Re: [time-nuts] LEA-M8T

[ken hartman]

What Bob Camp said about PRECISION navigation and as it applies to
precision time is true. Do not mix different constellations. There is
direct evidence.



On Thu, Apr 7, 2016 at 9:43 AM, Björn  wrote:

> For navigation more measurements have always been prefered - that is use
> as many GNSS systems as all your receicers support.
>
> That should be true also for common view timing.
>
> --
>Björn
>
>  Originalmeddelande Från: Bob Camp <
> kb...@n1k.org> Datum:2016-04-07  18:41  (GMT+07:00)
> Till: Bob Stewart , Discussion of precise time
> and frequency measurement  Rubrik: Re:
> [time-nuts] LEA-M8T 
> Hi
>
> Indeed, if you have not turned off the other systems for timing, you will
> have issues. Even for
> precision navigation, you need to turn them off. Until the European system
> goes up, there will
> not ba a coordinated approach between any two of the systems. Right now
> they each make their
> own assumptions and their own definitions. If you are driving a car down
> the road, that’s not a
> big deal. If you are trying to do TimeNuts stuff … A one meter delta is a
> big deal for timing. A “few”
> nanoseconds (say >10) is also a big deal.
>
> Bob
>
>
> > On Apr 6, 2016, at 9:39 PM, Bob Stewart  wrote:
> >
> > Hi Logan,
> >
> > I seem to remember Bob Camp mentioning that you can't have multiple
> satellite sources in the mix, because the other satellites are inferior to
> the GPS sats in timing.  Maybe Bob or someone could address this.  I would
> love to discover that I've set something wrong in all the many, many data
> structures.
> >
> > Bob
> >
> >
> > 
> > On Wed, 4/6/16, Logan Cummings  wrote:
> >
> > Subject: Re: [time-nuts] LEA-M8T
> > To: "Bob Stewart" , "Discussion of precise time and
> frequency measurement" 
> > Date: Wednesday, April 6, 2016, 8:18 PM
> >
> > Hi
> > Bob,
> > Can't speak to
> > jitter accuracy but the M8 series is definitely not the same
> > receiver in the 6 series. As you probably know, M8
> > introduced multi-GNSS support so in addition to GPS you have
> > Beidou and Glonass satellites.
> >   At work we've had some gnashing of
> > teeth about the wider filter passband requirements for
> > multi-GNSS support since we're operating in a noisy
> > environment, but I have nothing further on degraded
> > performance when using only GPS.
> >  Would be interesting to let
> > it have all the constellations and see what
> > happens.
> > -Logan
> > On Wed, Apr 6, 2016 at
> > 10:04 AM, Bob Stewart 
> > wrote:
> > I
> > recently bought a number of LEA-M8T receivers and I have to
> > say that I am unimpressed, so far.  They don't survey
> > to the same reported accuracy as the LEA-6T in the same
> > amount of time.  They certainly aren't better in the
> > jitter after sawtooth correction.  So, have I managed to
> > overlook some new field, or are they just not the same
> > receiver as the 6T?  I did shut all sats off except GPS
> > sats.
> >
> >
> >
> > Bob - AE6RV
> >
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Re: [time-nuts] quartz thermometers

[ken hartman]

I believe - if I understand correctly - that Magnus refers to realizations
based on what has been referred to as "the Schodowski patent"

Dual mode quartz thermometric sensing device
<https://scholar.google.com/citations?view_op=view_citation=en=tVnR8zIJ_for_view=tVnR8zIJ:u-x6o8ySG0sC>
SS Schodowski
US Patent 4,872,765

as referenced here:

Resonator self-temperature-sensing using a dual-harmonic-mode crystal
oscillator
<https://scholar.google.com/citations?view_op=view_citation=en=tVnR8zIJ_for_view=tVnR8zIJ:u5HHmVD_uO8C>
SS Schodowski
Frequency Control, 1989., Proceedings of the 43rd Annual Symposium on, 2-7

Not easy to do, but truly a measure of resonator temperature variations.





On Sat, Mar 12, 2016 at 7:33 AM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:

> Hi,
>
> For the 10811 you can modify it to change mode and then use that mode to
> measure and trim the temperature oven.
>
> There exists crystal oscillators where the 10 MHz is a traditional SC-cut
> mode and then a 30 MHz mode is exercised which measures the crystal
> temperature. In the Microprocessor Controlled Crystal Oscillator (MCXO) one
> then measure the difference in frequency and uses this to re-synthesize a
> correction on the 10 MHz. The benefit is that it is the temperature of the
> oscillating crystal that is being measured.
> Naturally, it could be used for oven control and/or EFC control too.
>
> The MCXOs exists in manufacturing, but whenever you ask about them they
> just wonder what military project are you working on.
>
> I'd love to experiment with this form of temperature sensing one day, when
> I have time... if that ever happens...
>
> Cheers,
> Magnus
>
>
> On 03/12/2016 10:21 AM, ken hartman wrote:
>
>> Interestingly, the use of AC-cut crystals (high linear tempco of
>> frequency)
>> is found in the development of OCXOs. Using a reference AC-cut resonator -
>> in place of the final AT/SC resonator - one can learn much about the
>> thermal  characteristics of the oven loop performance. While not a precise
>> temp sensor, it is a high sensitivity  indicator of  temperature
>> variations
>> of the resonator.
>>
>> On Fri, Mar 11, 2016 at 11:44 PM, Bill Hawkins <bill.i...@pobox.com>
>> wrote:
>>
>> It may be that the need for that kind of resolution died out.
>>>
>>> The next step up from quartz thermometry is resistance thermometry.
>>> The linearization equation for platinum has enough terms to make it
>>> uncertain around .01 C.
>>> Temperature calibration baths usually use platinum resistance sensors.
>>>
>>> It may be that the triple point of water does not have the certainty to
>>> reach '0.0001C'
>>>
>>> Disclaimer: I only worked with industrial sensors from Rosemount, Inc.
>>> as an employee.
>>>
>>> Bill Hawkins
>>>
>>>
>>> -Original Message-
>>> From: Alan Ambrose
>>> Sent: Friday, March 11, 2016 11:42 AM
>>>
>>> Hi,
>>>
>>> I hope this is still relevant and not too off-topic...but since it
>>> involves crystals and tempco...
>>>
>>> Quartz thermometers (e.g. the HP 2804A) with their 'linear cut' crystals
>>> and '0.0001C resolution' seem to have been a thing from the mid-60's to
>>> the mid-80's:
>>>
>>> http://www.hparchive.com/Journals/HPJ-1965-03.pdf
>>>
>>> There still appear to be some manufacturers making the crystals:
>>>
>>> http://www.statek.com/products/pdf/Temp%20Sensor%2010162%20Rev%20B.pdf
>>>
>>> Anyone know why they died out? Did a better technology replace them?
>>>
>>> TIA, Alan
>>>
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Re: [time-nuts] quartz thermometers

[ken hartman]

Interestingly, the use of AC-cut crystals (high linear tempco of frequency)
is found in the development of OCXOs. Using a reference AC-cut resonator -
in place of the final AT/SC resonator - one can learn much about the
thermal  characteristics of the oven loop performance. While not a precise
temp sensor, it is a high sensitivity  indicator of  temperature variations
of the resonator.

On Fri, Mar 11, 2016 at 11:44 PM, Bill Hawkins  wrote:

> It may be that the need for that kind of resolution died out.
>
> The next step up from quartz thermometry is resistance thermometry.
> The linearization equation for platinum has enough terms to make it
> uncertain around .01 C.
> Temperature calibration baths usually use platinum resistance sensors.
>
> It may be that the triple point of water does not have the certainty to
> reach '0.0001C'
>
> Disclaimer: I only worked with industrial sensors from Rosemount, Inc.
> as an employee.
>
> Bill Hawkins
>
>
> -Original Message-
> From: Alan Ambrose
> Sent: Friday, March 11, 2016 11:42 AM
>
> Hi,
>
> I hope this is still relevant and not too off-topic...but since it
> involves crystals and tempco...
>
> Quartz thermometers (e.g. the HP 2804A) with their 'linear cut' crystals
> and '0.0001C resolution' seem to have been a thing from the mid-60's to
> the mid-80's:
>
> http://www.hparchive.com/Journals/HPJ-1965-03.pdf
>
> There still appear to be some manufacturers making the crystals:
>
> http://www.statek.com/products/pdf/Temp%20Sensor%2010162%20Rev%20B.pdf
>
> Anyone know why they died out? Did a better technology replace them?
>
> TIA, Alan
>
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Re: [time-nuts] LORAN-C reception in the UK

[ken hartman]

from:

http://gpsworld.com/eloran-progresses-toward-gps-back-up-role-in-u-s-europe/


“Both Norway and France have declared an intention to cease Loran
transmissions at the end of 2015. Moreover, France intends to dismantle its
Loran infrastructure in 2016. Arrangements for the commercial operation of
the infrastructure are being investigated, but this depends on some form of
regional agreement. The European Union appears to have no policy for
resilient PNT, the European Radio Navigation Plan having twice been drafted
but never published. The view seems to bee that the introduction of Galileo
will achieve resilient PNT, which it will not.”

On Fri, Jul 10, 2015 at 7:14 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
drkir...@kirkbymicrowave.co.uk wrote:

 How good/bad would a LORAN-C frequency reference such as the Stanford
 Research FS700 work in the UK?  I live about 60 km to the east of central
 London.

 Is there any future for LORAN-C in the UK?

 I am looking for a frequency reference that is not GPS - I already have a
 GPS frequency reference but would like to compare it with something
 independent of GPS.  Just having two GPS receivers provides two signals
 which are probably highly correlated.

 Dave.
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Re: [time-nuts] NPR Story I heard this morning

[ken hartman]

Not to put too fine a point on it, but my practical understanding is that
any two or more clocks generally do *not* agree (that is - yield identical
phase/frequency information) ever, anyway. So atomic horology - and beyond
- means that we continue to ?adjust? ?compensate? clocks of whatever
stability and accuracy to the current, agreed upon ideal - even as the
ideal may move or evolve.

On Mon, Nov 3, 2014 at 4:27 PM, Tom Van Baak t...@leapsecond.com wrote:

  I don't see anything in the BIPM definition of the second regarding sea
 level.

 Hi Mike,

 The usual wording for the definition of the SI second also includes the
 word unperturbed. That little word covers a host of physics and
 engineering effects and can keep graduate students busy for years. You
 either have to eliminate them from your clock or your lab, or extra
 carefully measure then and back-out their effects on your clock's operating
 frequency.

 For a really good example of the sort of corrections that are made inside
 a cesium clock see: http://tf.nist.gov/general/pdf/1497.pdf

 By the time you read to page 30, you'll see table 3 and 4 which summarize
 the perturbing corrections.

 /tvb

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Re: [time-nuts] sub-minute time-precision in court-case

[ken hartman]

This precisely why I stopped wearing a watch years ago
Stranger: What time is it?
Me: When?
Stranger: What 'when'? - now of course!
Me: Now - where? - Now you? or Now me? (Hint ~ 3 nsec dt)
and so forth and so on.
better a watch don't have - no questions


On Tue, Sep 3, 2013 at 4:47 PM, Tom Van Baak t...@leapsecond.com wrote:

  Nowhere does the opinion mention if the timestamps were taken on
  the same clock or if the two clocks were synchronized.

 PHK,

 Correct. This is an age-old problem, whether its minutes or nanoseconds.
 Time-stamps are inherently relative to a local oscillator's time and rate
 offset, and affected by frequency drift and stability levels.

 A solution to this problem is for the first responder to take the cell
 phone(s) and simultaneously send a text message to himself from each phone.
 That could help establish a legal time difference (unless, there are
 variable reception or carrier-specific delays).

 They could also simultaneously send cell phone photos of a handheld GPS
 receiver's time display. That could help establish a legal time accuracy
 question (unless, the cell phone or GPS receiver were in some sort of
 hold-over mode).

 For extra credit, further photos can be sent each hour for hours or days
 to determine the cell phone frequency drift and stability parameters.

 Then again, realize that a jury of your fellow citizens, not a jury of
 your peers, will decide the question of timing. Thus to raise technical
 issues like syntonization vs. synchronization, or standard vs. Allan
 deviation, or GPS vs. UTC clocks will probably not help your case.

 /tvb


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[time-nuts] get them while they are hot - 9! 5061s

[ken hartman]

a current GSA auction.

 javascript:go(Login%20%20%20%20%20%20%20);
*ASSORTED LAB EQUIPMENT: ( 12 PIECES* *81QSCI10067024* 3,910 USD CO 6
05/29 11:44
AM CT *
ASSORTED LAB EQUIPMENT: ( 12 PIECES ) CONSISTING OF 9 EACH HP 5061 CESIUM
BEAM FREQUENCY STANDARD 1 EACH FTS CESIUM TIME  FREQ STANDARD; 1EA GE
MOTORS SKC VACUUM PUMP; 1EA RELATED EQUIPMENT. NOTE; ALL ITEMS ARE CONDITION
UNKNOWN AND MAY BE MISSING PARTS.USED-ONE LOT. LOC;7S.
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Re: [time-nuts] get them while they are hot - 9! 5061s

[ken hartman]

Frankly I'm not sure. I have never bid.
I should have included the link.
http://gsaauctions.gov/gsaauctions/aucitdsc/


On Sat, May 29, 2010 at 9:11 AM, J. L. Trantham jlt...@att.net wrote:

 S..  If one were inclined to pursue this, how, exactly, does
 that work?

 Is there a website, bidding requirements, where is the stuff located, etc.,
 etc.?  In other words, how does one become eligible to access this process?

 Thanks,

 Joe

 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of ken hartman
 Sent: Saturday, May 29, 2010 8:33 AM
 To: time-nuts@febo.com
 Subject: [time-nuts] get them while they are hot - 9! 5061s

 a current GSA auction.

  javascript:go(Login%20%20%20%20%20%20%20);
 *ASSORTED LAB EQUIPMENT: ( 12 PIECES* *81QSCI10067024* 3,910 USD CO 6
 05/29 11:44
 AM CT *
 ASSORTED LAB EQUIPMENT: ( 12 PIECES ) CONSISTING OF 9 EACH HP 5061 CESIUM
 BEAM FREQUENCY STANDARD 1 EACH FTS CESIUM TIME  FREQ STANDARD; 1EA GE
 MOTORS SKC VACUUM PUMP; 1EA RELATED EQUIPMENT. NOTE; ALL ITEMS ARE
 CONDITION
 UNKNOWN AND MAY BE MISSING PARTS.USED-ONE LOT. LOC;7S.
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[time-nuts] LORAN-C demise

[ken hartman]

Given the confusing and seemingly ambiguous infomation on the .gov site, a
clearer picture is given by this announcement:

http://www.gpsworld.com/gnss-system/news/coast-guard-jettisons-loran-9178

excerpted below:

Coast Guard Jettisons Loran
November 25, 2009
--

The U.S. Coast Guard Commandant has formally certified that termination of
the Loran-C signal will not adversely impact maritime navigation, signing a
document to that effect on November 20 and forwarding it to the Secretary of
Homeland Security Janet Napolitano. The first of the two criteria for
terminating the Loran-C signal has thus been met.

Anticipated next steps include a Coast Guard ALCOAST Internet message
release on this topic, the release of the Programmatic Environmental Impact
Statement Record of Decision, and a Federal Register Notice, all measures en
route to executing the termination of the Loran-C signal.

Actual termination depends upon a final determination by DHS Secretary
Napolitano that the Loran-C infrastructure is not required as a backup to
GPS. Until then, the Coast Guard will continue  moving towards termination
while operating the system. If/when that determination is made, actual
termination will take place.
For a recent *GPS World* blog and readers' comments on this subject, see Wide
Awake with No 
Back-Uphttp://www.gpsworld.com/gnss-system/wide-awake/wide-awake-with-no-back-9168
.

Inevitable , but still a misguided shame.
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Re: [time-nuts] LORAN-C demise

[ken hartman]

My impression is that significant stake-holders (e.g. Telecom service
providers, ILECs, AOPA, National Laboratories, FAA, NIST, DHS, CG, and
others) were unwilling  - at an institutional level - to embrace or own any
aspect of LORAN preservation and unable - at an individual level - to
influence policy decisions with *any* consideration for technical
viability or necessity.
Stated  differently  - this nations  NTP policy is totally driven  by
political considerations without regard to demonstrable critical
infrastructure technical evaluation.
Standard disclaimer: My opinions only
khartman


On Sat, Nov 28, 2009 at 2:36 PM, Chuck Harris cfhar...@erols.com wrote:

 Time and frequency measurement people were specifically
 exclude from the polls I have seen to determine whether
 or not Loran should continue.  They only wanted navigation
 users input... and I guess there weren't any.

 -Chuck


 J. Forster wrote:

 There are on-line petition sites where people can sign on to support a
 particular cause. Has anyone started such a petition to save LORAN?

 I've not seen one.

 Best,
 -John

 ==



  Given the confusing and seemingly ambiguous infomation on the .gov site,
 a
 clearer picture is given by this announcement:

 http://www.gpsworld.com/gnss-system/news/coast-guard-jettisons-loran-9178

 excerpted below:

 Coast Guard Jettisons Loran
 November 25, 2009
 --

 The U.S. Coast Guard Commandant has formally certified that termination
 of
 the Loran-C signal will not adversely impact maritime navigation, signing
 a
 document to that effect on November 20 and forwarding it to the Secretary
 of
 Homeland Security Janet Napolitano. The first of the two criteria for
 terminating the Loran-C signal has thus been met.

 Anticipated next steps include a Coast Guard ALCOAST Internet message
 release on this topic, the release of the Programmatic Environmental
 Impact
 Statement Record of Decision, and a Federal Register Notice, all measures
 en
 route to executing the termination of the Loran-C signal.

 Actual termination depends upon a final determination by DHS Secretary
 Napolitano that the Loran-C infrastructure is not required as a backup to
 GPS. Until then, the Coast Guard will continue  moving towards
 termination
 while operating the system. If/when that determination is made, actual
 termination will take place.
 For a recent *GPS World* blog and readers' comments on this subject, see
 Wide
 Awake with No
 Back-Up
 http://www.gpsworld.com/gnss-system/wide-awake/wide-awake-with-no-back-9168
 
 .

 Inevitable , but still a misguided shame.
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