Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
OK, I think I see my error.  I need to create a file of the successive phase 
differences in the timelab capture, right?  I haven't done this before, so...

Bob 

-
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Wednesday, May 3, 2017 11:11 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
If you convert the data to +/- 50 ns, you will have a problem at the edges. 
Much easier to deal with unwrapped data. The same CSV approach works for taking 
the pps data from a module, logging the sawtooth info and combining them. 
There’s no practical way to get the “real” RMS of the module without doing 
that. 
Bob

On May 3, 2017, at 11:56 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
Won't I have a problem with the phase wrap unless I convert the data to a range 
of +50ns to -50ns?  Or am I still looking at this incorrectly?
 Bob
-
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Wednesday, May 3, 2017 10:48 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
Dump it to a csv file and do it in Excel would be one way. You want to be 
ableto control the process a bit so that would give you the ability to tweak 
the measurement.
Bob

On May 3, 2017, at 11:01 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
What I should have asked is this: "how do I get that from a Timelab dataset?"   
Bob


  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: Tom Van Baak <t...@leapsecond.com>
 Sent: Wednesday, May 3, 2017 7:20 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
RMS:
https://en.wikipedia.org/wiki/Root_mean_square
When we talk about things like “6 sigma” in QA, the sigma is the RMS. 
Bob

On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Tom,
Could you clarify the term RMS?  Is there some sort of calculation I need to do 
on the raw data to get the RMS value?
I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 is 
from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 2.  
The ones I have on hand show about 4E-11 at 1s tau.  

After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the PRS.  
Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 5370.  
If you really don't want the GSPDO to clock the 5370, I'll run the same test 
using the internal 10811 as the clock, to compare the difference.

I also ran into an old test of the 5370 where START (10MHz) was fed by a GPSDO 
and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft cable 
from START to STOP.  I'll probably want to rerun that, as well, but it was an 
almost straight line from 2E-11 at 1s tau in that dataset.  Still, that test 
will verify that the 5370 hasn't degraded. Bob

  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Wednesday, May 3, 2017 12:02 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi BobS,


I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thanks for sharing that. To follow-up on recent emails...

When you start to push the limits of your own test equipment it's good to 
employ tricks such as 3-corner hat in order to get a few dB better measurement. 
But there's a limit to that. And you probably don't want me to suggest that you 
run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.

I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
TBolt (factory defaults, *untuned*)

bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over the 
place.

bob-gpsdo-5.gif -- ADEV comparison. See below for comments.

1)
When I look at the ADEV for your data set it's pretty clear that the limiting 
factor on the left (short tau) is the resolution of your 5370A counter. That's 
why the TBolt looks better. Don't worry about that.

2)
In the middle of the ADEV plot it would appear that both your 5370A counter and 
your PRS-45A cesium reference are sufficiently good to properly measure your 
GPSDO. That's good. The TBolt looks bad in the middle but t

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

If you convert the data to +/- 50 ns, you will have a problem at the edges. 
Much easier to deal with 
unwrapped data. The same CSV approach works for taking the pps data from a 
module, logging 
the sawtooth info and combining them. There’s no practical way to get the 
“real” RMS of the module 
without doing that. 

Bob

> On May 3, 2017, at 11:56 AM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> Won't I have a problem with the phase wrap unless I convert the data to a 
> range of +50ns to -50ns?  Or am I still looking at this incorrectly?
>  Bob
> 
> -
> AE6RV.com
> 
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net> 
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Sent: Wednesday, May 3, 2017 10:48 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> Dump it to a csv file and do it in Excel would be one way. You want to be able
> to control the process a bit so that would give you the ability to tweak the 
> measurement.
> 
> Bob
> 
>> On May 3, 2017, at 11:01 AM, Bob Stewart <b...@evoria.net 
>> <mailto:b...@evoria.net>> wrote:
>> 
>> Hi Bob,
>> 
>> What I should have asked is this: "how do I get that from a Timelab 
>> dataset?" 
>>  
>> Bob
>> 
>> 
>> From: Bob kb8tq <kb...@n1k.org <mailto:kb...@n1k.org>>
>> To: Bob Stewart <b...@evoria.net <mailto:b...@evoria.net>>; Discussion of 
>> precise time and frequency measurement <time-nuts@febo.com 
>> <mailto:time-nuts@febo.com>> 
>> Cc: Tom Van Baak <t...@leapsecond.com <mailto:t...@leapsecond.com>>
>> Sent: Wednesday, May 3, 2017 7:20 AM
>> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>> 
>> Hi
>> 
>> RMS:
>> 
>> https://en.wikipedia.org/wiki/Root_mean_square 
>> <https://en.wikipedia.org/wiki/Root_mean_square>
>> 
>> When we talk about things like “6 sigma” in QA, the sigma is the RMS. 
>> 
>> Bob
>> 
>>> On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net 
>>> <mailto:b...@evoria.net>> wrote:
>>> 
>>> Hi Tom,
>>> Could you clarify the term RMS?  Is there some sort of calculation I need 
>>> to do on the raw data to get the RMS value?
>>> I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO 
>>> Unit 2, with the same conditions as the tests involving the PRS.  IOW, the 
>>> 5370 is being clocked by GPSDO Unit 2, and the trigger for the EXT input to 
>>> the 5370 is from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from 
>>> GPSDO Unit 2.  The ones I have on hand show about 4E-11 at 1s tau.  
>>> 
>>> After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the 
>>> PRS.  Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock 
>>> the 5370.  If you really don't want the GSPDO to clock the 5370, I'll run 
>>> the same test using the internal 10811 as the clock, to compare the 
>>> difference.
>>> 
>>> I also ran into an old test of the 5370 where START (10MHz) was fed by a 
>>> GPSDO and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft 
>>> cable from START to STOP.  I'll probably want to rerun that, as well, but 
>>> it was an almost straight line from 2E-11 at 1s tau in that dataset.  
>>> Still, that test will verify that the 5370 hasn't degraded. Bob
>>> 
>>>  From: Tom Van Baak <t...@leapsecond.com <mailto:t...@leapsecond.com>>
>>> To: Discussion of precise time and frequency measurement 
>>> <time-nuts@febo.com <mailto:time-nuts@febo.com>> 
>>> Sent: Wednesday, May 3, 2017 12:02 AM
>>> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>>> 
>>> Hi BobS,
>>> 
>>>> I've also made the timelab file (compressed by 7z) available here:
>>>> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z 
>>>> <http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z>
>>> 
>>> Thanks for sharing that. To follow-up on recent emails...
>>> 
>>> When you start to push the limits of your own test equipment it's good to 
>>> employ tricks such as 3-corner hat in order to get a few dB better 
>>> measurement. But there's a limit to that. And you probably don't want me to 
>>> suggest tha

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
Won't I have a problem with the phase wrap unless I convert the data to a range 
of +50ns to -50ns?  Or am I still looking at this incorrectly?
 Bob
-
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Wednesday, May 3, 2017 10:48 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
Dump it to a csv file and do it in Excel would be one way. You want to be 
ableto control the process a bit so that would give you the ability to tweak 
the measurement.
Bob

On May 3, 2017, at 11:01 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
What I should have asked is this: "how do I get that from a Timelab dataset?"   
Bob


  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: Tom Van Baak <t...@leapsecond.com>
 Sent: Wednesday, May 3, 2017 7:20 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
RMS:
https://en.wikipedia.org/wiki/Root_mean_square
When we talk about things like “6 sigma” in QA, the sigma is the RMS. 
Bob

On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Tom,
Could you clarify the term RMS?  Is there some sort of calculation I need to do 
on the raw data to get the RMS value?
I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 is 
from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 2.  
The ones I have on hand show about 4E-11 at 1s tau.  

After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the PRS.  
Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 5370.  
If you really don't want the GSPDO to clock the 5370, I'll run the same test 
using the internal 10811 as the clock, to compare the difference.

I also ran into an old test of the 5370 where START (10MHz) was fed by a GPSDO 
and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft cable 
from START to STOP.  I'll probably want to rerun that, as well, but it was an 
almost straight line from 2E-11 at 1s tau in that dataset.  Still, that test 
will verify that the 5370 hasn't degraded. Bob

  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Wednesday, May 3, 2017 12:02 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi BobS,


I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thanks for sharing that. To follow-up on recent emails...

When you start to push the limits of your own test equipment it's good to 
employ tricks such as 3-corner hat in order to get a few dB better measurement. 
But there's a limit to that. And you probably don't want me to suggest that you 
run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.

I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
TBolt (factory defaults, *untuned*)

bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over the 
place.

bob-gpsdo-5.gif -- ADEV comparison. See below for comments.

1)
When I look at the ADEV for your data set it's pretty clear that the limiting 
factor on the left (short tau) is the resolution of your 5370A counter. That's 
why the TBolt looks better. Don't worry about that.

2)
In the middle of the ADEV plot it would appear that both your 5370A counter and 
your PRS-45A cesium reference are sufficiently good to properly measure your 
GPSDO. That's good. The TBolt looks bad in the middle but that's simply because 
it was using a way-too-short default time constant. With proper tuning the red 
trace would be mostly flat out to 1000 seconds.

3)
>From the look of the phase plot and the ADEV plot it almost seems to me like 
>your PRS-45A is the limiting factor on the right (long tau). If so, it would 
>explain the lack of diurnal and sidereal effects in your data. If you look at:
http://leapsecond.com/pages/tbolt-8d/sigma1.gif from 
http://www.leapsecond.com/pages/tbolt-8d/
you'll note the sidereal "blip" is below 4e-14. Your ADEV doesn't get near that 
level.


I say this because a rule-of-thumb is that a good M12+T timing receiver should 
get you down to 3 ns per day RMS. And a good ublox-6T can get you to 3 or 2 ns 
per day RMS. Your data shows something more like 5 ns -- which for a GPSDO is 
worse than no GPSDO at all. So something's wrong. What set of experiments can 
you perform to locate the problem? Or, what experiments

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi,

RMS is really a standard deviation estimation in classical context. This 
type of deviation estimation is however not useful for the types of 
noises we have, so that is why we needed a more powerful tool, and we 
ended up with the Allan Deviation in its place.


Just as with RMS being the estimator formula for standard deviation, 
there exist several estimator formulas for the Allan Deviation.


Cheers,
Magnus

On 05/03/2017 02:12 PM, Bob kb8tq wrote:

Hi

RMS:

https://en.wikipedia.org/wiki/Root_mean_square 
<https://en.wikipedia.org/wiki/Root_mean_square>

When we talk about things like “6 sigma” in QA, the sigma is the RMS.

Bob


On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net> wrote:

Hi Tom,
Could you clarify the term RMS?  Is there some sort of calculation I need to do 
on the raw data to get the RMS value?
I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 is 
from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 2.  
The ones I have on hand show about 4E-11 at 1s tau.

After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the PRS.  
Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 5370.  
If you really don't want the GSPDO to clock the 5370, I'll run the same test 
using the internal 10811 as the clock, to compare the difference.

I also ran into an old test of the 5370 where START (10MHz) was fed by a GPSDO 
and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft cable 
from START to STOP.  I'll probably want to rerun that, as well, but it was an 
almost straight line from 2E-11 at 1s tau in that dataset.  Still, that test 
will verify that the 5370 hasn't degraded. Bob

 From: Tom Van Baak <t...@leapsecond.com>
To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
Sent: Wednesday, May 3, 2017 12:02 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi BobS,


I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thanks for sharing that. To follow-up on recent emails...

When you start to push the limits of your own test equipment it's good to 
employ tricks such as 3-corner hat in order to get a few dB better measurement. 
But there's a limit to that. And you probably don't want me to suggest that you 
run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.

I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
TBolt (factory defaults, *untuned*)

bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over the 
place.

bob-gpsdo-5.gif -- ADEV comparison. See below for comments.

1)
When I look at the ADEV for your data set it's pretty clear that the limiting 
factor on the left (short tau) is the resolution of your 5370A counter. That's 
why the TBolt looks better. Don't worry about that.

2)
In the middle of the ADEV plot it would appear that both your 5370A counter and 
your PRS-45A cesium reference are sufficiently good to properly measure your 
GPSDO. That's good. The TBolt looks bad in the middle but that's simply because 
it was using a way-too-short default time constant. With proper tuning the red 
trace would be mostly flat out to 1000 seconds.

3)
From the look of the phase plot and the ADEV plot it almost seems to me like 
your PRS-45A is the limiting factor on the right (long tau). If so, it would 
explain the lack of diurnal and sidereal effects in your data. If you look at:
http://leapsecond.com/pages/tbolt-8d/sigma1.gif from 
http://www.leapsecond.com/pages/tbolt-8d/
you'll note the sidereal "blip" is below 4e-14. Your ADEV doesn't get near that 
level.


I say this because a rule-of-thumb is that a good M12+T timing receiver should 
get you down to 3 ns per day RMS. And a good ublox-6T can get you to 3 or 2 ns 
per day RMS. Your data shows something more like 5 ns -- which for a GPSDO is 
worse than no GPSDO at all. So something's wrong. What set of experiments can 
you perform to locate the problem? Or, what experiments can you perform that 
don't require buying expensive gear?

My first suggestion is for you run a standalone GPS timing receiver like a 
M12+T or ublox-6. Put all your GPSDO away. Just use that OEM board, and your 
TIC, and your PRS-45A. Collect sawtooth data too. You should get down to 2 or 3 
ns RMS.

/tvb

- Original Message -
From: "Bob Stewart" <b...@evoria.net>
To: "Discussion of Precise Time and Frequency Measurement" <time-nuts@febo.com>; "Magnus 
Danielson" <mag...@rubidium.se>
Sent: Thursday, April 27, 2017 9:48 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Magnus,
Try as I might, the weather and the local power company had other ideas ab

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

Dump it to a csv file and do it in Excel would be one way. You want to be able
to control the process a bit so that would give you the ability to tweak the 
measurement.

Bob

> On May 3, 2017, at 11:01 AM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> What I should have asked is this: "how do I get that from a Timelab dataset?" 
>  
> Bob
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
> Cc: Tom Van Baak <t...@leapsecond.com>
> Sent: Wednesday, May 3, 2017 7:20 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> RMS:
> 
> https://en.wikipedia.org/wiki/Root_mean_square 
> <https://en.wikipedia.org/wiki/Root_mean_square>
> 
> When we talk about things like “6 sigma” in QA, the sigma is the RMS. 
> 
> Bob
> 
>> On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net 
>> <mailto:b...@evoria.net>> wrote:
>> 
>> Hi Tom,
>> Could you clarify the term RMS?  Is there some sort of calculation I need to 
>> do on the raw data to get the RMS value?
>> I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO 
>> Unit 2, with the same conditions as the tests involving the PRS.  IOW, the 
>> 5370 is being clocked by GPSDO Unit 2, and the trigger for the EXT input to 
>> the 5370 is from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from 
>> GPSDO Unit 2.  The ones I have on hand show about 4E-11 at 1s tau.  
>> 
>> After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the 
>> PRS.  Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 
>> 5370.  If you really don't want the GSPDO to clock the 5370, I'll run the 
>> same test using the internal 10811 as the clock, to compare the difference.
>> 
>> I also ran into an old test of the 5370 where START (10MHz) was fed by a 
>> GPSDO and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft 
>> cable from START to STOP.  I'll probably want to rerun that, as well, but it 
>> was an almost straight line from 2E-11 at 1s tau in that dataset.  Still, 
>> that test will verify that the 5370 hasn't degraded. Bob
>> 
>>  From: Tom Van Baak <t...@leapsecond.com <mailto:t...@leapsecond.com>>
>> To: Discussion of precise time and frequency measurement <time-nuts@febo.com 
>> <mailto:time-nuts@febo.com>> 
>> Sent: Wednesday, May 3, 2017 12:02 AM
>> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>> 
>> Hi BobS,
>> 
>>> I've also made the timelab file (compressed by 7z) available here:
>>> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z 
>>> <http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z>
>> 
>> Thanks for sharing that. To follow-up on recent emails...
>> 
>> When you start to push the limits of your own test equipment it's good to 
>> employ tricks such as 3-corner hat in order to get a few dB better 
>> measurement. But there's a limit to that. And you probably don't want me to 
>> suggest that you run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.
>> 
>> I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
>> TBolt (factory defaults, *untuned*)
>> 
>> bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over 
>> the place.
>> 
>> bob-gpsdo-5.gif -- ADEV comparison. See below for comments.
>> 
>> 1)
>> When I look at the ADEV for your data set it's pretty clear that the 
>> limiting factor on the left (short tau) is the resolution of your 5370A 
>> counter. That's why the TBolt looks better. Don't worry about that.
>> 
>> 2)
>> In the middle of the ADEV plot it would appear that both your 5370A counter 
>> and your PRS-45A cesium reference are sufficiently good to properly measure 
>> your GPSDO. That's good. The TBolt looks bad in the middle but that's simply 
>> because it was using a way-too-short default time constant. With proper 
>> tuning the red trace would be mostly flat out to 1000 seconds.
>> 
>> 3)
>> From the look of the phase plot and the ADEV plot it almost seems to me like 
>> your PRS-45A is the limiting factor on the right (long tau). If so, it would 
>> explain the lack of diurnal and sidereal effects in your data. If you look 
>> at:
>> http://leapsecond.com/pages/tbolt-8d/sigma1.gif 
>> <http://leapsecond.com/pages/tbolt-8d/sigma1.gif> from 
>> http://www.leapsecond.com/pages/tbolt-8d/ 
>&

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
What I should have asked is this: "how do I get that from a Timelab dataset?"   
Bob


  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: Tom Van Baak <t...@leapsecond.com>
 Sent: Wednesday, May 3, 2017 7:20 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
RMS:
https://en.wikipedia.org/wiki/Root_mean_square
When we talk about things like “6 sigma” in QA, the sigma is the RMS. 
Bob

On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Tom,
Could you clarify the term RMS?  Is there some sort of calculation I need to do 
on the raw data to get the RMS value?
I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 is 
from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 2.  
The ones I have on hand show about 4E-11 at 1s tau.  

After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the PRS.  
Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 5370.  
If you really don't want the GSPDO to clock the 5370, I'll run the same test 
using the internal 10811 as the clock, to compare the difference.

I also ran into an old test of the 5370 where START (10MHz) was fed by a GPSDO 
and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft cable 
from START to STOP.  I'll probably want to rerun that, as well, but it was an 
almost straight line from 2E-11 at 1s tau in that dataset.  Still, that test 
will verify that the 5370 hasn't degraded. Bob

  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Wednesday, May 3, 2017 12:02 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi BobS,


I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thanks for sharing that. To follow-up on recent emails...

When you start to push the limits of your own test equipment it's good to 
employ tricks such as 3-corner hat in order to get a few dB better measurement. 
But there's a limit to that. And you probably don't want me to suggest that you 
run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.

I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
TBolt (factory defaults, *untuned*)

bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over the 
place.

bob-gpsdo-5.gif -- ADEV comparison. See below for comments.

1)
When I look at the ADEV for your data set it's pretty clear that the limiting 
factor on the left (short tau) is the resolution of your 5370A counter. That's 
why the TBolt looks better. Don't worry about that.

2)
In the middle of the ADEV plot it would appear that both your 5370A counter and 
your PRS-45A cesium reference are sufficiently good to properly measure your 
GPSDO. That's good. The TBolt looks bad in the middle but that's simply because 
it was using a way-too-short default time constant. With proper tuning the red 
trace would be mostly flat out to 1000 seconds.

3)
>From the look of the phase plot and the ADEV plot it almost seems to me like 
>your PRS-45A is the limiting factor on the right (long tau). If so, it would 
>explain the lack of diurnal and sidereal effects in your data. If you look at:
http://leapsecond.com/pages/tbolt-8d/sigma1.gif from 
http://www.leapsecond.com/pages/tbolt-8d/
you'll note the sidereal "blip" is below 4e-14. Your ADEV doesn't get near that 
level.


I say this because a rule-of-thumb is that a good M12+T timing receiver should 
get you down to 3 ns per day RMS. And a good ublox-6T can get you to 3 or 2 ns 
per day RMS. Your data shows something more like 5 ns -- which for a GPSDO is 
worse than no GPSDO at all. So something's wrong. What set of experiments can 
you perform to locate the problem? Or, what experiments can you perform that 
don't require buying expensive gear?

My first suggestion is for you run a standalone GPS timing receiver like a 
M12+T or ublox-6. Put all your GPSDO away. Just use that OEM board, and your 
TIC, and your PRS-45A. Collect sawtooth data too. You should get down to 2 or 3 
ns RMS.

/tvb

- Original Message - 
From: "Bob Stewart" <b...@evoria.net>
To: "Discussion of Precise Time and Frequency Measurement" 
<time-nuts@febo.com>; "Magnus Danielson" <mag...@rubidium.se>
Sent: Thursday, April 27, 2017 9:48 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Magnus,
Try as I might, the weather and the local power company had other ideas about 
my long term capture. I'm running everything but the 5370 from a UPS. I guess 
I

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

RMS:

https://en.wikipedia.org/wiki/Root_mean_square 
<https://en.wikipedia.org/wiki/Root_mean_square>

When we talk about things like “6 sigma” in QA, the sigma is the RMS. 

Bob

> On May 3, 2017, at 1:44 AM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Tom,
> Could you clarify the term RMS?  Is there some sort of calculation I need to 
> do on the raw data to get the RMS value?
> I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
> 2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
> being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 
> is from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 
> 2.  The ones I have on hand show about 4E-11 at 1s tau.  
> 
> After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the 
> PRS.  Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 
> 5370.  If you really don't want the GSPDO to clock the 5370, I'll run the 
> same test using the internal 10811 as the clock, to compare the difference.
> 
> I also ran into an old test of the 5370 where START (10MHz) was fed by a 
> GPSDO and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft 
> cable from START to STOP.  I'll probably want to rerun that, as well, but it 
> was an almost straight line from 2E-11 at 1s tau in that dataset.  Still, 
> that test will verify that the 5370 hasn't degraded. Bob
> 
>  From: Tom Van Baak <t...@leapsecond.com>
> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
> Sent: Wednesday, May 3, 2017 12:02 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi BobS,
> 
>> I've also made the timelab file (compressed by 7z) available here:
>> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z
> 
> Thanks for sharing that. To follow-up on recent emails...
> 
> When you start to push the limits of your own test equipment it's good to 
> employ tricks such as 3-corner hat in order to get a few dB better 
> measurement. But there's a limit to that. And you probably don't want me to 
> suggest that you run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.
> 
> I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
> TBolt (factory defaults, *untuned*)
> 
> bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over 
> the place.
> 
> bob-gpsdo-5.gif -- ADEV comparison. See below for comments.
> 
> 1)
> When I look at the ADEV for your data set it's pretty clear that the limiting 
> factor on the left (short tau) is the resolution of your 5370A counter. 
> That's why the TBolt looks better. Don't worry about that.
> 
> 2)
> In the middle of the ADEV plot it would appear that both your 5370A counter 
> and your PRS-45A cesium reference are sufficiently good to properly measure 
> your GPSDO. That's good. The TBolt looks bad in the middle but that's simply 
> because it was using a way-too-short default time constant. With proper 
> tuning the red trace would be mostly flat out to 1000 seconds.
> 
> 3)
> From the look of the phase plot and the ADEV plot it almost seems to me like 
> your PRS-45A is the limiting factor on the right (long tau). If so, it would 
> explain the lack of diurnal and sidereal effects in your data. If you look at:
> http://leapsecond.com/pages/tbolt-8d/sigma1.gif from 
> http://www.leapsecond.com/pages/tbolt-8d/
> you'll note the sidereal "blip" is below 4e-14. Your ADEV doesn't get near 
> that level.
> 
> 
> I say this because a rule-of-thumb is that a good M12+T timing receiver 
> should get you down to 3 ns per day RMS. And a good ublox-6T can get you to 3 
> or 2 ns per day RMS. Your data shows something more like 5 ns -- which for a 
> GPSDO is worse than no GPSDO at all. So something's wrong. What set of 
> experiments can you perform to locate the problem? Or, what experiments can 
> you perform that don't require buying expensive gear?
> 
> My first suggestion is for you run a standalone GPS timing receiver like a 
> M12+T or ublox-6. Put all your GPSDO away. Just use that OEM board, and your 
> TIC, and your PRS-45A. Collect sawtooth data too. You should get down to 2 or 
> 3 ns RMS.
> 
> /tvb
> 
> - Original Message - 
> From: "Bob Stewart" <b...@evoria.net>
> To: "Discussion of Precise Time and Frequency Measurement" 
> <time-nuts@febo.com>; "Magnus Danielson" <mag...@rubidium.se>
> Sent: Thursday, April 27, 2017 9:48 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> 
> Hi Magnus,
> Try as I might, the weather and the local power compa

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Tom,
Could you clarify the term RMS?  Is there some sort of calculation I need to do 
on the raw data to get the RMS value?
I'm going to begin by doing a fresh 8 hour test of GPSDO Unit 1 vs GPSDO Unit 
2, with the same conditions as the tests involving the PRS.  IOW, the 5370 is 
being clocked by GPSDO Unit 2, and the trigger for the EXT input to the 5370 is 
from GPSDO Unit 2.  START is from GSPDO Unit 1 and STOP is from GPSDO Unit 2.  
The ones I have on hand show about 4E-11 at 1s tau.  

After that, I'll run an 8 hour test of raw 1PPS from a LEA-6T against the PRS.  
Since I don't really trust the PRS, I'll use GPSDO Unit 2 to clock the 5370.  
If you really don't want the GSPDO to clock the 5370, I'll run the same test 
using the internal 10811 as the clock, to compare the difference.

I also ran into an old test of the 5370 where START (10MHz) was fed by a GPSDO 
and STOP (10MHz) was fed by the same GPSDO but with (I think) a 20 ft cable 
from START to STOP.  I'll probably want to rerun that, as well, but it was an 
almost straight line from 2E-11 at 1s tau in that dataset.  Still, that test 
will verify that the 5370 hasn't degraded. Bob

  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Wednesday, May 3, 2017 12:02 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi BobS,

> I've also made the timelab file (compressed by 7z) available here:
> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z

Thanks for sharing that. To follow-up on recent emails...

When you start to push the limits of your own test equipment it's good to 
employ tricks such as 3-corner hat in order to get a few dB better measurement. 
But there's a limit to that. And you probably don't want me to suggest that you 
run 3 GPSDO, 3 counters and 3 cesiums all simultaneously.

I've attached two plots showing 4+ days of your GPSDO data and 4+ days of a 
TBolt (factory defaults, *untuned*)

bob-gpsdo-3.gif -- Notice how much your GPSDO (blue trace) wanders all over the 
place.

bob-gpsdo-5.gif -- ADEV comparison. See below for comments.

1)
When I look at the ADEV for your data set it's pretty clear that the limiting 
factor on the left (short tau) is the resolution of your 5370A counter. That's 
why the TBolt looks better. Don't worry about that.

2)
In the middle of the ADEV plot it would appear that both your 5370A counter and 
your PRS-45A cesium reference are sufficiently good to properly measure your 
GPSDO. That's good. The TBolt looks bad in the middle but that's simply because 
it was using a way-too-short default time constant. With proper tuning the red 
trace would be mostly flat out to 1000 seconds.

3)
>From the look of the phase plot and the ADEV plot it almost seems to me like 
>your PRS-45A is the limiting factor on the right (long tau). If so, it would 
>explain the lack of diurnal and sidereal effects in your data. If you look at:
http://leapsecond.com/pages/tbolt-8d/sigma1.gif from 
http://www.leapsecond.com/pages/tbolt-8d/
you'll note the sidereal "blip" is below 4e-14. Your ADEV doesn't get near that 
level.


I say this because a rule-of-thumb is that a good M12+T timing receiver should 
get you down to 3 ns per day RMS. And a good ublox-6T can get you to 3 or 2 ns 
per day RMS. Your data shows something more like 5 ns -- which for a GPSDO is 
worse than no GPSDO at all. So something's wrong. What set of experiments can 
you perform to locate the problem? Or, what experiments can you perform that 
don't require buying expensive gear?

My first suggestion is for you run a standalone GPS timing receiver like a 
M12+T or ublox-6. Put all your GPSDO away. Just use that OEM board, and your 
TIC, and your PRS-45A. Collect sawtooth data too. You should get down to 2 or 3 
ns RMS.

/tvb

- Original Message - 
From: "Bob Stewart" <b...@evoria.net>
To: "Discussion of Precise Time and Frequency Measurement" 
<time-nuts@febo.com>; "Magnus Danielson" <mag...@rubidium.se>
Sent: Thursday, April 27, 2017 9:48 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Magnus,
Try as I might, the weather and the local power company had other ideas about 
my long term capture. I'm running everything but the 5370 from a UPS. I guess 
I'm going to have to get batteries for my other UPS and run the 5370 from that. 
A one second power loss was all it took to stop the test.

Anyway, I did manage to get 376,238 points of data. The data is captured on a 
5370A. The external clock input and the STOP channel are fed by the 10MHz from 
my PRS-45A. The START channel is fed by the 10MHz from one of my GPSDOs. The 
EXT channel is fed by the 1PPS from another of my GPSDO units. "EXT ARM" is 
enabled. So, essentially, at every 1PPS pulse, the phase difference between the 
two 10MHz feeds is captured.

I've attached a screenshot of the ph

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Jim,

Errors aligning up due to sidreal time is most likely due to the 
multipath errors and repeated upload shifts.


Solar shifts would align up on 24 h basis.

The filtering of the time-constant is expected.

Cheers,
Magnus

On 04/29/2017 04:14 PM, Jim Harman wrote:

On Thu, Apr 27, 2017 at 12:48 PM, Bob Stewart  wrote:


So, back to my question:  Where are the large ionospheric phase moves?
This question has been causing me doubt since I started on this project.
Or don't I still have enough data collected for this to happen?

Bob



Bob, my test setup is a good deal simpler than yours, but attached is a
plot that I think shows the variations you are looking for quite clearly.
This is data from my homebrew GPSDO, which uses an Adafruit non-timing GPS
module and a run-of-the-mill surplus OCXO. The plot records the phase
comparator output over a period of about 1 week. The time constant of the
PLL is 1024 seconds and it is plotting the 5-minute average TIC values.

The full horizontal scale is 24 hours.

The vertical scale shows the data from several days with the traces for
successive days offset upwards by the equivalent of 40 nsec.

As you can see there is pretty good correlation of the phase error from day
to day and the wiggles migrate to the left a little, corresponding to the
23:56:04 siderial repeat time of the GPS constellation.This is with a
pretty good antenna location, under a shingle roof in the attic. I
calculate the day-to-day correlation at about 0.8.

Making the time constant larger increases the variations somewhat, because
the loop does not adjust as much, and they definitely get worse if I use a
less optimal antenna location.






___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Jim Harman]

On Thu, Apr 27, 2017 at 12:48 PM, Bob Stewart  wrote:

> So, back to my question:  Where are the large ionospheric phase moves?
> This question has been causing me doubt since I started on this project.
> Or don't I still have enough data collected for this to happen?
>
> Bob
>

Bob, my test setup is a good deal simpler than yours, but attached is a
plot that I think shows the variations you are looking for quite clearly.
This is data from my homebrew GPSDO, which uses an Adafruit non-timing GPS
module and a run-of-the-mill surplus OCXO. The plot records the phase
comparator output over a period of about 1 week. The time constant of the
PLL is 1024 seconds and it is plotting the 5-minute average TIC values.

The full horizontal scale is 24 hours.

The vertical scale shows the data from several days with the traces for
successive days offset upwards by the equivalent of 40 nsec.

As you can see there is pretty good correlation of the phase error from day
to day and the wiggles migrate to the left a little, corresponding to the
23:56:04 siderial repeat time of the GPS constellation.This is with a
pretty good antenna location, under a shingle roof in the attic. I
calculate the day-to-day correlation at about 0.8.

Making the time constant larger increases the variations somewhat, because
the loop does not adjust as much, and they definitely get worse if I use a
less optimal antenna location.




-- 

--Jim Harman
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Angus]

Hi Bob, 

This is a phase plot of a rubidium to an M12 from a test that I did
back in 2008. The offset and ageing have been removed, but there is
still a bit of wander. 
As with your plot, constellation related issues appear the most
obvious. Peak to peak is fairly similar too.

Angus.


On Thu, 27 Apr 2017 16:48:37 + (UTC), you wrote:

>Hi Magnus,
>Try as I might, the weather and the local power company had other ideas about 
>my long term capture.  I'm running everything but the 5370 from a UPS.  I 
>guess I'm going to have to get batteries for my other UPS and run the 5370 
>from that.  A one second power loss was all it took to stop the test.
>
>Anyway, I did manage to get 376,238 points of data.  The data is captured on a 
>5370A.  The external clock input and the STOP channel are fed by the 10MHz 
>from my PRS-45A.  The START channel is fed by the 10MHz from one of my GPSDOs. 
> The EXT channel is fed by the 1PPS from another of my GPSDO units.  "EXT ARM" 
>is enabled.  So, essentially, at every 1PPS pulse, the phase difference 
>between the two 10MHz feeds is captured.
>
>I've attached a screenshot of the phase plot which can also be found 
>here:http://evoria.net/AE6RV/Timelab/Screenshot.png
>I've also made the timelab file (compressed by 7z) available here:
>http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z
>
>So, back to my question:  Where are the large ionospheric phase moves?  This 
>question has been causing me doubt since I started on this project.  Or don't 
>I still have enough data collected for this to happen?
>
>Bob
>
>-
>AE6RV.com
>
>GFS GPSDO list:
>groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>
>  From: Magnus Danielson <mag...@rubidium.dyndns.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
>Cc: mag...@rubidium.se
> Sent: Tuesday, April 18, 2017 1:09 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>   
>Hi Bob,
>
>That is a good solution indeed. Good luck with that measurement run!
>
>One of the fun stuff with Timelab is that you can walk by and check the 
>developments. I've found that very useful for long measurements (as in 
>hours and days).
>
>I prepared a cesium for one vendor, and initially they did not care so 
>much, but then they saw more deviations between the receivers, so they 
>wanted to sort it out, but discovered that they could not cancel out the 
>common mode of GPS signals (and its shifts), so then firing up that 
>cesium was the right thing. I remember writing support emails while 
>waiting for the airplane in Madrid airport, happy that they was doing a 
>first run for the right measurement reason. :)
>
>Cheers,
>Magnus
>
>On 04/18/2017 04:25 AM, Bob Stewart wrote:
>> Hi Magnus,
>> Today I started a long run against my PRS-45A.  Maybe this time I won't have 
>> a power outage.  I'll see what it tells me in a few days.
>> Bob
>
>   
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Jim,
I'm not sure you're plotting what you think you are, but perhaps I 
misunderstood.  The phase error data contains both the position uncertainty of 
the Adafruit (constellation, ionosphere, etc) and an error caused by correcting 
the OCXO using that phase error.  IOW, the fact that the phase error puts the 
OCXO back in phase is problematic.

You might think about disconnecting the EFC from the OCXO and feeding the OCXO 
directly with a fixed voltage derived from the VRef output of the OCXO, 
assuming it has one.  Then, carefully adjust the VRef voltage so that the phase 
error changes very slowly.  Let it cook for a few days and restabilize, then 
start logging your phase error.  Feed that to Timelab and see what the plot 
looks like.  Timelab should be able to remove the aging, so that you wind up 
with a plot that's mostly the Adafruit.  Of course, that depends on which OCXO 
you're using.  I've had good luck with the Trimble 34310-Ts that are about $20 
each depending on the vendor.

Bob 

  From: Jim Harman <j99har...@gmail.com>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
 Sent: Saturday, April 29, 2017 9:15 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   

On Thu, Apr 27, 2017 at 12:48 PM, Bob Stewart <b...@evoria.net> wrote:

So, back to my question:  Where are the large ionospheric phase moves?  This 
question has been causing me doubt since I started on this project.  Or don't I 
still have enough data collected for this to happen?

Bob

Bob, my test setup is a good deal simpler than yours, but attached is a plot 
that I think shows the variations you are looking for quite clearly. This is 
data from my homebrew GPSDO, which uses an Adafruit non-timing GPS module and a 
run-of-the-mill surplus OCXO. The plot records the phase comparator output over 
a period of about 1 week. The time constant of the PLL is 1024 seconds and it 
is plotting the 5-minute average TIC values. 
The full horizontal scale is 24 hours.
The vertical scale shows the data from several days with the traces for 
successive days offset upwards by the equivalent of 40 nsec.
As you can see there is pretty good correlation of the phase error from day to 
day and the wiggles migrate to the left a little, corresponding to the 23:56:04 
siderial repeat time of the GPS constellation.This is with a pretty good 
antenna location, under a shingle roof in the attic. I calculate the day-to-day 
correlation at about 0.8.
Making the time constant larger increases the variations somewhat, because the 
loop does not adjust as much, and they definitely get worse if I use a less 
optimal antenna location.



-- 

--Jim Harman


   
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Magnus,
OK, a couple of things about my location.  I'm in West Houston, and it's not 
summer yet, so there's a lot of variation in temperature from day to day.  Some 
nights it's in the 40sF and some nights it's in the high 70s or low 80sF.  Lots 
of variation in the days, as well.  My antenna is not optimal, at all.  The 
best I could do was to remove the dish from an unused DishTV antenna and 
install my GPS antenna on top of the little mast they use.  It's about the best 
I can do.  In fact, it's better than I expected.
The receiver is a LEA-6T that was put through a 24 hour survey and the position 
was saved in flash memory.  However, there have been lots of power cycles since 
that survey.  Whether or not that affects the result, I don't know.

Still, the point of the test was to understand why I'm not getting these large 
phase swings.  And I think Bob Camp's explanation was good.  Maybe in another 5 
years the sunspots will be back up and I can see the comparison to now. Bob

  From: Magnus Danielson <mag...@rubidium.se>
 To: Bob Stewart <b...@evoria.net>; Discussion of Precise Time and Frequency 
Measurement <time-nuts@febo.com> 
Cc: mag...@rubidium.se
 Sent: Saturday, April 29, 2017 6:45 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi Bob,

On 04/27/2017 06:48 PM, Bob Stewart wrote:
> Hi Magnus,
>
> Try as I might, the weather and the local power company had other ideas
> about my long term capture.  I'm running everything but the 5370 from a
> UPS.  I guess I'm going to have to get batteries for my other UPS and
> run the 5370 from that.  A one second power loss was all it took to stop
> the test.

Annoying, but you got some good values never the less.

> Anyway, I did manage to get 376,238 points of data.  The data is
> captured on a 5370A.  The external clock input and the STOP channel are
> fed by the 10MHz from my PRS-45A.  The START channel is fed by the 10MHz
> from one of my GPSDOs.  The EXT channel is fed by the 1PPS from another
> of my GPSDO units.  "EXT ARM" is enabled.  So, essentially, at every
> 1PPS pulse, the phase difference between the two 10MHz feeds is captured.

OK, this seems like a good setup.

> I've attached a screenshot of the phase plot which can also be found here:
> http://evoria.net/AE6RV/Timelab/Screenshot.png
>
> I've also made the timelab file (compressed by 7z) available here:
> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z

Thank you for providing the data, I downloaded it so I can play around 
with it, which I naturally did. :)

> So, back to my question:  Where are the large ionospheric phase moves?
> This question has been causing me doubt since I started on this
> project.  Or don't I still have enough data collected for this to happen?

Your data seems to be more affected by constellation shifts, as the 
period of about 43080 s seems to be a period of the constellation.
You either have averaged out to a somewhat incorrect position of your 
antenna or you have sub-optimal position of your antenna.

It gives you a peak-to-peak amplitude of about 10 ns or so.

The ionospheric errors has a period of 86400s, so to get a clear 
separation of these would take more data. However, playing around with 
the data in TimeLab allowed me to filter out some of the other systematics.

The day-to-day variations is noticeable. I wonder how much of that is 
thermal though. The building variations was filtered out in the process.

One has to identify a number of these potential disturbances, estimate 
their size in order to more clearly see other things. TimeLab has a 
notch filter to notch out a particular frequency. It would be nice if an 
alternative approach would be to give the notch a period.

One has to recall that even and odd harmonics to a disturbance frequency 
can be there, as it is not always a pure sine disturbance.

Cheers,
Magnus


   
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi Bob,

For that receiver, you have a pretty good result.
If you haven't moved your antenna, the average result should be fine.
However, with a cesium around you can experiment with minor adjustments 
of position. Best would be to build carrier phase pseudo-range 
measurements and compare with the time-difference to see if there is a 
correlation and then fine-tune that way. I don't recall what you get out 
of the LEA-6T.


You sure has some outdoor temperature variations right now.

It would be interesting to do an outdoor and indoor temperature log and 
try to see the correlation there.


Cheers,
Magnus

On 04/29/2017 04:35 PM, Bob Stewart wrote:

Hi Magnus,

OK, a couple of things about my location.  I'm in West Houston, and it's
not summer yet, so there's a lot of variation in temperature from day to
day.  Some nights it's in the 40sF and some nights it's in the high 70s
or low 80sF.  Lots of variation in the days, as well.  My antenna is not
optimal, at all.  The best I could do was to remove the dish from an
unused DishTV antenna and install my GPS antenna on top of the little
mast they use.  It's about the best I can do.  In fact, it's better than
I expected.

The receiver is a LEA-6T that was put through a 24 hour survey and the
position was saved in flash memory.  However, there have been lots of
power cycles since that survey.  Whether or not that affects the result,
I don't know.

Still, the point of the test was to understand why I'm not getting these
large phase swings.  And I think Bob Camp's explanation was good.  Maybe
in another 5 years the sunspots will be back up and I can see the
comparison to now.

Bob


*From:* Magnus Danielson <mag...@rubidium.se>
*To:* Bob Stewart <b...@evoria.net>; Discussion of Precise Time and
Frequency Measurement <time-nuts@febo.com>
*Cc:* mag...@rubidium.se
*Sent:* Saturday, April 29, 2017 6:45 AM
*Subject:* Re: [time-nuts] Three-cornered hat on timelab?

Hi Bob,

On 04/27/2017 06:48 PM, Bob Stewart wrote:

Hi Magnus,

Try as I might, the weather and the local power company had other ideas
about my long term capture.  I'm running everything but the 5370 from a
UPS.  I guess I'm going to have to get batteries for my other UPS and
run the 5370 from that.  A one second power loss was all it took to stop
the test.


Annoying, but you got some good values never the less.


Anyway, I did manage to get 376,238 points of data.  The data is
captured on a 5370A.  The external clock input and the STOP channel are
fed by the 10MHz from my PRS-45A.  The START channel is fed by the 10MHz
from one of my GPSDOs.  The EXT channel is fed by the 1PPS from another
of my GPSDO units.  "EXT ARM" is enabled.  So, essentially, at every
1PPS pulse, the phase difference between the two 10MHz feeds is captured.


OK, this seems like a good setup.


I've attached a screenshot of the phase plot which can also be found here:
http://evoria.net/AE6RV/Timelab/Screenshot.png

I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thank you for providing the data, I downloaded it so I can play around
with it, which I naturally did. :)


So, back to my question:  Where are the large ionospheric phase moves?
This question has been causing me doubt since I started on this
project.  Or don't I still have enough data collected for this to happen?


Your data seems to be more affected by constellation shifts, as the
period of about 43080 s seems to be a period of the constellation.
You either have averaged out to a somewhat incorrect position of your
antenna or you have sub-optimal position of your antenna.

It gives you a peak-to-peak amplitude of about 10 ns or so.

The ionospheric errors has a period of 86400s, so to get a clear
separation of these would take more data. However, playing around with
the data in TimeLab allowed me to filter out some of the other systematics.

The day-to-day variations is noticeable. I wonder how much of that is
thermal though. The building variations was filtered out in the process.

One has to identify a number of these potential disturbances, estimate
their size in order to more clearly see other things. TimeLab has a
notch filter to notch out a particular frequency. It would be nice if an
alternative approach would be to give the notch a period.

One has to recall that even and odd harmonics to a disturbance frequency
can be there, as it is not always a pure sine disturbance.


Cheers,
Magnus



___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi Bob,

On 04/27/2017 06:48 PM, Bob Stewart wrote:

Hi Magnus,

Try as I might, the weather and the local power company had other ideas
about my long term capture.  I'm running everything but the 5370 from a
UPS.  I guess I'm going to have to get batteries for my other UPS and
run the 5370 from that.  A one second power loss was all it took to stop
the test.


Annoying, but you got some good values never the less.


Anyway, I did manage to get 376,238 points of data.  The data is
captured on a 5370A.  The external clock input and the STOP channel are
fed by the 10MHz from my PRS-45A.  The START channel is fed by the 10MHz
from one of my GPSDOs.  The EXT channel is fed by the 1PPS from another
of my GPSDO units.  "EXT ARM" is enabled.  So, essentially, at every
1PPS pulse, the phase difference between the two 10MHz feeds is captured.


OK, this seems like a good setup.


I've attached a screenshot of the phase plot which can also be found here:
http://evoria.net/AE6RV/Timelab/Screenshot.png

I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z


Thank you for providing the data, I downloaded it so I can play around 
with it, which I naturally did. :)



So, back to my question:  Where are the large ionospheric phase moves?
This question has been causing me doubt since I started on this
project.  Or don't I still have enough data collected for this to happen?


Your data seems to be more affected by constellation shifts, as the 
period of about 43080 s seems to be a period of the constellation.
You either have averaged out to a somewhat incorrect position of your 
antenna or you have sub-optimal position of your antenna.


It gives you a peak-to-peak amplitude of about 10 ns or so.

The ionospheric errors has a period of 86400s, so to get a clear 
separation of these would take more data. However, playing around with 
the data in TimeLab allowed me to filter out some of the other systematics.


The day-to-day variations is noticeable. I wonder how much of that is 
thermal though. The building variations was filtered out in the process.


One has to identify a number of these potential disturbances, estimate 
their size in order to more clearly see other things. TimeLab has a 
notch filter to notch out a particular frequency. It would be nice if an 
alternative approach would be to give the notch a period.


One has to recall that even and odd harmonics to a disturbance frequency 
can be there, as it is not always a pure sine disturbance.


Cheers,
Magnus
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[jimlux]

On 4/27/17 3:10 PM, Bob Stewart wrote:

Hi Jim,
said:"Ionosphere is one - if you're near a ionosonde you might be able to get a data set to 
correlate against.  It's not necessarily a "worst at noon, best at midnight" thing - some 
of the satellites contributing to your fix will be on slant paths, so the solar ionization is not 
uniform." Are the Ublox timing receivers a lot better at getting rid of ionospheric phase 
shifts because they can see more sats than the older Motorola receivers?
And as a point of reference, the dataset I linked begins at ~9:21AM CST on 
4/22/2017.  I'm in west Houston, TX.

Bob


As a general thing, more satellites means more values into the average. 
But it's also where they are.


If you've got a big clump of ionization to the west of you, then it 
affects the satellites that are west of you, but not those that are 
east. But if your current solution is more west than east, that will 
pull it.


OTOH, most of the receivers also weight the contribution by the SNR. A 
higher Total Electron Content (more delay) also results in more 
attenuation.


1 TECU is about 16 cm in delay (call it 0.5 ns) (I think..)


typical TECU values are 50-100.. so you can see there's a pretty big effect.


ftp://ftp.ngdc.noaa.gov/STP/GPS_GNSS/Mihail's.pdf


___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi


> On Apr 27, 2017, at 6:10 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Jim,
> said:"Ionosphere is one - if you're near a ionosonde you might be able to get 
> a data set to correlate against.  It's not necessarily a "worst at noon, best 
> at midnight" thing - some of the satellites contributing to your fix will be 
> on slant paths, so the solar ionization is not uniform." Are the Ublox timing 
> receivers a lot better at getting rid of ionospheric phase shifts because 
> they can see more sats than the older Motorola receivers?

Not really. Most of the time you have less than a full set of sat’s visible on 
a uBlox no matter how it is set up. If you crank the elevation mask up, you may 
not see much difference between the two at all.  Also consider that the “old” 
Motorola receivers are (at this point) very old. The “new” 12 channel units 
have been around for quite a long time. We have even been through a couple of 
generations of replacements for them. 

Bob


> And as a point of reference, the dataset I linked begins at ~9:21AM CST on 
> 4/22/2017.  I'm in west Houston, TX.
> 
> Bob
> 
>  From: jimlux <jim...@earthlink.net>
> To: time-nuts@febo.com 
> Sent: Thursday, April 27, 2017 5:03 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> On 4/27/17 12:10 PM, Bob Stewart wrote:
>> Hi Bob,
>> said:
>> "You have roughly 25 ns p-p in the data you show."
>> OK, here's a misunderstanding on my part right off the bat.  You see the 
>> swing as a p-p value, when I've been looking at it as only +/- 12.5ns from 
>> the trendline.
>> 
>> said some time ago:
>> "Now toss in the basics of GPS. Depending on the day, you will get <10 ns to 
>>  >100 ns swing over a  24 hour period. Today may or may not be the same as 
>> tomorrow."
>> So maybe I'm thinking too much about the >100ns figure, and not so much 
>> about the <10ns figure you mentioned.  The average doesn't seem to do much 
>> for me, either.  So, is the probability curve between 10ns and 100ns, where 
>> 100ns is least probable, of the type  y=2^-x?  IOW, in a year, I might see 
>> one 100ns swing, I would probably see at least one or two 50ns swings, and 
>> will probably see anything less than that multiple times, with the probably 
>> increasing as the value gets lower.
>> 
>> Not trying to crucify you with your own words, Bob.  Like many of the 
>> time-nuts who don't post, I'm just trying to make some sense of this in 
>> terms I can deal with.
>> 
>> Bob
>> 
>>   From: Bob kb8tq <kb...@n1k.org>
>>   To: Bob Stewart <b...@evoria.net>; Discussion of precise time and 
>> frequency measurement <time-nuts@febo.com>
>> Cc: Magnus Danielson <mag...@rubidium.se>
>>   Sent: Thursday, April 27, 2017 1:18 PM
>>   Subject: Re: [time-nuts] Three-cornered hat on timelab?
>> 
>> Hi
>> 
>> 
>> You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
>> “cycles” in the data.
>> Any of this *may* be due to ionosphere. They also could be due to other 
>> issues.  With ~4.4 days of noisy
>> data, it may be tough to spot a trend. Since the ionosphere is a bit random, 
>> there is no guarantee that
>> you *will* always see a pretty sinusoidal trend line through the data. It’s 
>> a good bet that things quiet down
>> around midnight. There is no guarantee that they always go nuts (or go nuts 
>> to the same degree) around noon.
>> 
>> Bob
>> 
> 
> 
> I don't think it necessarily has a nice distribution.  precise phase 
> measurement with GPS has lots of effects that are in the "about a meter" 
> range.
> 
> Ionosphere is one - if you're near a ionosonde you might be able to get 
> a data set to correlate against.  It's not necessarily a "worst at noon, 
> best at midnight" thing - some of the satellites contributing to your 
> fix will be on slant paths, so the solar ionization is not uniform.
> 
> Solid earth tides are another effect in that general magnitude (10s of 
> cm) - see Wikipedia or:
> https://www.unavco.org/education/professional-development/short-courses/course-materials/strainmeter/2005-strainmeter-course-materials/tidenote.pdf
> 
> 
> Thermal expansion and contraction of a variety of things:
> 1) the structure supporting your antenna
> 2) the earth's surface
> 3) the coax from antenna to receiver
> 4) any filters
> 5) the antenna
> 
> For most of these, they *are* periodic in some sense: solid earth tides 
> are affected by moon and sun, which have reaso

[time-nuts] Three-cornered hat on timelab?

[Mark Sims]

One of the main reasons Lady Heather tracks the sun position, calculates solar 
noon, etc was at the request of some people researching solar effects on the 
GPS signal and multipath.  You can enable logging of the satellite 
constellation used each second and the sun position (it shows up at sat PRN 
256, the moon is PRN 257) with the W L C keyboard command.   The constellation 
data is output as comments in the normal log files and as  data in .XML 
and .GPX format log files.
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
OK, since we are in a low sunspot cycle, then it would follow that the 100ns 
movements would be rare.  Also, since I'm at about 29.8 degrees north, with few 
obstructions or reflectors to cause a problem, that improves what I'm capable 
of seeing out of what's available.  As to what problems are buried in my data 
due to equipment limitations, you're welcome to give me a long term loan of a 
nice H Maser and Timepod.  I promise I'll treat them well!  =)

Anyway, thanks for the explications.  As mentioned, I see figures bandied about 
on timenuts, but no explanation of the variables that cause those figures to be 
true or not true.  When I don't see them happening in my "lab", then I get 
confused.  I'm pretty certain I'm not the only one this happens to.  Several of 
you have been adamant about ionospheric effects north of 60ns.  I just haven't 
seen them.

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Thursday, April 27, 2017 4:17 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
Dig into space weather if you want to get into the details of the why and how 
often. It’s all out thereGoogle is your friend. Things like sun spot cycles are 
one of many drivers. The more perturbed the space weather is day to day, the 
more likely you are to see changes in the GPS.  Monitor the spaceweather sites 
on a regular basis and you will be able to make some guesses about what’s 
likely to happen. It’s only going to be a guess, no better than the 10 day 
weather forecast :) One of manysites: http://www.swpc.noaa.gov . A bit about 
what to watch for: 
http://www.swpc.noaa.gov/impacts/space-weather-and-gps-systemsThis one is a bit 
HF oriented: http://www.sws.bom.gov.au/HF_Systems/6/5
That’s only the first part.
The second part is that the delta ionosphere *is* fit by GPS data. What you are 
concerned with is not just a "bump' of space weather. You are concerned with 
one that does not fit well. That’s a normalthing when the weather is rough, but 
not an always thing.  A peak solar flux event that ramps upslow and decays 
slowly is very different than one with faster changes. You do get both. 
Patchydisruptions in the ionosphere are worse than a uniform high. They are 
hard to fit.
Next up …
The goodness of fit depends a lot on the sat’s you are using for your 
processing and where they arelocated in the sky. If you happen to have a sat 
that sends a signal across a big long patch of poorly fitionosphere,  you have 
a problem. If every single sat you are using is straight over head and your 
house is well fit, there is no problem.  Longer paths by their nature are more 
likely to be an issue.Bad fit only matters if you are depending to some extent 
on that part of the sky.  How much longer vs shorter contributes to your 
solution right now is always a “that depends” sort of thing. 
Is that all there is?
No, not hardly, that’s just the easy part. The troposphere also gets into the 
act and it flies around a bit. Last time I checked, they just use a static 
model there so it’s not a broadcast vs reality issue.You also get into things 
like location and sat angle from your location. If you are in northern 
Greenlandthings will be a bit different than in Ceylon. There are a few other 
issues I could probably dive into with a bit of research. 
So no, it’s not simple. How often do you see > 100 ns? Best data I’ve seen is 
that you hit that range a few times a year on average. More so at solar maxima 
and less so at solar minima. It’s no different than propagation on 10 meters. 
If you are looking for 100 ns every day, day in and day out, that’s not going 
to happen. 
You *are* looking for a peak to peak sort of swing. If you already have 20 ns 
wander in the data, you are going to have a hard time seeing anything much 
below 20 ns. What you are looking for is most likely to have a 86,000 second 
period (= day - night cycle). My guess is that you don’t see it because it’s 
buried in the noise of your data.
Not at all easy….
Bob


On Apr 27, 2017, at 3:10 PM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
said:
"You have roughly 25 ns p-p in the data you show."
OK, here's a misunderstanding on my part right off the bat.  You see the swing 
as a p-p value, when I've been looking at it as only +/- 12.5ns from the 
trendline.

said some time ago:
"Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>100 ns swing over a  24 hour period. Today may or may not be the same as 
tomorrow."
So maybe I'm thinking too much about the >100ns figure, and not so much about 
the <10ns figure you mentioned.  The average doesn't seem to do much for me, 
either.  So, is the probability curve between 10ns and 100ns, where 100ns is 
least probable, of the type  y=2^-x?  IOW, in a year, I might see one 100ns 
swin

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Jim,
said:"Ionosphere is one - if you're near a ionosonde you might be able to get a 
data set to correlate against.  It's not necessarily a "worst at noon, best at 
midnight" thing - some of the satellites contributing to your fix will be on 
slant paths, so the solar ionization is not uniform." Are the Ublox timing 
receivers a lot better at getting rid of ionospheric phase shifts because they 
can see more sats than the older Motorola receivers?
And as a point of reference, the dataset I linked begins at ~9:21AM CST on 
4/22/2017.  I'm in west Houston, TX.

Bob

  From: jimlux <jim...@earthlink.net>
 To: time-nuts@febo.com 
 Sent: Thursday, April 27, 2017 5:03 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
On 4/27/17 12:10 PM, Bob Stewart wrote:
> Hi Bob,
> said:
> "You have roughly 25 ns p-p in the data you show."
> OK, here's a misunderstanding on my part right off the bat.  You see the 
> swing as a p-p value, when I've been looking at it as only +/- 12.5ns from 
> the trendline.
>
> said some time ago:
> "Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
> >100 ns swing over a  24 hour period. Today may or may not be the same as 
> tomorrow."
> So maybe I'm thinking too much about the >100ns figure, and not so much about 
> the <10ns figure you mentioned.  The average doesn't seem to do much for me, 
> either.  So, is the probability curve between 10ns and 100ns, where 100ns is 
> least probable, of the type  y=2^-x?  IOW, in a year, I might see one 100ns 
> swing, I would probably see at least one or two 50ns swings, and will 
> probably see anything less than that multiple times, with the probably 
> increasing as the value gets lower.
>
> Not trying to crucify you with your own words, Bob.  Like many of the 
> time-nuts who don't post, I'm just trying to make some sense of this in terms 
> I can deal with.
>
> Bob
>
>      From: Bob kb8tq <kb...@n1k.org>
>  To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
>measurement <time-nuts@febo.com>
> Cc: Magnus Danielson <mag...@rubidium.se>
>  Sent: Thursday, April 27, 2017 1:18 PM
>  Subject: Re: [time-nuts] Three-cornered hat on timelab?
>
> Hi
>
>
> You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
> “cycles” in the data.
> Any of this *may* be due to ionosphere. They also could be due to other 
> issues.  With ~4.4 days of noisy
> data, it may be tough to spot a trend. Since the ionosphere is a bit random, 
> there is no guarantee that
> you *will* always see a pretty sinusoidal trend line through the data. It’s a 
> good bet that things quiet down
> around midnight. There is no guarantee that they always go nuts (or go nuts 
> to the same degree) around noon.
>
> Bob
>


I don't think it necessarily has a nice distribution.  precise phase 
measurement with GPS has lots of effects that are in the "about a meter" 
range.

Ionosphere is one - if you're near a ionosonde you might be able to get 
a data set to correlate against.  It's not necessarily a "worst at noon, 
best at midnight" thing - some of the satellites contributing to your 
fix will be on slant paths, so the solar ionization is not uniform.

Solid earth tides are another effect in that general magnitude (10s of 
cm) - see Wikipedia or:
https://www.unavco.org/education/professional-development/short-courses/course-materials/strainmeter/2005-strainmeter-course-materials/tidenote.pdf


Thermal expansion and contraction of a variety of things:
1) the structure supporting your antenna
2) the earth's surface
3) the coax from antenna to receiver
4) any filters
5) the antenna

For most of these, they *are* periodic in some sense: solid earth tides 
are affected by moon and sun, which have reasonably well known periods. 
Thermal effects typically have a strong 24 hour cycle (although I've 
seen some weird ones caused by shadows intermittently falling on stuff, 
but still, it has a 24 hour periodicity)


Then there's various geometry/multipath things - choke rings help if 
you're in a wide open area.
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[jimlux]

On 4/27/17 12:10 PM, Bob Stewart wrote:

Hi Bob,
said:
"You have roughly 25 ns p-p in the data you show."
OK, here's a misunderstanding on my part right off the bat.  You see the swing 
as a p-p value, when I've been looking at it as only +/- 12.5ns from the 
trendline.

said some time ago:
"Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  >100 
ns swing over a  24 hour period. Today may or may not be the same as tomorrow."
So maybe I'm thinking too much about the >100ns figure, and not so much about the 
<10ns figure you mentioned.  The average doesn't seem to do much for me, either.  
So, is the probability curve between 10ns and 100ns, where 100ns is least probable, 
of the type  y=2^-x?  IOW, in a year, I might see one 100ns swing, I would probably 
see at least one or two 50ns swings, and will probably see anything less than that 
multiple times, with the probably increasing as the value gets lower.

Not trying to crucify you with your own words, Bob.  Like many of the time-nuts 
who don't post, I'm just trying to make some sense of this in terms I can deal 
with.

Bob

 From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com>
Cc: Magnus Danielson <mag...@rubidium.se>
 Sent: Thursday, April 27, 2017 1:18 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi


You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
“cycles” in the data.
Any of this *may* be due to ionosphere. They also could be due to other issues. 
 With ~4.4 days of noisy
data, it may be tough to spot a trend. Since the ionosphere is a bit random, 
there is no guarantee that
you *will* always see a pretty sinusoidal trend line through the data. It’s a 
good bet that things quiet down
around midnight. There is no guarantee that they always go nuts (or go nuts to 
the same degree) around noon.

Bob




I don't think it necessarily has a nice distribution.  precise phase 
measurement with GPS has lots of effects that are in the "about a meter" 
range.


Ionosphere is one - if you're near a ionosonde you might be able to get 
a data set to correlate against.  It's not necessarily a "worst at noon, 
best at midnight" thing - some of the satellites contributing to your 
fix will be on slant paths, so the solar ionization is not uniform.


Solid earth tides are another effect in that general magnitude (10s of 
cm) - see Wikipedia or:

https://www.unavco.org/education/professional-development/short-courses/course-materials/strainmeter/2005-strainmeter-course-materials/tidenote.pdf


Thermal expansion and contraction of a variety of things:
1) the structure supporting your antenna
2) the earth's surface
3) the coax from antenna to receiver
4) any filters
5) the antenna

For most of these, they *are* periodic in some sense: solid earth tides 
are affected by moon and sun, which have reasonably well known periods. 
Thermal effects typically have a strong 24 hour cycle (although I've 
seen some weird ones caused by shadows intermittently falling on stuff, 
but still, it has a 24 hour periodicity)



Then there's various geometry/multipath things - choke rings help if 
you're in a wide open area.

___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

Dig into space weather if you want to get into the details of the why and how 
often. It’s all out there
Google is your friend. Things like sun spot cycles are one of many drivers. The 
more perturbed the 
space weather is day to day, the more likely you are to see changes in the GPS. 
 Monitor the space
weather sites on a regular basis and you will be able to make some guesses 
about what’s likely to 
happen. It’s only going to be a guess, no better than the 10 day weather 
forecast :) One of many
sites: http://www.swpc.noaa.gov <http://www.swpc.noaa.gov/> . A bit about what 
to watch for: http://www.swpc.noaa.gov/impacts/space-weather-and-gps-systems 
<http://www.swpc.noaa.gov/impacts/space-weather-and-gps-systems>
This one is a bit HF oriented: http://www.sws.bom.gov.au/HF_Systems/6/5 
<http://www.sws.bom.gov.au/HF_Systems/6/5>

That’s only the first part.

The second part is that the delta ionosphere *is* fit by GPS data. What you are 
concerned with is not just a 
"bump' of space weather. You are concerned with one that does not fit well. 
That’s a normal
thing when the weather is rough, but not an always thing.  A peak solar flux 
event that ramps up
slow and decays slowly is very different than one with faster changes. You do 
get both. Patchy
disruptions in the ionosphere are worse than a uniform high. They are hard to 
fit.

Next up …

The goodness of fit depends a lot on the sat’s you are using for your 
processing and where they are
located in the sky. If you happen to have a sat that sends a signal across a 
big long patch of poorly fit
ionosphere,  you have a problem. If every single sat you are using is straight 
over head and your 
house is well fit, there is no problem.  Longer paths by their nature are more 
likely to be an issue.
Bad fit only matters if you are depending to some extent on that part of the 
sky.  How much longer 
vs shorter contributes to your solution right now is always a “that depends” 
sort of thing. 

Is that all there is?

No, not hardly, that’s just the easy part. The troposphere also gets into the 
act and it flies around a 
bit. Last time I checked, they just use a static model there so it’s not a 
broadcast vs reality issue.
You also get into things like location and sat angle from your location. If you 
are in northern Greenland
things will be a bit different than in Ceylon. There are a few other issues I 
could probably dive into with a bit of research. 

So no, it’s not simple. How often do you see > 100 ns? Best data I’ve seen is 
that you hit that
 range a few times a year on average. More so at solar maxima and less so at 
solar minima. It’s no 
different than propagation on 10 meters. If you are looking for 100 ns every 
day, day in and day out, 
that’s not going to happen. 

You *are* looking for a peak to peak sort of swing. If you already have 20 ns 
wander in the data, you are 
going to have a hard time seeing anything much below 20 ns. What you are 
looking for is most likely to have 
a 86,000 second period (= day - night cycle). My guess is that you don’t see it 
because it’s buried in the noise of your data.

Not at all easy….

Bob


> On Apr 27, 2017, at 3:10 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> said:
> "You have roughly 25 ns p-p in the data you show."
> 
> OK, here's a misunderstanding on my part right off the bat.  You see the 
> swing as a p-p value, when I've been looking at it as only +/- 12.5ns from 
> the trendline.
> 
> said some time ago:
> "Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
> >100 ns swing over a  24 hour period. Today may or may not be the same as 
> tomorrow."
> 
> So maybe I'm thinking too much about the >100ns figure, and not so much about 
> the <10ns figure you mentioned.  The average doesn't seem to do much for me, 
> either.  So, is the probability curve between 10ns and 100ns, where 100ns is 
> least probable, of the type  y=2^-x?  IOW, in a year, I might see one 100ns 
> swing, I would probably see at least one or two 50ns swings, and will 
> probably see anything less than that multiple times, with the probably 
> increasing as the value gets lower.
> 
> Not trying to crucify you with your own words, Bob.  Like many of the 
> time-nuts who don't post, I'm just trying to make some sense of this in terms 
> I can deal with.
> 
> Bob
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
> Cc: Magnus Danielson <mag...@rubidium.se>
> Sent: Thursday, April 27, 2017 1:18 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> 
> You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
> “cycles” in the dat

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
said:
"You have roughly 25 ns p-p in the data you show."
OK, here's a misunderstanding on my part right off the bat.  You see the swing 
as a p-p value, when I've been looking at it as only +/- 12.5ns from the 
trendline.

said some time ago:
"Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>100 ns swing over a  24 hour period. Today may or may not be the same as 
tomorrow."
So maybe I'm thinking too much about the >100ns figure, and not so much about 
the <10ns figure you mentioned.  The average doesn't seem to do much for me, 
either.  So, is the probability curve between 10ns and 100ns, where 100ns is 
least probable, of the type  y=2^-x?  IOW, in a year, I might see one 100ns 
swing, I would probably see at least one or two 50ns swings, and will probably 
see anything less than that multiple times, with the probably increasing as the 
value gets lower.

Not trying to crucify you with your own words, Bob.  Like many of the time-nuts 
who don't post, I'm just trying to make some sense of this in terms I can deal 
with.

Bob

 From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: Magnus Danielson <mag...@rubidium.se>
 Sent: Thursday, April 27, 2017 1:18 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi


You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
“cycles” in the data. 
Any of this *may* be due to ionosphere. They also could be due to other issues. 
 With ~4.4 days of noisy
data, it may be tough to spot a trend. Since the ionosphere is a bit random, 
there is no guarantee that
you *will* always see a pretty sinusoidal trend line through the data. It’s a 
good bet that things quiet down
around midnight. There is no guarantee that they always go nuts (or go nuts to 
the same degree) around noon. 

Bob


> On Apr 27, 2017, at 12:48 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Magnus,
> Try as I might, the weather and the local power company had other ideas about 
> my long term capture.  I'm running everything but the 5370 from a UPS.  I 
> guess I'm going to have to get batteries for my other UPS and run the 5370 
> from that.  A one second power loss was all it took to stop the test.
> 
> Anyway, I did manage to get 376,238 points of data.  The data is captured on 
> a 5370A.  The external clock input and the STOP channel are fed by the 10MHz 
> from my PRS-45A.  The START channel is fed by the 10MHz from one of my 
> GPSDOs.  The EXT channel is fed by the 1PPS from another of my GPSDO units.  
> "EXT ARM" is enabled.  So, essentially, at every 1PPS pulse, the phase 
> difference between the two 10MHz feeds is captured.
> 
> I've attached a screenshot of the phase plot which can also be found 
> here:http://evoria.net/AE6RV/Timelab/Screenshot.png
> I've also made the timelab file (compressed by 7z) available here:
> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z
> 
> So, back to my question:  Where are the large ionospheric phase moves?  This 
> question has been causing me doubt since I started on this project.  Or don't 
> I still have enough data collected for this to happen?
> 
> Bob
> 
> -
> AE6RV.com
> 
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> 
>      From: Magnus Danielson <mag...@rubidium.dyndns.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
> Cc: mag...@rubidium.se
> Sent: Tuesday, April 18, 2017 1:09 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi Bob,
> 
> That is a good solution indeed. Good luck with that measurement run!
> 
> One of the fun stuff with Timelab is that you can walk by and check the 
> developments. I've found that very useful for long measurements (as in 
> hours and days).
> 
> I prepared a cesium for one vendor, and initially they did not care so 
> much, but then they saw more deviations between the receivers, so they 
> wanted to sort it out, but discovered that they could not cancel out the 
> common mode of GPS signals (and its shifts), so then firing up that 
> cesium was the right thing. I remember writing support emails while 
> waiting for the airplane in Madrid airport, happy that they was doing a 
> first run for the right measurement reason. :)
> 
> Cheers,
> Magnus
> 
> On 04/18/2017 04:25 AM, Bob Stewart wrote:
>> Hi Magnus,
>> Today I started a long run against my PRS-45A.  Maybe this time I won't have 
>> a power outage.  I'll see what it tells me in a few days.
>> Bob
> 
> _

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi


You have roughly 25 ns p-p in the data you show. There are a number of 10 ns 
“cycles” in the data. 
Any of this *may* be due to ionosphere. They also could be due to other issues. 
 With ~4.4 days of noisy
data, it may be tough to spot a trend. Since the ionosphere is a bit random, 
there is no guarantee that
you *will* always see a pretty sinusoidal trend line through the data. It’s a 
good bet that things quiet down
around midnight. There is no guarantee that they always go nuts (or go nuts to 
the same degree) around noon. 

Bob


> On Apr 27, 2017, at 12:48 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Magnus,
> Try as I might, the weather and the local power company had other ideas about 
> my long term capture.  I'm running everything but the 5370 from a UPS.  I 
> guess I'm going to have to get batteries for my other UPS and run the 5370 
> from that.  A one second power loss was all it took to stop the test.
> 
> Anyway, I did manage to get 376,238 points of data.  The data is captured on 
> a 5370A.  The external clock input and the STOP channel are fed by the 10MHz 
> from my PRS-45A.  The START channel is fed by the 10MHz from one of my 
> GPSDOs.  The EXT channel is fed by the 1PPS from another of my GPSDO units.  
> "EXT ARM" is enabled.  So, essentially, at every 1PPS pulse, the phase 
> difference between the two 10MHz feeds is captured.
> 
> I've attached a screenshot of the phase plot which can also be found 
> here:http://evoria.net/AE6RV/Timelab/Screenshot.png
> I've also made the timelab file (compressed by 7z) available here:
> http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z
> 
> So, back to my question:  Where are the large ionospheric phase moves?  This 
> question has been causing me doubt since I started on this project.  Or don't 
> I still have enough data collected for this to happen?
> 
> Bob
> 
> -
> AE6RV.com
> 
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
> 
>  From: Magnus Danielson <mag...@rubidium.dyndns.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
> Cc: mag...@rubidium.se
> Sent: Tuesday, April 18, 2017 1:09 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi Bob,
> 
> That is a good solution indeed. Good luck with that measurement run!
> 
> One of the fun stuff with Timelab is that you can walk by and check the 
> developments. I've found that very useful for long measurements (as in 
> hours and days).
> 
> I prepared a cesium for one vendor, and initially they did not care so 
> much, but then they saw more deviations between the receivers, so they 
> wanted to sort it out, but discovered that they could not cancel out the 
> common mode of GPS signals (and its shifts), so then firing up that 
> cesium was the right thing. I remember writing support emails while 
> waiting for the airplane in Madrid airport, happy that they was doing a 
> first run for the right measurement reason. :)
> 
> Cheers,
> Magnus
> 
> On 04/18/2017 04:25 AM, Bob Stewart wrote:
>> Hi Magnus,
>> Today I started a long run against my PRS-45A.  Maybe this time I won't have 
>> a power outage.  I'll see what it tells me in a few days.
>> Bob
> 
> ___
> 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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Magnus,
Try as I might, the weather and the local power company had other ideas about 
my long term capture.  I'm running everything but the 5370 from a UPS.  I guess 
I'm going to have to get batteries for my other UPS and run the 5370 from that. 
 A one second power loss was all it took to stop the test.

Anyway, I did manage to get 376,238 points of data.  The data is captured on a 
5370A.  The external clock input and the STOP channel are fed by the 10MHz from 
my PRS-45A.  The START channel is fed by the 10MHz from one of my GPSDOs.  The 
EXT channel is fed by the 1PPS from another of my GPSDO units.  "EXT ARM" is 
enabled.  So, essentially, at every 1PPS pulse, the phase difference between 
the two 10MHz feeds is captured.

I've attached a screenshot of the phase plot which can also be found 
here:http://evoria.net/AE6RV/Timelab/Screenshot.png
I've also made the timelab file (compressed by 7z) available here:
http://evoria.net/AE6RV/Timelab/GFSvsCS.4.22.17.7z

So, back to my question:  Where are the large ionospheric phase moves?  This 
question has been causing me doubt since I started on this project.  Or don't I 
still have enough data collected for this to happen?

Bob

-
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info

  From: Magnus Danielson <mag...@rubidium.dyndns.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: mag...@rubidium.se
 Sent: Tuesday, April 18, 2017 1:09 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi Bob,

That is a good solution indeed. Good luck with that measurement run!

One of the fun stuff with Timelab is that you can walk by and check the 
developments. I've found that very useful for long measurements (as in 
hours and days).

I prepared a cesium for one vendor, and initially they did not care so 
much, but then they saw more deviations between the receivers, so they 
wanted to sort it out, but discovered that they could not cancel out the 
common mode of GPS signals (and its shifts), so then firing up that 
cesium was the right thing. I remember writing support emails while 
waiting for the airplane in Madrid airport, happy that they was doing a 
first run for the right measurement reason. :)

Cheers,
Magnus

On 04/18/2017 04:25 AM, Bob Stewart wrote:
> Hi Magnus,
> Today I started a long run against my PRS-45A.  Maybe this time I won't have 
> a power outage.  I'll see what it tells me in a few days.
> Bob

   ___
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.

Re: [time-nuts] Three-cornered hat on timelab? -> GPS

[Bob kb8tq]

Hi

There are a number of survey grade receivers that pop up on eBay from time to 
time.
They rarely have “timing” features like an external reference and PPS output 
that both
work properly. There’s also a bit of risk buying them and finding out they are 
non-functional. 
All that said, if you shop for a while (= years) you can get them pretty cheap. 
The latest
NetRS is coming in for $100. 

SDR is still a bit of a confused arena. There are a lot of “hey I almost got 
this working” 
sort of projects by guys in basements. There are a few papers by universities 
and labs
that got things working on L1. The “big guys” often use fairly expensive 
hardware and not
the < $500 sort of thing the basement guys do. 

So far the number of SDR’s that are capable of multi-frequency operation are 
few and 
far between. For about $10K you *can* get a RF device that would do the job. 
You then 
run into the need to move the samples over to your computer. 10Gb ethernet (or 
multiple
10Gb’s) look like the leading approach for that. Based on various papers, your 
PC likely
needs > 20 cores to handle three bands / two systems on a parallel basis. 

The “unexplored” alternative to an all in one multi band approach would be a 
multi
board approach. More or less, use one board each for L1, L2, and L5. You might 
stuff in a PC per band / per GNSS system. How to split that up and get it all 
working
is not really clear. There’s also the “unload to an FPGA” approach that at 
least on
the surface makes a lot of sense. You likely would have an FPGA board per band 
and
per GNSS system. No matter how you slice it, its a lot of gear. 

The guys at Swift seem to have a very new board out that does L1/L2. It’s 
reasonably
priced ($600 for the board, $2K for the eval kit). It is sort of open source. 
It is abundantly
unclear how they handle the clocking into and out of the board. At this point 
it is GPS 
only with all sorts of things coming “real soon now”. It is SDR so upgrades via 
firmware
are a practical thing. 

Past that there are a number of OEM cards that do this and that. Most that I 
have found are
a “fill out a nine page form for a quote” sort of thing. In general there is 
never a reply 
after you fill out the form. The little I have found is that for about $6K or 
so you can
get a board that will handle L1/L2 with L5 coming real soon. GPS and Glonass are
supported with other systems “real soon”.  

Since this is TimeNuts and not SurveyNuts, we are not the target audience for 
any
of these guys. That makes the whole digging process even more fun. Simply 
finding 
out *if* the device has a working external reference or PPS may be nearly 
impossible 
(= wait 3 months for an answer). The existing open source software is not (yet) 
targeted 
at a timing application. That could easily change. A lot of labs are interested 
in this
same sort of thing. 

All that said, right now LimeSDR looks like a pretty good option. One has to 
trust that
they *will* ship real soon now. Boards are in the wild and appear to work. The 
$300
cost is rational for a single band board. They should do what a BladeRF will do 
for
half the cost. The HackRF One appears to simply have too many issues. The Ettus 
B200 / B210 would do the trick single band for around $1000. Their X310 with 
two 
dual rx boards would do the whole thing (for $10K). 

Lots of choices, lots of work. No clear winner in the race at this point. 
Anybody who
wants to send me the full X310 setup, contact me off list. I’ll pay shipping :) 
I already
have the computers….

Bob


> On Apr 17, 2017, at 9:33 PM, Hal Murray  wrote:
> 
> 
> mag...@rubidium.dyndns.org said:
>> You can fair better if you have a double-frequency GPS setup, as it can
>> first-degree measure and compensate the ionospheric shifts, which allows
>> for a benefit over L1 CA only receiver. 
> 
> Are any dual-frequency receivers available at hobbyist prices?
> 
> What is the status of open-source SDR for GPS?  Is this a good excuse to jump 
> on that bandwagon?
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> 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.

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi Bob,

That is a good solution indeed. Good luck with that measurement run!

One of the fun stuff with Timelab is that you can walk by and check the 
developments. I've found that very useful for long measurements (as in 
hours and days).


I prepared a cesium for one vendor, and initially they did not care so 
much, but then they saw more deviations between the receivers, so they 
wanted to sort it out, but discovered that they could not cancel out the 
common mode of GPS signals (and its shifts), so then firing up that 
cesium was the right thing. I remember writing support emails while 
waiting for the airplane in Madrid airport, happy that they was doing a 
first run for the right measurement reason. :)


Cheers,
Magnus

On 04/18/2017 04:25 AM, Bob Stewart wrote:

Hi Magnus,
Today I started a long run against my PRS-45A.  Maybe this time I won't have a 
power outage.  I'll see what it tells me in a few days.
Bob

  From: Magnus Danielson <mag...@rubidium.dyndns.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com>
Cc: mag...@rubidium.se
 Sent: Monday, April 17, 2017 5:28 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Bob,

First of all, there is a first degree of compensation from the GPS
transmitted Klobuchar ionspheric model. There is a limit to how well
those would match the actual values at the time and behavior for your
spot on the globe. The GPS models this to a fair fit for the globe.
Use of WAAS/EGNOS or even DGPS would allow for a better correction.

Second, these changes is slow, so you better measure them compared to a
cesium or maybe rubidium rather than the GPS itself or another GPS. A
GPS tracks in these deviations, so it will only be visible when compared
to an independent source. The frequency error and drift of the reference
clock can be compensated, but the remainder will dominantly be remaining
delay variations.

You can fair better if you have a double-frequency GPS setup, as it can
first-degree measure and compensate the ionospheric shifts, which allows
for a benefit over L1 CA only receiver.

Cheers,
Magnus

On 04/17/2017 10:38 PM, Bob Stewart wrote:

Hi Tom,
The reason I express so much confusion over this is because I don't see the 
wild phase excursions on my GFS units that people insist will happen due to 
ionospheric effects.  Is this because they are rare events, and I just haven't 
been saving data during a bad time?  I notice in your example page, you aren't 
seeing them, either during your 8+ day capture of the Tbolt.

Bob


  From: Tom Van Baak <t...@leapsecond.com>
  To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
  Sent: Monday, April 17, 2017 3:05 PM
  Subject: Re: [time-nuts] Three-cornered hat on timelab?

Bob S,

Here's an example of a one week GPSDO run:

http://leapsecond.com/pages/tbolt-8d/

IIRC, this was a default, untuned, self-surveyed TBolt. You can see some level 
of daily variations -- probably a mix of sky view, survey error, ionosphere, 
multi-path, sidereal effects [1], temperature (antenna, cable, GPSDO, 
reference), etc. It takes some time and equipment to sort out which is which, 
but even a simple test like this can give you an upper bound.

/tvb

[1] Fun GPS orbit stuff here:
http://leapsecond.com/pages/sidereal/index.htm
http://leapsecond.com/pages/sidereal/14years.htm
http://leapsecond.com/pages/sidereal/sv.htm
http://leapsecond.com/pages/gps-orbit/


- Original Message -
From: "Bob Stewart" <b...@evoria.net>
To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
Measurement" <time-nuts@febo.com>
Sent: Monday, April 17, 2017 9:33 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Bob,
OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
should be long enough to separate out the GFS from the PRS' drift direction 
from the ionosphere.

Bob



  From: Bob kb8tq <kb...@n1k.org>
  To: Bob Stewart <b...@evoria.net>
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
  Sent: Monday, April 17, 2017 11:28 AM
  Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi
The ionosphere is the culprit in terms of the daily swing. The swing is a function 
of the goodness of fit between the GPS broadcast dataand the ionosphere as it 
impacts the satellites you are using. There is no rime or reason to it beyond 
that. If you get “lucky” things don’t move much. If you live in exciting times, 
things move quite a bit. Unless you go to something like an L1/L2 receiver, the 
GPS module you use has little to do with it (unless it’s broke ….). Yes there are 
some fiddly little qualifiers relating to being at the north or south pole and GPS 
coverage (along with space weather impacts). Very few of us do our runs at either 
location :) Just for reference, the area

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi Hal,

On 04/18/2017 03:33 AM, Hal Murray wrote:


mag...@rubidium.dyndns.org said:

You can fair better if you have a double-frequency GPS setup, as it can
first-degree measure and compensate the ionospheric shifts, which allows
for a benefit over L1 CA only receiver.


Are any dual-frequency receivers available at hobbyist prices?


If you allow yourself to step up somewhat in price, you can get some.
Several of us have such gear.


What is the status of open-source SDR for GPS?  Is this a good excuse to jump
on that bandwagon?


I have not checked the current status. Should do that.

Cheers,
Magnus
___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Magnus,
Today I started a long run against my PRS-45A.  Maybe this time I won't have a 
power outage.  I'll see what it tells me in a few days.
Bob 

  From: Magnus Danielson <mag...@rubidium.dyndns.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: mag...@rubidium.se
 Sent: Monday, April 17, 2017 5:28 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Bob,

First of all, there is a first degree of compensation from the GPS 
transmitted Klobuchar ionspheric model. There is a limit to how well 
those would match the actual values at the time and behavior for your 
spot on the globe. The GPS models this to a fair fit for the globe.
Use of WAAS/EGNOS or even DGPS would allow for a better correction.

Second, these changes is slow, so you better measure them compared to a 
cesium or maybe rubidium rather than the GPS itself or another GPS. A 
GPS tracks in these deviations, so it will only be visible when compared 
to an independent source. The frequency error and drift of the reference 
clock can be compensated, but the remainder will dominantly be remaining 
delay variations.

You can fair better if you have a double-frequency GPS setup, as it can 
first-degree measure and compensate the ionospheric shifts, which allows 
for a benefit over L1 CA only receiver.

Cheers,
Magnus

On 04/17/2017 10:38 PM, Bob Stewart wrote:
> Hi Tom,
> The reason I express so much confusion over this is because I don't see the 
> wild phase excursions on my GFS units that people insist will happen due to 
> ionospheric effects.  Is this because they are rare events, and I just 
> haven't been saving data during a bad time?  I notice in your example page, 
> you aren't seeing them, either during your 8+ day capture of the Tbolt.
>
> Bob
>
>
>      From: Tom Van Baak <t...@leapsecond.com>
>  To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
>  Sent: Monday, April 17, 2017 3:05 PM
>  Subject: Re: [time-nuts] Three-cornered hat on timelab?
>
> Bob S,
>
> Here's an example of a one week GPSDO run:
>
> http://leapsecond.com/pages/tbolt-8d/
>
> IIRC, this was a default, untuned, self-surveyed TBolt. You can see some 
> level of daily variations -- probably a mix of sky view, survey error, 
> ionosphere, multi-path, sidereal effects [1], temperature (antenna, cable, 
> GPSDO, reference), etc. It takes some time and equipment to sort out which is 
> which, but even a simple test like this can give you an upper bound.
>
> /tvb
>
> [1] Fun GPS orbit stuff here:
> http://leapsecond.com/pages/sidereal/index.htm
> http://leapsecond.com/pages/sidereal/14years.htm
> http://leapsecond.com/pages/sidereal/sv.htm
> http://leapsecond.com/pages/gps-orbit/
>
>
> - Original Message -
> From: "Bob Stewart" <b...@evoria.net>
> To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
> Measurement" <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 9:33 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>
>
> Hi Bob,
> OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
> should be long enough to separate out the GFS from the PRS' drift direction 
> from the ionosphere.
>
> Bob
>
>
>
>      From: Bob kb8tq <kb...@n1k.org>
>  To: Bob Stewart <b...@evoria.net>
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
>  Sent: Monday, April 17, 2017 11:28 AM
>  Subject: Re: [time-nuts] Three-cornered hat on timelab?
>
> Hi
> The ionosphere is the culprit in terms of the daily swing. The swing is a 
> function of the goodness of fit between the GPS broadcast dataand the 
> ionosphere as it impacts the satellites you are using. There is no rime or 
> reason to it beyond that. If you get “lucky” things don’t move much. If you 
> live in exciting times, things move quite a bit. Unless you go to something 
> like an L1/L2 receiver, the GPS module you use has little to do with it 
> (unless it’s broke ….). Yes there are some fiddly little qualifiers relating 
> to being at the north or south pole and GPS coverage (along with space 
> weather impacts). Very few of us do our runs at either location :) Just for 
> reference, the area of concern also hasat least one day each year where the 
> sun sets for < 1 hours.
> Bob
>
>
>
>
> On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
> Hi Bob,
> Oh, I had completely forgotten about the many runs you gifted us with back 
> then. Fortunately, I kept all of them in my email archive. I can't compare 
> like for like, of course, but I think I can work up something 

Re: [time-nuts] Three-cornered hat on timelab?

[Hal Murray]

mag...@rubidium.dyndns.org said:
> You can fair better if you have a double-frequency GPS setup, as it can
> first-degree measure and compensate the ionospheric shifts, which allows
> for a benefit over L1 CA only receiver. 

Are any dual-frequency receivers available at hobbyist prices?

What is the status of open-source SDR for GPS?  Is this a good excuse to jump 
on that bandwagon?


-- 
These are my opinions.  I hate spam.



___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Bob,

First of all, there is a first degree of compensation from the GPS 
transmitted Klobuchar ionspheric model. There is a limit to how well 
those would match the actual values at the time and behavior for your 
spot on the globe. The GPS models this to a fair fit for the globe.

Use of WAAS/EGNOS or even DGPS would allow for a better correction.

Second, these changes is slow, so you better measure them compared to a 
cesium or maybe rubidium rather than the GPS itself or another GPS. A 
GPS tracks in these deviations, so it will only be visible when compared 
to an independent source. The frequency error and drift of the reference 
clock can be compensated, but the remainder will dominantly be remaining 
delay variations.


You can fair better if you have a double-frequency GPS setup, as it can 
first-degree measure and compensate the ionospheric shifts, which allows 
for a benefit over L1 CA only receiver.


Cheers,
Magnus

On 04/17/2017 10:38 PM, Bob Stewart wrote:

Hi Tom,
The reason I express so much confusion over this is because I don't see the 
wild phase excursions on my GFS units that people insist will happen due to 
ionospheric effects.  Is this because they are rare events, and I just haven't 
been saving data during a bad time?  I notice in your example page, you aren't 
seeing them, either during your 8+ day capture of the Tbolt.

Bob


  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 3:05 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Bob S,

Here's an example of a one week GPSDO run:

http://leapsecond.com/pages/tbolt-8d/

IIRC, this was a default, untuned, self-surveyed TBolt. You can see some level 
of daily variations -- probably a mix of sky view, survey error, ionosphere, 
multi-path, sidereal effects [1], temperature (antenna, cable, GPSDO, 
reference), etc. It takes some time and equipment to sort out which is which, 
but even a simple test like this can give you an upper bound.

/tvb

[1] Fun GPS orbit stuff here:
http://leapsecond.com/pages/sidereal/index.htm
http://leapsecond.com/pages/sidereal/14years.htm
http://leapsecond.com/pages/sidereal/sv.htm
http://leapsecond.com/pages/gps-orbit/


- Original Message -
From: "Bob Stewart" <b...@evoria.net>
To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
Measurement" <time-nuts@febo.com>
Sent: Monday, April 17, 2017 9:33 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Bob,
OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
should be long enough to separate out the GFS from the PRS' drift direction 
from the ionosphere.

Bob



  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 11:28 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi
The ionosphere is the culprit in terms of the daily swing. The swing is a function 
of the goodness of fit between the GPS broadcast dataand the ionosphere as it 
impacts the satellites you are using. There is no rime or reason to it beyond 
that. If you get “lucky” things don’t move much. If you live in exciting times, 
things move quite a bit. Unless you go to something like an L1/L2 receiver, the 
GPS module you use has little to do with it (unless it’s broke ….). Yes there are 
some fiddly little qualifiers relating to being at the north or south pole and GPS 
coverage (along with space weather impacts). Very few of us do our runs at either 
location :) Just for reference, the area of concern also hasat least one day each 
year where the sun sets for < 1 hours.
Bob




On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
Oh, I had completely forgotten about the many runs you gifted us with back 
then. Fortunately, I kept all of them in my email archive. I can't compare like 
for like, of course, but I think I can work up something that compares at the 
larger taus where the 5370 doesn't dominate.
I'm going to run another long term test of my GFS unit against my PRS-45A. The 
problem, the issue that made me ask for data is that everything from phase 
plots to ADEV plots of my unit are just so much better than the KS. In 
addition, I don't see the large ionospheric swings on my GFS unit that you and 
Bruce and others have spoken about. This bothers me a lot. Could it be my 
location here in Houston? Could it be the Ublox LEA-6T compared to the much 
older Motorola in the KS?

Bob

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 7:55 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?

Hi
The 

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

If you look at Tom’s data, he very definitely has a peak to peak in the 5 to 7 
ns range over a 24 hour period. He also gets the expected auto
correlation spikes. 

Bob

> On Apr 17, 2017, at 4:38 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Tom,
> The reason I express so much confusion over this is because I don't see the 
> wild phase excursions on my GFS units that people insist will happen due to 
> ionospheric effects.  Is this because they are rare events, and I just 
> haven't been saving data during a bad time?  I notice in your example page, 
> you aren't seeing them, either during your 8+ day capture of the Tbolt.
> 
> Bob 
> 
> 
>  From: Tom Van Baak <t...@leapsecond.com>
> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
> Sent: Monday, April 17, 2017 3:05 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Bob S,
> 
> Here's an example of a one week GPSDO run:
> 
> http://leapsecond.com/pages/tbolt-8d/
> 
> IIRC, this was a default, untuned, self-surveyed TBolt. You can see some 
> level of daily variations -- probably a mix of sky view, survey error, 
> ionosphere, multi-path, sidereal effects [1], temperature (antenna, cable, 
> GPSDO, reference), etc. It takes some time and equipment to sort out which is 
> which, but even a simple test like this can give you an upper bound.
> 
> /tvb
> 
> [1] Fun GPS orbit stuff here:
> http://leapsecond.com/pages/sidereal/index.htm
> http://leapsecond.com/pages/sidereal/14years.htm
> http://leapsecond.com/pages/sidereal/sv.htm
> http://leapsecond.com/pages/gps-orbit/
> 
> 
> - Original Message - 
> From: "Bob Stewart" <b...@evoria.net>
> To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
> Measurement" <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 9:33 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> 
> Hi Bob,
> OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
> should be long enough to separate out the GFS from the PRS' drift direction 
> from the ionosphere.
> 
> Bob 
> 
> 
> 
>       From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net> 
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 11:28 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>   
> Hi
> The ionosphere is the culprit in terms of the daily swing. The swing is a 
> function of the goodness of fit between the GPS broadcast dataand the 
> ionosphere as it impacts the satellites you are using. There is no rime or 
> reason to it beyond that. If you get “lucky” things don’t move much. If you 
> live in exciting times, things move quite a bit. Unless you go to something 
> like an L1/L2 receiver, the GPS module you use has little to do with it 
> (unless it’s broke ….). Yes there are some fiddly little qualifiers relating 
> to being at the north or south pole and GPS coverage (along with space 
> weather impacts). Very few of us do our runs at either location :) Just for 
> reference, the area of concern also hasat least one day each year where the 
> sun sets for < 1 hours. 
> Bob
> 
> 
> 
> 
> On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
> Hi Bob,
> Oh, I had completely forgotten about the many runs you gifted us with back 
> then. Fortunately, I kept all of them in my email archive. I can't compare 
> like for like, of course, but I think I can work up something that compares 
> at the larger taus where the 5370 doesn't dominate.
> I'm going to run another long term test of my GFS unit against my PRS-45A. 
> The problem, the issue that made me ask for data is that everything from 
> phase plots to ADEV plots of my unit are just so much better than the KS. In 
> addition, I don't see the large ionospheric swings on my GFS unit that you 
> and Bruce and others have spoken about. This bothers me a lot. Could it be my 
> location here in Houston? Could it be the Ublox LEA-6T compared to the much 
> older Motorola in the KS?
> 
> Bob 
> 
>   From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net> 
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 7:55 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>   
> Hi
> The data I have on the KS boxes was posted to the list back when they were.a 
> hot topic. I’m sure it is still in the archives.I’m guessing it’s not quite 
> what you are after. 
> 
> The closer the devices are to each other the

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Tom,
The reason I express so much confusion over this is because I don't see the 
wild phase excursions on my GFS units that people insist will happen due to 
ionospheric effects.  Is this because they are rare events, and I just haven't 
been saving data during a bad time?  I notice in your example page, you aren't 
seeing them, either during your 8+ day capture of the Tbolt.

Bob 


  From: Tom Van Baak <t...@leapsecond.com>
 To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
 Sent: Monday, April 17, 2017 3:05 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Bob S,

Here's an example of a one week GPSDO run:

http://leapsecond.com/pages/tbolt-8d/

IIRC, this was a default, untuned, self-surveyed TBolt. You can see some level 
of daily variations -- probably a mix of sky view, survey error, ionosphere, 
multi-path, sidereal effects [1], temperature (antenna, cable, GPSDO, 
reference), etc. It takes some time and equipment to sort out which is which, 
but even a simple test like this can give you an upper bound.

/tvb

[1] Fun GPS orbit stuff here:
http://leapsecond.com/pages/sidereal/index.htm
http://leapsecond.com/pages/sidereal/14years.htm
http://leapsecond.com/pages/sidereal/sv.htm
http://leapsecond.com/pages/gps-orbit/


- Original Message - 
From: "Bob Stewart" <b...@evoria.net>
To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
Measurement" <time-nuts@febo.com>
Sent: Monday, April 17, 2017 9:33 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Bob,
OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
should be long enough to separate out the GFS from the PRS' drift direction 
from the ionosphere.

Bob 



      From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 11:28 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
The ionosphere is the culprit in terms of the daily swing. The swing is a 
function of the goodness of fit between the GPS broadcast dataand the 
ionosphere as it impacts the satellites you are using. There is no rime or 
reason to it beyond that. If you get “lucky” things don’t move much. If you 
live in exciting times, things move quite a bit. Unless you go to something 
like an L1/L2 receiver, the GPS module you use has little to do with it (unless 
it’s broke ….). Yes there are some fiddly little qualifiers relating to being 
at the north or south pole and GPS coverage (along with space weather impacts). 
Very few of us do our runs at either location :) Just for reference, the area 
of concern also hasat least one day each year where the sun sets for < 1 hours. 
Bob




On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
Oh, I had completely forgotten about the many runs you gifted us with back 
then. Fortunately, I kept all of them in my email archive. I can't compare like 
for like, of course, but I think I can work up something that compares at the 
larger taus where the 5370 doesn't dominate.
I'm going to run another long term test of my GFS unit against my PRS-45A. The 
problem, the issue that made me ask for data is that everything from phase 
plots to ADEV plots of my unit are just so much better than the KS. In 
addition, I don't see the large ionospheric swings on my GFS unit that you and 
Bruce and others have spoken about. This bothers me a lot. Could it be my 
location here in Houston? Could it be the Ublox LEA-6T compared to the much 
older Motorola in the KS?

Bob 

      From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 7:55 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
The data I have on the KS boxes was posted to the list back when they were.a 
hot topic. I’m sure it is still in the archives.I’m guessing it’s not quite 
what you are after. 

The closer the devices are to each other the better the technique works. A 
simple way to look at it is as an attenuation. If it knocks noise down 10:1, 
the worst unit should be no more than 10X noise than the best unit. How much 
things are knockeddown is a function of the length of the runs compared to the 
longest tau. For a 10:1 ratio of tau to run, attenuation of noise by 10:1 is 
very optimistic. You usually need something beyond 100:1 to get that sort of 
performance. A lot depends on the noise involved. Some types of behavior simply 
don’t work well with the technique. 
The KS box goes from “better than” to “worse than” and back to “better than” 
most atomic standards you would compare it to overa range of tau from 0.1 S to 
1,000,000 seconds. To get the 1,000,000 second data accuratel

Re: [time-nuts] Three-cornered hat on timelab?

[Tom Van Baak]

Bob S,

Here's an example of a one week GPSDO run:

http://leapsecond.com/pages/tbolt-8d/

IIRC, this was a default, untuned, self-surveyed TBolt. You can see some level 
of daily variations -- probably a mix of sky view, survey error, ionosphere, 
multi-path, sidereal effects [1], temperature (antenna, cable, GPSDO, 
reference), etc. It takes some time and equipment to sort out which is which, 
but even a simple test like this can give you an upper bound.

/tvb

[1] Fun GPS orbit stuff here:
http://leapsecond.com/pages/sidereal/index.htm
http://leapsecond.com/pages/sidereal/14years.htm
http://leapsecond.com/pages/sidereal/sv.htm
http://leapsecond.com/pages/gps-orbit/


- Original Message - 
From: "Bob Stewart" <b...@evoria.net>
To: "Bob kb8tq" <kb...@n1k.org>; "Discussion of Precise Time and Frequency 
Measurement" <time-nuts@febo.com>
Sent: Monday, April 17, 2017 9:33 AM
Subject: Re: [time-nuts] Three-cornered hat on timelab?


Hi Bob,
OK, thanks. I've kicked off a 7 day run of a GFS against the PRS-45A. That 
should be long enough to separate out the GFS from the PRS' drift direction 
from the ionosphere.

Bob 



  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 11:28 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
The ionosphere is the culprit in terms of the daily swing. The swing is a 
function of the goodness of fit between the GPS broadcast dataand the 
ionosphere as it impacts the satellites you are using. There is no rime or 
reason to it beyond that. If you get “lucky” things don’t move much. If you 
live in exciting times, things move quite a bit. Unless you go to something 
like an L1/L2 receiver, the GPS module you use has little to do with it (unless 
it’s broke ….). Yes there are some fiddly little qualifiers relating to being 
at the north or south pole and GPS coverage (along with space weather impacts). 
Very few of us do our runs at either location :) Just for reference, the area 
of concern also hasat least one day each year where the sun sets for < 1 hours. 
Bob




On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
Oh, I had completely forgotten about the many runs you gifted us with back 
then. Fortunately, I kept all of them in my email archive. I can't compare like 
for like, of course, but I think I can work up something that compares at the 
larger taus where the 5370 doesn't dominate.
I'm going to run another long term test of my GFS unit against my PRS-45A. The 
problem, the issue that made me ask for data is that everything from phase 
plots to ADEV plots of my unit are just so much better than the KS. In 
addition, I don't see the large ionospheric swings on my GFS unit that you and 
Bruce and others have spoken about. This bothers me a lot. Could it be my 
location here in Houston? Could it be the Ublox LEA-6T compared to the much 
older Motorola in the KS?

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 7:55 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
The data I have on the KS boxes was posted to the list back when they were.a 
hot topic. I’m sure it is still in the archives.I’m guessing it’s not quite 
what you are after. 

The closer the devices are to each other the better the technique works. A 
simple way to look at it is as an attenuation. If it knocks noise down 10:1, 
the worst unit should be no more than 10X noise than the best unit. How much 
things are knockeddown is a function of the length of the runs compared to the 
longest tau. For a 10:1 ratio of tau to run, attenuation of noise by 10:1 is 
very optimistic. You usually need something beyond 100:1 to get that sort of 
performance. A lot depends on the noise involved. Some types of behavior simply 
don’t work well with the technique. 
The KS box goes from “better than” to “worse than” and back to “better than” 
most atomic standards you would compare it to overa range of tau from 0.1 S to 
1,000,000 seconds. To get the 1,000,000 second data accurately, you would need 
a 100,000,000 secondrun. The simple answer there is that nobody has that kind 
of time or that reliable a setup. Even the three month run to get good100,000 
second data is a challenge. None of that relates to three corner hat stuff, 
it’s just the confidence bars on ADEV. It givesyou another (say) 100:1 wait on 
top of the three corner stuff. 
Now toss in the basics of GPS. Depending on the day, you will get <10 ns to 
>100 ns swing over a 24 hour period. Today may or may not be the same as 
tomorrow. That’s with a “perfect” L1 setup. The variation comes from the 
ionosphere and the fact thatthe GPS

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
OK, thanks.  I've kicked off a 7 day run of a GFS against the PRS-45A.  That 
should be long enough to separate out the GFS from the PRS' drift direction 
from the ionosphere.

Bob 



  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 11:28 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
The ionosphere is the culprit in terms of the daily swing. The swing is a 
function of the goodness of fit between the GPS broadcast dataand the 
ionosphere as it impacts the satellites you are using. There is no rime or 
reason to it beyond that. If you get “lucky” things don’t move much. If you 
live in exciting times, things move quite a bit. Unless you go to something 
like an L1/L2 receiver, the GPS module you use has little to do with it (unless 
it’s broke ….). Yes there are some fiddly little qualifiers relating to being 
at the north or south pole and GPS coverage (along with space weather impacts). 
Very few of us do our runs at either location :) Just for reference, the area 
of concern also hasat least one day each year where the sun sets for < 1 hours. 
Bob




On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
Oh, I had completely forgotten about the many runs you gifted us with back 
then.  Fortunately, I kept all of them in my email archive.  I can't compare 
like for like, of course, but I think I can work up something that compares at 
the larger taus where the 5370 doesn't dominate.
I'm going to run another long term test of my GFS unit against my PRS-45A.  The 
problem, the issue that made me ask for data is that everything from phase 
plots to ADEV plots of my unit are just so much better than the KS.  In 
addition, I don't see the large ionospheric swings on my GFS unit that you and 
Bruce and others have spoken about.  This bothers me a lot.  Could it be my 
location here in Houston?  Could it be the Ublox LEA-6T compared to the much 
older Motorola in the KS?

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 7:55 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi
The data I have on the KS boxes was posted to the list back when they were.a 
hot topic. I’m sure it is still in the archives.I’m guessing it’s not quite 
what you are after. 

The closer the devices are to each other the better the technique works. A 
simple way to look at it is as an attenuation. If it knocks noise down 10:1, 
the worst unit should be no more than 10X noise than the best unit. How much 
things are knockeddown is a function of the length of the runs compared to the 
longest tau. For a 10:1 ratio of tau to run, attenuation of noise by 10:1 is 
very optimistic. You usually  need something beyond 100:1 to get that sort of 
performance. A lot depends on the noise involved. Some types of behavior simply 
don’t work well with the technique. 
The KS box goes from “better than” to “worse than” and back to “better than” 
most atomic standards you would compare it to overa range of tau from 0.1 S to 
1,000,000 seconds. To get the 1,000,000 second data accurately, you would need 
a 100,000,000 secondrun. The simple answer there is that nobody has that kind 
of time or that reliable a setup. Even the three month run to get good100,000 
second data is a challenge. None of that relates to three corner hat stuff, 
it’s just the confidence bars on ADEV. It givesyou another (say) 100:1 wait on 
top of the three corner stuff. 
Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>100 ns swing over a  24 hour period. Today may or may not be the same as 
tomorrow. That’s with a “perfect” L1 setup. The variation comes from the 
ionosphere and the fact thatthe GPS data does not allow you to fully correct 
for it.  In addition, you will get some interesting bumps related to 
constellations and your local antenna setup. Any GPSDO that is quartz based 
will happily follow the 24 hour swing in the GPS from the ionosphere. At 
100,000 seconds, a 100 ns swing is 1x10^-12. That’s a lot of disruption. It 
most certainly is not the sort of thing that ADEV expects to pop up in the 
middle of a run. 
The simple answer to all this is “don’t go there”. Three corner hat is fine for 
short term stuff. It’s a mess for long term runs. Getting datathat is good 
enough for a long term ADEV run out of a three corner setup is a major 
struggle. The time for the correlation to knock downthe noise on top of the 
time to get good ADEV data gets you into impractically long runs. 
Bob




On Apr 16, 2017, at 10:16 PM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
OK, I give up.  Try as I might, I can't fudge things enough to make any sense.  
I did run a se

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

One way to check what’s going on is to watch for 12 or 24 hour “blips” in the 
data. Unless you have a 
very unusual antenna setup, you should see some of them. They aren’t the 
ionosphere, but they are
normally there in most datasets. 

Bob

> On Apr 17, 2017, at 12:33 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> OK, thanks.  I've kicked off a 7 day run of a GFS against the PRS-45A.  That 
> should be long enough to separate out the GFS from the PRS' drift direction 
> from the ionosphere.
> 
> Bob
>  
> 
> 
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net> 
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 11:28 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> The ionosphere is the culprit in terms of the daily swing. The swing is a 
> function of the goodness of fit between the GPS broadcast data
> and the ionosphere as it impacts the satellites you are using. There is no 
> rime or reason to it beyond that. If you get “lucky” things don’t move 
> much. If you live in exciting times, things move quite a bit. Unless you go 
> to something like an L1/L2 receiver, the GPS module you use 
> has little to do with it (unless it’s broke ….). Yes there are some fiddly 
> little qualifiers relating to being at the north or south pole and GPS 
> coverage (along with space weather impacts). Very few of us do our runs at 
> either location :) Just for reference, the area of concern also has
> at least one day each year where the sun sets for < 1 hours. 
> 
> Bob
> 
> 
> 
> 
>> On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net 
>> <mailto:b...@evoria.net>> wrote:
>> 
>> Hi Bob,
>> 
>> Oh, I had completely forgotten about the many runs you gifted us with back 
>> then.  Fortunately, I kept all of them in my email archive.  I can't compare 
>> like for like, of course, but I think I can work up something that compares 
>> at the larger taus where the 5370 doesn't dominate.
>> 
>> I'm going to run another long term test of my GFS unit against my PRS-45A.  
>> The problem, the issue that made me ask for data is that everything from 
>> phase plots to ADEV plots of my unit are just so much better than the KS.  
>> In addition, I don't see the large ionospheric swings on my GFS unit that 
>> you and Bruce and others have spoken about.  This bothers me a lot.  Could 
>> it be my location here in Houston?  Could it be the Ublox LEA-6T compared to 
>> the much older Motorola in the KS?
>> 
>> Bob
>>  
>> 
>> 
>> From: Bob kb8tq <kb...@n1k.org <mailto:kb...@n1k.org>>
>> To: Bob Stewart <b...@evoria.net <mailto:b...@evoria.net>> 
>> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com 
>> <mailto:time-nuts@febo.com>>
>> Sent: Monday, April 17, 2017 7:55 AM
>> Subject: Re: [time-nuts] Three-cornered hat on timelab?
>> 
>> Hi
>> 
>> The data I have on the KS boxes was posted to the list back when they were.a 
>> hot topic. I’m sure it is still in the archives.
>> I’m guessing it’s not quite what you are after. 
>> 
>> The closer the devices are to each other the better the technique works. A 
>> simple way to look at it is as an attenuation. If 
>> it knocks noise down 10:1, the worst unit should be no more than 10X noise 
>> than the best unit. How much things are knocked
>> down is a function of the length of the runs compared to the longest tau. 
>> For a 10:1 ratio of tau to run, attenuation of noise by 10:1
>>  is very optimistic. You usually  need something beyond 100:1 to get that 
>> sort of performance. A lot depends on the noise involved. 
>> Some types of behavior simply don’t work well with the technique. 
>> 
>> The KS box goes from “better than” to “worse than” and back to “better than” 
>> most atomic standards you would compare it to over
>> a range of tau from 0.1 S to 1,000,000 seconds. To get the 1,000,000 second 
>> data accurately, you would need a 100,000,000 second
>> run. The simple answer there is that nobody has that kind of time or that 
>> reliable a setup. Even the three month run to get good
>> 100,000 second data is a challenge. None of that relates to three corner hat 
>> stuff, it’s just the confidence bars on ADEV. It gives
>> you another (say) 100:1 wait on top of the three corner stuff. 
>> 
>> Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>> >100 ns swing over a  24

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

The ionosphere is the culprit in terms of the daily swing. The swing is a 
function of the goodness of fit between the GPS broadcast data
and the ionosphere as it impacts the satellites you are using. There is no rime 
or reason to it beyond that. If you get “lucky” things don’t move 
much. If you live in exciting times, things move quite a bit. Unless you go to 
something like an L1/L2 receiver, the GPS module you use 
has little to do with it (unless it’s broke ….). Yes there are some fiddly 
little qualifiers relating to being at the north or south pole and GPS 
coverage (along with space weather impacts). Very few of us do our runs at 
either location :) Just for reference, the area of concern also has
at least one day each year where the sun sets for < 1 hours. 

Bob




> On Apr 17, 2017, at 11:33 AM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> Oh, I had completely forgotten about the many runs you gifted us with back 
> then.  Fortunately, I kept all of them in my email archive.  I can't compare 
> like for like, of course, but I think I can work up something that compares 
> at the larger taus where the 5370 doesn't dominate.
> 
> I'm going to run another long term test of my GFS unit against my PRS-45A.  
> The problem, the issue that made me ask for data is that everything from 
> phase plots to ADEV plots of my unit are just so much better than the KS.  In 
> addition, I don't see the large ionospheric swings on my GFS unit that you 
> and Bruce and others have spoken about.  This bothers me a lot.  Could it be 
> my location here in Houston?  Could it be the Ublox LEA-6T compared to the 
> much older Motorola in the KS?
> 
> Bob
>  
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net> 
> Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
> Sent: Monday, April 17, 2017 7:55 AM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> The data I have on the KS boxes was posted to the list back when they were.a 
> hot topic. I’m sure it is still in the archives.
> I’m guessing it’s not quite what you are after. 
> 
> The closer the devices are to each other the better the technique works. A 
> simple way to look at it is as an attenuation. If 
> it knocks noise down 10:1, the worst unit should be no more than 10X noise 
> than the best unit. How much things are knocked
> down is a function of the length of the runs compared to the longest tau. For 
> a 10:1 ratio of tau to run, attenuation of noise by 10:1
>  is very optimistic. You usually  need something beyond 100:1 to get that 
> sort of performance. A lot depends on the noise involved. 
> Some types of behavior simply don’t work well with the technique. 
> 
> The KS box goes from “better than” to “worse than” and back to “better than” 
> most atomic standards you would compare it to over
> a range of tau from 0.1 S to 1,000,000 seconds. To get the 1,000,000 second 
> data accurately, you would need a 100,000,000 second
> run. The simple answer there is that nobody has that kind of time or that 
> reliable a setup. Even the three month run to get good
> 100,000 second data is a challenge. None of that relates to three corner hat 
> stuff, it’s just the confidence bars on ADEV. It gives
> you another (say) 100:1 wait on top of the three corner stuff. 
> 
> Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
> >100 ns swing over a  24 hour period. Today 
> may or may not be the same as tomorrow. That’s with a “perfect” L1 setup. The 
> variation comes from the ionosphere and the fact that
> the GPS data does not allow you to fully correct for it.  In addition, you 
> will get some interesting bumps related to constellations and 
> your local antenna setup. Any GPSDO that is quartz based will happily follow 
> the 24 hour swing in the GPS from the ionosphere. At 
> 100,000 seconds, a 100 ns swing is 1x10^-12. That’s a lot of disruption. It 
> most certainly is not the sort of thing that ADEV expects 
> to pop up in the middle of a run. 
> 
> The simple answer to all this is “don’t go there”. Three corner hat is fine 
> for short term stuff. It’s a mess for long term runs. Getting data
> that is good enough for a long term ADEV run out of a three corner setup is a 
> major struggle. The time for the correlation to knock down
> the noise on top of the time to get good ADEV data gets you into 
> impractically long runs. 
> 
> Bob
> 
> 
> 
> 
>> On Apr 16, 2017, at 10:16 PM, Bob Stewart <b...@evoria.net 
>> <mailto:b...@evoria.net>> wrote:
>> 
>> Hi Bob,
>> 
>> OK, I give up.  Try as I might, I can't fudge things enough to make an

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
Oh, I had completely forgotten about the many runs you gifted us with back 
then.  Fortunately, I kept all of them in my email archive.  I can't compare 
like for like, of course, but I think I can work up something that compares at 
the larger taus where the 5370 doesn't dominate.
I'm going to run another long term test of my GFS unit against my PRS-45A.  The 
problem, the issue that made me ask for data is that everything from phase 
plots to ADEV plots of my unit are just so much better than the KS.  In 
addition, I don't see the large ionospheric swings on my GFS unit that you and 
Bruce and others have spoken about.  This bothers me a lot.  Could it be my 
location here in Houston?  Could it be the Ublox LEA-6T compared to the much 
older Motorola in the KS?

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net> 
Cc: Discussion of precise time and frequency measurement <time-nuts@febo.com>
 Sent: Monday, April 17, 2017 7:55 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi
The data I have on the KS boxes was posted to the list back when they were.a 
hot topic. I’m sure it is still in the archives.I’m guessing it’s not quite 
what you are after. 

The closer the devices are to each other the better the technique works. A 
simple way to look at it is as an attenuation. If it knocks noise down 10:1, 
the worst unit should be no more than 10X noise than the best unit. How much 
things are knockeddown is a function of the length of the runs compared to the 
longest tau. For a 10:1 ratio of tau to run, attenuation of noise by 10:1 is 
very optimistic. You usually  need something beyond 100:1 to get that sort of 
performance. A lot depends on the noise involved. Some types of behavior simply 
don’t work well with the technique. 
The KS box goes from “better than” to “worse than” and back to “better than” 
most atomic standards you would compare it to overa range of tau from 0.1 S to 
1,000,000 seconds. To get the 1,000,000 second data accurately, you would need 
a 100,000,000 secondrun. The simple answer there is that nobody has that kind 
of time or that reliable a setup. Even the three month run to get good100,000 
second data is a challenge. None of that relates to three corner hat stuff, 
it’s just the confidence bars on ADEV. It givesyou another (say) 100:1 wait on 
top of the three corner stuff. 
Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>100 ns swing over a  24 hour period. Today may or may not be the same as 
tomorrow. That’s with a “perfect” L1 setup. The variation comes from the 
ionosphere and the fact thatthe GPS data does not allow you to fully correct 
for it.  In addition, you will get some interesting bumps related to 
constellations and your local antenna setup. Any GPSDO that is quartz based 
will happily follow the 24 hour swing in the GPS from the ionosphere. At 
100,000 seconds, a 100 ns swing is 1x10^-12. That’s a lot of disruption. It 
most certainly is not the sort of thing that ADEV expects to pop up in the 
middle of a run. 
The simple answer to all this is “don’t go there”. Three corner hat is fine for 
short term stuff. It’s a mess for long term runs. Getting datathat is good 
enough for a long term ADEV run out of a three corner setup is a major 
struggle. The time for the correlation to knock downthe noise on top of the 
time to get good ADEV data gets you into impractically long runs. 
Bob




On Apr 16, 2017, at 10:16 PM, Bob Stewart <b...@evoria.net> wrote:
Hi Bob,
OK, I give up.  Try as I might, I can't fudge things enough to make any sense.  
I did run a set of 1 hour tests that seemed to confirm what I can infer from 
the phase plots in timelab, but anything longer than that and the curves either 
contradict the phase plots, or there are large gaps in at least one trace, or a 
trace is even missing entirely.  Oh well.  I seem to remember reading that the 
3c-hat was only useful in comparing similar devices.  The KS just isn't close 
enough to what I'm trying to compare it to, I guess.

If you or anyone else has an ADEV plot of the KS against some local standard 
(for any length of time, any standard, even just a bare OCXO that is not a 
Trimble 34310-T) could you please share it with me?  I'm looking for relative 
peformance, not a definitive test.  Of course if you also have one of a 34310-T 
against the same standard, that would be great!

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: John Miles <j...@miles.io>
 Sent: Thursday, April 13, 2017 7:19 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
  
Hi

There are a number of papers from the 70’s and 80’s digging into three corner 
hat data. The net result often
would turn out to be “less than zero” noise on one of the DUT’s. Since that’s 
physically impossi

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

The data I have on the KS boxes was posted to the list back when they were.a 
hot topic. I’m sure it is still in the archives.
I’m guessing it’s not quite what you are after. 

The closer the devices are to each other the better the technique works. A 
simple way to look at it is as an attenuation. If 
it knocks noise down 10:1, the worst unit should be no more than 10X noise than 
the best unit. How much things are knocked
down is a function of the length of the runs compared to the longest tau. For a 
10:1 ratio of tau to run, attenuation of noise by 10:1
 is very optimistic. You usually  need something beyond 100:1 to get that sort 
of performance. A lot depends on the noise involved. 
Some types of behavior simply don’t work well with the technique. 

The KS box goes from “better than” to “worse than” and back to “better than” 
most atomic standards you would compare it to over
a range of tau from 0.1 S to 1,000,000 seconds. To get the 1,000,000 second 
data accurately, you would need a 100,000,000 second
run. The simple answer there is that nobody has that kind of time or that 
reliable a setup. Even the three month run to get good
100,000 second data is a challenge. None of that relates to three corner hat 
stuff, it’s just the confidence bars on ADEV. It gives
you another (say) 100:1 wait on top of the three corner stuff. 

Now toss in the basics of GPS. Depending on the day, you will get <10 ns to  
>100 ns swing over a  24 hour period. Today 
may or may not be the same as tomorrow. That’s with a “perfect” L1 setup. The 
variation comes from the ionosphere and the fact that
the GPS data does not allow you to fully correct for it.  In addition, you will 
get some interesting bumps related to constellations and 
your local antenna setup. Any GPSDO that is quartz based will happily follow 
the 24 hour swing in the GPS from the ionosphere. At 
100,000 seconds, a 100 ns swing is 1x10^-12. That’s a lot of disruption. It 
most certainly is not the sort of thing that ADEV expects 
to pop up in the middle of a run. 

The simple answer to all this is “don’t go there”. Three corner hat is fine for 
short term stuff. It’s a mess for long term runs. Getting data
that is good enough for a long term ADEV run out of a three corner setup is a 
major struggle. The time for the correlation to knock down
the noise on top of the time to get good ADEV data gets you into impractically 
long runs. 

Bob




> On Apr 16, 2017, at 10:16 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi Bob,
> 
> OK, I give up.  Try as I might, I can't fudge things enough to make any 
> sense.  I did run a set of 1 hour tests that seemed to confirm what I can 
> infer from the phase plots in timelab, but anything longer than that and the 
> curves either contradict the phase plots, or there are large gaps in at least 
> one trace, or a trace is even missing entirely.  Oh well.  I seem to remember 
> reading that the 3c-hat was only useful in comparing similar devices.  The KS 
> just isn't close enough to what I'm trying to compare it to, I guess.
> 
> If you or anyone else has an ADEV plot of the KS against some local standard 
> (for any length of time, any standard, even just a bare OCXO that is not a 
> Trimble 34310-T) could you please share it with me?  I'm looking for relative 
> peformance, not a definitive test.  Of course if you also have one of a 
> 34310-T against the same standard, that would be great!
> 
> Bob
>  
> 
> 
> From: Bob kb8tq <kb...@n1k.org>
> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
> measurement <time-nuts@febo.com> 
> Cc: John Miles <j...@miles.io>
> Sent: Thursday, April 13, 2017 7:19 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Hi
> 
> There are a number of papers from the 70’s and 80’s digging into three corner 
> hat data. The net result often
> would turn out to be “less than zero” noise on one of the DUT’s. Since that’s 
> physically impossible the technique
> got a bit of “attention”.  The Cliff Notes version of the results is that 
> simultaneous measurements were the key
> to getting decent results. The closer to “same time” (as in microseconds or 
> nanoseconds) the better. Even with very careful 
> data collection, odd things can still happen. Phase noise pops up at crazy 
> low levels or ADEV goes to bizarre
> numbers. In many ways a TimePod (or other ADC based setup) is ideal for 
> getting the data synchronized. Running
> all three devices on one is by far the best way I have seen to make the 
> technique work. It still can have problems, 
> but less so that other ways of doing it. 
> 
> Bob
> 
> 
> 
> > On Apr 13, 2017, at 7:16 PM, Bob Stewart <b...@evoria.net 
> > <mailto:b...@evoria.net>> wrote:
> > 
> &g

Re: [time-nuts] Three-cornered hat on timelab?

[Magnus Danielson]

Hi,

This problem have since been addressed by Francois Vernotte as I saw in 
a presentation last year. He addressed the issue somewhat different than 
the traditional calculations to achieve the same problem.

Turns out that correlation eats your noise if I recall things right.

Cheers,
Magnus

On 04/14/2017 02:19 AM, Bob kb8tq wrote:

Hi

There are a number of papers from the 70’s and 80’s digging into three corner 
hat data. The net result often
would turn out to be “less than zero” noise on one of the DUT’s. Since that’s 
physically impossible the technique
got a bit of “attention”.  The Cliff Notes version of the results is that 
simultaneous measurements were the key
to getting decent results. The closer to “same time” (as in microseconds or 
nanoseconds) the better. Even with very careful
data collection, odd things can still happen. Phase noise pops up at crazy low 
levels or ADEV goes to bizarre
numbers. In many ways a TimePod (or other ADC based setup) is ideal for getting 
the data synchronized. Running
all three devices on one is by far the best way I have seen to make the 
technique work. It still can have problems,
but less so that other ways of doing it.

Bob




On Apr 13, 2017, at 7:16 PM, Bob Stewart <b...@evoria.net> wrote:

Hi John,
I had a chance to think about this some more after I pressed the send key.  The 
ionospheric effects are certainly going to be different if the distance in time 
between tests is large.  And, of course, there is the fact that the KS has a 
pretty old receiver compared the Ublox I use, so that even the reaction to the 
ionosphere is likely to be different.  So, I thought I'd experiment with some 
runs with both GPSDOs in holdover to see if that would even the score, so to 
speak.  Of course then I have the temperature variable, so it's never going to 
be perfect.
Anyway, thanks for the help.  If I get anything that seems useful out of this, 
I'll post links to the data.
Bob

 From: John Miles <j...@miles.io>
To: 'Discussion of precise time and frequency measurement' <time-nuts@febo.com>
Sent: Thursday, April 13, 2017 6:01 PM
Subject: Re: [time-nuts] Three-cornered hat on timelab?

Longer runs would be better to the extent that they give you smaller error bars 
in your tau range of interest, certainly.  But any effects that influence one 
of your runs but not the others will render the 3-cornered hat solution 
questionable, if not outright invalid.  Only through many repeated runs can you 
learn to tell the bogus data from the good stuff.  So I'd make shorter runs at 
first, until you're sure you know what you're looking at.



It doesn't matter which source is applied to the start versus stop channel, as 
long as the assignments are consistent with the source labels you apply.  I 
would use frequency-count mode to simplify things, at least at first.  This is 
already a very challenging measurement for all the reasons mentioned.



-- john, KE5FX

Miles Design LLC





From: Bob Stewart [mailto:b...@evoria.net]
Sent: Thursday, April 13, 2017 8:41 AM
To: Discussion of precise time and frequency measurement; John Miles
Subject: Re: [time-nuts] Three-cornered hat on timelab?



Hi John,



Thanks!  With lesser equipment, such as the 5370A, would longer runs be better? 
 I used a set of 1 hr runs and the result wasn't quite what I had expected.  
However, it may be that I had mislabeled the files, and thus got the sources 
confused.  Of course, it may be that the ionospheric effect was grossly 
different between the three tests.  So, with a 5370, Source A would be the 
START input and Source B would be the STOP input, right?  For my testing, the 
sources are all 10MHz signals, and I'm driving the EXT input with 1PPS from a 
GPSDO.





Bob

___
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.


___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi Bob,
OK, I give up.  Try as I might, I can't fudge things enough to make any sense.  
I did run a set of 1 hour tests that seemed to confirm what I can infer from 
the phase plots in timelab, but anything longer than that and the curves either 
contradict the phase plots, or there are large gaps in at least one trace, or a 
trace is even missing entirely.  Oh well.  I seem to remember reading that the 
3c-hat was only useful in comparing similar devices.  The KS just isn't close 
enough to what I'm trying to compare it to, I guess.

If you or anyone else has an ADEV plot of the KS against some local standard 
(for any length of time, any standard, even just a bare OCXO that is not a 
Trimble 34310-T) could you please share it with me?  I'm looking for relative 
peformance, not a definitive test.  Of course if you also have one of a 34310-T 
against the same standard, that would be great!

Bob 

  From: Bob kb8tq <kb...@n1k.org>
 To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency 
measurement <time-nuts@febo.com> 
Cc: John Miles <j...@miles.io>
 Sent: Thursday, April 13, 2017 7:19 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Hi

There are a number of papers from the 70’s and 80’s digging into three corner 
hat data. The net result often
would turn out to be “less than zero” noise on one of the DUT’s. Since that’s 
physically impossible the technique
got a bit of “attention”.  The Cliff Notes version of the results is that 
simultaneous measurements were the key
to getting decent results. The closer to “same time” (as in microseconds or 
nanoseconds) the better. Even with very careful 
data collection, odd things can still happen. Phase noise pops up at crazy low 
levels or ADEV goes to bizarre
numbers. In many ways a TimePod (or other ADC based setup) is ideal for getting 
the data synchronized. Running
all three devices on one is by far the best way I have seen to make the 
technique work. It still can have problems, 
but less so that other ways of doing it. 

Bob



> On Apr 13, 2017, at 7:16 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi John,
> I had a chance to think about this some more after I pressed the send key.  
> The ionospheric effects are certainly going to be different if the distance 
> in time between tests is large.  And, of course, there is the fact that the 
> KS has a pretty old receiver compared the Ublox I use, so that even the 
> reaction to the ionosphere is likely to be different.  So, I thought I'd 
> experiment with some runs with both GPSDOs in holdover to see if that would 
> even the score, so to speak.  Of course then I have the temperature variable, 
> so it's never going to be perfect.
> Anyway, thanks for the help.  If I get anything that seems useful out of 
> this, I'll post links to the data.
> Bob 
> 
>      From: John Miles <j...@miles.io>
> To: 'Discussion of precise time and frequency measurement' 
> <time-nuts@febo.com> 
> Sent: Thursday, April 13, 2017 6:01 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Longer runs would be better to the extent that they give you smaller error 
> bars in your tau range of interest, certainly.  But any effects that 
> influence one of your runs but not the others will render the 3-cornered hat 
> solution questionable, if not outright invalid.  Only through many repeated 
> runs can you learn to tell the bogus data from the good stuff.  So I'd make 
> shorter runs at first, until you're sure you know what you're looking at.
> 
> 
> 
> It doesn't matter which source is applied to the start versus stop channel, 
> as long as the assignments are consistent with the source labels you apply.  
> I would use frequency-count mode to simplify things, at least at first.  This 
> is already a very challenging measurement for all the reasons mentioned. 
> 
> 
> 
> -- john, KE5FX
> 
> Miles Design LLC
> 
> 
> 
> 
> 
> From: Bob Stewart [mailto:b...@evoria.net] 
> Sent: Thursday, April 13, 2017 8:41 AM
> To: Discussion of precise time and frequency measurement; John Miles
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> 
> 
> Hi John,
> 
> 
> 
> Thanks!  With lesser equipment, such as the 5370A, would longer runs be 
> better?  I used a set of 1 hr runs and the result wasn't quite what I had 
> expected.  However, it may be that I had mislabeled the files, and thus got 
> the sources confused.  Of course, it may be that the ionospheric effect was 
> grossly different between the three tests.  So, with a 5370, Source A would 
> be the START input and Source B would be the STOP input, right?  For my 
> testing, the sources are all 10MHz signals, and I'm driving the EXT input 
> with 1PPS from a GPSD

Re: [time-nuts] Three-cornered hat on timelab?

[Bob kb8tq]

Hi

There are a number of papers from the 70’s and 80’s digging into three corner 
hat data. The net result often
would turn out to be “less than zero” noise on one of the DUT’s. Since that’s 
physically impossible the technique
got a bit of “attention”.  The Cliff Notes version of the results is that 
simultaneous measurements were the key
to getting decent results. The closer to “same time” (as in microseconds or 
nanoseconds) the better. Even with very careful 
data collection, odd things can still happen. Phase noise pops up at crazy low 
levels or ADEV goes to bizarre
numbers. In many ways a TimePod (or other ADC based setup) is ideal for getting 
the data synchronized. Running
all three devices on one is by far the best way I have seen to make the 
technique work. It still can have problems, 
but less so that other ways of doing it. 

Bob



> On Apr 13, 2017, at 7:16 PM, Bob Stewart <b...@evoria.net> wrote:
> 
> Hi John,
> I had a chance to think about this some more after I pressed the send key.  
> The ionospheric effects are certainly going to be different if the distance 
> in time between tests is large.  And, of course, there is the fact that the 
> KS has a pretty old receiver compared the Ublox I use, so that even the 
> reaction to the ionosphere is likely to be different.  So, I thought I'd 
> experiment with some runs with both GPSDOs in holdover to see if that would 
> even the score, so to speak.  Of course then I have the temperature variable, 
> so it's never going to be perfect.
> Anyway, thanks for the help.  If I get anything that seems useful out of 
> this, I'll post links to the data.
> Bob 
> 
>  From: John Miles <j...@miles.io>
> To: 'Discussion of precise time and frequency measurement' 
> <time-nuts@febo.com> 
> Sent: Thursday, April 13, 2017 6:01 PM
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> Longer runs would be better to the extent that they give you smaller error 
> bars in your tau range of interest, certainly.  But any effects that 
> influence one of your runs but not the others will render the 3-cornered hat 
> solution questionable, if not outright invalid.  Only through many repeated 
> runs can you learn to tell the bogus data from the good stuff.  So I'd make 
> shorter runs at first, until you're sure you know what you're looking at.
> 
> 
> 
> It doesn't matter which source is applied to the start versus stop channel, 
> as long as the assignments are consistent with the source labels you apply.  
> I would use frequency-count mode to simplify things, at least at first.  This 
> is already a very challenging measurement for all the reasons mentioned. 
> 
> 
> 
> -- john, KE5FX
> 
> Miles Design LLC
> 
> 
> 
> 
> 
> From: Bob Stewart [mailto:b...@evoria.net] 
> Sent: Thursday, April 13, 2017 8:41 AM
> To: Discussion of precise time and frequency measurement; John Miles
> Subject: Re: [time-nuts] Three-cornered hat on timelab?
> 
> 
> 
> Hi John,
> 
> 
> 
> Thanks!  With lesser equipment, such as the 5370A, would longer runs be 
> better?  I used a set of 1 hr runs and the result wasn't quite what I had 
> expected.  However, it may be that I had mislabeled the files, and thus got 
> the sources confused.  Of course, it may be that the ionospheric effect was 
> grossly different between the three tests.  So, with a 5370, Source A would 
> be the START input and Source B would be the STOP input, right?  For my 
> testing, the sources are all 10MHz signals, and I'm driving the EXT input 
> with 1PPS from a GPSDO.
> 
> 
> 
> 
> 
> Bob 
> 
> ___
> 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.

___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi John,
I had a chance to think about this some more after I pressed the send key.  The 
ionospheric effects are certainly going to be different if the distance in time 
between tests is large.  And, of course, there is the fact that the KS has a 
pretty old receiver compared the Ublox I use, so that even the reaction to the 
ionosphere is likely to be different.  So, I thought I'd experiment with some 
runs with both GPSDOs in holdover to see if that would even the score, so to 
speak.  Of course then I have the temperature variable, so it's never going to 
be perfect.
Anyway, thanks for the help.  If I get anything that seems useful out of this, 
I'll post links to the data.
Bob 

  From: John Miles <j...@miles.io>
 To: 'Discussion of precise time and frequency measurement' 
<time-nuts@febo.com> 
 Sent: Thursday, April 13, 2017 6:01 PM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
Longer runs would be better to the extent that they give you smaller error bars 
in your tau range of interest, certainly.  But any effects that influence one 
of your runs but not the others will render the 3-cornered hat solution 
questionable, if not outright invalid.  Only through many repeated runs can you 
learn to tell the bogus data from the good stuff.  So I'd make shorter runs at 
first, until you're sure you know what you're looking at.

 

It doesn't matter which source is applied to the start versus stop channel, as 
long as the assignments are consistent with the source labels you apply.  I 
would use frequency-count mode to simplify things, at least at first.  This is 
already a very challenging measurement for all the reasons mentioned. 

 

-- john, KE5FX

Miles Design LLC

 

 

From: Bob Stewart [mailto:b...@evoria.net] 
Sent: Thursday, April 13, 2017 8:41 AM
To: Discussion of precise time and frequency measurement; John Miles
Subject: Re: [time-nuts] Three-cornered hat on timelab?

 

Hi John,

 

Thanks!  With lesser equipment, such as the 5370A, would longer runs be better? 
 I used a set of 1 hr runs and the result wasn't quite what I had expected.  
However, it may be that I had mislabeled the files, and thus got the sources 
confused.  Of course, it may be that the ionospheric effect was grossly 
different between the three tests.  So, with a 5370, Source A would be the 
START input and Source B would be the STOP input, right?  For my testing, the 
sources are all 10MHz signals, and I'm driving the EXT input with 1PPS from a 
GPSDO.



 

Bob 

___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[John Miles]

Longer runs would be better to the extent that they give you smaller error bars 
in your tau range of interest, certainly.  But any effects that influence one 
of your runs but not the others will render the 3-cornered hat solution 
questionable, if not outright invalid.  Only through many repeated runs can you 
learn to tell the bogus data from the good stuff.  So I'd make shorter runs at 
first, until you're sure you know what you're looking at.

 

It doesn't matter which source is applied to the start versus stop channel, as 
long as the assignments are consistent with the source labels you apply.  I 
would use frequency-count mode to simplify things, at least at first.  This is 
already a very challenging measurement for all the reasons mentioned. 

 

-- john, KE5FX

Miles Design LLC

 

 

From: Bob Stewart [mailto:b...@evoria.net] 
Sent: Thursday, April 13, 2017 8:41 AM
To: Discussion of precise time and frequency measurement; John Miles
Subject: Re: [time-nuts] Three-cornered hat on timelab?

 

Hi John,

 

Thanks!  With lesser equipment, such as the 5370A, would longer runs be better? 
 I used a set of 1 hr runs and the result wasn't quite what I had expected.  
However, it may be that I had mislabeled the files, and thus got the sources 
confused.  Of course, it may be that the ionospheric effect was grossly 
different between the three tests.  So, with a 5370, Source A would be the 
START input and Source B would be the STOP input, right?  For my testing, the 
sources are all 10MHz signals, and I'm driving the EXT input with 1PPS from a 
GPSDO.



 

Bob 

___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[Bob Stewart]

Hi John,
Thanks!  With lesser equipment, such as the 5370A, would longer runs be better? 
 I used a set of 1 hr runs and the result wasn't quite what I had expected.  
However, it may be that I had mislabeled the files, and thus got the sources 
confused.  Of course, it may be that the ionospheric effect was grossly 
different between the three tests.  So, with a 5370, Source A would be the 
START input and Source B would be the STOP input, right?  For my testing, the 
sources are all 10MHz signals, and I'm driving the EXT input with 1PPS from a 
GPSDO.

Bob 


  From: John Miles <j...@miles.io>
 To: 'Discussion of precise time and frequency measurement' 
<time-nuts@febo.com> 
 Sent: Thursday, April 13, 2017 1:07 AM
 Subject: Re: [time-nuts] Three-cornered hat on timelab?
   
> It was mentioned that Timelab can do a three-cornered hat.  I can't find it.  
> Is
> this something that can only be done with multiple Timepods connected, or
> is there an option that I'm missing?  Or is there some other tool that needs
> to be used?  For the record, I want to create the 3c-hat from data that was
> run at different times, and I understand (at least somewhat) the
> shortcomings of doing that.  But, it would be interesting to see what would
> result.  And, not having three 5370s in good condition, it's the best I can 
> do.

Hi, Bob --

N-cornered hat measurement is a beta feature, not in the docs yet.  A single 
TimePod can generate the required three plots simultaneously, but you can use 
individual plots from TICs and frequency counters as long as you start with 
highly-reproducible measurements and are careful with your interpretation of 
the results.  If your setup returns inconsistent results from one run to the 
next, then any attempt at a separated-variance plot will be GIGO.

You can see some examples at http://www.ke5fx.com/gpscomp.htm .  Various 
finicky conditions need to be met before the 3-cornered hat display will become 
available; check out 
https://www.febo.com/pipermail/time-nuts/2015-September/094039.html for some 
tips.  

-- john, KE5FX
Miles Design LLC


___
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.

Re: [time-nuts] Three-cornered hat on timelab?

[John Miles]

> It was mentioned that Timelab can do a three-cornered hat.  I can't find it.  
> Is
> this something that can only be done with multiple Timepods connected, or
> is there an option that I'm missing?  Or is there some other tool that needs
> to be used?  For the record, I want to create the 3c-hat from data that was
> run at different times, and I understand (at least somewhat) the
> shortcomings of doing that.  But, it would be interesting to see what would
> result.  And, not having three 5370s in good condition, it's the best I can 
> do.

Hi, Bob --

N-cornered hat measurement is a beta feature, not in the docs yet.  A single 
TimePod can generate the required three plots simultaneously, but you can use 
individual plots from TICs and frequency counters as long as you start with 
highly-reproducible measurements and are careful with your interpretation of 
the results.  If your setup returns inconsistent results from one run to the 
next, then any attempt at a separated-variance plot will be GIGO.

You can see some examples at http://www.ke5fx.com/gpscomp.htm .   Various 
finicky conditions need to be met before the 3-cornered hat display will become 
available; check out 
https://www.febo.com/pipermail/time-nuts/2015-September/094039.html for some 
tips.  

-- john, KE5FX
Miles Design LLC


___
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] Three-cornered hat on timelab?

[Bob Stewart]

It was mentioned that Timelab can do a three-cornered hat.  I can't find it.  
Is this something that can only be done with multiple Timepods connected, or is 
there an option that I'm missing?  Or is there some other tool that needs to be 
used?  For the record, I want to create the 3c-hat from data that was run at 
different times, and I understand (at least somewhat) the shortcomings of doing 
that.  But, it would be interesting to see what would result.  And, not having 
three 5370s in good condition, it's the best I can do.

Bob 

-
AE6RV.com

GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
___
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.