Re: [time-nuts] Austron 2100 LORAN C manual I have a pdf!

[paul swed]

John
Glad it could help.
Its a shame we don't have some transmitters to work with.
They do turn on occasionally but it seems fewer and fewer these days.
Though lightsquared satellite will be decided on within a month if thats
our alternate PNT source over eLoran.
Regards
Paul
WB8TSL

On Thu, Apr 26, 2018 at 8:20 PM, John C. Westmoreland, P.E. <
j...@westmorelandengineering.com> wrote:

> Hello Paul,
>
> I wanted to say 'Thanks' - I downloaded that recently.
>
> I'm obviously interested in any Austron schematics; manuals; references;
> datasheets... .
>
> 73's,
> John
> AJ6BC
>
>
> On Thu, Jul 30, 2015 at 9:46 AM, paul swed  wrote:
>
> > In looking at the threads and putting away the Austron catalog I
> realized I
> > have a 2100 pdf with schematics.
> > Its 8.9 MB so will send it to the Diddiers KO4BB site tonight.
> > Regards
> > Paul
> > WB8TSL
> > ___
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Re: [time-nuts] Austron 2100 LORAN C manual I have a pdf!

[John C. Westmoreland, P.E.]

Hello Paul,

I wanted to say 'Thanks' - I downloaded that recently.

I'm obviously interested in any Austron schematics; manuals; references;
datasheets... .

73's,
John
AJ6BC


On Thu, Jul 30, 2015 at 9:46 AM, paul swed  wrote:

> In looking at the threads and putting away the Austron catalog I realized I
> have a 2100 pdf with schematics.
> Its 8.9 MB so will send it to the Diddiers KO4BB site tonight.
> Regards
> Paul
> WB8TSL
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Re: [time-nuts] Question about frequency counter testing

[Bob kb8tq]

Hi

The degree to which your samples converge to a specific value while being 
averaged
is dependent on a bunch of things. The noise processes on the clock and the 
measured
signal are pretty hard to avoid. It is *very* easy to over estimate how fast 
things converge.

Bob

> On Apr 26, 2018, at 5:28 PM, Oleg Skydan  wrote:
> 
> From: "Hal Murray" 
> Sent: Thursday, April 26, 2018 10:28 PM
> 
>> Is there a term for what I think you are doing?
> 
> I saw different terms like "omega counter" or multiple time-stamp
> average counter, probably there are others too.
> 
>> If I understand (big if), you are doing the digital version of magic
>> down-conversion with an A/D.  I can't even think of the name for that.
> 
> No, it is much simpler. The hardware saves time-stamps to the memory at
> each (event) rise of the input signal (let's consider we have digital logic
> input signal for simplicity). So after some time we have many pairs of
> {event number, time-stamp}. We can plot those pairs with event number on
> X-axis and time on Y-axis, now if we fit the line on that dataset the
> inverse slope of the line will correspond to the estimated frequency.
> 
> The line is fitted using linear regression.
> 
> This technique improves frequency uncertainty as
> 
> 2*sqrt(3)*tresolution/(MeasurementTime * sqrt(NumberOfEvents-2))
> 
> So If I have 2.5ns HW time resolution, and collect 5e6 events,
> processing should result in 3.9ps resolution.
> 
> Of cause this is for the ideal case. The first real life problem is
> signal drift for example.
> 
> Hope I was able to tell of what I am doing.
> 
> BTW, I have fixed a little bug in firmware and now ADEV looks a bit better.
> Probably I should look for better OCXOs. Interesting thing - the counter
> processed 300GB of time-stamps data during that 8+hour run :).
> 
> All the best!
> Oleg 
> <1133.png>___
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Re: [time-nuts] nuts about position

[Michael Wouters]

The US-based services work fine with non-local data. I've  used them with
Australian locations. The IGS network is global so nearby stations in the
IGS network are used for the solution. There are non-US services too, like
AusPos.

The topic of better antenna coordinates seems to come up now and again. It
might be a good cooperative  timenuts project to put together a travelling
receiver system that could be used to survey antenna positions. With a bit
more effort, it could also be used to calibrate delays, where receiver data
is being post-processed for time-transfer.

Cheers
Michael

On Fri, 27 Apr 2018 at 8:02 am, Bob kb8tq  wrote:

> Hi
>
> If you shop for a while on eBay, you can find older L1 / L2 survey
> receivers for < $300 and
> an antenna that will work for them for < $100. Yes it will take a bit of
> heavy duty shopping and
> some level of “wait and see”.  How well they work and how much of a pain
> is associated with
> this process ….. who knows.
>
> Once you have a radio you can get data out of, submitting the files to any
> of the free services
> in the US is pretty easy. If you are outside the US, you may still be fine
> or you may have a tough
> time with the data reduction.
>
> Bob
>
> > On Apr 26, 2018, at 1:04 PM, Scott McGrath  wrote:
> >
> > Swiftnav has a centimeter accurate multi band receiver RTK-585. Its
> about 600 bucks minus antenna.
> >
> > You would need a choke ring antenna to get centimeter accuracy i think
> but receiver with a quality timing antenna will provide necessary accuracy
> >
> > On Apr 25, 2018, at 8:06 AM, George Watson  wrote:
> >
> > Create your own DGPS?
> >
> > Trimble is good at this.
> >
> > George K. Watson
> > K0IW
> >
> >> On Apr 25, 2018, at 10:56 AM, Tom Van Baak  wrote:
> >>
> >> List -- I had a recent query by a researcher who would like to pinpoint
> the location of his telescope(s) within 0.3 meters. Also (he must be a true
> scientist) he wants to do this on-the-cheap. He may have timing
> requirements as well, but that's another posting.
> >>
> >> So I toss the GPS question to the group. Surely some of you have
> crossed the line from precise time to precise location?
> >>
> >> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D
> position?
> >>
> >> When we run our GPSDO in survey mode how accurate a position do we get
> after an hour, or even 24 or 48 hours? And here I mean accurate, not
> stable. Have any of you compared that self-reported, self-survey result
> against an independently measured professional result or known benchmark?
> >>
> >> Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1
> foot accuracy given enough time?
> >>
> >> If not, what improvement would -T models and RINEX-based web-service
> post-processing provide?
> >>
> >> It that's still not close enough to 0.3 m, is one then forced to use
> more expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS,
> Galileo) to achieve this level of precision? If so, how cheaply can one do
> this? Or is the learning curve more expensive than just hiring an survey
> specialist to make a one-time cm-level measurement for you?
> >>
> >> Something tells me 1 foot accuracy in position is possible and actually
> easier than 1 ns accuracy in time. I'm hoping some of you can help
> recommend solution(s) to the researcher's question or shed light on this
> interesting challenge.
> >>
> >> Thanks,
> >> /tvb
> >>
> >> ___
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> >> and follow the instructions there.
> >>
> >
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Re: [time-nuts] Question about frequency counter testing

[Azelio Boriani]

If your hardware is capable of capturing up to 10 millions of
timestamps per second and calculating LR "on the fly", it is not a so
simple hardware, unless you consider simple hardware a 5megagates
Spartan3 (maybe more is needed). Moreover: if your clock is, say, at
most in an FPGA, 300MHz, your timestamps will have a one-shot
resolution of few nanoseconds. Where have you found a detailed
description of the CNT91 counting method? The only detailed
description I have found is the CNT90 (not 91) service manual and it
uses interpolators (page 4-13 of the service manual).

On Thu, Apr 26, 2018 at 2:45 PM, Bob kb8tq  wrote:
> Hi
>
> Even with a fast counter, there are going to be questions about clock jitter 
> and just
> how well that last digit performs in the logic. It’s never easy to squeeze 
> the very last
> bit of performance out …..
>
> Bob
>
>> On Apr 26, 2018, at 3:06 AM, Azelio Boriani  wrote:
>>
>> Very fast time-stamping like a stable 5GHz counter? The resolution of
>> a 200ps (one shot) interpolator can be replaced by a 5GHz
>> time-stamping counter.
>>
>> On Thu, Apr 26, 2018 at 12:28 AM, Bob kb8tq  wrote:
>>> Hi
>>>
>>> Unfortunately there is no “quick and dirty” way to come up with an accurate 
>>> “number of digits” for a
>>> math intensive counter. There are a *lot* of examples of various counter 
>>> architectures that have specific
>>> weak points in what they do. One sort of signal works one way, another 
>>> signal works very differently.
>>>
>>> All that said, the data you show suggests you are in the 10 digits per 
>>> second range.
>>>
>>> Bob
>>>
 On Apr 25, 2018, at 3:01 PM, Oleg Skydan  wrote:

 Dear Ladies and Gentlemen,

 Let me tell a little story so you will be able to better understand what 
 my question and what I am doing.

 I needed to check frequency in several GHz range from time to time. I do 
 not need high absolute precision (anyway this is a reference oscillator 
 problem, not a counter), but I need fast high resolution instrument (at 
 least 10 digits in one second). I have only a very old slow unit so, I 
 constructed a frequency counter (yes, yet another frequency counter 
 project :-). I is a bit unusual - I decided not to use interpolators and 
 maximally simplify hardware and provide the necessary resolution by very 
 fast timestamping and heavy math processing. In the current configuration 
 I should get 11+ digits in one second, for input frequencies more then 
 5MHz.

 But this is theoretical number and it does not count for some factors. Now 
 I have an ugly build prototype with insanely simple hardware running the 
 counter core. And I need to check how well it performs.

 I have already done some checks and even found and fixed some FW bugs :). 
 Now it works pretty well and I enjoyed looking how one OCXO drifts against 
 the other one in the mHz range. I would like to check how many significant 
 digits I am getting in reality.

 The test setup now comprises of two 5MHz OCXO (those are very old units 
 and far from the perfect oscillators - the 1sec and 10sec stability is 
 claimed to be 1e-10, but they are the best I have now). I measure the 
 frequency of the first OCXO using the second one as counter reference. The 
 frequency counter processes data in real time and sends the continuous one 
 second frequency stamps to the PC. Here are experiment results - plots 
 from the Timelab. The frequency difference (the oscillators are being on 
 for more than 36hours now, but still drift against each other) and ADEV 
 plots. There are three measurements and six traces - two for each 
 measurement. One for the simple reciprocal frequency counting (with R 
 letter in the title) and one with the math processing (LR in the title). 
 As far as I understand I am getting 10+ significant digits of frequency in 
 one second and it is questionable if I see counter noise or oscillators 
 one.

 I also calculated the usual standard deviation for the measurements 
 results (and tried to remove the drift before the calculations), I got STD 
 in the 3e-4..4e-4Hz (or 6e-11..8e-11) range in many experiments.

 Now the questions:
 1. Are there any testing methods that will allow to determine if I see 
 oscillators noise or counter does not perform in accordance with the 
 theory (11+ digits)? I know this can be done with better OCXO, but 
 currently I cannot get better ones.
 2. Is my interpretation of the ADEV value at tau=1sec (that I have 10+ 
 significant digits) right?

 As far as I understand the situation I need better OCXO's to check if 
 HW/SW really can do 11+ significant digits frequency measurement in one 
 second.

 Your comments are greatly appreciated!

Re: [time-nuts] Question about frequency counter testing

[Oleg Skydan]

From: "Hal Murray" 
Sent: Thursday, April 26, 2018 10:28 PM


Is there a term for what I think you are doing?


I saw different terms like "omega counter" or multiple time-stamp
average counter, probably there are others too.


If I understand (big if), you are doing the digital version of magic
down-conversion with an A/D.  I can't even think of the name for that.


No, it is much simpler. The hardware saves time-stamps to the memory at
each (event) rise of the input signal (let's consider we have digital logic
input signal for simplicity). So after some time we have many pairs of
{event number, time-stamp}. We can plot those pairs with event number on
X-axis and time on Y-axis, now if we fit the line on that dataset the
inverse slope of the line will correspond to the estimated frequency.

The line is fitted using linear regression.

This technique improves frequency uncertainty as

2*sqrt(3)*tresolution/(MeasurementTime * sqrt(NumberOfEvents-2))

So If I have 2.5ns HW time resolution, and collect 5e6 events,
processing should result in 3.9ps resolution.

Of cause this is for the ideal case. The first real life problem is
signal drift for example.

Hope I was able to tell of what I am doing.

BTW, I have fixed a little bug in firmware and now ADEV looks a bit better.
Probably I should look for better OCXOs. Interesting thing - the counter
processed 300GB of time-stamps data during that 8+hour run :).

All the best!
Oleg 
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Re: [time-nuts] nuts about position

[Tim Lister]

On Thu, Apr 26, 2018 at 12:08 PM, Gary E. Miller  wrote:
> Scott!
>
> On Thu, 26 Apr 2018 10:04:54 -0700
> Scott McGrath  wrote:
>
>> Swiftnav has a centimeter accurate multi band receiver RTK-585. Its
>> about 600 bucks minus antenna.
>
> Link?  With RTK in the name it prolly needs a base and rover?  Or post
> processing?

It's this one: https://www.swiftnav.com/piksi-multi One thing to bear
in mind is it only L2C, the new civilian channel on the lower
frequency L2 band. This is not available on approx. 1/2 of the
satellites currently. There are several articles evaluating in
comparison with e.g. a ublox M8T at
https://rtklibexplorer.wordpress.com/tag/swift-piksi-multi/

>
> RGDS
> GARY

Cheers,
Tim
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Re: [time-nuts] nuts about position

[Bob kb8tq]

Hi

If you shop for a while on eBay, you can find older L1 / L2 survey receivers 
for < $300 and 
an antenna that will work for them for < $100. Yes it will take a bit of heavy 
duty shopping and
some level of “wait and see”.  How well they work and how much of a pain is 
associated with
this process ….. who knows. 

Once you have a radio you can get data out of, submitting the files to any of 
the free services
in the US is pretty easy. If you are outside the US, you may still be fine or 
you may have a tough
time with the data reduction.

Bob

> On Apr 26, 2018, at 1:04 PM, Scott McGrath  wrote:
> 
> Swiftnav has a centimeter accurate multi band receiver RTK-585. Its about 600 
> bucks minus antenna.
> 
> You would need a choke ring antenna to get centimeter accuracy i think but 
> receiver with a quality timing antenna will provide necessary accuracy
> 
> On Apr 25, 2018, at 8:06 AM, George Watson  wrote:
> 
> Create your own DGPS?
> 
> Trimble is good at this.
> 
> George K. Watson
> K0IW
> 
>> On Apr 25, 2018, at 10:56 AM, Tom Van Baak  wrote:
>> 
>> List -- I had a recent query by a researcher who would like to pinpoint the 
>> location of his telescope(s) within 0.3 meters. Also (he must be a true 
>> scientist) he wants to do this on-the-cheap. He may have timing requirements 
>> as well, but that's another posting.
>> 
>> So I toss the GPS question to the group. Surely some of you have crossed the 
>> line from precise time to precise location?
>> 
>> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D 
>> position?
>> 
>> When we run our GPSDO in survey mode how accurate a position do we get after 
>> an hour, or even 24 or 48 hours? And here I mean accurate, not stable. Have 
>> any of you compared that self-reported, self-survey result against an 
>> independently measured professional result or known benchmark?
>> 
>> Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1 foot 
>> accuracy given enough time?
>> 
>> If not, what improvement would -T models and RINEX-based web-service 
>> post-processing provide?
>> 
>> It that's still not close enough to 0.3 m, is one then forced to use more 
>> expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to 
>> achieve this level of precision? If so, how cheaply can one do this? Or is 
>> the learning curve more expensive than just hiring an survey specialist to 
>> make a one-time cm-level measurement for you?
>> 
>> Something tells me 1 foot accuracy in position is possible and actually 
>> easier than 1 ns accuracy in time. I'm hoping some of you can help recommend 
>> solution(s) to the researcher's question or shed light on this interesting 
>> challenge.
>> 
>> Thanks,
>> /tvb
>> 
>> ___
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>> and follow the instructions there.
>> 
> 
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Re: [time-nuts] Question about frequency counter testing

[Hal Murray]

olegsky...@gmail.com said:
> The plots I showed were made with approx. 5*10^6 timestamps  per second, so
> theoretically I should get approx. 4ps equivalent  resolution (or 11+
> significant digits in one second). 

Is there a term for what I think you are doing?

If I understand (big if), you are doing the digital version of magic 
down-conversion with an A/D.  I can't even think of the name for that.

If I have a bunch of digital samples and count the transitions I can conpute 
a frequency.  But I would get the same results if the input frequency was X 
plus the sampling frequency.  Or 2X.  ...  The digital stream is the beat 
between the input and the sampling frequency.

That technique depends on having a low jitter clock.  There should be some 
good math in there, but I don't see it.

A related trick is getting the time from something that ticks slowly, like 
the RTC/CMOS clocks on PCs.   They only tick once per second, but you can get 
the time with (much) higher resolution if you poll until it ticks.

Don't forget about metastability.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] nuts about position

[Gary E. Miller]

Scott!

On Thu, 26 Apr 2018 10:04:54 -0700
Scott McGrath  wrote:

> Swiftnav has a centimeter accurate multi band receiver RTK-585. Its
> about 600 bucks minus antenna.

Link?  With RTK in the name it prolly needs a base and rover?  Or post
processing?

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588

Veritas liberabit vos. -- Quid est veritas?
"If you can’t measure it, you can’t improve it." - Lord Kelvin
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Re: [time-nuts] Want a student to do some experiment on timetnuts - Re: nuts about position

[Bob kb8tq]

Hi

Having once been very much involved in research grants and all the math that 
goes in-between
the “zero pay labor” and the amount billed to on high ….. it can be pretty 
amazing just how little
you can get done for $20K using free labor. :)



Do software projects count? An analysis library in C to look at phase data ( 
more or less the guts 
of Stable-32) certainly comes to mind. There are a lot of lumps and bumps 
trying to deal with the 
RINEX outputs from gps modules. We have talked about a “pps output “ module for 
NTP ….

Lots to do …..

Bob

> On Apr 26, 2018, at 9:03 AM, jimlux  wrote:
> 
> On 4/25/18 10:16 PM, Peter Monta wrote:
> 
>> But this is a bit of a dicey science project; I'd suggest that the
>> researcher borrow a survey receiver for a few days (mild learning curve for
>> the online solver tools) or hire a surveyor (no learning curve).
> 
> If anyone knows a student at any of the following colleges who would be 
> interested in doing this, I just got a (small) bucket of money to spend on 
> it, but I have to get the details turned in today.
> 
> (actually any sort of time-nuts project, if it can be done for around $20-30k 
> to the institution, is fine).
> 
> Has to be one of those schools, and I need a contact name to call to set up 
> the details.
> 
> 
> Florida A
> Howard University
> Morgan State University
> North Carolina Central University
> Southern University
> Tennessee State University
> Tuskegee University-College of Engineering
> UC Riverside
> University of Nevada Las Vegas (UNLV)
> The University of Texas at El Paso
> 
> 
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Re: [time-nuts] nuts about position

[Scott McGrath]

Swiftnav has a centimeter accurate multi band receiver RTK-585. Its about 600 
bucks minus antenna.

You would need a choke ring antenna to get centimeter accuracy i think but 
receiver with a quality timing antenna will provide necessary accuracy

On Apr 25, 2018, at 8:06 AM, George Watson  wrote:

Create your own DGPS?

Trimble is good at this.

George K. Watson
K0IW

> On Apr 25, 2018, at 10:56 AM, Tom Van Baak  wrote:
> 
> List -- I had a recent query by a researcher who would like to pinpoint the 
> location of his telescope(s) within 0.3 meters. Also (he must be a true 
> scientist) he wants to do this on-the-cheap. He may have timing requirements 
> as well, but that's another posting.
> 
> So I toss the GPS question to the group. Surely some of you have crossed the 
> line from precise time to precise location?
> 
> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D 
> position?
> 
> When we run our GPSDO in survey mode how accurate a position do we get after 
> an hour, or even 24 or 48 hours? And here I mean accurate, not stable. Have 
> any of you compared that self-reported, self-survey result against an 
> independently measured professional result or known benchmark?
> 
> Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1 foot 
> accuracy given enough time?
> 
> If not, what improvement would -T models and RINEX-based web-service 
> post-processing provide?
> 
> It that's still not close enough to 0.3 m, is one then forced to use more 
> expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to 
> achieve this level of precision? If so, how cheaply can one do this? Or is 
> the learning curve more expensive than just hiring an survey specialist to 
> make a one-time cm-level measurement for you?
> 
> Something tells me 1 foot accuracy in position is possible and actually 
> easier than 1 ns accuracy in time. I'm hoping some of you can help recommend 
> solution(s) to the researcher's question or shed light on this interesting 
> challenge.
> 
> Thanks,
> /tvb
> 
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> 

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Re: [time-nuts] Question about frequency counter testing

[Bob kb8tq]

Hi

Even with a fast counter, there are going to be questions about clock jitter 
and just 
how well that last digit performs in the logic. It’s never easy to squeeze the 
very last
bit of performance out …..

Bob

> On Apr 26, 2018, at 3:06 AM, Azelio Boriani  wrote:
> 
> Very fast time-stamping like a stable 5GHz counter? The resolution of
> a 200ps (one shot) interpolator can be replaced by a 5GHz
> time-stamping counter.
> 
> On Thu, Apr 26, 2018 at 12:28 AM, Bob kb8tq  wrote:
>> Hi
>> 
>> Unfortunately there is no “quick and dirty” way to come up with an accurate 
>> “number of digits” for a
>> math intensive counter. There are a *lot* of examples of various counter 
>> architectures that have specific
>> weak points in what they do. One sort of signal works one way, another 
>> signal works very differently.
>> 
>> All that said, the data you show suggests you are in the 10 digits per 
>> second range.
>> 
>> Bob
>> 
>>> On Apr 25, 2018, at 3:01 PM, Oleg Skydan  wrote:
>>> 
>>> Dear Ladies and Gentlemen,
>>> 
>>> Let me tell a little story so you will be able to better understand what my 
>>> question and what I am doing.
>>> 
>>> I needed to check frequency in several GHz range from time to time. I do 
>>> not need high absolute precision (anyway this is a reference oscillator 
>>> problem, not a counter), but I need fast high resolution instrument (at 
>>> least 10 digits in one second). I have only a very old slow unit so, I 
>>> constructed a frequency counter (yes, yet another frequency counter project 
>>> :-). I is a bit unusual - I decided not to use interpolators and maximally 
>>> simplify hardware and provide the necessary resolution by very fast 
>>> timestamping and heavy math processing. In the current configuration I 
>>> should get 11+ digits in one second, for input frequencies more then 5MHz.
>>> 
>>> But this is theoretical number and it does not count for some factors. Now 
>>> I have an ugly build prototype with insanely simple hardware running the 
>>> counter core. And I need to check how well it performs.
>>> 
>>> I have already done some checks and even found and fixed some FW bugs :). 
>>> Now it works pretty well and I enjoyed looking how one OCXO drifts against 
>>> the other one in the mHz range. I would like to check how many significant 
>>> digits I am getting in reality.
>>> 
>>> The test setup now comprises of two 5MHz OCXO (those are very old units and 
>>> far from the perfect oscillators - the 1sec and 10sec stability is claimed 
>>> to be 1e-10, but they are the best I have now). I measure the frequency of 
>>> the first OCXO using the second one as counter reference. The frequency 
>>> counter processes data in real time and sends the continuous one second 
>>> frequency stamps to the PC. Here are experiment results - plots from the 
>>> Timelab. The frequency difference (the oscillators are being on for more 
>>> than 36hours now, but still drift against each other) and ADEV plots. There 
>>> are three measurements and six traces - two for each measurement. One for 
>>> the simple reciprocal frequency counting (with R letter in the title) and 
>>> one with the math processing (LR in the title). As far as I understand I am 
>>> getting 10+ significant digits of frequency in one second and it is 
>>> questionable if I see counter noise or oscillators one.
>>> 
>>> I also calculated the usual standard deviation for the measurements results 
>>> (and tried to remove the drift before the calculations), I got STD in the 
>>> 3e-4..4e-4Hz (or 6e-11..8e-11) range in many experiments.
>>> 
>>> Now the questions:
>>> 1. Are there any testing methods that will allow to determine if I see 
>>> oscillators noise or counter does not perform in accordance with the theory 
>>> (11+ digits)? I know this can be done with better OCXO, but currently I 
>>> cannot get better ones.
>>> 2. Is my interpretation of the ADEV value at tau=1sec (that I have 10+ 
>>> significant digits) right?
>>> 
>>> As far as I understand the situation I need better OCXO's to check if HW/SW 
>>> really can do 11+ significant digits frequency measurement in one second.
>>> 
>>> Your comments are greatly appreciated!
>>> 
>>> P.S. If I feed the counter reference to its input I got 13 absolutely 
>>> stable and correct digits and can get more, but this test method is not 
>>> very useful for the used counter architecture.
>>> 
>>> Thanks!
>>> Oleg
>>> 73 de UR3IQO
>>> <1124.png><1127.png>___
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>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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>> 
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Re: [time-nuts] Question about frequency counter testing

[Oleg Skydan]

From: "Azelio Boriani" 
Sent: Thursday, April 26, 2018 10:06 AM

Very fast time-stamping like a stable 5GHz counter? 

No, it is not 5GHz counter. It does the trick I first saw in CNT91
counters. The hardware is capable of capturing up to 10 millions 
of timestamps per second and calculating LR "on the fly".


The plots I showed were made with approx. 5*10^6 timestamps 
per second, so theoretically I should get approx. 4ps equivalent 
resolution (or 11+ significant digits in one second).



The resolution of
a 200ps (one shot) interpolator can be replaced by a 5GHz
time-stamping counter.

I am not interesting in measuring timings of the single event,
and I did not try to make a full featured timer-counter-analyser. 
It is just a high resolution RF frequency counter with very 
simple all digital hardware.


Oleg 
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Re: [time-nuts] nuts about position

[Joseph Gwinn]

On Wed, 25 Apr 2018 18:02:53 -0400, time-nuts-requ...@febo.com wrote:
> time-nuts Digest, Vol 165, Issue 50
> 
> Message: 3
> Date: Wed, 25 Apr 2018 10:19:38 -0500
> From: Dana Whitlow 
> To: Tom Van Baak ,  Discussion of precise time and
>   frequency measurement 
> Subject: Re: [time-nuts] nuts about position
> Message-ID:
>   

Re: [time-nuts] nuts about position

[Bob kb8tq]

Hi

On something like a phone, you are likely looking at a combination of what the
phone does and a contribution from “the cloud”. Part of that cloud contribution 
depends a bit on the carrier and how well they are doing their part of things. 
In
one area you might have surveyed towers and a full GPS / Glonass synthesis. 
If you bought your service from Crazy Bob, there may be no local correction 
information. Forget about GPS / Glonass in that case (at least in the US). 

Bob

> On Apr 25, 2018, at 10:46 PM, Brooke Clarke  wrote:
> 
> Hi J:
> 
> I had a number of survey stakes I placed using a manual transit and tape 
> measure and hired a local surveyor to tell me where they were and also tell 
> me where my GPS antenna was located.
> 
> He setup a GPS antenna on one tripod and a (Trimble?) combined GPS-total 
> station on another tripod and ran a cable between the two.  After some time 
> (tens of minutes or ??) he used the theodolite to sight my stakes and the GPS 
> antenna.  I got a report back in a week or so.  Total cost a few hundred 
> dollars.
> 
> I'm in the process of looking at how accurate the GPS is in my new LG G6 
> phone.
> 
> -- 
> Have Fun,
> 
> Brooke Clarke
> http://www.PRC68.com
> http://www.end2partygovernment.com/2012Issues.html
> 
>  Original Message 
>> I think to really be confident about a position you really need the 
>> dual-frequency data (or that data from a nearby reference station), 
>> otherwise you could end up in a situation where you're consistent, but that 
>> consistency has a bias. IIRC, anyhow -- I'm not sure how the math actually 
>> works out.
>> 
>> Anyhow, I play around with PPP stuff on occasion, and the last run I did was 
>> in November using the Novatel OEM628 kit that was briefly available for 
>> cheap on eBay, and the included 702-GG antenna (which, conveniently, has 
>> calibrations available). Running a day's worth of data through CSRS-PPP 
>> produced sigmas (95%) of 0.004m latitude, 0.008m longitude, and 0.024m in 
>> elevation. I've done some shorter runs since then that appear to fall in 
>> that same range ... I really need to do a few more full runs and see what 
>> kind of variance there is.
>> 
>> At any rate, theoretically you can get ^^^ that close, anyhow. CSRS even 
>> takes solid earth tides into account, though I didn't do that because I was 
>> never able to figure out which specific type of solid earth tide data I 
>> needed. I imagine there's still some issues with any given datum being 
>> somewhat imperfect, as far as altitude is concerned, and I don't really know 
>> how to correctly deal with that if exact altitude matters. Maybe we should 
>> all just agree to use XYZ/ECEF coordinates for everything and give up on 
>> this whole altitude thing altogether... ;)
>> 
>> (As an aside, I've been tempted to get someone to come professionally survey 
>> my antenna and tell me where it _actually_ is, so I could see how well I 
>> could actually do with my GPS kit, but I imagine it's pretty expensive -- 
>> anyone happen to know what getting that kind of thing done actually ends up 
>> costing?)
>> 
>> -j
> 
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[time-nuts] Want a student to do some experiment on timetnuts - Re: nuts about position

[jimlux]

On 4/25/18 10:16 PM, Peter Monta wrote:


But this is a bit of a dicey science project; I'd suggest that the
researcher borrow a survey receiver for a few days (mild learning curve for
the online solver tools) or hire a surveyor (no learning curve).



If anyone knows a student at any of the following colleges who would be 
interested in doing this, I just got a (small) bucket of money to spend 
on it, but I have to get the details turned in today.


(actually any sort of time-nuts project, if it can be done for around 
$20-30k to the institution, is fine).


Has to be one of those schools, and I need a contact name to call to set 
up the details.



Florida A
Howard University
Morgan State University
North Carolina Central University
Southern University
Tennessee State University
Tuskegee University-College of Engineering
UC Riverside
University of Nevada Las Vegas (UNLV)
The University of Texas at El Paso


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Re: [time-nuts] LEA-6T TCXO measurements

[Bob kb8tq]

Hi

What you are looking at appear to be sawtooth jumps. Simply put, the module is 
looking at the closest edge on the TCXO to do it’s timing. When the device 
drifts, 
it can “slip” to another cycle. If you watch the PPS out, there are also 
artifacts that
result from this process operating in a non-ideal fashion. Lots of details on 
that in
the archives.

Bob

> On Apr 25, 2018, at 8:56 PM, Gabs Ricalde  wrote:
> 
> The NAV-TIMEUTC message of the u-blox LEA-6T has a fractional seconds
> field, which is the receiver clock offset estimate and can be used to
> measure the internal TCXO. Attached are the ADEV and frequency
> difference plots (blue traces). For comparison, I also have PPS logs
> from a TL-WR703N NTP server (pink traces) with ntpd stopped.
> 
> I'm wondering why the LEA-6T has that kind of frequency jumps.
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Re: [time-nuts] nuts about position

[Ole Petter Ronningen]

Hi

I just ran a quick test - a Ublox 6T was configured to output the RXM-RAW
messages every second and logging for some 14 hours using U-Center. The
.ubx-file was converted to RINEX using teqc.exe, and uplaoded to NrCAN PPP.
NrCAN PPP will process single frequency observations and correct using
ionospheric maps I *believe*. (If I am wrong, ignore this post!)

I also continously log observations from a Trimble NetRS dual frequency GPS
receiver, hooked up to the same antenna. I trust the PPP-calculated
position accuracy of this receiver to within low double digits to high
single digit millimeters.

(For comparison, the report from NrCAN gives a 95% error ellipse on the
UBlox as semi-major: 2.494dm, semi-minor: 1.760dm. The corresponding
numbers for the NetRS is semi-major: 1.245cm, semi-minor: 0.760cm - the
reports are usually below 10 mm in both axis. Note difference in units.)

Comparing the calculated ECEF coordinates from the ppp-results using
Pythagoras gives me a distance of 76 cm - 53 cm if we simply ignore height.

This is with a survey grade antenna in a good location. It might be
possible to shrink this to 30 cm and still have confidence in the results,
but I think it would not be easy. I would guess a lot more data would be
required, and it is also possible that delaying processing until more
accurate ionospheric maps are available could help.

I will reprocess in a couple of days and see if theres much of a difference.

Ole

On Wed, Apr 25, 2018 at 4:56 PM, Tom Van Baak  wrote:

> List -- I had a recent query by a researcher who would like to pinpoint
> the location of his telescope(s) within 0.3 meters. Also (he must be a true
> scientist) he wants to do this on-the-cheap. He may have timing
> requirements as well, but that's another posting.
>
> So I toss the GPS question to the group. Surely some of you have crossed
> the line from precise time to precise location?
>
> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D
> position?
>
> When we run our GPSDO in survey mode how accurate a position do we get
> after an hour, or even 24 or 48 hours? And here I mean accurate, not
> stable. Have any of you compared that self-reported, self-survey result
> against an independently measured professional result or known benchmark?
>
> Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1 foot
> accuracy given enough time?
>
> If not, what improvement would -T models and RINEX-based web-service
> post-processing provide?
>
> It that's still not close enough to 0.3 m, is one then forced to use more
> expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to
> achieve this level of precision? If so, how cheaply can one do this? Or is
> the learning curve more expensive than just hiring an survey specialist to
> make a one-time cm-level measurement for you?
>
> Something tells me 1 foot accuracy in position is possible and actually
> easier than 1 ns accuracy in time. I'm hoping some of you can help
> recommend solution(s) to the researcher's question or shed light on this
> interesting challenge.
>
> Thanks,
> /tvb
>
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Re: [time-nuts] nuts about position

[Bob kb8tq]

Hi

Keep in mind when you look at the “peak to peak” numbers for solid tides that 
you may
have to observe things for 20,000 years to see the full peak to peak…… They 
also are
variable depending on just how close you are to what sort of coastline. ( = 
they interact
with sea tides when you get close). 

Bob

> On Apr 25, 2018, at 3:26 PM, Hal Murray  wrote:
> 
> 
>> How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D 
>> position?
> 
> Elevation gets interesting.  Earth has tides in solid rock that are ballpark 
> of that scale peak-peak.
> 
> It would be interesting to see if you could see the tides with low cost gear.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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[time-nuts] nuts about position

[Mark Sims]

You will probably have a some difficulty finding a surveyor that does 
geodetic/mm accuracy surveys.  Most  surveyors that use GPS seem to work down 
to inches/a few cm.
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Re: [time-nuts] Question about frequency counter testing

[Azelio Boriani]

Very fast time-stamping like a stable 5GHz counter? The resolution of
a 200ps (one shot) interpolator can be replaced by a 5GHz
time-stamping counter.

On Thu, Apr 26, 2018 at 12:28 AM, Bob kb8tq  wrote:
> Hi
>
> Unfortunately there is no “quick and dirty” way to come up with an accurate 
> “number of digits” for a
> math intensive counter. There are a *lot* of examples of various counter 
> architectures that have specific
> weak points in what they do. One sort of signal works one way, another signal 
> works very differently.
>
> All that said, the data you show suggests you are in the 10 digits per second 
> range.
>
> Bob
>
>> On Apr 25, 2018, at 3:01 PM, Oleg Skydan  wrote:
>>
>> Dear Ladies and Gentlemen,
>>
>> Let me tell a little story so you will be able to better understand what my 
>> question and what I am doing.
>>
>> I needed to check frequency in several GHz range from time to time. I do not 
>> need high absolute precision (anyway this is a reference oscillator problem, 
>> not a counter), but I need fast high resolution instrument (at least 10 
>> digits in one second). I have only a very old slow unit so, I constructed a 
>> frequency counter (yes, yet another frequency counter project :-). I is a 
>> bit unusual - I decided not to use interpolators and maximally simplify 
>> hardware and provide the necessary resolution by very fast timestamping and 
>> heavy math processing. In the current configuration I should get 11+ digits 
>> in one second, for input frequencies more then 5MHz.
>>
>> But this is theoretical number and it does not count for some factors. Now I 
>> have an ugly build prototype with insanely simple hardware running the 
>> counter core. And I need to check how well it performs.
>>
>> I have already done some checks and even found and fixed some FW bugs :). 
>> Now it works pretty well and I enjoyed looking how one OCXO drifts against 
>> the other one in the mHz range. I would like to check how many significant 
>> digits I am getting in reality.
>>
>> The test setup now comprises of two 5MHz OCXO (those are very old units and 
>> far from the perfect oscillators - the 1sec and 10sec stability is claimed 
>> to be 1e-10, but they are the best I have now). I measure the frequency of 
>> the first OCXO using the second one as counter reference. The frequency 
>> counter processes data in real time and sends the continuous one second 
>> frequency stamps to the PC. Here are experiment results - plots from the 
>> Timelab. The frequency difference (the oscillators are being on for more 
>> than 36hours now, but still drift against each other) and ADEV plots. There 
>> are three measurements and six traces - two for each measurement. One for 
>> the simple reciprocal frequency counting (with R letter in the title) and 
>> one with the math processing (LR in the title). As far as I understand I am 
>> getting 10+ significant digits of frequency in one second and it is 
>> questionable if I see counter noise or oscillators one.
>>
>> I also calculated the usual standard deviation for the measurements results 
>> (and tried to remove the drift before the calculations), I got STD in the 
>> 3e-4..4e-4Hz (or 6e-11..8e-11) range in many experiments.
>>
>> Now the questions:
>> 1. Are there any testing methods that will allow to determine if I see 
>> oscillators noise or counter does not perform in accordance with the theory 
>> (11+ digits)? I know this can be done with better OCXO, but currently I 
>> cannot get better ones.
>> 2. Is my interpretation of the ADEV value at tau=1sec (that I have 10+ 
>> significant digits) right?
>>
>> As far as I understand the situation I need better OCXO's to check if HW/SW 
>> really can do 11+ significant digits frequency measurement in one second.
>>
>> Your comments are greatly appreciated!
>>
>> P.S. If I feed the counter reference to its input I got 13 absolutely stable 
>> and correct digits and can get more, but this test method is not very useful 
>> for the used counter architecture.
>>
>> Thanks!
>> Oleg
>> 73 de UR3IQO
>> <1124.png><1127.png>___
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Re: [time-nuts] nuts about position

[Peter Monta]

Hi Tom,


> It that's still not close enough to 0.3 m, is one then forced to use more
> expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to
> achieve this level of precision? If so, how cheaply can one do this? Or is
> the learning curve more expensive than just hiring an survey specialist to
> make a one-time cm-level measurement for you?
>

I suspect just L1 would be fine in areas with dense CORS.  I have not tried
it, but how about this ultra-cheap strategy:

1. obtain L1 observables with a cheap board and cheap patch antenna;
convert to RINEX
2. synthesize fake L2 data, using nominal iono conditions, and add it to
the RINEX
3. submit to NOAA's rapid static solver, OPUS-RS, which currently accepts
only dual-frequency data
4. examine the quality report from OPUS-RS to see if the ambiguities were
reliably resolved

But this is a bit of a dicey science project; I'd suggest that the
researcher borrow a survey receiver for a few days (mild learning curve for
the online solver tools) or hire a surveyor (no learning curve).

Cheers,
Peter
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