[time-nuts] time-nuts Digest, Vol 98, Issue 31

[Ronald Held]

I am a moderator at the HAQ forum.  If you would post uour
requirements there for a TC watch, you will get helpful responses.
     Ronald

On 9/10/12, time-nuts-request at febo.com <time-nuts-request at febo.com> wrote:
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> Today's Topics:
>
>    1. Re: GPSDO Component Selection (Azelio Boriani)
>    2. Re: REF osc distribution. (Gaudin Luc)
>    3. HP z3801a dc-dc converter (g3ueq at talktalk.net)
>    4. Re: HP z3801a dc-dc converter (Azelio Boriani)
>    5. Re: Re; New Wrist watch (David McGaw)
>    6. Re: Re; New Wrist watch (David McGaw)
>    7. Re: Re; New Wrist watch (Pierpaolo Bernardi)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 10 Sep 2012 14:11:48 +0200
> From: Azelio Boriani <azelio.boriani at screen.it>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] GPSDO Component Selection
> Message-ID:
> 	<CAL8XPmPavv7MyPuDDRYJTEC9j6zct+HhpfAr=MqYTjZkUmkrTw at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
>  There is something missing in this sentence:
>>The integration period determines
>>how much of the very accurate long term GPS information <missing verb?>
> with the short
>>term, highly stable, clock information. Hence a GPSDO.
> That is: how much of the very accurate GPS information leak? are
> transferred to? Interact? with the short term...
> I expect that the integration time is related to the end of the short term
> oscillator variation and the start of the long term GPS steering. This
> should help in the proper selection of this time: maybe the time should be
> adapted to the temperature variation too.
>
>
> On Mon, Sep 10, 2012 at 11:56 AM, Michael Perrett
> <mkperrett at gmail.com>wrote:
>
>> First - I realize 95% of the folks reading this are well aware of what I
>> am
>> going to say.
>>
>> No matter how good your equipment (receiver/antenna) is, the short term
>> accuracy of GPS time is defined in *GLOBAL POSITIONING SYSTEM STANDARD
>> POSITIONING SERVICE PERFORMANCE STANDARD (2008)*. This document can be
>> found at http://www.gps.gov/technical/ps/#spsps.
>>
>> The guaranteed timing accuracy (short term) is found in Table 3.8-3. SPS
>> Position/Time Accuracy Standards. The time domain transfer accuracy is
>> defined as "? 40 nsec time transfer error 95% of time
>> (SIS only)". In order to achieve this the "(SIS only)" comment means you
>> have a perfect receiver that introduces no errors (good luck with that
>> one). Most commercial users set their probability at around 30 nS, and
>> experience virtually no estimates out of that boundary.
>>
>> The 30 nS error can be reduced to a better number if position is
>> accurately
>> known and the receiver "knows" that it is stationary - but still 5% of
>> the
>> time you can get noisy / degraded time and still be "in spec.". I am not
>> sure over what time span the 95% number is used.
>>
>> Now: The real answer is to take the relatively noisy GPS timing
>> information
>> and use it to discipline a device that is (extremely) stable over a short
>> time such as a OCXO or Rubidium standard. The integration period
>> determines
>> how much of the very accurate long term GPS information with the short
>> term, highly stable, clock information. Hence a GPSDO.
>>
>> Michael / K7HIL
>>
>>
>>
>> On Sun, Sep 9, 2012 at 3:10 PM, Jerry <jsternmd at att.net> wrote:
>>
>> > Sounds like the Heisenberg Uncertainty principle at work :-)
>> >
>> > jerry
>> >
>> > -----Original Message-----
>> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> > Behalf Of Bob Camp
>> > Sent: Sunday, September 09, 2012 5:53 PM
>> > To: Discussion of precise time and frequency measurement
>> > Subject: Re: [time-nuts] GPSDO Component Selection
>> >
>> > Hi
>> >
>> > Position accuracy and timing accuracy are two very different things.
>> > Firmware is optimized to improve either one. "Position" firmware is
>> > often
>> > pretty poor for timing.
>> >
>> > Bob
>> >
>> > On Sep 9, 2012, at 5:05 PM, Chris Albertson <albertson.chris at gmail.com>
>> > wrote:
>> >
>> > > On Sun, Sep 9, 2012 at 1:14 PM,  <bg at lysator.liu.se> wrote:
>> > >
>> > >> True for a cheap oem navigation receiver. Not true for a geodetic
>> > >> quality receiver, who usually have some options (external frequency
>> > >> input, PPS_in) to make them the best timing receivers available.
>> > >> However they are much more expensive than the typical single
>> > >> frequency
>> > timing reciver.
>> > >
>> > > I looked at every link and can't see where they give a timing
>> > > accuracy
>> > > spec on the PPS with respect to UTC.   Possition accurracy is very
>> > > good and we might assume the timing is as good.  But they don't say
>> > > it
>> > > is.  What's interesting is these GPSes will accept an accurate clock
>> > > input in order to give better location data.   That is the opposite
>> > > of
>> > > a timing GPS where you tell it accurate location data so that it can
>> > > get better timing.   Cutting down the unknown in one lets you do
>> > > better in the other.   I assume these all cost well over $50.  You
>> > > can
>> > > get a pretty good timing GPS for $30 and it WILL have the PPS error
>> > > specified.
>> > >
>> > > To the OP.  None of this matters a lot because PPS is a standard
>> > > input
>> > > signal.  It is easy to swap out a GPS receiver later.  Same with the
>> > > OCXO.  From a control point of view they are all pretty much the
>> > > same.
>> > > You can swap them out later
>> > >
>> > >
>> > > Chris Albertson
>> > > Redondo Beach, California
>> > >
>> > > _______________________________________________
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>> >
>> >
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>
> ------------------------------
>
> Message: 2
> Date: Mon, 10 Sep 2012 14:13:49 +0200
> From: "Gaudin Luc" <lgaudin at naelcom.com>
> To: "'Robert Atkinson'" <robert8rpi at yahoo.co.uk>,	"'Discussion of
> 	precise time and frequency measurement'"	<time-nuts at febo.com>
> Subject: Re: [time-nuts] REF osc distribution.
> Message-ID: <07b201cd8f4d$c13df7d0$43b9e770$@com>
> Content-Type: text/plain;	charset="iso-8859-1"
>
> Hello,
>
> I understand your remarks but so far nobody who buy these unit complain
> about the performances.
> People are using it for 5DB to 13dB 10MHz Sine wave distribution, others
> are
> using it for 1PPS distribution in TTL (O-5volt) or in TTL (0-3.3Volt).
> Performance are good enough for the telecom and military application we are
> offering the unit.
> The gain of the unit is 0dB (1): same output than input level and slew rate
> is 2KV/microsec.
> Each output have his own op amps.
> For price contact me by email luc.gaudin at naelcom.com.
> Regards
>
> Luc
>
> -----Message d'origine-----
> De?: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
> part de Robert Atkinson
> Envoy??: vendredi 7 septembre 2012 08:31
> ??: Discussion of precise time and frequency measurement
> Objet?: Re: [time-nuts] REF osc distribution.
>
> Hi
> It may be a language issue, but the datasheet does not present this
> amplifier very well. I wondered about the specification for squarewave
> input
> "TTL 3.3V" TTL is 5V. What is the slew rate of the amplifier? It's
> specified
> to 50MHz, will it accurately reproduce a 50MHz square wave? A 1V RMS output
> is not going to reproduce a TTL 1PPS or 10MHz clock?very well. It does
> state
> that each output is isolated and?buffered. It reads as a general purpose
> wideband amplifier rather than one optimised for a particular timing
> application.
> ?
> Robert G8RPI
>
>
> ________________________________
> From: Charles P. Steinmetz <charles_steinmetz at lavabit.com>
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Sent: Thursday, 6 September 2012, 20:54
> Subject: Re: [time-nuts] REF osc distribution.
>
> Luc wrote:
>
>> We have a product that have been specially design for these : NGA-DIS
>
> Thank you for the link.? The data sheet raises a few questions:
>
> The sine wave input level is specified as "1Vrms nominal 0.5V Peak to
> peak."? Of course, 1Vrms is ~2.8Vp-p.? It is not clear what this
> specification means.
>
> Gain and noise are not specified, nor is isolation from output to input or
> from the outputs to each other.? These are parameters that many buyers will
> want to know.
>
> Have you characterized the NGA-DIS for phase noise?? That is also a
> parameter many buyers will want to know.
>
> Does each output have its own output amplifier, or does one amplifier drive
> multiple outputs through individual build-out resistors?
>
> Does the NGA-DIS use op amps, or discrete circuitry?
>
> What is the price?
>
> Best regards,
>
> Charles
>
>
>
>
>
>
>
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>
> ------------------------------
>
> Message: 3
> Date: Mon, 10 Sep 2012 09:14:17 -0400
> From: "g3ueq at talktalk.net" <g3ueq at talktalk.net>
> To: time-nuts at febo.com
> Subject: [time-nuts] HP z3801a dc-dc converter
> Message-ID: <380-22012911013141726 at M2W134.mail2web.com>
> Content-Type: text/plain; charset=iso-8859-1
>
> Hi
> Does anyone have a spare Datel DC-DC converter for this standard, mine has
> died after not being used for 3 years, it has a short on the +15V o/p and
> they seem to be like hens teeth now.
> Regards
>
> Andy
>
>
> --------------------------------------------------------------------
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> http://link.mail2web.com/mail2web
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>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 10 Sep 2012 15:48:44 +0200
> From: Azelio Boriani <azelio.boriani at screen.it>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] HP z3801a dc-dc converter
> Message-ID:
> 	<CAL8XPmNi-fb3dW5wkFFCd-4y=o0jU+eWH=PXWHoxiyMjX=aU2g at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Sure it is the DC-DC with the output shorted? Maybe the short is on the
> board. Try to measure with the DC-DC removed. Anyway if the Datel DC-DC is
> a 2x2 inches unit then it is an industry standard and you can try other
> brands.
>
> On Mon, Sep 10, 2012 at 3:14 PM, g3ueq at talktalk.net
> <g3ueq at talktalk.net>wrote:
>
>> Hi
>> Does anyone have a spare Datel DC-DC converter for this standard, mine
>> has
>> died after not being used for 3 years, it has a short on the +15V o/p and
>> they seem to be like hens teeth now.
>> Regards
>>
>> Andy
>>
>>
>> --------------------------------------------------------------------
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>> http://link.mail2web.com/mail2web
>>
>>
>>
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>
> ------------------------------
>
> Message: 5
> Date: Mon, 10 Sep 2012 09:57:40 -0400
> From: David McGaw <n1hac at Alum.Dartmouth.ORG>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] Re; New Wrist watch
> Message-ID: <504DF1D4.8060003 at alum.dartmouth.org>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> He's making a joke - If you are traveling across time zones, why not
> just set it to UTC and be done with it?  :-)
>
> David
>
>
> On 9/10/12 7:57 AM, Azelio Boriani wrote:
>> Precision is precision, whatever time scale you use. UTC, CET, TAI, use
>> what you want but stability and accuracy is the must.
>>
>> On Mon, Sep 10, 2012 at 1:22 PM, Rich and Marcia Putz
>> <rputz at bnin.net>wrote:
>>
>>> Bob;
>>>
>>> Being this is Time-Nuts and all, shouldn't you be using UTC anyway? ;)
>>>
>>> Rich
>>> _______________________________________________
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>> _______________________________________________
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>
>
>
> ------------------------------
>
> Message: 6
> Date: Mon, 10 Sep 2012 10:04:01 -0400
> From: David McGaw <n1hac at Alum.Dartmouth.ORG>
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Subject: Re: [time-nuts] Re; New Wrist watch
> Message-ID: <504DF351.60602 at alum.dartmouth.org>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> It was mentioned a while back that there are watches that are
> temperature compensated.  I would be interested in knowing which are.
> The self-setting ones are nice and I have one, but I am often in places
> that are not in range the transmitter (Greenland, Antarctica for
> instance) and I would like it not to drift.
>
> Thanks,
>
> David
>
>
> On 9/10/12 9:57 AM, David McGaw wrote:
>> He's making a joke - If you are traveling across time zones, why not
>> just set it to UTC and be done with it?  :-)
>>
>> David
>>
>>
>> On 9/10/12 7:57 AM, Azelio Boriani wrote:
>>> Precision is precision, whatever time scale you use. UTC, CET, TAI, use
>>> what you want but stability and accuracy is the must.
>>>
>>> On Mon, Sep 10, 2012 at 1:22 PM, Rich and Marcia Putz
>>> <rputz at bnin.net>wrote:
>>>
>>>> Bob;
>>>>
>>>> Being this is Time-Nuts and all, shouldn't you be using UTC anyway? ;)
>>>>
>>>> Rich
>>>> _______________________________________________
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>>> _______________________________________________
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>>
>>
>> _______________________________________________
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>
>
>
> ------------------------------
>
> Message: 7
> Date: Mon, 10 Sep 2012 16:17:23 +0200
> From: Pierpaolo Bernardi <olopierpa at gmail.com>
> To: David McGaw <n1hac at alum.dartmouth.org>, 	Discussion of precise
> 	time and frequency measurement <time-nuts at febo.com>
> Subject: Re: [time-nuts] Re; New Wrist watch
> Message-ID:
> 	<CANY8u7GZMX37jvJTDDFK3RLxLegJq2VNjV71apO=490M-=qbxg at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> On Mon, Sep 10, 2012 at 4:04 PM, David McGaw <n1hac at alum.dartmouth.org>
> wrote:
>> It was mentioned a while back that there are watches that are temperature
>> compensated.  I would be interested in knowing which are.  The
>> self-setting
>> ones are nice and I have one, but I am often in places that are not in
>> range
>> the transmitter (Greenland, Antarctica for instance) and I would like it
>> not
>> to drift.
>
> The equivalent of the time nuts list, but for watches is the "High
> Accuracy Quartz watches" forum, which lives here:
> http://forums.watchuseek.com/f9/
>
> In the sticky topics of this forum there's a compilation of the watch
> movements you are looking for.
>
> Cheers
> P.
>
>
>
> ------------------------------
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> End of time-nuts Digest, Vol 98, Issue 31
> *****************************************
>