Re: [time-nuts] Cure for hot 5370B counters

[Charles Steinmetz]

Bob wrote:


If you can touch the heat sink for 2 seconds, you're made of sterner stuff than 
I am!  They run very hot.


As I've said before, get a little desk fan (see attached photo). 
Position it behind the counter, blowing straight into the heatsink from 
2-3 inches away.  The ones I have are all sturdy metal, with blades 5 or 
6 inches in diameter.  They spin much slower than muffin-type fans, so 
they are very quiet.  (Even if you have replaced the internal fan with a 
much quieter one, you will still not hear the external fan.)


I've done this with all of my 5370Bs, and the heatsinks run barely warm 
to the touch.  What an improvement!


I paid about $12 each at the local hardware store, but there is probably 
a wide range of asking prices.



Best regards,

Charles


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Re: [time-nuts] A Leap Second is coming

[Philip Gladstone]

This is my clock (NTP synchronized) -- with a bit of luck, the second 
hand will stop (for a second) at the appropriate instant (7PM Eastern). 
I intend to catch it on video.


Unfortunately, this being an inexpensive clock, the plastic gears result 
in the hands not aligning quite correctly (it depends on the force of 
gravity). By the next leap second, I'll upgrade to a better clock.




Philip

On 30/12/2016 19:30, Azelio Boriani wrote:

The leap second warning is present in the PTB clock too (Europe):


On Fri, Dec 30, 2016 at 8:49 PM, Nick Sayer via time-nuts
  wrote:

I'm going to definitely observe my GPS clock to check its behavior. It *should* 
repeat second zero (in my case of 4PM PST). Not the most exactingly accurate 
depiction, but it's the best I can do with the architecture.

Sent from my iPhone


On Dec 29, 2016, at 12:22 AM, David J Taylor  
wrote:

Is everybody setup to watch it and collect lots of data?

Anybody have a list of tools/toys for collecting data?

An old favorite:
www.cl.cam.ac.uk/~mgk25/time/leap/test/timelog.c
=

Some tools here, to see which NTP servers are announcing the event:

http://www.satsignal.eu/software/net.htm#NTPLeapTrace

Perhaps they may be of use to someone?

Cheers,
David




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Re: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Jim Harman]

You could try hooking up a transformer with a 20V secondary as an
autotransformer to reduce the line voltage.

On Fri, Dec 30, 2016, 9:09 PM Bob Stewart  wrote:

> If you can touch the heat sink for 2 seconds, you're made of sterner stuff
> than I am!  They run very hot.  It's a good idea to get a GPIB extender so
> your GPIB cable can clear the heat sink.  Somebody, can't remember who,
> worked up a nice looking conversion to a pair of switching supplies.  I
> bought a couple of the supplies from ebay, but that project hasn't shuffled
> to the top of the list, yet.  Maybe the next time I forget and reach back
> there and get burned...
>
> Bob
>
>
>
>   From: Dr. David Kirkby - Kirkby Microwave Ltd <
> drkir...@kirkbymicrowave.co.uk>
>  To: Discussion of precise time and frequency measurement <
> time-nuts@febo.com>
>  Sent: Friday, December 30, 2016 5:58 PM
>  Subject: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob
> for the 5370B TI counter?
>
> I bought a 5370B TI counter which arrived today. It needs a bit of TLC, but
> nothing too bad. But one of the rotary knobs is incomplete. Does anyone
> have a
> spare knob? Contact me off list if you do.
>
> I had one of these things about 10 years ago. I have forgotten how to
> drive it.
>
> It is running very warm. I can hold my fingers on the heatsink for only a
> couple
> of seconds - not a very scientific test I must admit.
>
> Obviously the mains voltage varies a bit, but it is usually well over the
> 230
> VAC we are supposed to be. I just measured it at 248 VAC. Unfortunately I'm
> right on top of the 11 kV transformer, so other properties around me
> probably
> get poorer voltage regulation, but a few less volts.
>
>
> Dave
>
>
> --
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3
> 6DT, UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
>
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>
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Re: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Chris Albertson]

A knob?  Sounds like a good use for a 3D printer.
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Re: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Bob Stewart]

If you can touch the heat sink for 2 seconds, you're made of sterner stuff than 
I am!  They run very hot.  It's a good idea to get a GPIB extender so your GPIB 
cable can clear the heat sink.  Somebody, can't remember who, worked up a nice 
looking conversion to a pair of switching supplies.  I bought a couple of the 
supplies from ebay, but that project hasn't shuffled to the top of the list, 
yet.  Maybe the next time I forget and reach back there and get burned...

Bob



  From: Dr. David Kirkby - Kirkby Microwave Ltd 

 To: Discussion of precise time and frequency measurement  
 Sent: Friday, December 30, 2016 5:58 PM
 Subject: [time-nuts] Anyone (ideally in the UK) got a spare rotary knob for 
the 5370B TI counter?
   
I bought a 5370B TI counter which arrived today. It needs a bit of TLC, but 
nothing too bad. But one of the rotary knobs is incomplete. Does anyone have a 
spare knob? Contact me off list if you do.

I had one of these things about 10 years ago. I have forgotten how to drive it.

It is running very warm. I can hold my fingers on the heatsink for only a 
couple 
of seconds - not a very scientific test I must admit.

Obviously the mains voltage varies a bit, but it is usually well over the 230 
VAC we are supposed to be. I just measured it at 248 VAC. Unfortunately I'm 
right on top of the 11 kV transformer, so other properties around me probably 
get poorer voltage regulation, but a few less volts.


Dave


-- 
Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)

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[time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Mark Sims]

I forgot to mention... I still have some 3-board extender card kits for the 
5370's.  Two boards are used to extend one of the main cards.  The other fits 
the front panel board (and one of the other minor boards in the machine).  
Contact me off list if needed...
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[time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Mark Sims]

I don't have a knob,  but something that fits should be easy to find.

One warning...  some of the pots have plastic shafts that can be brittle.  They 
can shear off either due to accident,  turning too hard against the stops, or 
just old age.  I seem to remember that one of them has a switch on the back 
(SPDT?) and it is a bugger to find a replacement pot/switch.
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Re: [time-nuts] A Leap Second is coming

[Azelio Boriani]

The leap second warning is present in the PTB clock too (Europe):


On Fri, Dec 30, 2016 at 8:49 PM, Nick Sayer via time-nuts
 wrote:
> I'm going to definitely observe my GPS clock to check its behavior. It 
> *should* repeat second zero (in my case of 4PM PST). Not the most exactingly 
> accurate depiction, but it's the best I can do with the architecture.
>
> Sent from my iPhone
>
>> On Dec 29, 2016, at 12:22 AM, David J Taylor  
>> wrote:
>>
>> Is everybody setup to watch it and collect lots of data?
>>
>> Anybody have a list of tools/toys for collecting data?
>>
>> An old favorite:
>> www.cl.cam.ac.uk/~mgk25/time/leap/test/timelog.c
>> =
>>
>> Some tools here, to see which NTP servers are announcing the event:
>>
>> http://www.satsignal.eu/software/net.htm#NTPLeapTrace
>>
>> Perhaps they may be of use to someone?
>>
>> Cheers,
>> David
>> --
>> SatSignal Software - Quality software written to your requirements
>> Web: http://www.satsignal.eu
>> Email: david-tay...@blueyonder.co.uk
>> Twitter: @gm8arv
>> ___
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>> and follow the instructions there.
>
> ___
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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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Re: [time-nuts] Configuring LH5 for use with an HP 58503A

[Stan]

Hi Mark,

 

Thanks for the advice-it did the trick!

 

Regards,

Stan

 

Heather wants the device to be in half-duplex mode where it does not echo
the serial port characters.  Unfortunately in version 5  the command that it
sends to turn echo off does not work on all receivers.  It is fixed in the
next version.

 

Right now, try starting heather with the /rx5 /bt command line options.  The
/bt will start Heather in a terminal emulator mode.   Type in the command
(without the quotes):

 

  ":SYST:COMM:SER1:FDUP  0"

 

Type in "SYST:STAT?" and verify that what you typed is not echoed.   Press
END to exit terminal mode.

 

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[time-nuts] Anyone (ideally in the UK) got a spare rotary knob for the 5370B TI counter?

[Dr. David Kirkby - Kirkby Microwave Ltd]

I bought a 5370B TI counter which arrived today. It needs a bit of TLC, but 
nothing too bad. But one of the rotary knobs is incomplete. Does anyone have a 
spare knob? Contact me off list if you do.


I had one of these things about 10 years ago. I have forgotten how to drive it.

It is running very warm. I can hold my fingers on the heatsink for only a couple 
of seconds - not a very scientific test I must admit.


Obviously the mains voltage varies a bit, but it is usually well over the 230 
VAC we are supposed to be. I just measured it at 248 VAC. Unfortunately I'm 
right on top of the 11 kV transformer, so other properties around me probably 
get poorer voltage regulation, but a few less volts.



Dave


--
Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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Re: [time-nuts] Measuring sidereal/solar time?

[Bob Camp]

HI

> On Dec 30, 2016, at 4:53 PM, Chris Albertson  
> wrote:
> 
> Yes, the below is basically correct.  But you save a ton of time and
> get better results if you simply bolt the telescope down to the Earth
> so that it can't move at all.   The aim point just needs to be "close"
> and then later you determine where it is aimed.If you are only
> measuring period you don't need a surveyed location.   If measuring
> absolutely time you do.
> 
> Using a fixed mount is what makes this affordable by amateurs.  Epoxy
> the camera to a fixed masonry building.  This removes an unknown and
> dramatically simplifies the processing and also saves most of the cost
> witch is always the mechanical stuff.  One package of JB Weld epoxy
> replaces thousands of dollars of motors and encoders and precision
> gears.
> 
> With a fixed mount camera you have two kinds of "tine", that observed
> by the camera and a second from your GPSDO.  If they diverge then you
> deduce that it must be the Earth's rotation that changed.   But maybe
> you wonder of maybe the camera moved or some effect you forgot to
> remove.  So it is but to have some buddies running the same setup in
> different cities around the world and check that you all see the same
> results.   That is what we did.  It is FAR EASIER to do this kind of
> replication when the setup is very inexpensive.
> 
> Today you could build a camera for a LOT less then we did.  I'm
> thinking of a surplus used lens from a 35mm film camera.  A 250mm lens
> or so and a 3D printed plastic part that holds this to a cheap point
> and shoot camera.

If by 3D print you mean a filament machine, pretty much all of the useful
filaments will soffen / deform / melt if left in the hot sun for a day. The few
that are more temperature tolerant require an unusual printer to work with 
and are a real pain to work with. 

One alternative would be a 3D printed mould and a metal casting process. 
It would take more than a few steps to get to metal. You also would need
to clean up the casting before it was of any use. 

Bob


>   We used epoxy to held the lens to the camera,  it
> meant you'd never be abler to take it apart again but it was going on
> a roof top, rain and all.
> 
> 
> On Fri, Dec 30, 2016 at 3:16 AM, Ilia Platone  wrote:
>> Bruce,
>> 
>> I think that you refer on prjects like Astrometry plate solving. I think one
>> should got a reference to get a time reference instead of scope "pointing"
>> reference, so, once one's got local coordinates in encoder positions, for
>> example the values of the north pole with an alt/az mounting, can use a
>> sub/arcsec plate solver to obtain good sidereal timing reference. using two
>> encoders helps much.
>> 
>> The problem can be visibility of the reference points, however.
>> 
>> Best Regards,
>> 
>> Ilia.
>> 
>> 
>> 
>> On 12/30/16 10:59, Bruce Griffiths wrote:
>>> 
>>> Attila
>>> Lookup "Stellar compass" as used for determining space probe attitude.Can
>>> also be used to determine the direction of the centre of an image of a field
>>> of bright stars.Subarcsecond accuracy is fairly routine.Pattern recognition
>>> techniques combined with measures of the relative brightness of the stars is
>>> used to identify them.Subpixel accuracy in determining the location of the
>>> stellar image centroids is also routine.
>>> There is at least one US PhD thesis on such stellar compass techniques.A
>>> stellar compass technique has been used to determine the pointing direction
>>> of small portable telescopes without requiring precision axis encoders etc.
>>> Bruce
>>> 
>>> On Friday, 30 December 2016 11:43 PM, Attila Kinali
>>>  wrote:
>>> 
>>>  On Fri, 30 Dec 2016 10:59:03 +0200
>>> Anders Wallin  wrote:
>>> 
 out of curiosity, are there any amateur/semi-pro experiments that can
 measure the length of the solar or sidereal day to sub-millisecond
 resolution?
 To reproduce data like this:
 
 https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg
 
 Something in the sky that goes "ping" every day - detected with a
 pointing
 accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
 satellite-dishes pointed at the sun and
 noise-correlation/interferometry??
>>> 
>>> I don't know of any such experiment already performed, but I am not up
>>> to date on what's going on in the hobby astronomy community.
>>> 
>>> I am not sure whether sub-milisecond resolution is feasible, but
>>> I think the "easiest" method would be to do a "modern" version of
>>> an meridian telescope:
>>> 
>>> Using a camera fix mounted (ie not moving and if possible vibration
>>> isolated)
>>> on a pedestal pointed at the sky, approximately looking south. A simple
>>> webcam would be probably enough for first experiments, as long as you get
>>> a good picture of the stars. A good compact camera which 

[time-nuts] HP5062C Chassis available

[cdelect]

Hi,

I have Seven HP5062C chassis collected over the years.
Not sure how many tubes are installed (I can check) or their condition.
I'm pretty sure most of the quartz oscillators are missing but I see two
sitting by the pile.
Might be a very few modules missing.
Most of the top and bottom covers are missing.
I'd like to dispose of them as a lot for $500.00.
Due to the weight and size I'd prefer local pickup.
If no interest I'll pull all the cards and modules prior to scrapping the
chassis and sell them 
as gold scrap on eBay.

Also will be selling two or three tested HP5061B with good "mini" (recent
smaller diameter) tubes.

I'm in Lompoc, CA

Cheers,

Corby

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Re: [time-nuts] Measuring sidereal/solar time?

[Chris Albertson]

Yes, the below is basically correct.  But you save a ton of time and
get better results if you simply bolt the telescope down to the Earth
so that it can't move at all.   The aim point just needs to be "close"
and then later you determine where it is aimed.If you are only
measuring period you don't need a surveyed location.   If measuring
absolutely time you do.

Using a fixed mount is what makes this affordable by amateurs.  Epoxy
the camera to a fixed masonry building.  This removes an unknown and
dramatically simplifies the processing and also saves most of the cost
witch is always the mechanical stuff.  One package of JB Weld epoxy
replaces thousands of dollars of motors and encoders and precision
gears.

With a fixed mount camera you have two kinds of "tine", that observed
by the camera and a second from your GPSDO.  If they diverge then you
deduce that it must be the Earth's rotation that changed.   But maybe
you wonder of maybe the camera moved or some effect you forgot to
remove.  So it is but to have some buddies running the same setup in
different cities around the world and check that you all see the same
results.   That is what we did.  It is FAR EASIER to do this kind of
replication when the setup is very inexpensive.

Today you could build a camera for a LOT less then we did.  I'm
thinking of a surplus used lens from a 35mm film camera.  A 250mm lens
or so and a 3D printed plastic part that holds this to a cheap point
and shoot camera.   We used epoxy to held the lens to the camera,  it
meant you'd never be abler to take it apart again but it was going on
a roof top, rain and all.


On Fri, Dec 30, 2016 at 3:16 AM, Ilia Platone  wrote:
> Bruce,
>
> I think that you refer on prjects like Astrometry plate solving. I think one
> should got a reference to get a time reference instead of scope "pointing"
> reference, so, once one's got local coordinates in encoder positions, for
> example the values of the north pole with an alt/az mounting, can use a
> sub/arcsec plate solver to obtain good sidereal timing reference. using two
> encoders helps much.
>
> The problem can be visibility of the reference points, however.
>
> Best Regards,
>
> Ilia.
>
>
>
> On 12/30/16 10:59, Bruce Griffiths wrote:
>>
>> Attila
>> Lookup "Stellar compass" as used for determining space probe attitude.Can
>> also be used to determine the direction of the centre of an image of a field
>> of bright stars.Subarcsecond accuracy is fairly routine.Pattern recognition
>> techniques combined with measures of the relative brightness of the stars is
>> used to identify them.Subpixel accuracy in determining the location of the
>> stellar image centroids is also routine.
>> There is at least one US PhD thesis on such stellar compass techniques.A
>> stellar compass technique has been used to determine the pointing direction
>> of small portable telescopes without requiring precision axis encoders etc.
>> Bruce
>>
>>  On Friday, 30 December 2016 11:43 PM, Attila Kinali
>>  wrote:
>>
>>   On Fri, 30 Dec 2016 10:59:03 +0200
>> Anders Wallin  wrote:
>>
>>> out of curiosity, are there any amateur/semi-pro experiments that can
>>> measure the length of the solar or sidereal day to sub-millisecond
>>> resolution?
>>> To reproduce data like this:
>>>
>>> https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg
>>>
>>> Something in the sky that goes "ping" every day - detected with a
>>> pointing
>>> accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
>>> satellite-dishes pointed at the sun and
>>> noise-correlation/interferometry??
>>
>> I don't know of any such experiment already performed, but I am not up
>> to date on what's going on in the hobby astronomy community.
>>
>> I am not sure whether sub-milisecond resolution is feasible, but
>> I think the "easiest" method would be to do a "modern" version of
>> an meridian telescope:
>>
>> Using a camera fix mounted (ie not moving and if possible vibration
>> isolated)
>> on a pedestal pointed at the sky, approximately looking south. A simple
>> webcam would be probably enough for first experiments, as long as you get
>> a good picture of the stars. A good compact camera which allows to use
>> a remote shutter with a proper lens and exposure control should be better.
>> Probably the best resource here are the people/websites that deal with
>> book scanning, as they tend to automate the whole picture taking process.
>> Using magic lantern (http://magiclantern.fm) with Canon cameras might
>> give additional features needed for the task.
>>
>> >From the pictures taken, calculate the positions of the stars (by fitting
>> circles onto the bright pixels) and figure out which star is which (using
>> astronomical list of stars). For this step there is a plethora of open
>> source
>> astronomical software available, but I don't know how well they fit the
>> task
>> of figuring 

Re: [time-nuts] Measuring sidereal/solar time?

[Chris Albertson]

On Fri, Dec 30, 2016 at 2:42 AM, Attila Kinali  wrote:
> On Fri, 30 Dec 2016 10:59:03 +0200
> Anders Wallin  wrote:
>
>> out of curiosity, are there any amateur/semi-pro experiments that can
>> measure the length of the solar or sidereal day to sub-millisecond
>> resolution?

Yes.  It is not hard at all to measure the Earth's rotational period,
if all you needs is "sub millisecond"  It would get harder if you
cared about nanoseconds.

I worked on an amateur project with some others and while measuring
the Earth was not the goal we had to know the Earth's rational period
to do the work.   The project was about stellar photometry.  But I
leave that part out.

Basically what we did was mount a camera made out of a small CCD
sensor and a 135mm f/2.8 camera lens salvaged from  an old 35mm film
camera.  The camera was fixed to the roof of my garage. (This was THE
big cost saving feature:  The camera could not move.  The mount as
fixed at one location in the sky forever, right at the equator)  I
placed it in one end of a long wood crate and it looked up at the
equator through a square hole on the upper end of the box.   The box
provided some protection from the elements and provided a lot of light
shielding.

To measure Earth's rotation all you need to do in know exactly when
you took an image and to have a GOOD catalog of star locations.  Let's
say your image captures 200 stars.   They are rather blurry and each
covers maybe 5 pixels but even so you compute the centroid of each
"gaussian blob" and then do a least squares fit of all those centroids
to the astrometric catalog.  The catalog is "good" to several
milliacrseconds and with hundreds of centroids you can figure out were
the camera was printed to a few  "MAS" (Milli Arc Seconds). We
took many images every clear night for several years.Hardware cost
today is "not much" and you can use salvaged camera equipment  Almost
all of the software is available for free. Certainly matching stares
to catalog images is.  Yes the lens has geometric distortion and the
CCD is likely not exactly 90 degrees to the optical axis but the
software models this.  This is possible because millions of star
positions are known to insane levels of accuracy and if they appear in
the "wrong" place in your image you can bet the cause is geometric
distortion in your camera, especially after seeing the same error in
hundreds of images.  We used narrow filters to limit the image to just
one "color" so the chromatic aberration in the optics i not an issue,
filters are cheap.

As part of our processing we time-tagged each image and also recored
where the optical xis was pointed at.

So you'd need a small telescope or big camera lens and a camera that
can be triggered by a computer and software.  Not really expensive.
I'd invest in the best used optics you can and get a monochrome
camera.

Some people in the past century used transit telescopes to manually
measure the time a star crossed a hairline in an eyepiece.  Then the
next night to observe the same star again.  Now you know the length of
the day (after you reduce the data)   Put you can measure a dozen
stars every night and take an average.   In concept it is very simple.
  But today we can measure a tens of thousands of stars per day from a
suburban roof top.


Almost all other methods of measuring the Earth's rotation do not
collect enough data.  You need tens or hundreds of thousands of data
points. if you want to know the sidereal period to Time Nut standards


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[David]

To improve the accuracy, I would integrate several measurements. There
is no reason a sampled measurement at only one time needs to be made.

On Fri, 30 Dec 2016 09:18:17 -0800, you wrote:

>Hi Anders:
>
>That's something I've thought about for decades using an optical system.  A 
>few  years ago I looked at it again and 
>found that astronomical "seeing" limits the accuracy.  So the accuracy 
>achieved by a spaceborne "Stellar compass" will 
>be much better than a ground based observation.  A radio based observation 
>might work since the atmosphere would not be 
>a factor.
>http://www.prc68.com/I/StellarTime.shtml
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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Brooke Clarke]

Hi:

Maybe this could be done with GPS or higher frequencies so the angular 
resolution would be better?

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.

 Original Message 

Brooke,

The problem in radio ground observation can be resolution accuracy, but there's also a good transmission into far 
infrared wavelengths, which could require smaller dishes to get stellar images. The problem of far IR is the cost of 
right filters/sensor, which are a bit difficult to find.


Radio objects, on the other hand, can be solved using an interferometer: LOFAR interferometers work at frequencies 
higher than 10MHz, frequencies totally transparent to the atmosphere and easily computable even by consumer PCs. There 
is some work done with common PCs using two RTL-SDR dongles and two satellite dishes.


see http://www.sbrac.org/files/DTP_RX.pdf

Best Regards,

Ilia.


On 12/30/16 17:18, Brooke Clarke wrote:

Hi Anders:

That's something I've thought about for decades using an optical system.  A few  years ago I looked at it again and 
found that astronomical "seeing" limits the accuracy.  So the accuracy achieved by a spaceborne "Stellar compass" 
will be much better than a ground based observation.  A radio based observation might work since the atmosphere would 
not be a factor.

http://www.prc68.com/I/StellarTime.shtml





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Re: [time-nuts] A Leap Second is coming

[Nick Sayer via time-nuts]

I'm going to definitely observe my GPS clock to check its behavior. It *should* 
repeat second zero (in my case of 4PM PST). Not the most exactingly accurate 
depiction, but it's the best I can do with the architecture. 

Sent from my iPhone

> On Dec 29, 2016, at 12:22 AM, David J Taylor  
> wrote:
> 
> Is everybody setup to watch it and collect lots of data?
> 
> Anybody have a list of tools/toys for collecting data?
> 
> An old favorite:
> www.cl.cam.ac.uk/~mgk25/time/leap/test/timelog.c
> =
> 
> Some tools here, to see which NTP servers are announcing the event:
> 
> http://www.satsignal.eu/software/net.htm#NTPLeapTrace
> 
> Perhaps they may be of use to someone?
> 
> Cheers,
> David
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[jimlux]

On 12/30/16 9:53 AM, Ilia Platone wrote:

Brooke,

The problem in radio ground observation can be resolution accuracy, but
there's also a good transmission into far infrared wavelengths, which
could require smaller dishes to get stellar images. The problem of far
IR is the cost of right filters/sensor, which are a bit difficult to find.

Radio objects, on the other hand, can be solved using an interferometer:
LOFAR interferometers work at frequencies higher than 10MHz, frequencies
totally transparent to the atmosphere and easily computable even by
consumer PCs. There is some work done with common PCs using two RTL-SDR
dongles and two satellite dishes.




the earth's ionosphere is hardly perfectly transparent at frequencies 
below, say, 10 GHz.   The effect is small at GPS L-band frequencies 
around 1.5 GHz, but still large enough that you need to either make 
measurements at two frequencies (so you can calculate the effect) or use 
other data, if you want accurate "sub-meter precision" data.


At HF, the effect is huge: during daytime, you might not even be able to 
see the signals you're looking for, either from D-layer absorbption or 
F-layer reflection/refraction.


The real challenge at HF (e.g. LOFAR) is that it's not just a time of 
flight thing, because the propagation is not in a straight line: the 
anisotropic ionosphere bends the rays: and even better, the bend depends 
on the polarization.  For GPS, the signal is CP, and the effect is 
small, so they typically look at it as an overall propagation speed 
effect. At HF, the effect is so large that's not really valid.


The ionosphere is also only stable on a time scale of <1 second: that 
is, on a HF skywave path (and by inference, on a HF "through ionosphere" 
path), signals are pretty much decorrelated at time scales greater than 
3 seconds as clumps of ionization move around.  This is the fundamental 
accuracy limit on things like the ARRL Frequency Measuring Test (FMT).


It's true that you can do the interferometry easily on a PC, but taking 
out the ionosphere effect is tough, unless you carefully choose 
observing time and avoid high solar activity events, etc.


I suppose one can do some sort of inversion process on measured data 
from known sources at multiple frequencies to infer the ionospheric 
structure, but this is a *hard* problem.



If you want to use RF interferometry, I'd go higher:  maybe Ku-band- 
cheap electronics and dishes available.  There's some water vapor 
attenuation, and I'm sure that changes the propagation speed a bit too, 
but it's measureable with radiometry, you can easily tell whether there 
are clouds in the path with a pretty simple Ku-band radiometer.  You'd 
want to throw out days when there's rain.


I don't know if there's any useful celestial sources at Ku-band.  DSN 
uses bright quasars as pointing & timing reference when doing Delta 
Doppler One way Ranging (Delta DOR) but on the other hand, they're also 
using cryogenic receivers with 34 meter apertures- something not 
available to the casual (or even dedicated) amateur.

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[time-nuts] Heather V5 Holdover

[Mark Sims]

If you started Heather and it shows a holdover time in GREEN,  that means that 
the receiver's last holdover event was 51 seconds long.  A holdover time in 
YELLOW, means that  a 51 second holdover occurred while while Heather was 
running.   A RED value means the receiver is currently in holdover.  

Holdover events show up in the plot area as a red line at the top of the plot.  
Things like out-of-sequence time stamps show up as red tick marks at the top of 
the plot.

Try issuing the keyboard commands:
V0  - (set view interval to 1 second per pixel)
HOME - (moves to the start of the plot data)
Move the mouse cursor into the plot area.
Press '%' to skip the plot forward to the next anomaly.  Repeat the '%' until 
you get to the end of the plot.
Press END - (move to the end of the plot data)
Press DEL - (exit plot review mode)

The number of satellites being tracked is shown as the CYAN plot at the bottom 
of the plot area (1 sat per pixel).  You will probably see the sat count drop 
just before and during the holdover events.

--

>  I just installed the new version of Heather, she's saying "Holdover:  51
secs"  what's she trying to tell me please?
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Re: [time-nuts] HP Z3801 RB fun

[Charles Steinmetz]

paul wrote:


The 10811 is far more difficult to pin down as several articles from TVB
and others say the 10811 actually has a wider control range then the
standard. Something like 10 Hz over 10V. Traditional is 1 Hz over 10 V. But
as I say seems to be different answers depending on what you read.


HP made lots of different sub-models of the 10811.  According to the 
specs, they all had EFC sensitivities of either "at least" +/- 1Hz or 
"at least" +/- 2.5Hz for the -5v to +5v EFC range.  The most 
commonly-encountered sub-models are specified as "at least" +/- 1Hz.


However, the HP spec for the EFC range of the 10811-60158, which was 
used in the Z3801, is (quoting directly here) "> ± 2.0x10-7 (± 2.5 Hz) 
for control range of -5V to +5V".  (Note that 2e-7 of 10MHz is 2Hz, not 
2.5Hz, so there is some internal inconsistency in the spec.)


So, the spec says to expect "at least" 4 or 5Hz (total, or +/- 2 to 
2.5Hz) for the 10v control range (or, "at least" 0.4 to 0.5 Hz/V).  I 
don't believe I've measured one that went 10Hz (total, or +/- 5Hz), but 
I have not taken careful measurements of the EFC tuning rates of many 
10811-60158s.  I certainly wouldn't be shocked to find examples with 
10Hz EFC ranges (1Hz/V), based on the published spec.


Best regards,

Charles


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[time-nuts] Mystery hp Oven UPDATE

[cdelect]

Back in June I picked up the mystery oven assy that turned out to be the
oscillator  assy. of an HP 106A.
Since then I have repaired it and another 106B oscillator assy for a
friend.
My oscillators main problem was that one of the inner oven windings was
open.
Just for testing I installed an array of resistors on one end of the oven
and surprisingly the unit came up properly! This unit might have been a
prototype or special order as there was no fine mechanical tuning of the
EFC via an internal pot, just the coarse capacitor tuning.
My friends had 3 problems. The temperature adjust pots for both the outer
and inner ovens were open! Also after a couple days of operation with the
new pots the AGC test point wire shorted internally to the supply
voltage. went in and disconnected it internally and routed the test point
via an added wire.
His unit is performing (AD)at 2.0E-13th at 1 and 10 Seconds!
My unit is 3.15E-13th at 32 Seconds and is aging at 4.0X10-11th per day.

Not bad for old tech but HP built them well back then!

Cheers and Happy New Year,

Corby

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[time-nuts] HP Z3801 RB fun

[Mark Sims]

If you have a Thunderbolt and have it configured for an external oscillator,  
Lady Heathers'   "" autotune command will determine and display the 
oscillator EFC sensitivity.   It works by setting the DAC voltage a few 
millivolts high,  measuring the frequency,  setting the EFC a few millivolts 
low,  measuring the frequency,  and calculating the gain value in Hz/volt.  The 
process takes a couple of minutes.  Typical values for the standard Tbolt 
oscillator are around -3.5 Hz/volt.
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[time-nuts] Configuring LH5 for use with an HP 58503A

[Mark Sims]

Heather wants the device to be in half-duplex mode where it does not echo the 
serial port characters.  Unfortunately in version 5  the command that it sends 
to turn echo off does not work on all receivers.  It is fixed in the next 
version.

Right now, try starting heather with the /rx5 /bt command line options.  The 
/bt will start Heather in a terminal emulator mode.   Type in the command 
(without the quotes):

  ":SYST:COMM:SER1:FDUP  0"

Type in "SYST:STAT?" and verify that what you typed is not echoed.   Press END 
to exit terminal mode.


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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Ilia Platone]

Brooke,

The problem in radio ground observation can be resolution accuracy, but 
there's also a good transmission into far infrared wavelengths, which 
could require smaller dishes to get stellar images. The problem of far 
IR is the cost of right filters/sensor, which are a bit difficult to find.


Radio objects, on the other hand, can be solved using an interferometer: 
LOFAR interferometers work at frequencies higher than 10MHz, frequencies 
totally transparent to the atmosphere and easily computable even by 
consumer PCs. There is some work done with common PCs using two RTL-SDR 
dongles and two satellite dishes.


see http://www.sbrac.org/files/DTP_RX.pdf

Best Regards,

Ilia.


On 12/30/16 17:18, Brooke Clarke wrote:

Hi Anders:

That's something I've thought about for decades using an optical 
system.  A few  years ago I looked at it again and found that 
astronomical "seeing" limits the accuracy.  So the accuracy achieved 
by a spaceborne "Stellar compass" will be much better than a ground 
based observation.  A radio based observation might work since the 
atmosphere would not be a factor.

http://www.prc68.com/I/StellarTime.shtml



--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999

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Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Brooke Clarke]

Hi Anders:

That's something I've thought about for decades using an optical system.  A few  years ago I looked at it again and 
found that astronomical "seeing" limits the accuracy.  So the accuracy achieved by a spaceborne "Stellar compass" will 
be much better than a ground based observation.  A radio based observation might work since the atmosphere would not be 
a factor.

http://www.prc68.com/I/StellarTime.shtml

--
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.

 Original Message 

out of curiosity, are there any amateur/semi-pro experiments that can
measure the length of the solar or sidereal day to sub-millisecond
resolution?
To reproduce data like this:
https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg

Something in the sky that goes "ping" every day - detected with a pointing
accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
satellite-dishes pointed at the sun and noise-correlation/interferometry??

Anders
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[time-nuts] Configuring LH5 for use with an HP 58503A

[Stan]

I just resurrected an HP 58503A and have been using it successfully for the
last few days with the GPSCon program. I would prefer to use Lady Heather,
but can't seem to get it configured properly. My system is a Windows 10 PC
with a USB to serial cable at COM3. The serial protocol on the 58503A is
9600,8,N,1. 

 

I've added /3 for the COM port to the startup command line. All other config
file parameters are unchanged from the default.

 

When I start LH it finds the 58503A and identifies it as a SCPI receiver,
but then it hangs with no position data or time data, and the PC speaker
chimes continuously at slightly slower than once per second. The only way to
exit the program is to kill the process with the task manager. There are no
other programs vying for the COM port.

 

Any and all help is appreciated!

 

Thanks,

Stan

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Re: [time-nuts] HP Z3801 RB fun

[paul swed]

Magnus
Good afternoon. I am having a hard time following this. Conflicting data I
believe..
Using the FRS-C because its the clearest. On page 3-14 it says +/- 1E-9 for
5V (5V is later in the book) Wouldn't that be 2E-9th for 5V?
The 10811 is far more difficult to pin down as several articles from TVB
and others say the 10811 actually has a wider control range then the
standard. Something like 10 Hz over 10V. Traditional is 1 Hz over 10 V. But
as I say seems to be different answers depending on what you read.

When these details are settled you then came up with the need for a gain of
8. Did you use a rule of thumb?

Thanks
Paul
WB8TSL

On Fri, Dec 30, 2016 at 9:06 AM, Magnus Danielson 
wrote:

> I think the numbers given for 10811 sensitivity was grossly incorrect from
> the source I had, so it should be +/- 1E-6 for +/- 5V, thus giving 2E-6
> over 10V thus giving a sensitivity of 2E-7/V. Compare to 4E-10/V fro the
> FRS-C and just redo the work.
>
> I thought the numbers where funny but too tired to do extensive digging,
> but I just wanted to show the general idea.
>
> Cheers,
> Magnus
>
>
> On 12/30/2016 04:05 AM, paul swed wrote:
>
>> Been interesting.
>> Did increase the gain to 8 and remove the attenuation 10:1 needed for
>> the piezo ocxo. Not sure I would say the system locks but it certainly
>> slows the drift down to 10ns/30 minutes. I also added an offset after
>> the amplifier. This allowed the Z3801 EFC to set its range more towards
>> 50%.
>> Though the FRS manual says the range is 0-5V for EFC the FRS is clearly
>> offset with age to the +1.7V for center. (The other FRS was +.6V)
>>
>> Its interesting  to see at the startup of the Z3801 the EFC range in the
>> RB. Nice steps down towards a fairly low angle line according to Lady
>> Heather.
>>
>> Have had to stop the experimentation late today to give a hand to a
>> fellow on a HP 70-110GHz signal source. Till today I was a 10 GHz sort
>> of guy.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>> On Wed, Dec 28, 2016 at 6:51 PM, Magnus Danielson
>> > wrote:
>>
>> Hi,
>>
>> Well, that was the data I was able to find (and I referred to TvBs
>> page where I found it). If you have more accurate data, please share
>> so we can get the numbers right.
>>
>> The Z3801A will do a least square estimate of frequency error and then
>> translate that into an initial DAC setting assuming it knows the EFC
>> sensitivity, and the loop will work out the rest from there
>> (hopefully).
>> Getting EFC in the right neighborhood is probably wise for this
>> reason.
>>
>> Cheers,
>> Magnus
>>
>>
>> On 12/29/2016 12:32 AM, Bob Camp wrote:
>>
>> Hi
>>
>> Ummm ….. er ….
>>
>> The 10811 that is used in the Z3801 has a *larger* electrical
>> tuning range than the standard
>> 10811 not a smaller one. It’s tuning range and the TBolt OCXO’s
>> tuning range are
>> very similar.
>>
>> Bob
>>
>> On Dec 28, 2016, at 6:22 PM, Magnus Danielson
>> > > wrote:
>>
>> Paul,
>>
>> We just want to help you with that curiosity, it sounds like
>> a fun little project. :)
>>
>> The FRS-C [1] has a range of +/- 1E-9 over 0-5V, so EFC
>> sensitivity is 4E-10/V.
>>
>> The Z3801A has a range of 5.20E-10 [2] over -5V to +5V [3],
>> so EFC sensitivity is 5.2E-11/V.
>>
>> So, it looks like you need to have a gain of 8 and raise the
>> EFC 2.5 V.
>>
>> Cheers,
>> Magnus
>>
>> [1] http://www.to-way.com/tf/frs.pdf
>> 
>>
>> [2] http://www.leapsecond.com/pages/z3801a-efc/
>> 
>>
>> [3] http://www.realhamradio.com/joe-geller.htm
>> 
>>
>> On 12/28/2016 11:42 PM, paul swed wrote:
>>
>> Magnus and Bob,
>> Thank you for your response. As far as the original HO
>> 10811 oscillator
>> goes there is some well written details on it behavior
>> and sensitivity. It
>> was not the same as a standard 10811. A far smaller
>> range as I recall. But
>> the data is there.
>> Its funny on the RB I have the EFC range from the spec
>> sheet. It really
>> tunes from 0-5V. But I find it interesting that the best
>> alignment with
>> other references is sub 1V. Its an old FRS C and I have
>> others that may
>> present a more centered range.
>>
>> I'll 

Re: [time-nuts] HP Z3801 RB fun

[Magnus Danielson]

I think the numbers given for 10811 sensitivity was grossly incorrect 
from the source I had, so it should be +/- 1E-6 for +/- 5V, thus giving 
2E-6 over 10V thus giving a sensitivity of 2E-7/V. Compare to 4E-10/V 
fro the FRS-C and just redo the work.


I thought the numbers where funny but too tired to do extensive digging, 
but I just wanted to show the general idea.


Cheers,
Magnus


On 12/30/2016 04:05 AM, paul swed wrote:

Been interesting.
Did increase the gain to 8 and remove the attenuation 10:1 needed for
the piezo ocxo. Not sure I would say the system locks but it certainly
slows the drift down to 10ns/30 minutes. I also added an offset after
the amplifier. This allowed the Z3801 EFC to set its range more towards 50%.
Though the FRS manual says the range is 0-5V for EFC the FRS is clearly
offset with age to the +1.7V for center. (The other FRS was +.6V)

Its interesting  to see at the startup of the Z3801 the EFC range in the
RB. Nice steps down towards a fairly low angle line according to Lady
Heather.

Have had to stop the experimentation late today to give a hand to a
fellow on a HP 70-110GHz signal source. Till today I was a 10 GHz sort
of guy.
Regards
Paul
WB8TSL



On Wed, Dec 28, 2016 at 6:51 PM, Magnus Danielson
> wrote:

Hi,

Well, that was the data I was able to find (and I referred to TvBs
page where I found it). If you have more accurate data, please share
so we can get the numbers right.

The Z3801A will do a least square estimate of frequency error and then
translate that into an initial DAC setting assuming it knows the EFC
sensitivity, and the loop will work out the rest from there (hopefully).
Getting EFC in the right neighborhood is probably wise for this reason.

Cheers,
Magnus


On 12/29/2016 12:32 AM, Bob Camp wrote:

Hi

Ummm ….. er ….

The 10811 that is used in the Z3801 has a *larger* electrical
tuning range than the standard
10811 not a smaller one. It’s tuning range and the TBolt OCXO’s
tuning range are
very similar.

Bob

On Dec 28, 2016, at 6:22 PM, Magnus Danielson
> wrote:

Paul,

We just want to help you with that curiosity, it sounds like
a fun little project. :)

The FRS-C [1] has a range of +/- 1E-9 over 0-5V, so EFC
sensitivity is 4E-10/V.

The Z3801A has a range of 5.20E-10 [2] over -5V to +5V [3],
so EFC sensitivity is 5.2E-11/V.

So, it looks like you need to have a gain of 8 and raise the
EFC 2.5 V.

Cheers,
Magnus

[1] http://www.to-way.com/tf/frs.pdf


[2] http://www.leapsecond.com/pages/z3801a-efc/


[3] http://www.realhamradio.com/joe-geller.htm


On 12/28/2016 11:42 PM, paul swed wrote:

Magnus and Bob,
Thank you for your response. As far as the original HO
10811 oscillator
goes there is some well written details on it behavior
and sensitivity. It
was not the same as a standard 10811. A far smaller
range as I recall. But
the data is there.
Its funny on the RB I have the EFC range from the spec
sheet. It really
tunes from 0-5V. But I find it interesting that the best
alignment with
other references is sub 1V. Its an old FRS C and I have
others that may
present a more centered range.

I'll have to compare the detials that I have on the
10811 and FRS C. But I
actually pulled out a 100:1 antenuator I was using on
the Piezo crystal
that indeed does lock.

Goal in all of this is nothing special simply curiosity.
Thanks again. When I have some real numbers to share I will.
Regards
Paul
WB8TSL

On Tue, Dec 27, 2016 at 10:26 PM, Bob Camp
> wrote:

Hi

The loop gain (as Magnus mentions) needs to be
“correct” for the Rb. Since
the firmware was written for an OCXO with a PPM(ish)
trim range, tacking it
on to a PPB(ish) Rb will require everything to scale
by 1000:1. That’s 10
bits.
You may (or may not) have enough resolution 

Re: [time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Jim Palfreyman]

I don't think we could call it "amateur/semi-pro" but the millisecond
pulsar J0437-4715 would be perfect for this. Bright and precise.

Only for southern hemisphere people though.

:-)


Jim Palfreyman


On 30 December 2016 at 19:59, Anders Wallin 
wrote:

> out of curiosity, are there any amateur/semi-pro experiments that can
> measure the length of the solar or sidereal day to sub-millisecond
> resolution?
> To reproduce data like this:
> https://upload.wikimedia.org/wikipedia/commons/5/5b/
> Deviation_of_day_length_from_SI_day.svg
>
> Something in the sky that goes "ping" every day - detected with a pointing
> accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
> satellite-dishes pointed at the sun and noise-correlation/interferometry??
>
> Anders
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> and follow the instructions there.
>
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Re: [time-nuts] FPGA SDR? (GnuRadio related)

[Attila Kinali]

On Fri, 30 Dec 2016 11:45:06 +
Ilia Platone  wrote:


> By the way, I read about various Software Defined Radio projects and got 
> interested on this. In past I designed a 30MHz SAR ADC/DAC board using 
> an FPGA, and wanted to implement this into an SDR project. This is not 
> related to my past posts like astronomy or else: it's only for passion 
> and knowledge. Can anyone point me on how to interface with a GnuRadio 
> software and on how GnuRadio works? Links and documents are well accepted.

Almost everything you need to know is documented on the GnuRadio homepage[1].
The best place to ask is probably the "discuss" mailinglist [2]. There
is also a #gnuradio IRC channel on freenode which is very active.

The easiest way is probably to emulate one of the many SDR projects
out there and use their driver interface. Other than that it shouldn't
be too difficult to get the data into GR, once you get it into your PC.
Writing an signal source for GR is pretty easy. The big challenge is
getting the data into the PC with high rate and that largely depends on
your choice of hardware interface between the FPGA and the PC.

Attila Kinali


[1] http://gnuradio.org/
[2] http://gnuradio.org/redmine/projects/gnuradio/wiki/MailingLists

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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[time-nuts] FPGA SDR? (GnuRadio related)

[Ilia Platone]

I got an old valve radio, an Italian Wundercart FM610, not really The 
radio, but I like it because it can receive MW and SW bands in AM 
modulation :), and FM at 88/110MHz of course. an 82-years old electronic 
friend helped me to get it working and I'm so happy for this.


By the way, I read about various Software Defined Radio projects and got 
interested on this. In past I designed a 30MHz SAR ADC/DAC board using 
an FPGA, and wanted to implement this into an SDR project. This is not 
related to my past posts like astronomy or else: it's only for passion 
and knowledge. Can anyone point me on how to interface with a GnuRadio 
software and on how GnuRadio works? Links and documents are well accepted.


Thanks to everybody,
Best Regards,
Ilia.

--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999

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Re: [time-nuts] Measuring sidereal/solar time?

[Ilia Platone]

Bruce,

I think that you refer on prjects like Astrometry plate solving. I think 
one should got a reference to get a time reference instead of scope 
"pointing" reference, so, once one's got local coordinates in encoder 
positions, for example the values of the north pole with an alt/az 
mounting, can use a sub/arcsec plate solver to obtain good sidereal 
timing reference. using two encoders helps much.


The problem can be visibility of the reference points, however.

Best Regards,

Ilia.


On 12/30/16 10:59, Bruce Griffiths wrote:

Attila
Lookup "Stellar compass" as used for determining space probe attitude.Can also 
be used to determine the direction of the centre of an image of a field of bright 
stars.Subarcsecond accuracy is fairly routine.Pattern recognition techniques combined 
with measures of the relative brightness of the stars is used to identify them.Subpixel 
accuracy in determining the location of the stellar image centroids is also routine.
There is at least one US PhD thesis on such stellar compass techniques.A 
stellar compass technique has been used to determine the pointing direction of 
small portable telescopes without requiring precision axis encoders etc.
Bruce

 On Friday, 30 December 2016 11:43 PM, Attila Kinali  
wrote:
  


  On Fri, 30 Dec 2016 10:59:03 +0200
Anders Wallin  wrote:


out of curiosity, are there any amateur/semi-pro experiments that can
measure the length of the solar or sidereal day to sub-millisecond
resolution?
To reproduce data like this:
https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg

Something in the sky that goes "ping" every day - detected with a pointing
accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
satellite-dishes pointed at the sun and noise-correlation/interferometry??

I don't know of any such experiment already performed, but I am not up
to date on what's going on in the hobby astronomy community.

I am not sure whether sub-milisecond resolution is feasible, but
I think the "easiest" method would be to do a "modern" version of
an meridian telescope:

Using a camera fix mounted (ie not moving and if possible vibration isolated)
on a pedestal pointed at the sky, approximately looking south. A simple
webcam would be probably enough for first experiments, as long as you get
a good picture of the stars. A good compact camera which allows to use
a remote shutter with a proper lens and exposure control should be better.
Probably the best resource here are the people/websites that deal with
book scanning, as they tend to automate the whole picture taking process.
Using magic lantern (http://magiclantern.fm) with Canon cameras might
give additional features needed for the task.

>From the pictures taken, calculate the positions of the stars (by fitting
circles onto the bright pixels) and figure out which star is which (using
astronomical list of stars). For this step there is a plethora of open source
astronomical software available, but I don't know how well they fit the task
of figuring out what the position of the stars relative to the camera reference
frame. After that, it's just some simple math of calculating the difference
between the position of the stars and where you would have expecteded them
at the time when the picture has been taken.

Some usefull software projects are:
http://astro.corlan.net/gcx/
http://www.clearskyinstitute.com/xephem/
http://starlink.eao.hawaii.edu/starlink
http://astro.corlan.net/avsomat/index.html
http://rhodesmill.org/pyephem/

HTH

 Attila Kinali



--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999

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Re: [time-nuts] Measuring sidereal/solar time?

[Hal Murray]

att...@kinali.ch said:
> After that, it's just some simple math of calculating the difference between
> the position of the stars and where you would have expecteded them at the
> time when the picture has been taken.

You will probably have to correct for the distortion of the lens.  That is a 
line in the sky will have a slight curve on the pixels.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Measuring sidereal/solar time?

[Ilia Platone]

Another solution from ground can be radio observation using a precise 
interferometer: radio wavelengths are transparent to the earth 
atmosphere and there are various references like sun during day, and (if 
antennas are sensible) bright pulsars and other radio sources during night.



Best Regards,

Ilia.


On 12/30/16 10:42, Attila Kinali wrote:

On Fri, 30 Dec 2016 10:59:03 +0200
Anders Wallin  wrote:


out of curiosity, are there any amateur/semi-pro experiments that can
measure the length of the solar or sidereal day to sub-millisecond
resolution?
To reproduce data like this:
https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg

Something in the sky that goes "ping" every day - detected with a pointing
accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
satellite-dishes pointed at the sun and noise-correlation/interferometry??

I don't know of any such experiment already performed, but I am not up
to date on what's going on in the hobby astronomy community.

I am not sure whether sub-milisecond resolution is feasible, but
I think the "easiest" method would be to do a "modern" version of
an meridian telescope:

Using a camera fix mounted (ie not moving and if possible vibration isolated)
on a pedestal pointed at the sky, approximately looking south. A simple
webcam would be probably enough for first experiments, as long as you get
a good picture of the stars. A good compact camera which allows to use
a remote shutter with a proper lens and exposure control should be better.
Probably the best resource here are the people/websites that deal with
book scanning, as they tend to automate the whole picture taking process.
Using magic lantern (http://magiclantern.fm) with Canon cameras might
give additional features needed for the task.

>From the pictures taken, calculate the positions of the stars (by fitting
circles onto the bright pixels) and figure out which star is which (using
astronomical list of stars). For this step there is a plethora of open source
astronomical software available, but I don't know how well they fit the task
of figuring out what the position of the stars relative to the camera reference
frame. After that, it's just some simple math of calculating the difference
between the position of the stars and where you would have expecteded them
at the time when the picture has been taken.

Some usefull software projects are:
http://astro.corlan.net/gcx/
http://www.clearskyinstitute.com/xephem/
http://starlink.eao.hawaii.edu/starlink
http://astro.corlan.net/avsomat/index.html
http://rhodesmill.org/pyephem/

HTH

Attila Kinali



--
Ilia Platone
via Ferrara 54
47841
Cattolica (RN), Italy
Cell +39 349 1075999

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Re: [time-nuts] Measuring sidereal/solar time?

[Bruce Griffiths]

Attila
Lookup "Stellar compass" as used for determining space probe attitude.Can also 
be used to determine the direction of the centre of an image of a field of 
bright stars.Subarcsecond accuracy is fairly routine.Pattern recognition 
techniques combined with measures of the relative brightness of the stars is 
used to identify them.Subpixel accuracy in determining the location of the 
stellar image centroids is also routine. 
There is at least one US PhD thesis on such stellar compass techniques.A 
stellar compass technique has been used to determine the pointing direction of 
small portable telescopes without requiring precision axis encoders etc.
Bruce 

On Friday, 30 December 2016 11:43 PM, Attila Kinali  
wrote:
 

 On Fri, 30 Dec 2016 10:59:03 +0200
Anders Wallin  wrote:

> out of curiosity, are there any amateur/semi-pro experiments that can
> measure the length of the solar or sidereal day to sub-millisecond
> resolution?
> To reproduce data like this:
> https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg
> 
> Something in the sky that goes "ping" every day - detected with a pointing
> accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
> satellite-dishes pointed at the sun and noise-correlation/interferometry??

I don't know of any such experiment already performed, but I am not up
to date on what's going on in the hobby astronomy community.

I am not sure whether sub-milisecond resolution is feasible, but
I think the "easiest" method would be to do a "modern" version of
an meridian telescope:

Using a camera fix mounted (ie not moving and if possible vibration isolated)
on a pedestal pointed at the sky, approximately looking south. A simple
webcam would be probably enough for first experiments, as long as you get
a good picture of the stars. A good compact camera which allows to use
a remote shutter with a proper lens and exposure control should be better.
Probably the best resource here are the people/websites that deal with
book scanning, as they tend to automate the whole picture taking process.
Using magic lantern (http://magiclantern.fm) with Canon cameras might
give additional features needed for the task.

>From the pictures taken, calculate the positions of the stars (by fitting
circles onto the bright pixels) and figure out which star is which (using
astronomical list of stars). For this step there is a plethora of open source
astronomical software available, but I don't know how well they fit the task
of figuring out what the position of the stars relative to the camera reference
frame. After that, it's just some simple math of calculating the difference
between the position of the stars and where you would have expecteded them
at the time when the picture has been taken.

Some usefull software projects are:
http://astro.corlan.net/gcx/
http://www.clearskyinstitute.com/xephem/
http://starlink.eao.hawaii.edu/starlink
http://astro.corlan.net/avsomat/index.html
http://rhodesmill.org/pyephem/

HTH

            Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Measuring sidereal/solar time?

[Attila Kinali]

On Fri, 30 Dec 2016 10:59:03 +0200
Anders Wallin  wrote:

> out of curiosity, are there any amateur/semi-pro experiments that can
> measure the length of the solar or sidereal day to sub-millisecond
> resolution?
> To reproduce data like this:
> https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg
> 
> Something in the sky that goes "ping" every day - detected with a pointing
> accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
> satellite-dishes pointed at the sun and noise-correlation/interferometry??

I don't know of any such experiment already performed, but I am not up
to date on what's going on in the hobby astronomy community.

I am not sure whether sub-milisecond resolution is feasible, but
I think the "easiest" method would be to do a "modern" version of
an meridian telescope:

Using a camera fix mounted (ie not moving and if possible vibration isolated)
on a pedestal pointed at the sky, approximately looking south. A simple
webcam would be probably enough for first experiments, as long as you get
a good picture of the stars. A good compact camera which allows to use
a remote shutter with a proper lens and exposure control should be better.
Probably the best resource here are the people/websites that deal with
book scanning, as they tend to automate the whole picture taking process.
Using magic lantern (http://magiclantern.fm) with Canon cameras might
give additional features needed for the task.

>From the pictures taken, calculate the positions of the stars (by fitting
circles onto the bright pixels) and figure out which star is which (using
astronomical list of stars). For this step there is a plethora of open source
astronomical software available, but I don't know how well they fit the task
of figuring out what the position of the stars relative to the camera reference
frame. After that, it's just some simple math of calculating the difference
between the position of the stars and where you would have expecteded them
at the time when the picture has been taken.

Some usefull software projects are:
http://astro.corlan.net/gcx/
http://www.clearskyinstitute.com/xephem/
http://starlink.eao.hawaii.edu/starlink
http://astro.corlan.net/avsomat/index.html
http://rhodesmill.org/pyephem/

HTH

Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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[time-nuts] Heather V5 Holdover

[David C. Partridge]

I just installed the new version of Heather, she's saying "Holdover:  51
secs"  what's she trying to tell me please?

Dave

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[time-nuts] Measuring sidereal/solar time? Re: A Leap Second is coming

[Anders Wallin]

out of curiosity, are there any amateur/semi-pro experiments that can
measure the length of the solar or sidereal day to sub-millisecond
resolution?
To reproduce data like this:
https://upload.wikimedia.org/wikipedia/commons/5/5b/Deviation_of_day_length_from_SI_day.svg

Something in the sky that goes "ping" every day - detected with a pointing
accuracy of < 1ms/24h or <0.01 arc-seconds (!?). Or perhaps two
satellite-dishes pointed at the sun and noise-correlation/interferometry??

Anders
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