frequecy produces more light to the
> >> detector.  In the Rb system, the Rb cell
> >> acts simply as a light filter such that when on frequency the light
level
> >> is
> >> reduced as seen by the detector.
> >>
> >> This Symmetricom CSAC device uses the same process as the Rb method
> above.
> >> It uses a laser to push light through
> >> a chamber of Cesium gas.  This Cesium gas is acting as a simple light
> >> filter.  So in its current state it will
> >> not rival it superior cousins except in size and power comsumption and
> >> possibly price for performance in some
> >> applications.
> >>
> >> BillWB6BNQ
> >>
> >>
> >>
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >>
> >>
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
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> >> and follow the instructions there.
> >>
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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Magnus Danielson]

On 01/18/2011 07:48 PM, Mark Spencer wrote:

The long term aging spec is interesting to me, as a cesium physics package is a
primary standard wouldn't there be an ultimate limit to the total long term
aging ?  (I took a quick glance at the full data sheet and didn't see any
reference to this.)


This clock would not be a primary reference, but a secondary reference 
alongside rubidium gas-cells, as it is a caesium gas-cell rather than 
carefully built caesium beam. Nothing wrong with that, just a bit different.


Cheers,
Magnus

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Re: [time-nuts] Lady Heather V2.00

[Magnus Danielson]

On 01/18/2011 03:08 AM, Tom Van Baak wrote:

Come to think of it... it would be fun to see if there is a time-error
correlation on location on sky. It would help to indicate multi-path
errors and possibly be instructive to identify and mitigate multi-path
sources. Could potentially also show the difference of antenna
multi-path handling capabilities.


Magnus,

If you look at the recent plots for the cheap GPS receiver
http://www.leapsecond.com/pages/MG1613S/
you can see some correlation between position error and
nsv (number of sats) or hdop (which I just added). Or if
nothing else you see dramatic periodicity in receiver
operation over 24 hours, as one would expect with GPS.


Actually, just sitting and watching the time-offset of my thunderbolt 
jump around using the less than optimum antenna location during position 
average prooves the point all too well to me. I have a fair idea of how 
it works out anyways.



Most of the GPSDO we've been talking about over the years
use a fixed time constant and the excitement and effort goes
into characterizing what TC to select -- based on the GPS
engine, the ADEV of the OCXO, the resolution of the phase
comparator, the ambient temperature range, antenna quality,
sky view quality, or other environmental factors, etc.

But it seems to me this is sub-optimal. You can pick a nice
TC for the best case to be sure. And when you loose GPS
lock the GPSDO goes into holdover mode. The TC is at the
heart of how much the 10 MHz output is influenced by the
GPS receiver vs. the OCXO. In theory you slide the TC to
0 and all you get is a rough GPS 1PPS; you slide the TC
to infinity and you get a fine free-running OCXO. In this
view holdover mode is really nothing more than a temporary
pushing of TC to a large (infinity) value.

So how about running a GPSDO (e.g., TBolt) for many days
and building up a profile of SVN, Az/El, S/N, NSV, HDOP,
etc. and correlating any of that to timing error? You measure
the timing error with accuracy by comparing with external
(cesium) ref or get measure it approximately by monitoring
the internal TIC value. Either way you get a profile of good
times vs. bad times, good sats vs. better sats, good Az/El
vs. poor Az/El.


Dynamically changing the TC according to the situation is indeed one of 
the tricks you can play.


Another is to learn which Az/El should be avoided and filter out 
satellites in "bad" spots (which Tbolt and many other GPSes allows) such 
that bad multipath spots is avoided... even if the signal strength is good.


If one where able to "hack-in" biases for multipath of sats according to 
their Az/El the multipath could possibly be mitigated and the sat would 
still contribute to reduction of HDOP and friends. If the receiver 
accepts DGPS corrections this would be possible to try. Hmm...


With a good recording of pseudo-ranges, orbits etc. for a sufficiently 
long time multipath, location and time error should separate right out.


You need to combat the systematic effects of multipath first, and best 
way is to do that on the pseudo-range. You need to separate the 
multipath error from the location error in order to reduce effects being 
played as individual sats acceptance and removal plays around with the 
time error outcome. I think that it could be a more fruitful solution. 
Trouble is... the T-bolt doesn't take DGPS corrections.



You can go one step further and based on packet 0x8F-A7,
recompute the timing residuals and thus change the weight
of certain SVN or Az/El combinations (multipath).

Then, and here's the trick -- you dynamically change the TC
according to your profile. The TC would be shorter during those
minutes when you had a high quality GPS fix and the TC would
be longer during those periods of lesser quality. But the TC is
no longer a hardcoded constant, it's completely based on past
history or current indicators. It will vary from rather short to
very long depending on actual live conditions.


You can achieve better performance by adapting filters, if you have an 
adequate model.


This is all heading towards Kalman filters it seems...


Holdover would then not be a special case, it would simply be
when the TC was made large.


Holdover is a special-case in how you recover from it.


Furthermore, if the default TC was selected for an ideal room
temperature but the learned/learning profile discovered that
the temp is changing more rapidly than expected, it simply
reduces the TC to accommodate this.


It would be one solution... another would be to trim up the D term of a 
PID style compensation. The source of that frequency error is the 
temperature input and not the GPS position/frequency error which the TC 
battles with. TC reduction due to sizeable temperature derivative would 
be possible but really the wrong medicine.



Thus the GPSDO adapts itself to current conditions, whether
they are SV related, or sky-view related, or environmental,
or changes in the OCXO, or OCXO oven, etc.

This is a general ca

Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[paul swed]

tnx

On Tue, Jan 18, 2011 at 5:49 PM, John Miles  wrote:

> No, not at this time.  It would take a lot of hacking.
>
> -- john, KE5FX
>
> > -Original Message-
> > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> > Behalf Of paul swed
> > Sent: Tuesday, January 18, 2011 2:18 PM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
> >
> >
> > A quick question
> > I thought lady heather was a Tbolt program only.
> > Does it work with other GPSDP like the hp 3801 etc???
> > Thanks
> >
> > On Tue, Jan 18, 2011 at 9:20 AM, J. L. Trantham  wrote:
> >
> > > The Z3816A responded to the command nicely.  I was also able to use the
> > > command:
> > >*tst?
> > > to reboot the receiver without having to turn off the Z3816A.  This was
> > > using Symmetricom SatStat v5.0.  I have not tried with HP SatStat v4.2.
> > >
> > > Initially, the time was off by what appeared to be the leap second
> value
> > > with a TFOM of 6.  Now it is back to a TFOM of 3 and the time appears
> > > correct.
> > >
> > > Thanks,
> > >
> > > Joe
> > >
> > > -Original Message-
> > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> > > Behalf Of J. L. Trantham
> > > Sent: Tuesday, January 18, 2011 6:36 AM
> > > To: 'Discussion of precise time and frequency measurement'
> > > Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
> > >
> > >
> > > Michael,
> > >
> > > Thanks for the hint.  I've looked at that site a thousand times
> > but never
> > > found that hint until now.  I'll give it a try.
> > >
> > > Thanks again.
> > >
> > > Joe
> > >
> > > -Original Message-
> > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]
> On
> > > Behalf Of cook michael
> > > Sent: Tuesday, January 18, 2011 2:20 AM
> > > To: time-nuts@febo.com
> > > Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
> > >
> > >
> > > Le 18/01/2011 05:07, J. L. Trantham a écrit :
> > > > An unrelated question.  My Z3816A reports GPS time.  I have looked
> but
> > > > have not found a command to make it switch to UTC.  Does such a
> > > > command exist? If so, what is it?
> > > >
> > > The command to do the same on the Z3801A might work with this
> > box aswell.
> > >
> > > Using info from K8CU;
> > > http://www.realhamradio.com/GPS_Frequency_Standard.htm
> > >
> > > Issue the command:
> > >
> > >:diag:gps:utc?
> > >
> > > If it returns 0 you are in GPS mode; if 1 you are in UTC
> > >
> > > Use the command:
> > >
> > >:diag:gps:utc 1
> > >
> > > followed by
> > >
> > >:syst:pon
> > >
> > > to set it to UTC mode.  Some units have to be powered off to
> > actually reset
> > > to UTC depending on software version.
> > >
> > >
> > >
> > >
> > > ___
> > > time-nuts mailing list -- time-nuts@febo.com
> > > To unsubscribe, go to
> > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > >
> > > ___
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> > > and follow the instructions there.
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> > > Checked by AVG - www.avg.com
> > > Version: 9.0.872 / Virus Database: 271.1.1/3386 - Release Date:
> 01/17/11
> > > 01:34:00
> > >
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> > > ___
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> > > and follow the instructions there.
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Re: [time-nuts] Not getting microsecond accurate time in Linux with GPS setup

[cook michael]

Hi,
  A couple of things not mentioned in the previous responses:

 " precision" here is not how accurate your laptops clock is. 
"precision" is a measure of how much the time changes during successive 
reading of the system clock as viewed by ntpd. Its minimum value is 1us 
due to the  timeval structure variable types.


  Your ntpq data is showing a high offset 24,5 ms but that it also has 
high jitter , adding the two gives you around 67 secs reported.


  Laptops often have variable speed oscillators to save power when not 
much is going on. This will cause unreliable timing and may be the 
source of your jitter. If your machine has that facility I suggest you 
turn it off (probably in the bios) and see if the stability improves.


 As mentioned , the time source is not optimal. I am pretty sure you 
only have the NMEA sentences to get time info and they are sent after 
the 1sec GPS mark. Check to see if the SHM driver has a fudge variable 
to take that into configuration. If you are seeing a constant offset of 
25ms and the shm driver has a fudge to allow for it, then configure it.
 However I doubt that you will be able to get better than 10s of ms 
accuracy with the hardware you have.


 You should be configuring more time servers. Take them off the ntp 
pool for instance over the network.



Le 18/01/2011 21:21, Mark Ngbapai a écrit :

Hi all. I've grown interested in precise timekeeping so I decided to
buy an inexpensive Transystem iBlue 737 GPSr clone with MTK 3301 +
3179 chipset (32-channel, -158dBm tracking sensitivity, Silicon Wave
Bluetooth 1.2 chipset) for use with my Fedora 12 Linux Netbook (An
Acer Aspire One D150). Having lock indoors of 5/9 satellites I've
succeeded connecting the device via rfcomm to my netbook and using
gpsd for parsing the data. I restart the nptd server in the machine
and after a few minutes I get:


[root@PHOENIX Streamer]# ntpq -p
  remote   refid  st t when poll reach   delay   offset  jitter
==
*SHM(0)  .GPS.0 l-   16  3770.000   24.511  42.977


If I execute ntpstat, it shows:

[root@PHOENIX Streamer]# ntpstat
synchronised to modem at stratum 1
time correct to within 67 ms
polling server every 16 s


In /var/log/mesages I see the lines:

Jan 18 20:38:39 PHOENIX ntpd[6898]: ntpd 4.2.4p8@1.1612-o Wed Dec  9
11:49:22 UTC 2009 (1)
Jan 18 20:38:39 PHOENIX ntpd[6899]: precision = 5.448 usec
Jan 18 20:39:28 PHOENIX ntpd[6899]: synchronized to SHM(0), stratum 0


So why my system is telling me the time is correct within 67 ms and
not 5.44 usec? My GPSr is located at 1-1.5 meters from my netbook
(GPSr battery lasts around 40 hours, low power is not an issue). Does
my Linux installation need special Kernel patching or I'm missing
something?


Thanks in advance,

Mark

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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Bob Camp]

Hi

In this case, it's an itty bitty gizmo that has some significant compromises in 
performance compared to it's bigger cousins. 

Bob


On Jan 18, 2011, at 5:47 PM, William H. Fite wrote:

> Oh gosh, it would never, EVER do to find a li'l bitty product that performs
> as well as our big ole spare rooms full of costly, bulky, heavy, mostly
> antiquated equipment.  [?]
> 
> 
> 
> On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp  wrote:
> 
>> Hi
>> 
>> Simply having cesium in it does not make it a primary standard. Since it's
>> more like a rubidium than anything else, it's a lot easier to think of it
>> as
>> a "really small low power rubidium". One other advantage it may have is
>> that
>> the LED may have a longer life than a normal "light bulb" source. I suspect
>> it's a little early to forecast 20 year (or not) life on these yet.
>> 
>> Bob
>> 
>> -Original Message-
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
>> Behalf Of WB6BNQ
>> Sent: Tuesday, January 18, 2011 5:03 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>> 
>> To the list,
>> 
>> If you listen carefully to the Symmetricom slide show, particularly page 3,
>> it will tell you all you need to
>> know:
>> 
>> 
>> http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pause=1&;
>> appKey=77
>> 
>> You will discover that that it is indeed a Cesium operated device.  HOWEVER
>> !  It is operated in the same manner
>> as a Rubidium device.  Doing such does NOT make it a primary standard.
>> 
>> In a Cesium Primary standard, a beam of Cesium atoms are energized to a
>> higher state whose decay give off a
>> photon of light such that being on frequecy produces more light to the
>> detector.  In the Rb system, the Rb cell
>> acts simply as a light filter such that when on frequency the light level
>> is
>> reduced as seen by the detector.
>> 
>> This Symmetricom CSAC device uses the same process as the Rb method above.
>> It uses a laser to push light through
>> a chamber of Cesium gas.  This Cesium gas is acting as a simple light
>> filter.  So in its current state it will
>> not rival it superior cousins except in size and power comsumption and
>> possibly price for performance in some
>> applications.
>> 
>> BillWB6BNQ
>> 
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[John Miles]

No, not at this time.  It would take a lot of hacking.

-- john, KE5FX

> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> Behalf Of paul swed
> Sent: Tuesday, January 18, 2011 2:18 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
>
>
> A quick question
> I thought lady heather was a Tbolt program only.
> Does it work with other GPSDP like the hp 3801 etc???
> Thanks
>
> On Tue, Jan 18, 2011 at 9:20 AM, J. L. Trantham  wrote:
>
> > The Z3816A responded to the command nicely.  I was also able to use the
> > command:
> >*tst?
> > to reboot the receiver without having to turn off the Z3816A.  This was
> > using Symmetricom SatStat v5.0.  I have not tried with HP SatStat v4.2.
> >
> > Initially, the time was off by what appeared to be the leap second value
> > with a TFOM of 6.  Now it is back to a TFOM of 3 and the time appears
> > correct.
> >
> > Thanks,
> >
> > Joe
> >
> > -Original Message-
> > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> > Behalf Of J. L. Trantham
> > Sent: Tuesday, January 18, 2011 6:36 AM
> > To: 'Discussion of precise time and frequency measurement'
> > Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
> >
> >
> > Michael,
> >
> > Thanks for the hint.  I've looked at that site a thousand times
> but never
> > found that hint until now.  I'll give it a try.
> >
> > Thanks again.
> >
> > Joe
> >
> > -Original Message-
> > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> > Behalf Of cook michael
> > Sent: Tuesday, January 18, 2011 2:20 AM
> > To: time-nuts@febo.com
> > Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
> >
> >
> > Le 18/01/2011 05:07, J. L. Trantham a écrit :
> > > An unrelated question.  My Z3816A reports GPS time.  I have looked but
> > > have not found a command to make it switch to UTC.  Does such a
> > > command exist? If so, what is it?
> > >
> > The command to do the same on the Z3801A might work with this
> box aswell.
> >
> > Using info from K8CU;
> > http://www.realhamradio.com/GPS_Frequency_Standard.htm
> >
> > Issue the command:
> >
> >:diag:gps:utc?
> >
> > If it returns 0 you are in GPS mode; if 1 you are in UTC
> >
> > Use the command:
> >
> >:diag:gps:utc 1
> >
> > followed by
> >
> >:syst:pon
> >
> > to set it to UTC mode.  Some units have to be powered off to
> actually reset
> > to UTC depending on software version.
> >
> >
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> > No virus found in this incoming message.
> > Checked by AVG - www.avg.com
> > Version: 9.0.872 / Virus Database: 271.1.1/3386 - Release Date: 01/17/11
> > 01:34:00
> >
> >
> > ___
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> > To unsubscribe, go to
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> > and follow the instructions there.
> >
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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[William H. Fite]

Oh gosh, it would never, EVER do to find a li'l bitty product that performs
as well as our big ole spare rooms full of costly, bulky, heavy, mostly
antiquated equipment.  [?]



On Tue, Jan 18, 2011 at 5:10 PM, Bob Camp  wrote:

> Hi
>
> Simply having cesium in it does not make it a primary standard. Since it's
> more like a rubidium than anything else, it's a lot easier to think of it
> as
> a "really small low power rubidium". One other advantage it may have is
> that
> the LED may have a longer life than a normal "light bulb" source. I suspect
> it's a little early to forecast 20 year (or not) life on these yet.
>
> Bob
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of WB6BNQ
> Sent: Tuesday, January 18, 2011 5:03 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
>
> To the list,
>
> If you listen carefully to the Symmetricom slide show, particularly page 3,
> it will tell you all you need to
> know:
>
>
> http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pause=1&;
> appKey=77
>
> You will discover that that it is indeed a Cesium operated device.  HOWEVER
> !  It is operated in the same manner
> as a Rubidium device.  Doing such does NOT make it a primary standard.
>
> In a Cesium Primary standard, a beam of Cesium atoms are energized to a
> higher state whose decay give off a
> photon of light such that being on frequecy produces more light to the
> detector.  In the Rb system, the Rb cell
> acts simply as a light filter such that when on frequency the light level
> is
> reduced as seen by the detector.
>
> This Symmetricom CSAC device uses the same process as the Rb method above.
> It uses a laser to push light through
> a chamber of Cesium gas.  This Cesium gas is acting as a simple light
> filter.  So in its current state it will
> not rival it superior cousins except in size and power comsumption and
> possibly price for performance in some
> applications.
>
> BillWB6BNQ
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>
>
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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[paul swed]

A quick question
I thought lady heather was a Tbolt program only.
Does it work with other GPSDP like the hp 3801 etc???
Thanks

On Tue, Jan 18, 2011 at 9:20 AM, J. L. Trantham  wrote:

> The Z3816A responded to the command nicely.  I was also able to use the
> command:
>*tst?
> to reboot the receiver without having to turn off the Z3816A.  This was
> using Symmetricom SatStat v5.0.  I have not tried with HP SatStat v4.2.
>
> Initially, the time was off by what appeared to be the leap second value
> with a TFOM of 6.  Now it is back to a TFOM of 3 and the time appears
> correct.
>
> Thanks,
>
> Joe
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
> Behalf Of J. L. Trantham
> Sent: Tuesday, January 18, 2011 6:36 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
>
>
> Michael,
>
> Thanks for the hint.  I've looked at that site a thousand times but never
> found that hint until now.  I'll give it a try.
>
> Thanks again.
>
> Joe
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of cook michael
> Sent: Tuesday, January 18, 2011 2:20 AM
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question
>
>
> Le 18/01/2011 05:07, J. L. Trantham a écrit :
> > An unrelated question.  My Z3816A reports GPS time.  I have looked but
> > have not found a command to make it switch to UTC.  Does such a
> > command exist? If so, what is it?
> >
> The command to do the same on the Z3801A might work with this box aswell.
>
> Using info from K8CU;
> http://www.realhamradio.com/GPS_Frequency_Standard.htm
>
> Issue the command:
>
>:diag:gps:utc?
>
> If it returns 0 you are in GPS mode; if 1 you are in UTC
>
> Use the command:
>
>:diag:gps:utc 1
>
> followed by
>
>:syst:pon
>
> to set it to UTC mode.  Some units have to be powered off to actually reset
> to UTC depending on software version.
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
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Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[Bob Camp]

Hi

Simply having cesium in it does not make it a primary standard. Since it's
more like a rubidium than anything else, it's a lot easier to think of it as
a "really small low power rubidium". One other advantage it may have is that
the LED may have a longer life than a normal "light bulb" source. I suspect
it's a little early to forecast 20 year (or not) life on these yet. 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of WB6BNQ
Sent: Tuesday, January 18, 2011 5:03 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

To the list,

If you listen carefully to the Symmetricom slide show, particularly page 3,
it will tell you all you need to
know:

http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pause=1&;
appKey=77

You will discover that that it is indeed a Cesium operated device.  HOWEVER
!  It is operated in the same manner
as a Rubidium device.  Doing such does NOT make it a primary standard.

In a Cesium Primary standard, a beam of Cesium atoms are energized to a
higher state whose decay give off a
photon of light such that being on frequecy produces more light to the
detector.  In the Rb system, the Rb cell
acts simply as a light filter such that when on frequency the light level is
reduced as seen by the detector.

This Symmetricom CSAC device uses the same process as the Rb method above.
It uses a laser to push light through
a chamber of Cesium gas.  This Cesium gas is acting as a simple light
filter.  So in its current state it will
not rival it superior cousins except in size and power comsumption and
possibly price for performance in some
applications.

BillWB6BNQ



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[time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

[WB6BNQ]

To the list,

If you listen carefully to the Symmetricom slide show, particularly page 3, it 
will tell you all you need to
know:

http://www.brainshark.com/Steve_FatSymmetricom/vu?pi=691826191&dm=5&pause=1&appKey=77

You will discover that that it is indeed a Cesium operated device.  HOWEVER !  
It is operated in the same manner
as a Rubidium device.  Doing such does NOT make it a primary standard.

In a Cesium Primary standard, a beam of Cesium atoms are energized to a higher 
state whose decay give off a
photon of light such that being on frequecy produces more light to the 
detector.  In the Rb system, the Rb cell
acts simply as a light filter such that when on frequency the light level is 
reduced as seen by the detector.

This Symmetricom CSAC device uses the same process as the Rb method above.  It 
uses a laser to push light through
a chamber of Cesium gas.  This Cesium gas is acting as a simple light filter.  
So in its current state it will
not rival it superior cousins except in size and power comsumption and possibly 
price for performance in some
applications.

BillWB6BNQ



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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Sync...

[J.D. Schoedel]

Quoting from a white paper on their site:
"it uses a tiny hollowed-out silicon cube filled with cesium gas."

On 01/18/11 20:17, paul swed wrote:

Quick question is this a rb reference.
Looked at the symetricom site they never actually say or I missed it.

On Tue, Jan 18, 2011 at 2:37 PM,  wrote:

   

Here is a link to the press release with more technical details and
pictures:

_
http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-app
roaches-performance-of-modules-2_
(
http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-approaches-performance-of-modules-2
)


In a message dated 1/18/2011 11:32:33 Pacific Standard Time,
bro...@pacific.net writes:

Hi  Mark:

I got the idea that it's a Rubidium clock.

Have  Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer  wrote:
 

The long term aging spec is interesting to me, as a cesium  physics
   

package is a
 

primary standard wouldn't there be an ultimate  limit to the total long
   

term
 

aging ?  (I took a quick glance at  the full data sheet and didn't see
   

any
 

reference to  this.)


- Original Message 
From:  Julien Goodwin
To: Discussion of  precise time and frequency
   

measurement
 

Sent:  Tue, January 18, 2011 8:04:20 AM
Subject: Re: [time-nuts] Symmetricom  Launches CSAC Product for Precise
   

Timing
 

and  Synchronization

On 19/01/11 02:35, Pierpaolo Bernardi  wrote:

   

Though this could be of  interest...

  http://www.insidegnss.com/node/2446

 

  "The SA.45s reportedly provides ... short-term stability (Allan
  Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

  >   From the data sheet of the bigger Rubidium micro-clocks:

  SA.33/35m:
1 Sec stability-<3E-11
1 month aging - +/1  1E-10

Neat, but only really of benefit to *really*  space/weight/power critical
devices.

"The cesium atoms  are “excited,” or heated to a vapor state by a beam
generated from a  vertical-cavity surface emitting laser (VCSEL) that
passes between  upper and lower polymide heater/suspension strips. The
VCSEL was  designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC  team."

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Re: [time-nuts] Not getting microsecond accurate time in Linux with GPS setup

[Chris Albertson]

Some thoughts..

1) Can you really even expect 1uS timing with a BlueTooth GPS that
lacks a direct, wired 1PPS interface?  My guess is "no".

2) Next, add some pool servers to the ntp.conf file and let ntp get
your computer clock's rate of advance "in the ball park"  As is
"drift" and "offset" are being compared to what?  Let it run with pool
servers for an hour or more

3) A "few minutes" is not enough time to know what the final steady
state result will be.  Try 1/2 hour or over night.

I'd like it if someone could prove me wrong, but I think 1uS or better
timing will require different hardware and a more "direct" connection
to  the GPS' PPS.

As a basic check, can you see how the location reported by the GPS
moves around.  Ideally it would never move by even an inch but the
system is not perfect and there will be a spread in reported lat.
long.  Just write down the low order digits every couple minutes for
an hour or so.  the spread will change as the sats geometry changes.
At this point a rough estimate is good enough, is the GPS bouncing
around at the 100 meter level or  the 1m level?

I tried using an old Garmin 12 GPS with NMEA only NTP driver and got
about 10X worse then your result.  Basically the "12" was useless.
That was with good reception too as a put the GPS in the roof and ran
a long RS232 cable back to the computer.  On the other hand my Oncore
UT+ GPS gives results on order of 1000X or 500x better then you
report.  Not all GPS units are good for timing

On Tue, Jan 18, 2011 at 12:21 PM, Mark Ngbapai
 wrote:
> Hi all. I've grown interested in precise timekeeping so I decided to
> buy an inexpensive Transystem iBlue 737 GPSr clone with MTK 3301 +
> 3179 chipset (32-channel, -158dBm tracking sensitivity, Silicon Wave
> Bluetooth 1.2 chipset) for use with my Fedora 12 Linux Netbook (An
> Acer Aspire One D150). Having lock indoors of 5/9 satellites I've
> succeeded connecting the device via rfcomm to my netbook and using
> gpsd for parsing the data. I restart the nptd server in the machine
> and after a few minutes I get:
>
>
> [root@PHOENIX Streamer]# ntpq -p
>     remote           refid      st t when poll reach   delay   offset  jitter
> ==
> *SHM(0)          .GPS.            0 l    -   16  377    0.000   24.511  42.977
>
>
> If I execute ntpstat, it shows:
>
> [root@PHOENIX Streamer]# ntpstat
> synchronised to modem at stratum 1
>   time correct to within 67 ms
>   polling server every 16 s
>
>
> In /var/log/mesages I see the lines:
>
> Jan 18 20:38:39 PHOENIX ntpd[6898]: ntpd 4.2.4p8@1.1612-o Wed Dec  9
> 11:49:22 UTC 2009 (1)
> Jan 18 20:38:39 PHOENIX ntpd[6899]: precision = 5.448 usec
> Jan 18 20:39:28 PHOENIX ntpd[6899]: synchronized to SHM(0), stratum 0
>
>
> So why my system is telling me the time is correct within 67 ms and
> not 5.44 usec? My GPSr is located at 1-1.5 meters from my netbook
> (GPSr battery lasts around 40 hours, low power is not an issue). Does
> my Linux installation need special Kernel patching or I'm missing
> something?
>
>
> Thanks in advance,
>
> Mark
>
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>



-- 
=
Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Not getting microsecond accurate time in Linux with GPS setup

[John Ackermann N8UR]

You'll probably get better (and more interesting!) answers on the NTP 
group/mailing list, but a first thought is that NTP takes quite a long 
time to stabilize after startup.


From the jitter value below being larger than the offset, I'm guessing 
you took this ntpq snapshot after only a few polling intervals.  Give it 
a couple of hours and see where you end up.  (Because of the slow 
convergence, the typical laptop usage pattern is not conducive to good 
NTP performance.)


John


On 1/18/2011 3:21 PM, Mark Ngbapai wrote:

Hi all. I've grown interested in precise timekeeping so I decided to
buy an inexpensive Transystem iBlue 737 GPSr clone with MTK 3301 +
3179 chipset (32-channel, -158dBm tracking sensitivity, Silicon Wave
Bluetooth 1.2 chipset) for use with my Fedora 12 Linux Netbook (An
Acer Aspire One D150). Having lock indoors of 5/9 satellites I've
succeeded connecting the device via rfcomm to my netbook and using
gpsd for parsing the data. I restart the nptd server in the machine
and after a few minutes I get:


[root@PHOENIX Streamer]# ntpq -p
  remote   refid  st t when poll reach   delay   offset  jitter
==
*SHM(0)  .GPS.0 l-   16  3770.000   24.511  42.977


If I execute ntpstat, it shows:

[root@PHOENIX Streamer]# ntpstat
synchronised to modem at stratum 1
time correct to within 67 ms
polling server every 16 s


In /var/log/mesages I see the lines:

Jan 18 20:38:39 PHOENIX ntpd[6898]: ntpd 4.2.4p8@1.1612-o Wed Dec  9
11:49:22 UTC 2009 (1)
Jan 18 20:38:39 PHOENIX ntpd[6899]: precision = 5.448 usec
Jan 18 20:39:28 PHOENIX ntpd[6899]: synchronized to SHM(0), stratum 0


So why my system is telling me the time is correct within 67 ms and
not 5.44 usec? My GPSr is located at 1-1.5 meters from my netbook
(GPSr battery lasts around 40 hours, low power is not an issue). Does
my Linux installation need special Kernel patching or I'm missing
something?


Thanks in advance,

Mark

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[time-nuts] Not getting microsecond accurate time in Linux with GPS setup

[Mark Ngbapai]

Hi all. I've grown interested in precise timekeeping so I decided to
buy an inexpensive Transystem iBlue 737 GPSr clone with MTK 3301 +
3179 chipset (32-channel, -158dBm tracking sensitivity, Silicon Wave
Bluetooth 1.2 chipset) for use with my Fedora 12 Linux Netbook (An
Acer Aspire One D150). Having lock indoors of 5/9 satellites I've
succeeded connecting the device via rfcomm to my netbook and using
gpsd for parsing the data. I restart the nptd server in the machine
and after a few minutes I get:


[root@PHOENIX Streamer]# ntpq -p
 remote   refid  st t when poll reach   delay   offset  jitter
==
*SHM(0)  .GPS.0 l-   16  3770.000   24.511  42.977


If I execute ntpstat, it shows:

[root@PHOENIX Streamer]# ntpstat
synchronised to modem at stratum 1
   time correct to within 67 ms
   polling server every 16 s


In /var/log/mesages I see the lines:

Jan 18 20:38:39 PHOENIX ntpd[6898]: ntpd 4.2.4p8@1.1612-o Wed Dec  9
11:49:22 UTC 2009 (1)
Jan 18 20:38:39 PHOENIX ntpd[6899]: precision = 5.448 usec
Jan 18 20:39:28 PHOENIX ntpd[6899]: synchronized to SHM(0), stratum 0


So why my system is telling me the time is correct within 67 ms and
not 5.44 usec? My GPSr is located at 1-1.5 meters from my netbook
(GPSr battery lasts around 40 hours, low power is not an issue). Does
my Linux installation need special Kernel patching or I'm missing
something?


Thanks in advance,

Mark

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Sync...

[paul swed]

Quick question is this a rb reference.
Looked at the symetricom site they never actually say or I missed it.

On Tue, Jan 18, 2011 at 2:37 PM,  wrote:

> Here is a link to the press release with more technical details and
> pictures:
>
> _
> http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-app
> roaches-performance-of-modules-2_
> (
> http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-approaches-performance-of-modules-2
> )
>
>
> In a message dated 1/18/2011 11:32:33 Pacific Standard Time,
> bro...@pacific.net writes:
>
> Hi  Mark:
>
> I got the idea that it's a Rubidium clock.
>
> Have  Fun,
>
> Brooke Clarke
> http://www.PRC68.com
>
>
> Mark Spencer  wrote:
> > The long term aging spec is interesting to me, as a cesium  physics
> package is a
> > primary standard wouldn't there be an ultimate  limit to the total long
> term
> > aging ?  (I took a quick glance at  the full data sheet and didn't see
> any
> > reference to  this.)
> >
> >
> > - Original Message 
> > From:  Julien Goodwin
> > To: Discussion of  precise time and frequency
> measurement
> > Sent:  Tue, January 18, 2011 8:04:20 AM
> > Subject: Re: [time-nuts] Symmetricom  Launches CSAC Product for Precise
> Timing
> > and  Synchronization
> >
> > On 19/01/11 02:35, Pierpaolo Bernardi  wrote:
> >
> >> Though this could be of  interest...
> >>
> >>  http://www.insidegnss.com/node/2446
> >>
> >  "The SA.45s reportedly provides ... short-term stability (Allan
> >  Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
> >
> >  > From the data sheet of the bigger Rubidium micro-clocks:
> >
> >  SA.33/35m:
> > 1 Sec stability-<3E-11
> > 1 month aging - +/1  1E-10
> >
> > Neat, but only really of benefit to *really*  space/weight/power critical
> > devices.
> >
> > "The cesium atoms  are “excited,” or heated to a vapor state by a beam
> > generated from a  vertical-cavity surface emitting laser (VCSEL) that
> > passes between  upper and lower polymide heater/suspension strips. The
> > VCSEL was  designed by Sandia Labs, one of Symmetricom’s partners on the
> > CSAC  team."
> >
> > ___
> >  time-nuts mailing list -- time-nuts@febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the  instructions there.
> >
> >
> >
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> >
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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[cook michael]

Le 18/01/2011 20:59, Poul-Henning Kamp a écrit :

In message<4d35ef76.7020...@pacific.net>, Brooke Clarke writes:

The research that was announced some years ago was Cs atoms:
http://physicsworld.com/cws/article/news/20177

There is a technology pdf available on their site. It gives more detail 
and perf data - you need a login to get it. It states that it is cesium.



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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Poul-Henning Kamp]

In message <4d35ef76.7020...@pacific.net>, Brooke Clarke writes:

The research that was announced some years ago was Cs atoms:
http://physicsworld.com/cws/article/news/20177

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Brooke Clarke]

Hi Mark:

That press release says something like "Cesium like performance".
But the diagram of the unit looks like a Rb standard.
That's to say they are shining light through a heated cell.

Have Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer wrote:

Strangely, the article from the original email in this thread
http://www.insidegnss.com/node/2446#Baseband_Technologies_Inc_

mentions the useage of cesium atoms in a resonance cell.   The data sheet does
not mention cesium (at least from what I can see.)   





  



- Original Message 
From: Brooke Clarke
To: Discussion of precise time and frequency measurement
Sent: Tue, January 18, 2011 11:32:21 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing
and Synchronization

Hi Mark:

I got the idea that it's a Rubidium clock.

Have Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer wrote:
   

The long term aging spec is interesting to me, as a cesium physics package is
 

a
   

primary standard wouldn't there be an ultimate limit to the total long term
aging ?  (I took a quick glance at the full data sheet and didn't see any
reference to this.)


- Original Message 
From: Julien Goodwin
To: Discussion of precise time and frequency measurement
Sent: Tue, January 18, 2011 8:04:20 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing
and Synchronization

On 19/01/11 02:35, Pierpaolo Bernardi wrote:

 

Though this could be of interest...

http://www.insidegnss.com/node/2446

   

"The SA.45s reportedly provides ... short-term stability (Allan
Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

 

 From the data sheet of the bigger Rubidium micro-clocks:
   

SA.33/35m:
1 Sec stability-<3E-11
1 month aging - +/1 1E-10

Neat, but only really of benefit to *really* space/weight/power critical
devices.

"The cesium atoms are “excited,” or heated to a vapor state by a beam
generated from a vertical-cavity surface emitting laser (VCSEL) that
passes between upper and lower polymide heater/suspension strips. The
VCSEL was designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC team."

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Mark Spencer]

Strangely, the article from the original email in this thread 
http://www.insidegnss.com/node/2446#Baseband_Technologies_Inc_

mentions the useage of cesium atoms in a resonance cell.   The data sheet does 
not mention cesium (at least from what I can see.)    




 


- Original Message 
From: Brooke Clarke 
To: Discussion of precise time and frequency measurement 
Sent: Tue, January 18, 2011 11:32:21 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing 
and Synchronization

Hi Mark:

I got the idea that it's a Rubidium clock.

Have Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer wrote:
> The long term aging spec is interesting to me, as a cesium physics package is 
a
> primary standard wouldn't there be an ultimate limit to the total long term
> aging ?  (I took a quick glance at the full data sheet and didn't see any
> reference to this.)
>
>
> - Original Message 
> From: Julien Goodwin
> To: Discussion of precise time and frequency measurement
> Sent: Tue, January 18, 2011 8:04:20 AM
> Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing
> and Synchronization
>
> On 19/01/11 02:35, Pierpaolo Bernardi wrote:
>    
>> Though this could be of interest...
>>
>> http://www.insidegnss.com/node/2446
>>      
> "The SA.45s reportedly provides ... short-term stability (Allan
> Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
>
> > From the data sheet of the bigger Rubidium micro-clocks:
>
> SA.33/35m:
> 1 Sec stability-<3E-11
> 1 month aging - +/1 1E-10
>
> Neat, but only really of benefit to *really* space/weight/power critical
> devices.
>
> "The cesium atoms are “excited,” or heated to a vapor state by a beam
> generated from a vertical-cavity surface emitting laser (VCSEL) that
> passes between upper and lower polymide heater/suspension strips. The
> VCSEL was designed by Sandia Labs, one of Symmetricom’s partners on the
> CSAC team."
>
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>    

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Sync...

[Mike Feher]

Looks familiar Said. Regards - Mike

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell


-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf 
Of saidj...@aol.com
Sent: Tuesday, January 18, 2011 2:37 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing 
and Sync...

Here is a link to the press release with more technical details and  
pictures:
 
_http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-app
roaches-performance-of-modules-2_ 
(http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-approaches-performance-of-modules-2)
 
 


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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Sync...

[SAIDJACK]

Here is a link to the press release with more technical details and  
pictures:
 
_http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-app
roaches-performance-of-modules-2_ 
(http://www.eetimes.com/electronics-news/4212176/Chip-scale-atomic-clock-approaches-performance-of-modules-2)
 
 
 
In a message dated 1/18/2011 11:32:33 Pacific Standard Time,  
bro...@pacific.net writes:

Hi  Mark:

I got the idea that it's a Rubidium clock.

Have  Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer  wrote:
> The long term aging spec is interesting to me, as a cesium  physics 
package is a
> primary standard wouldn't there be an ultimate  limit to the total long 
term
> aging ?  (I took a quick glance at  the full data sheet and didn't see any
> reference to  this.)
>
>
> - Original Message 
> From:  Julien Goodwin
> To: Discussion of  precise time and frequency 
measurement
> Sent:  Tue, January 18, 2011 8:04:20 AM
> Subject: Re: [time-nuts] Symmetricom  Launches CSAC Product for Precise 
Timing
> and  Synchronization
>
> On 19/01/11 02:35, Pierpaolo Bernardi  wrote:
>
>> Though this could be of  interest...
>>
>>  http://www.insidegnss.com/node/2446
>>  
>  "The SA.45s reportedly provides ... short-term stability (Allan
>  Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
>
>  > From the data sheet of the bigger Rubidium micro-clocks:
>
>  SA.33/35m:
> 1 Sec stability-<3E-11
> 1 month aging - +/1  1E-10
>
> Neat, but only really of benefit to *really*  space/weight/power critical
> devices.
>
> "The cesium atoms  are “excited,” or heated to a vapor state by a beam
> generated from a  vertical-cavity surface emitting laser (VCSEL) that
> passes between  upper and lower polymide heater/suspension strips. The
> VCSEL was  designed by Sandia Labs, one of Symmetricom’s partners on the
> CSAC  team."
>
> ___
>  time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Brooke Clarke]

Hi Mark:

I got the idea that it's a Rubidium clock.

Have Fun,

Brooke Clarke
http://www.PRC68.com


Mark Spencer wrote:

The long term aging spec is interesting to me, as a cesium physics package is a
primary standard wouldn't there be an ultimate limit to the total long term
aging ?  (I took a quick glance at the full data sheet and didn't see any
reference to this.)


- Original Message 
From: Julien Goodwin
To: Discussion of precise time and frequency measurement
Sent: Tue, January 18, 2011 8:04:20 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing
and Synchronization

On 19/01/11 02:35, Pierpaolo Bernardi wrote:
   

Though this could be of interest...

http://www.insidegnss.com/node/2446
 

"The SA.45s reportedly provides ... short-term stability (Allan
Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

> From the data sheet of the bigger Rubidium micro-clocks:

SA.33/35m:
1 Sec stability-<3E-11
1 month aging - +/1 1E-10

Neat, but only really of benefit to *really* space/weight/power critical
devices.

"The cesium atoms are “excited,” or heated to a vapor state by a beam
generated from a vertical-cavity surface emitting laser (VCSEL) that
passes between upper and lower polymide heater/suspension strips. The
VCSEL was designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC team."

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[time-nuts] SECAM vs NTSC

[Murray Greenman]

Rick,
Maybe the French had a point... we all know NTSC stands for 'Never Twice
Same Colour'!

Regards,
Murray Greenman


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Re: [time-nuts] Thunderbolt cooling vs heating for stability

[EWKehren]

Peltier takes to much power and generates more heat. A fan will work  
nicely.
Bert Kehren
 
 
In a message dated 1/18/2011 12:17:00 P.M. Eastern Standard Time,  
p...@petelancashire.com writes:

Been  getting ready to build a box for the t'bolt and instead of it all
getting  hotter to maintain a stable temp
is the idea of cooling with a Peltier  cooler, or a mix of a Peltier
and a heater ?

Extending life time is  the major  concern

-pete

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Mark Spencer]

The 1 pps input for disciplining and the RS 232 control capability is also 
interesting.   




- Original Message 
From: Poul-Henning Kamp 
To: Discussion of precise time and frequency measurement 
Sent: Tue, January 18, 2011 11:03:07 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing 
and Synchronization

In message <848524.71272...@web38803.mail.mud.yahoo.com>, Mark Spencer writes:

Don't overlook the start-up time: 2 minutes, that's pretty darn good...



-- 
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
p...@freebsd.org        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Galileo - CEO of sat builder fired

[Bob Bownes]

Eppur si muove. (Yet it still moves.) :)





On Tue, Jan 18, 2011 at 1:51 PM, Rick Karlquist  wrote:
>
> The comment about Galileo mainly being for the benefit of
> France reminds me of the old joke about the French acronym
> SECAM standing for System Engineered Contrary to American Methods.
>
> Rick
>
>
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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Poul-Henning Kamp]

In message <848524.71272...@web38803.mail.mud.yahoo.com>, Mark Spencer writes:

Don't overlook the start-up time: 2 minutes, that's pretty darn good...



-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Galileo - CEO of sat builder fired

[Rick Karlquist]

The comment about Galileo mainly being for the benefit of
France reminds me of the old joke about the French acronym
SECAM standing for System Engineered Contrary to American Methods.

Rick


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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Mark Spencer]

The long term aging spec is interesting to me, as a cesium physics package is a 
primary standard wouldn't there be an ultimate limit to the total long term 
aging ?  (I took a quick glance at the full data sheet and didn't see any 
reference to this.)


- Original Message 
From: Julien Goodwin 
To: Discussion of precise time and frequency measurement 
Sent: Tue, January 18, 2011 8:04:20 AM
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing 
and Synchronization

On 19/01/11 02:35, Pierpaolo Bernardi wrote:
> Though this could be of interest...
> 
> http://www.insidegnss.com/node/2446

"The SA.45s reportedly provides ... short-term stability (Allan
Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

From the data sheet of the bigger Rubidium micro-clocks:

SA.33/35m:
1 Sec stability- <3E-11
1 month aging - +/1 1E-10

Neat, but only really of benefit to *really* space/weight/power critical
devices.

"The cesium atoms are “excited,” or heated to a vapor state by a beam
generated from a vertical-cavity surface emitting laser (VCSEL) that
passes between upper and lower polymide heater/suspension strips. The
VCSEL was designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC team."

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Re: [time-nuts] Galileo - CEO of sat builder fired

[Poul-Henning Kamp]

In message , Pete
 Lancashire writes:


>http://www.pddnet.com/news-ap-german-firms-ceo-removed-over-wikileaks-cable-011811/?et_cid=991385&et_rid=45624211&linkid=http%3a%2f%2fwww.pddnet.com%2fnews-ap-german-firms-ceo-removed-over-wikileaks-cable-011811%2f


Talking truth about Galileo never got anybody anything good...

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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Re: [time-nuts] Thunderbolt cooling vs heating for stability

[Pete Lancashire]

I've done a couple projects/contracts with them, still have a few
dozen units, power supplies,
heat pipes etc.

but I've ditched the idea. Spare T'Bolt or two should exceed my life.

-pete

On Tue, Jan 18, 2011 at 10:12 AM, Chris Albertson
 wrote:
> On Tue, Jan 18, 2011 at 9:16 AM, Pete Lancashire
>  wrote:
>> Been getting ready to build a box for the t'bolt and instead of it all
>> getting hotter to maintain a stable temp
>> is the idea of cooling with a Peltier cooler, or a mix of a Peltier
>
> I've used Peltier cooling.  It works very well.  You epoxy the Peltier
> device to big chunk of aluminum with embed thermistors.  The
> controller servos the Peltier current to keep the thermistors at a
> setpoint.  You can get to better then 0.1C that way.
>
> Problems:  (1) This will use a "ton" of electric current.  (2) You
> will need a huge heat sink on the side of the Peltier not facing the
> device to be cooled.  So huge that you will likely need for it to be a
> water based system with a pump
>
> Good news is that Melcor sells everything you need, the peltiers, heat
> exchangers and so on.  And they have all the technical data you need
> and tutorials too.     Also the exact same Peltier setup will either
> heat or cool
>
> You will need a lot of very good insulation.  Specifically to prevent
> heat from flowing between  the two sides of the peltier.    We used
> vacuum because it is very effective but it is expensive and complex to
> maintain.  You would likely find spray in place foam to work and the
> stuff is cheap and easy to spary between the hot and cold side heat
> sinks
>
> OK, my point is, yes it will work but it will be far from cheap and easy
>
> --
> =
> Chris Albertson
> Redondo Beach, California
>
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Re: [time-nuts] Thunderbolt cooling vs heating for stability

[Pete Lancashire]

sound like not worth it. My idea of 'cooling' was say keeping the insides
at something like 25C. Just having a 2nd TBolt as a spare would be easier

-pete

On Tue, Jan 18, 2011 at 9:41 AM, Bob Camp  wrote:
> Hi
>
> There's pretty much nothing in a TBolt that wears out. The heat rise on the
> parts on the pc board is modest and the only heated part is the OCXO.
> Cooling down the OCXO actually increases the stress on it (more heater power
> pulled => more stress on the heater).
>
> Obviously you can get it to hot. The OCXO does have an upper temperature
> limit. I don't think that extreme measures are needed to keep it at a
> rational temperature. Simple fans and boxes seem to be working pretty well
> for people. Any setup that results in sub 60C temperatures at the OCXO is
> likely to have very little impact on reliability or performance.
>
> The more important question is how you package it to reduce gradients. If
> you use the internal sensor, it's location is a bit sub-optimal for tracking
> the OCXO. You could put all sorts of sensors throughout the package. An
> easier thing to watch is the correlation between external temperature and
> EFC voltage. As long as EFC correlates (positive or negative) with outside
> temperature, you have room for improvement.
>
> Bob
>
>
>
> -Original Message-
> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
> Behalf Of Pete Lancashire
> Sent: Tuesday, January 18, 2011 12:16 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Thunderbolt cooling vs heating for stability
>
> Been getting ready to build a box for the t'bolt and instead of it all
> getting hotter to maintain a stable temp
> is the idea of cooling with a Peltier cooler, or a mix of a Peltier
> and a heater ?
>
> Extending life time is the major concern
>
> -pete
>
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Re: [time-nuts] Thunderbolt cooling vs heating for stability

[Chris Albertson]

On Tue, Jan 18, 2011 at 9:16 AM, Pete Lancashire
 wrote:
> Been getting ready to build a box for the t'bolt and instead of it all
> getting hotter to maintain a stable temp
> is the idea of cooling with a Peltier cooler, or a mix of a Peltier

I've used Peltier cooling.  It works very well.  You epoxy the Peltier
device to big chunk of aluminum with embed thermistors.  The
controller servos the Peltier current to keep the thermistors at a
setpoint.  You can get to better then 0.1C that way.

Problems:  (1) This will use a "ton" of electric current.  (2) You
will need a huge heat sink on the side of the Peltier not facing the
device to be cooled.  So huge that you will likely need for it to be a
water based system with a pump

Good news is that Melcor sells everything you need, the peltiers, heat
exchangers and so on.  And they have all the technical data you need
and tutorials too. Also the exact same Peltier setup will either
heat or cool

You will need a lot of very good insulation.  Specifically to prevent
heat from flowing between  the two sides of the peltier.We used
vacuum because it is very effective but it is expensive and complex to
maintain.  You would likely find spray in place foam to work and the
stuff is cheap and easy to spary between the hot and cold side heat
sinks

OK, my point is, yes it will work but it will be far from cheap and easy

-- 
=
Chris Albertson
Redondo Beach, California

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[time-nuts] Galileo - CEO of sat builder fired

[Pete Lancashire]

http://www.pddnet.com/news-ap-german-firms-ceo-removed-over-wikileaks-cable-011811/?et_cid=991385&et_rid=45624211&linkid=http%3a%2f%2fwww.pddnet.com%2fnews-ap-german-firms-ceo-removed-over-wikileaks-cable-011811%2f

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Re: [time-nuts] "PYLT" Python LabTools

[Lester Veenstra]

Book seems a rather lite on actually getting Python to work with GPIB.
Instead it really a book on data manipulation using Python



Lester B Veenstra  MØYCM K1YCM
les...@veenstras.com
m0...@veenstras.com
k1...@veenstras.com
 

US Postal Address:
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prohibited.

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of supp...@prologix.biz
Sent: Monday, January 17, 2011 7:21 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] "PYLT" Python LabTools

Dear Poul,

Excellent! Looking forward to playing with it more.

On a related note, O'Reilly has a new book out on developing  
instrument control software
using Python:

Real World Instrumentation with Python: Automated Data Acquisition and  
Control Systems by
John M. Hughes
http://oreilly.com/catalog/9780596809577

(Self-interest disclosure: John's book mentions Prologix GPIB-USB
Controller.)

Regards,
Abdul


Quoting Poul-Henning Kamp :

> In message <4d32fef2.5000...@erols.com>, Chuck Harris writes:
>
>
>> I was
>> a little more back-of-the-envelope with my stuff, and basically kept
>> the low level stuff with the upper level control functions.
>
> Yeah, that's how I started out also, and then I ended up in the
> "now where did I put that function I wrote which..." mode and got
> fed up with it.
>
> The instrument that got the ball rolling was the U2004 Power Sensor
> with its USB interface, that took a couple of days to figure out.
> (SCPI over IEEE488.2 over USB488 over USBTMC over USB, who are these
> bozos ???)
>
> Anyway, I hope it proves useful for some people and as always, patches
> are welcome :-)
>
> --
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by
incompetence.
>
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> To unsubscribe, go to
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Re: [time-nuts] Achievable temperature stability for Thunderbolt

[Bob Camp]

Hi

If you are going to use a fan, I would seal up the part nice and tight. Very
small drafts could have pretty major effects on gradients inside the gizmo.
Simple fiddling with aluminum tape should do the trick pretty well. A roll
of the stuff from Home Depot will last you forever...

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of ewkeh...@aol.com
Sent: Tuesday, January 18, 2011 9:12 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Achievable temperature stability for Thunderbolt

Looking at ways to optimize GPS-Rb-OCXO performance, using dewar, foam and  
fan cooling, using a fan was an eye opener. I have now come to the 
conclusion  that for the temperature environment we are working in, a fan is
the 
best way  for all three. I am using a 5X5X1 cm fan drawing 50 mA at 12 Volt,

results are  amazing. Realizing that Tbolt and Rb's have to be cooled not 
heated I powered up  a FRS with out heat sink and monitored the back plate.

With 22 C ambient  it increased on the bench to 58 C. Placing the fan 5 cm 
away, the temperature  dropped to 38.9 C in 2.5 minutes! I repeated the test

using a laptop heat pipe  with the fan running at 5 Volt and 170 mA the back

plate temperature dropped to  30 C. Presently running a HP 10811 with
similar 
results. I am convinced that I  will be able to get better than .1 C control

in all three applications.  Having large temp. fluctuations outside this 
time of the year I will take  advantage of the large fluctuations. I think
the 
challenge will be at higher  ambient's, it will determine the set point. 
Right now I am looking at the 40 to  45 C range. A small amount of air flow 
goes a long way. Noise and vibration is  small and manageable. 
Any comments? Fan power is lower than heating how ever all three devices  
power consumption is increased overcoming the lower case temp.
Bert Kehren
 
 
In a message dated 1/18/2011 6:42:29 A.M. Eastern Standard Time,  
hol...@hotmail.com writes:


Generally you have to do some playing with the fan position and  internal 
baffling and thermal mass for best performance of the temperature  
controller.  You don't want direct airflow onto the tbolt.  Also you
probably don't 
want an large/aggressive fan...  a little airflow can go a  long way.  

Some thermal mass can  be useful...  I use a  2 kg stainless steel 
calibration weight (but probably need to do some testing  without it.
Warren's 
setup seems to be a little better than mine,  but he probably does not need
to 
deal with the heating/air conditioning  extremes that I do)

One thing that I have is an ESI SR104  hyper-accurate 10K resistance 
standard.  These have two temperatures  where their resistance is exactly
10K.  I 
have it (and a Fluke 732B 10V  precision voltage reference) mounted in a box

with a tbolt set to one of those  temperatures...  cheap temperature 
controlled cal lab in a cardboard  box.
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Re: [time-nuts] Thunderbolt cooling vs heating for stability

[Bob Camp]

Hi

There's pretty much nothing in a TBolt that wears out. The heat rise on the
parts on the pc board is modest and the only heated part is the OCXO.
Cooling down the OCXO actually increases the stress on it (more heater power
pulled => more stress on the heater). 

Obviously you can get it to hot. The OCXO does have an upper temperature
limit. I don't think that extreme measures are needed to keep it at a
rational temperature. Simple fans and boxes seem to be working pretty well
for people. Any setup that results in sub 60C temperatures at the OCXO is
likely to have very little impact on reliability or performance. 

The more important question is how you package it to reduce gradients. If
you use the internal sensor, it's location is a bit sub-optimal for tracking
the OCXO. You could put all sorts of sensors throughout the package. An
easier thing to watch is the correlation between external temperature and
EFC voltage. As long as EFC correlates (positive or negative) with outside
temperature, you have room for improvement. 

Bob 



-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Pete Lancashire
Sent: Tuesday, January 18, 2011 12:16 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Thunderbolt cooling vs heating for stability

Been getting ready to build a box for the t'bolt and instead of it all
getting hotter to maintain a stable temp
is the idea of cooling with a Peltier cooler, or a mix of a Peltier
and a heater ?

Extending life time is the major concern

-pete

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Bob Camp]

Hi

If you had one delivered to your door today, what on your bench would you
replace with it?

A lot of what it does is not "as good as" a $30 e-place DOCXO. Other than
power / weight / size, you can significantly beat it today with a sub $100
Rb from the same sources. For stationary time nut in the basement stuff,
it's tough to find a place for it. 

That said, it's a very cool little gizmo. If you do need low power / tight
accuracy it's going to be hard to beat. It's certainly a good part for
portable applications. Packing around enough battery to run a 10 W Rb for a
few days isn't very practical. Running one of these off a couple of lithium
cells would work pretty well. 

Bob

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of paul swed
Sent: Tuesday, January 18, 2011 11:57 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Symmetricom Launches CSAC Product for Precise
Timing and Synchronization

Wonder what the lifetime is?
Surely for time nuts they will have a special deal. Like $199 for today
only.
Well we might dream.

On Tue, Jan 18, 2011 at 11:20 AM, Pierpaolo Bernardi
wrote:

> On Tue, Jan 18, 2011 at 17:04, Julien Goodwin
>  wrote:
> > On 19/01/11 02:35, Pierpaolo Bernardi wrote:
> >> Though this could be of interest...
> >>
> >> http://www.insidegnss.com/node/2446
> >
> > "The SA.45s reportedly provides ... short-term stability (Allan
> > Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
> >
> > From the data sheet of the bigger Rubidium micro-clocks:
> >
> > SA.33/35m:
> > 1 Sec stability- <3E-11
> > 1 month aging - +/1 1E-10
> >
> > Neat, but only really of benefit to *really* space/weight/power critical
> > devices.
>
> Also for low cost applications, I think.
>
> It says 1500 USD for low volume.  And surely the price is going to
> decrease in the near future?
>
> Cheers
> P.
>
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[time-nuts] Thunderbolt cooling vs heating for stability

[Pete Lancashire]

Been getting ready to build a box for the t'bolt and instead of it all
getting hotter to maintain a stable temp
is the idea of cooling with a Peltier cooler, or a mix of a Peltier
and a heater ?

Extending life time is the major concern

-pete

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Pete Lancashire]

On Tue, Jan 18, 2011 at 8:20 AM, Pierpaolo Bernardi  wrote:
> On Tue, Jan 18, 2011 at 17:04, Julien Goodwin
>  wrote:
>> On 19/01/11 02:35, Pierpaolo Bernardi wrote:
>>> Though this could be of interest...
>>>
>>> http://www.insidegnss.com/node/2446
>>
>> "The SA.45s reportedly provides ... short-term stability (Allan
>> Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
>>
>> From the data sheet of the bigger Rubidium micro-clocks:
>>
>> SA.33/35m:
>> 1 Sec stability- <3E-11
>> 1 month aging - +/1 1E-10
>>
>> Neat, but only really of benefit to *really* space/weight/power critical
>> devices.
>
> Also for low cost applications, I think.
>
> It says 1500 USD for low volume.  And surely the price is going to
> decrease in the near future?
>
> Cheers
> P.

If history repeats. Look up what the first GPS units cost, or that HP
5060A cost adjusted for inflation ! Now lets hope some cell company
will use them and a couple years from now they will be $100.

Curious what was the real price of a Thunderbolt from the factory ?

-pete

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[paul swed]

Wonder what the lifetime is?
Surely for time nuts they will have a special deal. Like $199 for today
only.
Well we might dream.

On Tue, Jan 18, 2011 at 11:20 AM, Pierpaolo Bernardi wrote:

> On Tue, Jan 18, 2011 at 17:04, Julien Goodwin
>  wrote:
> > On 19/01/11 02:35, Pierpaolo Bernardi wrote:
> >> Though this could be of interest...
> >>
> >> http://www.insidegnss.com/node/2446
> >
> > "The SA.45s reportedly provides ... short-term stability (Allan
> > Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
> >
> > From the data sheet of the bigger Rubidium micro-clocks:
> >
> > SA.33/35m:
> > 1 Sec stability- <3E-11
> > 1 month aging - +/1 1E-10
> >
> > Neat, but only really of benefit to *really* space/weight/power critical
> > devices.
>
> Also for low cost applications, I think.
>
> It says 1500 USD for low volume.  And surely the price is going to
> decrease in the near future?
>
> Cheers
> P.
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Pierpaolo Bernardi]

On Tue, Jan 18, 2011 at 17:04, Julien Goodwin
 wrote:
> On 19/01/11 02:35, Pierpaolo Bernardi wrote:
>> Though this could be of interest...
>>
>> http://www.insidegnss.com/node/2446
>
> "The SA.45s reportedly provides ... short-term stability (Allan
> Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"
>
> From the data sheet of the bigger Rubidium micro-clocks:
>
> SA.33/35m:
> 1 Sec stability- <3E-11
> 1 month aging - +/1 1E-10
>
> Neat, but only really of benefit to *really* space/weight/power critical
> devices.

Also for low cost applications, I think.

It says 1500 USD for low volume.  And surely the price is going to
decrease in the near future?

Cheers
P.

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Re: [time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Julien Goodwin]

On 19/01/11 02:35, Pierpaolo Bernardi wrote:
> Though this could be of interest...
> 
> http://www.insidegnss.com/node/2446

"The SA.45s reportedly provides ... short-term stability (Allan
Deviation) of 2E-10 @ 1 sec, long-term aging of 3E-10/month"

From the data sheet of the bigger Rubidium micro-clocks:

SA.33/35m:
1 Sec stability- <3E-11
1 month aging - +/1 1E-10

Neat, but only really of benefit to *really* space/weight/power critical
devices.

"The cesium atoms are “excited,” or heated to a vapor state by a beam
generated from a vertical-cavity surface emitting laser (VCSEL) that
passes between upper and lower polymide heater/suspension strips. The
VCSEL was designed by Sandia Labs, one of Symmetricom’s partners on the
CSAC team."

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[time-nuts] Symmetricom Launches CSAC Product for Precise Timing and Synchronization

[Pierpaolo Bernardi]

Though this could be of interest...

http://www.insidegnss.com/node/2446

Cheers
P.

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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[J. L. Trantham]

The Z3816A responded to the command nicely.  I was also able to use the
command:
*tst?
to reboot the receiver without having to turn off the Z3816A.  This was
using Symmetricom SatStat v5.0.  I have not tried with HP SatStat v4.2.

Initially, the time was off by what appeared to be the leap second value
with a TFOM of 6.  Now it is back to a TFOM of 3 and the time appears
correct.

Thanks,

Joe

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
Behalf Of J. L. Trantham
Sent: Tuesday, January 18, 2011 6:36 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question


Michael,

Thanks for the hint.  I've looked at that site a thousand times but never
found that hint until now.  I'll give it a try.

Thanks again.

Joe

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of cook michael
Sent: Tuesday, January 18, 2011 2:20 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question


Le 18/01/2011 05:07, J. L. Trantham a écrit :
> An unrelated question.  My Z3816A reports GPS time.  I have looked but
> have not found a command to make it switch to UTC.  Does such a
> command exist? If so, what is it?
>
The command to do the same on the Z3801A might work with this box aswell.

Using info from K8CU; http://www.realhamradio.com/GPS_Frequency_Standard.htm

Issue the command:

:diag:gps:utc?

If it returns 0 you are in GPS mode; if 1 you are in UTC

Use the command:

:diag:gps:utc 1

followed by

:syst:pon

to set it to UTC mode.  Some units have to be powered off to actually reset
to UTC depending on software version.




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No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 9.0.872 / Virus Database: 271.1.1/3386 - Release Date: 01/17/11
01:34:00


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Re: [time-nuts] Achievable temperature stability for Thunderbolt

[EWKehren]

Looking at ways to optimize GPS-Rb-OCXO performance, using dewar, foam and  
fan cooling, using a fan was an eye opener. I have now come to the 
conclusion  that for the temperature environment we are working in, a fan is 
the 
best way  for all three. I am using a 5X5X1 cm fan drawing 50 mA at 12 Volt, 
results are  amazing. Realizing that Tbolt and Rb's have to be cooled not 
heated I powered up  a FRS with out heat sink and monitored the back plate.  
With 22 C ambient  it increased on the bench to 58 C. Placing the fan 5 cm 
away, the temperature  dropped to 38.9 C in 2.5 minutes! I repeated the test 
using a laptop heat pipe  with the fan running at 5 Volt and 170 mA the back 
plate temperature dropped to  30 C. Presently running a HP 10811 with similar 
results. I am convinced that I  will be able to get better than .1 C control 
in all three applications.  Having large temp. fluctuations outside this 
time of the year I will take  advantage of the large fluctuations. I think the 
challenge will be at higher  ambient's, it will determine the set point. 
Right now I am looking at the 40 to  45 C range. A small amount of air flow 
goes a long way. Noise and vibration is  small and manageable. 
Any comments? Fan power is lower than heating how ever all three devices  
power consumption is increased overcoming the lower case temp.
Bert Kehren
 
 
In a message dated 1/18/2011 6:42:29 A.M. Eastern Standard Time,  
hol...@hotmail.com writes:


Generally you have to do some playing with the fan position and  internal 
baffling and thermal mass for best performance of the temperature  
controller.  You don't want direct airflow onto the tbolt.  Also you  probably 
don't 
want an large/aggressive fan...  a little airflow can go a  long way.  

Some thermal mass can  be useful...  I use a  2 kg stainless steel 
calibration weight (but probably need to do some testing  without it.  Warren's 
setup seems to be a little better than mine,  but he probably does not need to 
deal with the heating/air conditioning  extremes that I do)

One thing that I have is an ESI SR104  hyper-accurate 10K resistance 
standard.  These have two temperatures  where their resistance is exactly 10K.  
I 
have it (and a Fluke 732B 10V  precision voltage reference) mounted in a box 
with a tbolt set to one of those  temperatures...  cheap temperature 
controlled cal lab in a cardboard  box.
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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[J. L. Trantham]

Mark,

That is what I understood from the 'Readme' but I could not get the program
to respond until after it had recognized the TBolt which required me to put
the TBolt on COM 1 to start with.

Thanks,

Joe

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Mark Sims
Sent: Tuesday, January 18, 2011 5:22 AM
To: time-nuts@febo.com
Subject: [time-nuts] LH v3.0 Beta and Z3816A Question



You can specify the com port number on the command line.  COM2 would use the
/2 parameter, etc

If you type in ? from the keyboard or /? on the command line you get a
dialog box that shows most of the command line options.


-
Is there a way to make Lady Heather 'wake up' looking at COM 2?

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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[J. L. Trantham]

Michael,

Thanks for the hint.  I've looked at that site a thousand times but never
found that hint until now.  I'll give it a try.

Thanks again.

Joe

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of cook michael
Sent: Tuesday, January 18, 2011 2:20 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] LH v3.0 Beta and Z3816A Question


Le 18/01/2011 05:07, J. L. Trantham a écrit :
> An unrelated question.  My Z3816A reports GPS time.  I have looked but 
> have not found a command to make it switch to UTC.  Does such a 
> command exist? If so, what is it?
>
The command to do the same on the Z3801A might work with this box aswell.

Using info from K8CU; http://www.realhamradio.com/GPS_Frequency_Standard.htm

Issue the command:

:diag:gps:utc?

If it returns 0 you are in GPS mode; if 1 you are in UTC

Use the command:

:diag:gps:utc 1

followed by

:syst:pon

to set it to UTC mode.  Some units have to be powered off to actually reset
to UTC depending on software version.




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[time-nuts] Achievable temperature stability for Thunderbolt

[Mark Sims]

Generally you have to do some playing with the fan position and internal 
baffling and thermal mass for best performance of the temperature controller.  
You don't want direct airflow onto the tbolt.  Also you probably don't want an 
large/aggressive fan...  a little airflow can go a long way.  

Some thermal mass can  be useful...  I use a 2 kg stainless steel calibration 
weight (but probably need to do some testing without it.  Warren's setup seems 
to be a little better than mine,  but he probably does not need to deal with 
the heating/air conditioning extremes that I do)

One thing that I have is an ESI SR104 hyper-accurate 10K resistance standard.  
These have two temperatures where their resistance is exactly 10K.  I have it 
(and a Fluke 732B 10V precision voltage reference) mounted in a box with a 
tbolt set to one of those temperatures...  cheap temperature controlled cal lab 
in a cardboard box.   
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[time-nuts] LH v3.0 Beta and Z3816A Question

[Mark Sims]

You can specify the com port number on the command line.  COM2 would use the /2 
parameter, etc

If you type in ? from the keyboard or /? on the command line you get a dialog 
box that shows most of the command line options.


-
Is there a way to make Lady Heather 'wake up' looking at COM 2? 
  
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Re: [time-nuts] Achievable temperature stability for Thunderbolt

[WarrenS]

Achim, DH2VA

AFTER temperature is being controlled pretty good with the default settings 
(modified if necessary),
What I use to fine tune the PID values is the "Quick Auto Tune" command 
"K,A,4,Enter".
The quick command is much faster (typ < 30 min) than the full Auto Tune 
command, and can and should be used even with a hack and whenever there is a 
change in the Temperature H/W.
(The "quick auto tune" command skips a lot of steps by assuming that the 
temperature is at the set-point and under reasonable stable control and not 
oscillating)


To set the PID values to the slow default use "K,W,Enter", for the faster 
default settings "K,M,Enter"  (there may be others?)
For best results, I keep the inner case that holds the sensor & OCXO closed, 
and do not let air blow inside it.
Note, unlike passive temperature control where the more the mass the better, 
that is Not the case for this simple active PID temperature controller.
The more the mass, the slower the response, and the harder it can be for the 
temperature loop to stabilizing.


ws

*

[time-nuts] Achievable temperature stability for Thunderbolt environment?
Achim Vollhardt avollhar at physik.uzh.ch
Tue Jan 18 08:21:48 UTC 2011

Dear Warren and Mark,

I have hacked together a very simple setup with the transistor circuit
and the opened Thunderbolt case (not its own case, but the front lid of
my outer case opened). The CPU fan was placed about 2" away, only
blowing indirectly into the case..

The results are simply amazing! The temperature pk-pk excursions are
down to 0.03K, approx. 30x less than before.. and I even have not
figured out how to tune the controller parameters..
.. which will have to wait. I don't think is useful to tune a hacked
setup. I will add as much thermal mass (aluminum) into the case as I can
and do a proper fan installation.. then back to PID tuning.

Thank you very much for this great tool! I wish I knew C/C++ better so I
would have less problems understanding the code..

73s Achim, DH2VA 



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Re: [time-nuts] Achievable temperature stability for Thunderbolt environment?

[Achim Vollhardt]

Dear Warren and Mark,

I have hacked together a very simple setup with the transistor circuit 
and the opened Thunderbolt case (not its own case, but the front lid of 
my outer case opened). The CPU fan was placed about 2" away, only 
blowing indirectly into the case..


The results are simply amazing! The temperature pk-pk excursions are 
down to 0.03K, approx. 30x less than before.. and I even have not 
figured out how to tune the controller parameters..
.. which will have to wait. I don't think is useful to tune a hacked 
setup. I will add as much thermal mass (aluminum) into the case as I can 
and do a proper fan installation.. then back to PID tuning.


Thank you very much for this great tool! I wish I knew C/C++ better so I 
would have less problems understanding the code..


73s Achim, DH2VA

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Re: [time-nuts] LH v3.0 Beta and Z3816A Question

[cook michael]

Le 18/01/2011 05:07, J. L. Trantham a écrit :

An unrelated question.  My Z3816A reports GPS time.  I have looked but have
not found a command to make it switch to UTC.  Does such a command exist?
If so, what is it?


The command to do the same on the Z3801A might work with this box aswell.

Using info from K8CU;
http://www.realhamradio.com/GPS_Frequency_Standard.htm

Issue the command:

   :diag:gps:utc?

If it returns 0 you are in GPS mode; if 1 you are in UTC

Use the command:

   :diag:gps:utc 1

followed by

   :syst:pon

to set it to UTC mode.  Some units have to be powered off to actually reset
to UTC depending on software version.




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