Re: [time-nuts] Time-nut going England!

[Eric Scace]

Do not neglect a visit to the Clockworks  museum. 
Examples of the most accurate pendulum clocks ever put into production e.g., 
(LeRoy, Riefler, Shortt-Synchronome and Fedchenko) are among the collection 
there. Free — and the staff are very friendly and extremely knowledgable.

— Eric

> On 2017 Apr 27, at 05:10 , Tony Finch  wrote:
> 
> Clint Jay  wrote:
> 
>> Greenwich as recommended by others is a must, the science museum is also a
>> good way to spend a day.
> 
> Look for the clock and watch gallery in the Science Museum, lots of great
> devices from the collection of the Worshipful Company of Clockmakers.
> http://www.clockmakers.org/the-clockmakers-museum-library/the-clockmakers-museum-library/
> http://www.sciencemuseum.org.uk/visitmuseum/Plan_your_visit/exhibitions/clockmakers-museum?keywords=clockmakers
> 
> And the British Horological Institute has a museum too (very limited
> opening hours, tho) http://bhi.co.uk/museum/the-bhi-museum-trust/
> 
> Tony.
> --
> f.anthony.n.finch    http://dotat.at/  -  I xn--zr8h punycode
> Fisher: Cyclonic becoming north 4 or 5, occasionally 6 at first. Moderate.
> Rain then showers. Moderate or good.
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Re: [time-nuts] TAPR Oncore M12+ kit

[Art Sepin]

Folks,

The TAPR GPS Kit documentation has been updated and revised for clarity (I 
hope). it includes details for purchasing end plates and also dimensions 
required to fabricate end plates. The TAPR GPS Kit document, and a motherboard 
schematic for reference, is now available on Synergy's "GPS for Scholars" page:
http://www.synergy-gps.com/index.php?option=com_content=view=54=73

Art 

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gregory Beat
Sent: Tuesday, March 28, 2017 11:48 AM
To: Larry McDavid ; time-nuts@febo.com
Subject: Re: [time-nuts] TAPR Oncore M12+ kit

Larry -

Interface Boards for Motorola (and Garmin) receivers have been discussed (and 
sold) by TAPR since late 1990s.  TAPR archives all of this documentation, for 
discontinued GPS kits, can be seen on the left margin.
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tapr.org%2Fgps_exp-kit.html=01%7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=5ruapgEiQudgnwP07FQuZd1RF2r23b0YTZnMagdcLkI%3D=0

Tom Clark, W3IWI Total Accurate Clock (TAC) project (1996) covers the entire 
topic.
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tapr.org%2Fkits_tac2.html=01%7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=2ddW07UU31UDl5%2FQTy2DspkkX11FX00qrmKfc%2BRnNLw%3D=0

Simple interface board schematics (Serial Level converters, and voltage 
adjustments for external antennas/ 3.3 or 5 V) can be found throughout the 
Internet since mid-1990s.
Numerous radio amateurs DIY their own (breadboard) or sold small interfaces at 
hamfests (1996-2006), until newer GPS solutions became surplus (and smartphones 
with built-in GPS appeared after 2007).

Doug McKinney, KC3RL (SK, December 2006) offered interface boards for the 
Garmin (GPS-25) and Motorola receivers until about 2005.  I have one of Doug's 
boards in my GPS parts box.  These were sold by TAPR until their inventory was 
exhausted.
--
Garmin
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tapr.org%2Fgps_garminib.html=01%7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=1rtHBUexr2FVGuHKY2qxBhzriCuFREe%2F6NAS7gi9RNY%3D=0
Motorola
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tapr.org%2Fgps_vpib.html=01%7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=R5%2FyBXV%2BAV2%2Fi3e%2BKfPlua5PKMhRqrbUwhIMPrbiArQ%3D=0

Synergy M12-MB board (web link to photo [jpg] below) IF you look closely at the 
Synergy Board, you see the board outline and 2x5 (10-pin) header for the 
earlier 8-channel Motorola receivers
https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.tapr.org%2Fimages%2FM12-MB.jpg=01%7C01%7Cart%40synergy-gps.com%7C4dc2f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1=VnOToRye%2Be6pu62p6Os1ohPVVa%2FzDEFh1%2F0vo%2Fi5ag4%3D=0

greg
w9gb

Sent from iPad Air

> On Mar 28, 2017, at 12:18 PM, Larry McDavid  wrote:
> 
> What "OEM supplier?" Do you mean from Synergy Systems? Or, is there an 
> enclosure supplier to Synergy?
> 
> Do you know if there is a schematic of the Synergy interface board available?
> 
> Larry W6FUB
> 
>> On 3/27/2017 9:31 AM, Gregory Beat wrote:
>> The TAPR offering is a "partial kit" from the Synergy's SynPaQ/E product.
>> Here is that data sheet:
>> https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.s
>> ynergy-gps.com%2Fimages%2Fstories%2Fpdf%2Fsynpaq%2520product%2520data
>> %2520sheet%2520040110.pdf=01%7C01%7Cart%40synergy-gps.com%7C4dc2
>> f4b8f72f4e2fc73108d47615ead3%7Cc81f9fdec0e04d8c95779afaa0cad9ed%7C1
>> data=WF1IWYKvN5q6C0WMToPljgax2dpKhBqLxTAyhvKrYzw%3D=0
>> Blank aluminum end-plates can be fabricated, or purchased from the OEM 
>> supplier.
>> 
>> w9gb
> --
> Best wishes,
> 
> Larry McDavid W6FUB
> Anaheim, California  (SE of Los Angeles, near Disneyland)
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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


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

[Bob kb8tq]

Hi


> On Apr 27, 2017, at 6:10 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?

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 
> 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 
>>   To: Bob Stewart ; Discussion of precise time and 
>> frequency measurement 
>> Cc: Magnus Danielson 
>>   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.
> ___
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> and follow the instructions there.
> 
> 
> 
> 

[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.
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[time-nuts] XL microwave model 3401

[Bill]

Hi,

I am looking for a service manual for XL Microwave Model 3401 Frequency Counter.
Please advise if you have one for sale or one I could dowmload.

Bill Reed

br...@otelco.net


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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 
 To: Bob Stewart  
Cc: Discussion of precise time and frequency measurement 
 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  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 

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 
 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 
>  To: Bob Stewart ; Discussion of precise time and frequency 
>measurement 
> Cc: Magnus Danielson 
>  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.
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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 
 To: Bob Stewart ; Discussion of precise time and frequency 
measurement 
Cc: Magnus Danielson 
 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.

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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  . A bit about what 
to watch for: 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 


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  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 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> Cc: Magnus Danielson 
> 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
> 

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 
 To: Bob Stewart ; Discussion of precise time and frequency 
measurement  
Cc: Magnus Danielson 
 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  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 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> 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
> 
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To 

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  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 
> To: Bob Stewart ; Discussion of precise time and frequency 
> measurement  
> 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
> 
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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 
 To: Bob Stewart ; Discussion of precise time and frequency 
measurement  
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

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Re: [time-nuts] Time-nut going England!

[Tom Leedy via time-nuts]

Hi:
 
A very worthwhile, and often overlooked, museum is located at The  
Worshipful Company of Clockmakers
(1 Throgmorton Avenue, London EC2N 2BY,  Telephone: 020 7998 8120).  It is 
not very large, but has some unusual  objects including many of the tools 
that were used in making clocks.  Their  Web site is: 
http://www.clockmakers.org/ 
 
Tom Leedy
Clarksburg, MD
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Re: [time-nuts] Time-nut going England!

[John Lofgren]

Seconded.  Did both last August and it was great.  The amount of restored 
hardware that's operational is impressive and docents are knowledgeable.
If you get to the computing museum, having a chat with whoever is in the 
Colossus gallery is worth your time.

Admission to BP is £17.75 and the Computing Museum is £7.50.  Both are well 
worth the admission price plus the train ride.

Cheers,
John

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Clint Jay
Sent: Thursday, April 27, 2017 6:16 AM
To: Discussion of precise time and frequency measurement ; 
Dave B 
Subject: Re: [time-nuts] Time-nut going England!

Yes, Bletchley is a good day out but be aware the national museum of computing 
is a separate entity and has its own entry fee.

On 27 Apr 2017 12:00 pm, "Dave B via time-nuts"  wrote:

> On 26/04/17 17:00, time-nuts-requ...@febo.com wrote:
>
> > Message: 12
> > Date: Wed, 26 Apr 2017 15:05:52 +0200
> > From: Attila Kinali 
> > To: time-nuts@febo.com
> > Subject: [time-nuts] Time-nut going England!
> > Message-ID: <20170426150552.93c33e4cbe356663386bb...@kinali.ch>
> > Content-Type: text/plain; charset=US-ASCII
> >
> > Hi
> >
> > I'll be in the UK for three weeks and will have a "free" week 
> > between 13th and 20th of May. I will most probably be around the 
> > London area and maybe spend a day or two in Southampton.
> >
> > If someone wants to meet for a beer or cup of hot chocolate, or 
> > knows of time-nutty things to do, please let me know.
> >
> > I would also appreciate if someone knows an affordable place to stay 
> > at in London, so that it doesn't strain the purse of this poor 
> > student too much.
> >
> >   Attila Kinali
>
> --
> -- Not exactly "TN" material, but you'd find this an interesting day 
> out.
>
> https://www.bletchleypark.org.uk/
>
> Get an off peak return rail ticket from Euston to Bletchley, it's a 
> short walk from the rail station.
>
> The National museum of computing (and other special interests) are 
> there too.
>
> Else the various museums in London will more than keep you occupied!
>
> Regards.
>
> Dave B, not that far from BP, but no idea what I'll be doing the time 
> you plan to be in the UK. "Domestic Management" has not told me the 
> plans for that far ahead yet!  :)
>
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> the instructions there.
>
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Re: [time-nuts] Frequency counter questions

[Bob kb8tq]

Hi

Single mixer into a computing counter was the way this stuff was done for a
*lot* of years. The sort of resolution you needed a fancy counter for back in 
1969 is well within the F7 board’s capabilities. What you get for resolution
is often less of an issue than the accuracy of the readings. (= you can get a 
lot 
of digits ).  We certainly did ADEV work into the parts in 10^-13 range (one 
second tau)  
with single mixer systems for a lot of years. No fancy (today) state of the art 
limiters involved …Cheap setups to run thousands of oscillators through. 

Bob

> On Apr 26, 2017, at 7:10 PM, Bert Kehren via time-nuts  
> wrote:
> 
> We do it and get at 1 sec 1 E-13 resolution and 1 E-12 accuracy for the  
> work we do. 
> Bert Kehren
> 
> 
> In a message dated 4/26/2017 3:00:54 P.M. Eastern Daylight Time,  
> alw.k...@gmail.com writes:
> 
> I am  surprised that no one has mentioned the idea of heterodyning a
> known  frequency with the unknown to measure the unknown. I use a
> Minicircuits  doubly balanced mixer fed on one port from a PTS160
> synthesizer that is  locked to 10 mhz. from a TrueTime xl-ak GPS locked
> receiver. The second  port is fed by the unknown though an attenuator.
> The third port of the  mixer gives me the sum and difference. If the
> difference is an audio note  then a cheep but frequency locked counter
> will read out the difference or  measure the period of the beat note
> which can be added to the frequency of  the synthesizer. A program such
> as Lady Heather can also be used to  determine the audio frequency to
> much less then sub-cycle accuracy. The  only fly in the ointment is
> figuring out which side of the unknown the  synthesizer is set to.
> 
> Alternatively, the PTS160 with 0.1 cycle control  can be set to nearly
> zero beat with the unknown. Then watching either  lissajous or dual
> trace scope patterns and timing the beat notes one can  get the unknown
> frequency very close.
> 
> Al, retired, mostly
> AKA  k9si
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Re: [time-nuts] Time-nut going England!

[Clint Jay]

Yes, Bletchley is a good day out but be aware the national museum of
computing is a separate entity and has its own entry fee.

On 27 Apr 2017 12:00 pm, "Dave B via time-nuts"  wrote:

> On 26/04/17 17:00, time-nuts-requ...@febo.com wrote:
>
> > Message: 12
> > Date: Wed, 26 Apr 2017 15:05:52 +0200
> > From: Attila Kinali 
> > To: time-nuts@febo.com
> > Subject: [time-nuts] Time-nut going England!
> > Message-ID: <20170426150552.93c33e4cbe356663386bb...@kinali.ch>
> > Content-Type: text/plain; charset=US-ASCII
> >
> > Hi
> >
> > I'll be in the UK for three weeks and will have a "free" week
> > between 13th and 20th of May. I will most probably be around
> > the London area and maybe spend a day or two in Southampton.
> >
> > If someone wants to meet for a beer or cup of hot chocolate,
> > or knows of time-nutty things to do, please let me know.
> >
> > I would also appreciate if someone knows an affordable place
> > to stay at in London, so that it doesn't strain the purse
> > of this poor student too much.
> >
> >   Attila Kinali
>
> 
> Not exactly "TN" material, but you'd find this an interesting day out.
>
> https://www.bletchleypark.org.uk/
>
> Get an off peak return rail ticket from Euston to Bletchley, it's a
> short walk from the rail station.
>
> The National museum of computing (and other special interests) are there
> too.
>
> Else the various museums in London will more than keep you occupied!
>
> Regards.
>
> Dave B, not that far from BP, but no idea what I'll be doing the time
> you plan to be in the UK. "Domestic Management" has not told me the
> plans for that far ahead yet!  :)
>
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> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
>
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[time-nuts] Time-nut going England!

[Dave B via time-nuts]

On 26/04/17 17:00, time-nuts-requ...@febo.com wrote:

> Message: 12
> Date: Wed, 26 Apr 2017 15:05:52 +0200
> From: Attila Kinali 
> To: time-nuts@febo.com
> Subject: [time-nuts] Time-nut going England!
> Message-ID: <20170426150552.93c33e4cbe356663386bb...@kinali.ch>
> Content-Type: text/plain; charset=US-ASCII
>
> Hi
>
> I'll be in the UK for three weeks and will have a "free" week
> between 13th and 20th of May. I will most probably be around
> the London area and maybe spend a day or two in Southampton.
>
> If someone wants to meet for a beer or cup of hot chocolate,
> or knows of time-nutty things to do, please let me know.
>
> I would also appreciate if someone knows an affordable place
> to stay at in London, so that it doesn't strain the purse
> of this poor student too much.
>
>   Attila Kinali


Not exactly "TN" material, but you'd find this an interesting day out.

https://www.bletchleypark.org.uk/

Get an off peak return rail ticket from Euston to Bletchley, it's a
short walk from the rail station.

The National museum of computing (and other special interests) are there
too.

Else the various museums in London will more than keep you occupied!

Regards.

Dave B, not that far from BP, but no idea what I'll be doing the time
you plan to be in the UK. "Domestic Management" has not told me the
plans for that far ahead yet!  :)

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Re: [time-nuts] Frequency counter questions

[Bert Kehren via time-nuts]

We do it and get at 1 sec 1 E-13 resolution and 1 E-12 accuracy for the  
work we do. 
Bert Kehren
 
 
In a message dated 4/26/2017 3:00:54 P.M. Eastern Daylight Time,  
alw.k...@gmail.com writes:

I am  surprised that no one has mentioned the idea of heterodyning a
known  frequency with the unknown to measure the unknown. I use a
Minicircuits  doubly balanced mixer fed on one port from a PTS160
synthesizer that is  locked to 10 mhz. from a TrueTime xl-ak GPS locked
receiver. The second  port is fed by the unknown though an attenuator.
The third port of the  mixer gives me the sum and difference. If the
difference is an audio note  then a cheep but frequency locked counter
will read out the difference or  measure the period of the beat note
which can be added to the frequency of  the synthesizer. A program such
as Lady Heather can also be used to  determine the audio frequency to
much less then sub-cycle accuracy. The  only fly in the ointment is
figuring out which side of the unknown the  synthesizer is set to.

Alternatively, the PTS160 with 0.1 cycle control  can be set to nearly
zero beat with the unknown. Then watching either  lissajous or dual
trace scope patterns and timing the beat notes one can  get the unknown
frequency very close.

Al, retired, mostly
AKA  k9si
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Re: [time-nuts] Time-nut going England!

[Tony Finch]

Clint Jay  wrote:

> Greenwich as recommended by others is a must, the science museum is also a
> good way to spend a day.

Look for the clock and watch gallery in the Science Museum, lots of great
devices from the collection of the Worshipful Company of Clockmakers.
http://www.clockmakers.org/the-clockmakers-museum-library/the-clockmakers-museum-library/
http://www.sciencemuseum.org.uk/visitmuseum/Plan_your_visit/exhibitions/clockmakers-museum?keywords=clockmakers

And the British Horological Institute has a museum too (very limited
opening hours, tho) http://bhi.co.uk/museum/the-bhi-museum-trust/

Tony.
-- 
f.anthony.n.finch    http://dotat.at/  -  I xn--zr8h punycode
Fisher: Cyclonic becoming north 4 or 5, occasionally 6 at first. Moderate.
Rain then showers. Moderate or good.
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Re: [time-nuts] Time-nut going England!

[Tony Finch]

Mike Millen  wrote:
>
> If you can travel to Cambridge ( a short train trip from London ), the the
> Corpus Clock is well worth seeing:
>
> https://en.wikipedia.org/wiki/Corpus_Clock
>
> https://youtu.be/pHO1JTNPPOU

My notes on the Corpus Clock:

http://fanf.livejournal.com/94043.html
http://fanf.livejournal.com/98545.html

If you are in Cambridge, listen out for the chimes from Great St Mary's
church next to the market square - the GSM chimes were copied for the
palace of Westminster's clock tower.

Also listen out for Trinity's clock which strikes the hour twice, and
which has a very informative web site: http://trin-hosts.trin.cam.ac.uk/clock/
Trinity's clock is based on the design of the palace of Westminster's
clock.

Frank King has information about some notable sundials:
http://www.cl.cam.ac.uk/~fhk1/Sundials/WriteUps/CBsundialWalk.pdf

The Royal Greenwich Observatory was housed next to Cambridge University's
Institute of Astronomy for several years before it was finally shut down.
I don't know of any notable timekeeping activities, though.

Tony.
-- 
f.anthony.n.finch    http://dotat.at/  -  I xn--zr8h punycode
Faeroes: Northwesterly 5 or 6 becoming variable 3 or 4, then southerly 5 or 6
later in west. Moderate or rough becoming slight or moderate. Showers. Good,
occasionally moderate.
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Re: [time-nuts] Time-nut going England!

[Mike Millen]

On Wed, Apr 26, 2017 at 8:05 AM, Attila Kinali  wrote:


Hi

I'll be in the UK for three weeks and will have a "free" week
between 13th and 20th of May. I will most probably be around
the London area and maybe spend a day or two in Southampton.


If you can travel to Cambridge ( a short train trip from London ), the 
the Corpus Clock is well worth seeing:


https://en.wikipedia.org/wiki/Corpus_Clock

https://youtu.be/pHO1JTNPPOU

Mike
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