Re: [time-nuts] Cheap jitter measurements

[Andy ZL3AG via time-nuts]

There's a "realtime" kernel available for Linux that improves timing - no idea 
if this would help in this situation.

See: linux-image-rt-amd64 in debian, for instance




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Re: [time-nuts] Weird Stuff WareHouse shutting down

[Andy ZL3AG via time-nuts]

On 9/04/2018, at 3:52 AM, jimlux wrote:

> Test equipment tends to be aged - Unless you have a particular need for a HP 
> 600 series microwave signal generator, there are probably better sources 
> available much cheaper that use more modern components. In this day and age, 
> I don't think people should suffer through 141T spectrum analyzers or even a 
> 8568- Spend your money an a nice USB unit instead.
> 
Blasphemy!


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Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

[Andy Backus]

Thank you, Bill.  Your comments on noise I find interesting.


I have tracked the TE of the Western Interconnection for 2-1/2 years now.  For 
reliability's sake I use three separate systems that count in different ways.  
Transients are my biggest problem.  I use low pass filters and optical links 
and clipping zeners.  I blank out counter input for most of the 16.67 msec 
between counts.  Still, I lose count on one or another of the systems every 
once in a while.  There is a lot of junk on the grid.


Andy Backus

Bellingham, WA



From: time-nuts <time-nuts-boun...@febo.com> on behalf of Bill Hawkins 
<bill.i...@pobox.com>
Sent: Saturday, March 10, 2018 11:40 PM
To: 'Bob Albert'; 'Discussion of precise time and frequency measurement'; 
'Patrick Murphy'
Subject: Re: [time-nuts] Recommendations for Mains Power Monitor / Logger

Well, this synchronization follows the laws of physics. If the energy
generated doesn't equal the energy consumed, then the frequency may
raise or lower. This is for steam turbines. If the energy come front an
inverter from a DC tie line, as it does from the four regions in the US,
the frequency is anything it wants to be. Well not quite. Raising the
inverter frequency a hair causes the tie line to be the major source of
energy. One could track the use of energy by frequency to make
investment decisions in manufacturer's stocks.

The problem with zero crossing triggers is the amount of noise caused by
solid state power supplies and by tap changing by the power companies to
match loads to minimize transmission losses. I've considered using a
mechanical synchronous motor and slotted wheel to eliminate noise near
the zero crossing, but now that I am 80, I don't give a darn, you see.

Bill Hawkins


 -Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
Albert via time-nuts
Sent: Saturday, March 10, 2018 5:58 PM

 There isn't a whole lot of justification for measuring power line
frequency.  We are all synchronized (in the first world at least) and
while there are phase instabilities, it's seldom the frequency varies
enough to overcome the noise.
As for voltage, it's much more steady than several years ago.  Most
people have 122 Volts, give or take a couple.  Again, not a whole lot of
purpose in recording it.
The distortion is another story.  It's never quite sinusoidal but there
is also some random noise picked up between the generators and the
load.  Looking at the 'scope it's seldom it looks like the textbook
picture of a sine wave.  Chances are most distortion is odd harmonic.
Distortion probably mostly comes from loads which are not resistive,
such as switching power supplies, rectifiers, fluorescent lamps, and
such.  These loads draw currents that are not sinusoids and so cause
voltage drops that are also of that character.
Bob

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Re: [time-nuts] Frequency deviations in Europe affect clocks

[Andy Backus]

Please forgive that I am a lurker and have not contributed.


But this last thread caught my eye since I monitor the time error for the 
Western Grid here in the US.


Over the last year the usual variation is very much the same as in David's 
graph for 2017 -- i.e., +/- 30 seconds.  The power folks worldwide must all 
read the same journals.


There was a time, before October, 2015, that the TE here was kept to +/- 10 sec 
(and years before that even closer).  Maintaining tight TE, however, threatens 
the stability of load/source balancing.  And there are fewer and fewer 
synchronous clocks in use.


If anyone is interested I have data (every minute) for the last two years.


Andy Backus

Bellingham, WA



From: time-nuts <time-nuts-boun...@febo.com> on behalf of David G. McGaw 
<david.g.mc...@dartmouth.edu>
Sent: Thursday, March 8, 2018 9:01 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Frequency deviations in Europe affect clocks

Can someone please explain why not paying your bills causes the grid and
therefore the clocks to slow down?  None of the reports, either for the
technical or lay person, give a reason.

David N1HAC


On 3/8/18 5:00 PM, Pieter-Tjerk de Boer wrote:
> Hello all,
>
> Here's my graph of the mains grid phase deviation over the last month, and
> for comparison the normal behaviour during the previous year:
>
>
> https://na01.safelinks.protection.outlook.com/?url=http:%2F%2Fwwwhome.ewi.utwente.nl%2F~ptdeboer%2Fmisc%2Fmains-2018.html=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Cea149d08d4134d49c94908d58552ea8e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636561513531276977=LwRuSvSr0HOkxvFoI26uFxgjAxbFif6ytgxe4U2Q%2BQE%3D=0
>
> This is measured in Enschede, the Netherlands, by time-stamping every mains
> cycle using NTP for reference.
>
> Naturally, the 2018 part of the graph nicely matches the graph Detlef posted.
>
> Regards,
>Pieter-Tjerk de Boer (PA3FWM)
>
>
>
> On Thu, Mar 08, 2018 at 03:50:42PM +0100, d.schuec...@avm.de wrote:
>> Hi,
>>
>> from new years eve until today 00:00 the European Electricity Grid entsoe
>> lost 16891 sinewaves, nearly 338 seconds. Enclosed you find the sketch of
>> the development. From March 2 they are going to catch up again, it seems.
>>
>> I do a record of the grid frequency. My timebase is a TCXO, 0.4ppm off. I
>> get a frequency value for any single sinewave, precision is 1.4*10^-4 Hz.
>>
>> Cheers
>> Detlef Schücker
>> DD4WV
>>
>> (See attached file: lostseconds.pdf)
>>
>> "time-nuts" <time-nuts-boun...@febo.com> schrieb am 08.03.2018 02:16:55:
>>
>>> Von: Gerhard Hoffmann <dk...@arcor.de>
>>> An: time-nuts@febo.com
>>> Datum: 08.03.2018 02:41
>>> Betreff: Re: [time-nuts] Frequency deviations in Europe affect clocks
>>> Gesendet von: "time-nuts" <time-nuts-boun...@febo.com>
>>>
>>>
>>>
>>> Am 07.03.2018 um 22:09 schrieb Poul-Henning Kamp:
>>>>> This explains why my oven clock and the time/temperature display
>>>>> on the building outside my apartment in Switzerland are six minutes
>>>>> slow since January. It was a great mystery to me.
>>>> Can you get a picture of this ?  It would be wonderful to have for
>>> future discussions...
>>> Does that help?
>>>
>>> <
>>> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.flickr.com%2Fphotos%2F137684711%40N07%2F38870750440%2Fin%2F=02%7C01%7Cdavid.g.mcgaw%40dartmouth.edu%7Cea149d08d4134d49c94908d58552ea8e%7C995b093648d640e5a31ebf689ec9446f%7C0%7C0%7C636561513531276977=tOoi%2BsnXyQjy0%2FGXCyOtOInytUmckrvoKGIO1G%2FRpnE%3D=0
>>> album-72157662535945536/
>>>   >
>>>
>>> Input to the counter is just an AC wall wart with a voltage divider to
>> 4Vpp.
>>> Now, the frequency has risen to above 50.02 Hz constantly. It is in the
>>> middle of the night after all.
>>> They have to catch up.
>>>
>>> BTW I have decided to build an analog phase noise tester of my own. This
>>> weekend
>>> I did most of the mechanical things, but it is still in a kit state.
>>>
>>> The pictures are to the left of the 49 Hz-Pic.
>>> The 1-to-6 coax relays are part of the switchable lambda/4 delay line,
>>> so I can enforce
>>> quadrature everywhere above 5 MHz, including unknown amplifiers etc.
>>> Still looking for 2 more 1:6 relays.
>>>
>>> The mixers and dividers are in stereo, so I can do cross correlation in
>>> the 89441A.
>>> One of the mixer/preamp

Re: [time-nuts] Curious, how many t-nuts have 5065A

[Andy ZL3AG via time-nuts]

http://www.timeok.it/hp5065a-corner-3/

See: HP5065asnlist (serial number list)

On 23/02/2018, at 3:44 AM, Pete Lancashire wrote:

> no reason other then  curious
> 
> -pete
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Re: [time-nuts] unidentified HF time pips

[Andy]

>
> Ha, so I was jumping around looking for the same and found a guy on
> 15.016Mhz running through random characters phonetically and then signing,
> “this completes X characters, Horsefly out.”  What the heck was that?
>

That sounds like a variation on the well-known (or maybe not so well known)
'numbers station'.

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

Andy
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Re: [time-nuts] Performance verification for time counters

[Andy ZL3AG via time-nuts]

HP 5359A Time Synthesiser?


On 30/11/2017, at 10:24 AM, Leo Bodnar wrote:

> I am looking for an established and widely accepted procedure for verifying 
> performance of high resolution time counters.
> 
> I have designed a time stamping counter for qualifying 1PPS signal 
> performance against external reference (e.g. 10MHz master clock.)
> 
> Simple design verification check I am doing at the moment is gating random 
> selection of master clock edges back into device's signal input and letting 
> the device measure this test signal offset against its reference clock - 
> which, for ideal design, should result in zero offset (modulo 100ns.)  My 
> results are roughly in line with what I expect to see 
> http://leobodnar.com/balloons/NTP/time-sampler-test1.png
> 
> Now, what would be recognised procedure for sweeping external input pulse 
> delay over few hundred ns in a controlled, measurable and repeatable way? 
> 
> I can see few naïve approaches:
> 1) Using selectively gated (or divided) reference clock followed by 
> adjustable delay line.  E.g. something like mechanically adjusted delay lines 
> used in HP test sets.  Or, perhaps, calibrated rigid coax sections?  
> 2) Slightly offset another master clock (e.g. second Rb oscillator) gated in 
> a similar way but without delay line, followed by statistical data analysis 
> 3) Trusted pulse generator with high resolution delay adjustment fed from the 
> same master clock as the counter 
> 
> I am looking for something with ~10ps accuracy, 100ns+ range, and reasonably 
> low jitter (~5ps or better.)  
> It is possible that the range needs to be split up (e.g. fixed rigid coax 
> delay line followed by a mechanically adjust section.)
> 
> This is a low budget fun project so something simple and common sense is 
> preferred to "price on application" NIST traceable equipment.
> 
> Thanks!
> Leo
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Re: [time-nuts] Very large X9.2 solar flare.

[Andy]

Mike Cook wrote:

> When I saw the OP I did a quick check of my GPS receivers status. One of
> them, a Jackson Labs M2M replacement (actually a U-blox M8T) had just reset
> and gone to a 111ms offset.
> Was that due to the CME?
>

No, not the CME.  A CME is particles of matter traveling at
non-relativistic speeds and usually takes a couple of days to reach earth.

The initial effects of a solar flare include the arrival of X-rays
(coincident with us seeing the flare), and those ionize the upper
atmosphere and cause radio blackouts.  That was what you saw the effects of.

David G. McGaw wrote:

> No, the flare also produced a CME, which is expected to reach us tomorrow
> and may (hopefully?) trigger a G-3 class geomagnetic storm.
>

This one surprised us and arrived earlier today (Thursday), way ahead of
schedule.  It was quite energetic.  It triggered a few instances of a G-4
(4 out of 5, "Severe") geomagnetic storm.  Also Kp=8.3.

Alas, I am unable to see any auroras yet.  :-(   Still hoping.

Regards,
Andy
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Re: [time-nuts] Very large X9.2 solar flare.

[Andy]

>
> The flare has been and gone!...is this another case of journalists
> mixing up a flare with a CME ?
>

There was some of both.  SDO saw a flare, STEREO saw a CME.

Andy
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Re: [time-nuts] The clocks at Windsor Castle, UK

[Andy]

Jerry Hancock wrote:

I’m missing something here.   ...


Really?  What do you think you're missing?

The difficulty with setting clocks +11 hours is that you can't just crank
the minute hand in a circle 11 times.  You have to wait for the clock to
ring before advancing the next hour.

Stopping clocks for an hour is OK but you have to remember to go back and
start them, and it's all a pain if you have 450 of them.  Either way, it
takes ... you guessed it ... time.

Turning clocks backwards is probably OK if the clock doesn't have strikes
for the hour (and perhaps half hour).  If the clock just keeps time and
nothing else, then perhaps you can move the hands either way.  It's the
strike mechanisms that get fouled up or break, if you attempt to turn the
hands backwards.

Andy
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Re: [time-nuts] Machining some aluminum help!

[Andy ZL3AG via time-nuts]

Or go for thicker wall aluminium tube, oversized endplates and long bolts or 
threaded rods running the entire length down the outside of the tube so you're 
clamping both ends in one operation. No tapping required. Simples!




On 19/05/2017, at 6:16 AM, Tim Shoppa wrote:

> I bet you went to 0.25" wall square tubing only because you want to tap the
> walls for 4-40. Alternative designs can let you use much thinner material
> and a very different flange on the ends, but the costs will likely move
> towards welding/brazing rather than machining.
> 
> Tim N3QE
> 
> On Thu, May 18, 2017 at 12:54 PM,  wrote:
> 
>> Hi,
>> 
>> I have a square aluminum tube 5" X 5" with a .25" wall it's 8 1/2" long.
>> 
>> I need 20 holes in each end tapped for 4/40 and 1/2" deep.
>> 
>> This is for a Rubidium project.
>> 

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Re: [time-nuts] Machining some aluminum help!

[Andy ZL3AG via time-nuts]

Why are my eyes watering?

On 19/05/2017, at 5:03 AM, Bob Darlington wrote:

>  I had
> to soak my cavity ring in nitric acid for a month to get the tap out.
> 

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Re: [time-nuts] Line Frequeny Stablity

[Andy]

Several years ago (c. 1980) I remember an occasion when the local utility
slipped about 20-25 minutes of effective 'time' over the course of one
night.

I didn't know much about power grids then, except that they existed, and
contributed to certain power blackouts.  But what happened was that the
local utility had gotten disconnected from the rest of the northeast USA
grid, and free-ran overnight at a significantly offset frequency.  I think
it would have been running at around 57 Hz or lower.

Andy
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Re: [time-nuts] TAPR TICC boxed (input protection)

[Andy]

Another thing to watch out for if you need very low leakage, is if the
package is transparent.  All junctions are photodiodes.

Maybe it's less of a problem now with SMTs, than it was with glass body
diodes or translucent transistor packages.

Andy
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Re: [time-nuts] PLL performance?

[Andy]

Second file successfully opened in Irfanview.

Three other PDF readers, including Adobe, could not open it.

Andy
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Re: [time-nuts] new year crashes

[Andy ZL3AG via time-nuts]

Agreed, but new years eve is a special case for emergency services in 
particular.


On 2/01/2017, at 2:38 AM, Bob Camp wrote:

> Hi
> 
> Insertion times that are convenient for some could be a major pain for 
> others. There is no 
> single “good” time to insert a leap second. You might argue that doing it 
> while the financial 
> markets are closed is a good idea. That sort of rules out the middle of the 
> week. You also
> could argue that you do it when everybody is on hand to fix things. That sort 
> of rules out
> weekends. With two simple “rules”, the entire week has been crossed off the 
> list ….
> 
> If you go back in the archives, you will find significant discussion going on 
> about dropping
> leap seconds altogether. That would indeed eliminate the need to schedule 
> them. It also 
> would eventually result in some odd adjustments to local time. 
> 
> 
> Bob
> 
>> On Jan 1, 2017, at 8:07 AM, Andy ZL3AG via time-nuts <time-nuts@febo.com> 
>> wrote:
>> 
>> 
>> If so, they should think about adding the leap second on the night of the 
>> 2nd wednesday of January, or such a time when things are quieter around the 
>> world.
>> 
>> Do they add the leap second at the same moment in time throughout the world, 
>> or are the clocks here in NZ running 13 hours and 1 second ahead of those in 
>> the UK for half of Jan 1st?
>> 

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Re: [time-nuts] new year crashes

[Andy ZL3AG via time-nuts]

If so, they should think about adding the leap second on the night of the 2nd 
wednesday of January, or such a time when things are quieter around the world.

Do they add the leap second at the same moment in time throughout the world, or 
are the clocks here in NZ running 13 hours and 1 second ahead of those in the 
UK for half of Jan 1st?

On 2/01/2017, at 1:54 AM, Adrian Godwin wrote:

> I wonder if someone wasn't ready for their extra second :
> 
> http://www.bbc.co.uk/news/uk-38482746
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Re: [time-nuts] Totally unrelated, but..

[Andy]

>
> I looked at the reg input and output with scope and spectrum analyzer, and
> I don't see anything that indicates excessive noise or oscillation.
>

Does the receiver's noise persist with the scope or spectrum analyzer
attached?  Connecting their probes might temporarily "fix" the problem so
that it can never be observed.

Andy
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Re: [time-nuts] Questionable content webcomic channels some time nuttery

[Andy ZL3AG via time-nuts]

At first, I avoided clicking the link as seeing it posted there with no hint as 
to the content, it screamed "this person's email account has been hijacked by a 
virus".

Once someone replied +1, I took a look and had a wee chortle.

On 8/11/2016, at 9:57 AM, Don Latham wrote:

> glad there are some other readers out there…
> 
>> On Nov 7, 2016, at 8:33 AM, Christopher Hoover  wrote:
>> 
>> +1
>> 
>> On Nov 7, 2016 4:05 PM, "Gregory Maxwell"  wrote:
>> 
>>> http://questionablecontent.net/view.php?comic=3346
>>> ___


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Re: [time-nuts] I love the smell of tantalum in the morning

[Andy ZL3AG via time-nuts]

Yes. Unless you're grinding it away with a dremel (which I wouldn't recommend 
as far as chemical dust is concerned), nibbling away with sidecutters would be 
trying to force the 2 ends of the component apart. That may be stressing the 
pads they're soldered to, leading to a possible pad lifting at some stage.

Any of the methods mentioned that heat both ends at the same time - allowing 
the component to be wiped off the board - would have to be the best, 
stress-wise.

On 6/11/2016, at 3:00 PM, Scott Stobbe wrote:

> For through hole parts sure, but I would not recommend that on SMD parts,
> the copper foil of a little pad is pretty easy to tear off and it's a royal
> pain if you have to mount a device missing some of its landing pads.
> 
> On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller  wrote:
> 
>> I usually nibble away at the center of the part until it is two separate
>> pieces. Then unsolder each piece. Clean the pads off with wick then install
>> the new part.
>> 
>> Use a good sharp pair of flush cut side cutters.
>> 
>> Tom
>> 
>> 

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Re: [time-nuts] HP 5065A questions

[Andy ZL3AG]

Thanks for the link to those handy documents, Luciano.

I have a serial 1420A that I plan on resurrecting once my lab is built.

Since seeing the capacitor warning, I checked it just now and sure enough, 1 
capacitor had vomited on the PCB, so I've removed it and cleaned the PCB ready 
for replacing all the suspect caps in the future.

My one has H89 option installed, and a extra output at 4.433MHZ = PAL TV 
subcarrier frequency. So I suspect that is what option H89 is.

Cheers,

Andy


On 26/09/2016, at 6:58 PM, timeok wrote:

> 
> I think that these pages can help you:
> http://www.timeok.it/wp-content/uploads/2015/09/First-aid-when-you-buy-an-hp5065A-v-1.2.pdf
> http://www.timeok.it/wp-content/uploads/2015/09/First-aid-II-when-you-buy-an-hp5065A-v-1.0.pdf
> 
>   Luciano
> 

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Re: [time-nuts] HP-105B Battery Replacement?

[Andy ZL3AG]

If you know where to get them from, you can get used 19" rack mount UPS's for 
scrap value. They might have fried batteries, but that's easily solved.

 
On 16/09/2016, at 11:06 AM, Bob kb8tq wrote:

> Hi
> 
> They are very common when you look at server UPS or larger units. There are 
> literally hundreds of models to pick between. Prices are from roughly $400 up 
> to a few hundred thousand dollars per unit.
> 
> Bob

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Re: [time-nuts] Need 10 MHz for DSN space-probe hunting

[Andy ZL3AG]

That sounds like fun!

Do they have a mailing list they hang out on?

https://eyes.nasa.gov/dsn/dsn.html



On 14/09/2016, at 5:04 AM, Mike Baker wrote:

> Hello, Time-Nutters--
> 
> Full disclosure--  I am a complete newbie at understanding the
> intricacies of generating a really stable, low phase noise, accurate
> frequency reference for microwave reception up around the 8 GHz
> DSN (Deep Space Network) band.  I have been following the back
> and forth comments on the Time-Nuts list about improving the
> Trimble T-bolt's 10 MHz output but confess that most of it is pretty
> much deeper technical voo-doo than I am comfortable with.

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Re: [time-nuts] ke5fx.com - something's up

[Andy ZL3AG]

Domain name expired on September 8th - needs renewing!

On 11/09/2016, at 10:48 AM, Nick Sayer via time-nuts wrote:

> I tried to look for Lady Heather docs today, but it appears like the ke5fx 
> domain is… funky.
> 
> The name servers are NS1.PENDINGRENEWALDELETION.COM and there are other 
> indications that maybe the domain lapsed…?

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Re: [time-nuts] HF frequency counting receiver

[Andy ZL3AG]

http://www.cliftonlaboratories.com/off-the-air_frequency_measurement.htm

If you peruse http://www.b4h.net/fmt/fmtresults201204.php you will see that 
HP3336A's also feature regularly.

On Jun 21, 2016, at 4:52 AM, Pete Lancashire wrote:

> Never tried it but a Selective Level Meter aka HP 3586A/B/C ?
> 


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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Andy]

On Wed, May 25, 2016 at 12:59 PM, Mike Monett <timen...@binsamp.e4ward.com>
wrote:

LTspice shows  switching  at 0V is the best point in  time.  ...



Bzzzt!  Your simulation is seriously flawed, and your conclusions are
wrong.  What you forgot, or may not have realized, is that SPICE's initial
transient solution is obtained by having the signal sources already turned
on (at the moment of the Big Bang) and set to their initial value, so the
current through L2 is limited by DC conditions.  That is not anything close
to switching the driving voltages on.  It is having one waveform sit at
+169.7V DC for a very long time ('forever'), and then letting it follow a
cosine wave.

Re-run the simulation with "UIC" added to the .tran statement (.tran 50ms
uic) and see what it shows.  Using UIC forces the initial voltage to be 0V
at time=0, the start of the simulation.  That's like having the switch
initially open.

Or if you don't like that, multiply the sources by a PWL waveform that
starts both voltages at 0V and then switches them on, a few milliseconds
into the simulation, with the appropriate phase.

Or use an actual switch.  LTspice has a switch element you could use.

I guarantee you, the case with the voltage switching on at the 0V point in
the voltage waveform, causes greater currents.

The smaller surge current happens when the source is connected at the
moment when the current i(t) would be 0A if it were a continuous waveform.
For an inductive load, this happens when the voltage v(t) would be +/- peak
(or near peak, for a real load which has both inductance and a little
resistance).  This condition also results in no surge, thus no L/R decay.

All of this might not be relevant to a mechanical system, where surge
current is caused by rotational inertia, rather than anything electrical.

Regards,
Andy
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Re: [time-nuts] Maser 0.7 nsec jumps solved

[Andy]

On Sun, May 22, 2016 at 11:15 PM, Jim Palfreyman <jim77...@gmail.com> wrote:

As far as a remedy goes we are going to try a solid state relay that only
> switches on at 0V in the AC waveform. This should slow the inrush current,
> and hopefully the magnetic impulse.
>

If the load being switched on is inductive, it would be better to switch
the AC waveform at the voltage peaks, not at 0V.  This might seem
counter-intuitive, but it's real.  Switching on at the 0V crossing may
maximize the current pulse through the magnetics.

OTOH, if the origin of the impulse is mechanical in nature, neither remedy
may help.

Regards,
Andy
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Re: [time-nuts] When does NIST change to DST?

[Andy]

Yes, what I meant by "switch to DST" was that it flips the DST bit.
Not that the timecode itself changes.

Since the time many clocks use to sync up with WWVB is (from what I
recall) around 2AM, it seems kind of dicey whether they would make the
change on the right day.

I think that doesn't explain the change happening at 2000J -- unless
your receiver was receiving and syncing to WWVB at that time and they
had already flipped the bit.

Andy
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Re: [time-nuts] When does NIST change to DST?

[Andy]

I wonder if WWVB switches to DST around 0200Z, maybe?  Since it can't
tell where your local zone is.

Andy
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Re: [time-nuts] Effect of the Antenna Delay in setting in Z380!A

[Andy]

Dave wrote:

For those of who might care I would assume that actually taking the coax
> and measuring the delay at 1.5GHZ would be better than relying on the
> manufactures published specs for velocity factor.  I was going to set up
> and measure the delay with a signal generator and  good oscilloscope (I
> have a 7104 1GHZ scope which still shows decent signal at 1.5 GHZ)
>

Technically I think what you would want to measure is the group delay, not
the phase delay.

Andy
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Re: [time-nuts] moon bounce for synchronization

[Andy ZL3AG]

Hat tip to the 8405A Vector Voltmeter in the other rack.

Yeah. Great photo!

On Jan 31, 2016, at 7:43 AM, Jeremy Nichols wrote:

> Ooh! Ooh! Not only a 5245 with a 5265 voltmeter plug-in but a 5360 Computing 
> Pig! Great picture, thanks for posting it.
> 
> Jeremy
> N6WFO
> 

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Re: [time-nuts] Casio Watches 13 Year Drift in Seattle

[Andy]

   If this was normal back at the turn of the 20th century, why wouldn't
Casio, and others at least do as well?  Especially now that all
electronic watches have a microprocessor built in... complete with
temperature sensing diodes, battery monitors, and other nifty gadgets.

I am guessing the vast majority of Casio owners don't especially care if
their watch gains or loses a minute every month.  So why bother to add
sensors and circuitry to compensate for its environment?

Furthermore, it requires setting the initial frequency on each watch built,
to compensate for the crystal's initial error.  And that jacks up the cost,
perhaps more than adding those sensors would.  Better to just churn them
out with as little per-unit testing as possible.

That's just my guess ... but who am I to say?

Regards,
Andy
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Re: [time-nuts] Casio Watches 13 Year Drift in Seattle

[Andy]

Measuring a 32kHz frequency to ~100 PPB accuracy takes some time, even for
ATE.  Time is money.

I didn't think the hardware to do the computations and the digital offset
was any problem.  I thought the temperature and voltage sensors might be,
since they are analog.  But you can integrate them into a good mixed
technology IC process.  I just didn't think that was what they are using.

Andy
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Re: [time-nuts] Performance of 74LVC series ICs

[Andy]

The gates on that page

   http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/trangate.html

use bipolar transistors.  The 74LVC parts are CMOS.  There are various
effects caused by that difference.

And those examples have vastly inferior control over input switching
levels, compared to just about any well made digital IC from the last half
century.  (Funny to think that it has been half of a century!)

2N type transistors might have switching delays upwards of 100 ns
(depending on load), whereas the LVC parts switch in the 1-5 ns range.

   On the other hand: A well designed discrete circuit can beat a general
purpose integrated circuit in almost all performance measures.

Some performance metrics would be hard to beat with even a well designed
discrete circuit.  On-die capacitance and inductance tends to be much
smaller than any discrete circuit can achieve.

Andy
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Re: [time-nuts] Some questions related to time-interval measurements and modulation domain analysis

[Andy]

Ole wrote:

   So here is my first question - since this signal is amplitude modulated,
the only way this can (should) show up on the counter is if the
triggering
is not perfect - that is, it does not trigger at precisely 0v +
whatever
DC offset may or may not be on the signal. Is my undestandig here
correct?
A perfect zero-crossing detector would be immune to AM?

I believe that should be true.  Assuming that the source has no AM/PM
conversion, that no other noise is present with the signal, and that the
detector is immune to edge rate, the period of an AM signal should not
change.

Andy
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Re: [time-nuts] Frequency doubler 5/10 and distribution amplifier for Lucent KS-24361

[Andy Bardagjy]

It is possible to convert Altium files to Kicad 

https://github.com/thesourcerer8/altium2kicad/

This might also work, but Altium seems to be a work in progress

https://github.com/upverter/schematic-file-converter

Andy ◉ Bardagjy.com ◉ +1-404-964-1641

On Apr 5, 2015, at 8:08 AM, John Allen j...@pcsupportsolutions.com wrote:

 Hi Time-Nuts - FWIW, the is a 30 day free trial of Altium Designer at
 http://www.altium.com/free-trial?gclid=CKnpkaux38QCFQotaQodoaYAWQ
 
 The download requires a company name and email address.
 
 I for one, would like at least one of each of Gerhard's boards.
 
 Would anybody like to volunteer to create 10-20 boards and sell them?
 
 If people are interested in boards, they can pm me at 
 j...@pcsupportsolutions.com
 And I will make a list and post it.
 
 In your email, provide your name and email address and how many multiplier 
 boards and how many low noise 220pV/sqrtHz preamp boards?
 
 I have no time to do any more than that.
 
 Is this worth being a TAPR project?
 
 Trying to help, John K1AE
 j...@pcsupportsolutions.com
 
 -Original Message-
 From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Anthony Roby
 Sent: Saturday, April 04, 2015 10:12 PM
 To: g...@hoffmann-hochfrequenz.de; Discussion of precise time and frequency 
 measurement
 Subject: Re: [time-nuts] Frequency doubler 5/10 and distribution amplifier 
 for Lucent KS-24361
 
 Gerhard - I would like to make the board if you could make the layout 
 available.  I don't have Altium, so would need the artwork to be able to 
 toner transfer the board.  Is it available?
 
 Thanks
 
 -Original Message-
 From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gerhard 
 Hoffmann
 Sent: Saturday, April 04, 2015 7:19 AM
 To: time-nuts@febo.com
 Subject: Re: [time-nuts] Frequency doubler 5/10 and distribution amplifier 
 for Lucent KS-24361
 
 Am 03.04.2015 um 04:04 schrieb Philip Gladstone:
 I'm coming late to this thread from January -- but did anybody ever 
 make the PCBs for Gerhard's 10MHz output board? I'm interested.
 
 I just got my pair of RFTG's.
 
 Congratulations!
 
 There isn't a lot of news.. The interest on the net quickly boiled down, my 
 sample works and so there was not a great incentive to follow that with much 
 energy. And getting boards out does not mean that those are really built or 
 that there is any feedback at all, as I saw with my 220pV/sqrtHz preamp.
 
 The Altium Designer files are available, maybe the regulators should be 
 changed to sth. bigger (TO220 with small heat sink or so)
 
 regards, Gerhard
 
 (who will spend this rainycold Easter weekend on a 1pps generator whose 
 outputs can be skewed in ps-steps to check the linearity of T2D converters or 
 time stretchers.) ___
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 This email has been checked for viruses by Avast antivirus software.
 http://www.avast.com
 
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Re: [time-nuts] OXCO insulation

[Andy Bardagjy]

Fiberglass seems like an obvious choice for high temperature insulation. 

Andy ◉ Bardagjy.com ◉ +1-404-964-1641

 On Feb 23, 2015, at 12:51 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
 drkir...@kirkbymicrowave.co.uk wrote:
 
 On 22 Feb 2015 22:07, Dave M dgmin...@mediacombb.net wrote:
 
 Yes, I'm aware that the newer OXCOs don't have any insulation other than
 air inside the package.  I failed to mention that in my post.  I am
 primarily interested in the older OXCOs that have foam insulation inside.
 I have a couple of them, including the crystal oven from an old HP 5245L
 counter that needs new insulation.
 
 I don't know what is used, but clearly whatever is used *must* be stable
 under heat for *long* periods of time.
 
 Domestic gas / oil / coal boilers must use insulation,  and whatever is
 used would I assume be able to take heat for extended periods of time. I
 wonder if you could get something like that.
 
 The trouble I see with other chemicals (spray foam etc), is you have no
 idea if it will sustain heat for long periods of time.
 
 Dave.
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[time-nuts] Mechanical 1PPS Oscillator Disciplining

[Andy Bardagjy]

From a fascinating (albeit long) article about transatlantic communication 
cables

http://archive.wired.com/wired/archive/4.12/ffglass.html

On the bottom of page 45 to the top of page 46

Each piece of equipment on this tabletop is built around a motor that turns 
over at the same precise frequency. None of it would work - no device could 
communicate with any other device - unless all of those motors were spinning in 
lockstep with one another. The transmitter, regenerator/retransmitter, and 
printer all had to be in sync even though they were thousands of miles apart.

This feat is achieved by means of a collection of extremely precise analog 
machinery. The heart of the system is another polished box that contains a 
vibrating reed, electromagnetically driven, thrumming along at 30 cycles per 
second, generating the clock pulses that keep all the other machines turning 
over at the right pace. The reed is as precise as such a thing can be, but over 
time it is bound to drift and get out of sync with the other vibrating reeds in 
the other stations.

In order to control this tendency, a pair of identical pendulum clocks hang 
next to each other on the wall above. These clocks feed steady, one-second 
timing pulses into the box housing the reed. The reed, in turn, is driving a 
motor that is geared so that it should turn over at one revolution per second, 
generating a pulse with each revolution. If the frequency of the reed's 
vibration begins to drift, the motor's speed will drift along with it, and the 
pulse will come a bit too early or a bit too late. But these pulses are being 
compared with the steady one-second pulses generated by the double pendulum 
clock, and any difference between them is detected by a feedback system that 
can slightly speed up or slow down the vibration of the reed in order to 
correct the error. The result is a clock so steady that once one of them is set 
up in, say, London, and another is set up in, say, Cape Town, the machinery in 
those two cities will remain synched with each other indefinitely.

Does anyone know any other history about that particular piece of equipment?

Cheers!

Andy ◉ Bardagjy.com ◉ +1-404-964-1641

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Re: [time-nuts] HP-58503A

[Andy Bardagjy]

Sounds like the GPS receiver is hosed. I think there are two different 
receivers used in the 58503a, unfortunately I'm away from my lab, otherwise I 
could check mine. It is a standard part, and may be available on the surplus 
market. 

Before replacing, I'd check the usual suspects, power supply health (look for 
failed electrolytics) and re-seat the gps board to board connector.  

Happy to measure things on my 58503a. 

Andy ◉ Bardagjy.com ◉ +1-404-964-1641

 On Dec 30, 2014, at 12:35 PM, Richard Thorpe kisso...@gmail.com wrote:
 
 This list was recommended to me by the elecraft list.  I have an HP-58503A 
 sat disciplined “clock” that puts out a steady 10MHz to my K3 radio.  Its 
 been working 24/7 for years, I monitor it with David Anderson's Mac GPS 
 Control X software on my iMac. Several days ago error messages showed up 
 i.e.: Health- err, Self Test-err, Int Power- OK, OCXO- OK, EFC-OK GPS 
 RCV-err. Its not tracking any sats and now I cannot event communicate with it 
 at all even with a simple com program.  Is there anyone out therE who can fix 
 these things?  Any suggestions would be appreciated.  Thank you.
 
 Richard Thorpe K6CG
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Re: [time-nuts] Sun Outage

[Andy]

Jim Lux wrote:

WHy yes they do: that's what weather radar is. It detects the reflections
 from the rain drops or ice crystals in the storms. ...


But radar is much different than passively receiving known radio signals
that penetrate the atmosphere from above.

Conceivably one could have hundreds of small receivers, scattered around
within the range of one WX radar.  Much less cost than the radar, and no
emissions so no need to license it.  I don't know if it matters but they
measure transmission, not scattering and reflectivity, and they look at the
droplets from below, not the side.  With the proliferation of personal
weather stations, it seems like another source of information that could be
exploited cheaply.

Andy
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Re: [time-nuts] Sun Outage

[Andy]

Bob Stewart b...@evoria.net wrote:

...  Also, the cartoons I was recording for my granddaughter were
 unaffected, but the station I was watching had the outage.  That doesn't
 all fit together unless it was the uplink that had the problem.


I don't think the uplink itself can have this problem.

But DirecTV uses multiple transponders per satellite, and in some cases
more than one satellite, so all the channels are not affected equally.

When I had DirecTV, we had two dishes.  The installer boggled up the first
install so they came back and put up another one several feet away, mounted
on a more stable surface (not roof shingles).  The first dish was one that
could be used for multiple satellites.  It had three 'focal' points with
three little radomes that either had, or could have, LNAs in them.  Each
points to a different spot in the sky.  The second dish had only one.
Regardless, we received only one satellite.

I don't recall ever being affected by a solar outage, but rain and ice were
real killers!  Yeah they say rain shouldn't cause an outage, but it does
when the rain density is high enough.  I could use that to predict when we
were about to be hit by a downpour.  There was about a 3 minute lag between
losing all the channels, and the downpour starting.

It occurred to me that one could use satellite signals as a meteorological
instrument to measure the water density in the atmosphere above you.  I
wonder if the NWS does that.

Andy
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Re: [time-nuts] Clock level conversion 5V - 3.3V

[Andy]

If it were me, I'd avoid the active buffers since there is no need for them
when going from higher to lower voltage swings.  The output of a
buffer/inverter is guaranteed to be at least a little less clean than what
you started with.

First, check to see if the 5V output really is a 5V signal.  If it's TTL,
it might swing only to about 3.5V anyway.  (Connecting a weak load to
ground can make this more pronounced.)  Check to see if your 3.3V part's
input tolerates 5V signals.  The chances may be small, but it might just be
that you can go direct with absolutely nothing in between.

You could use a resistive divider at the destination device that serves two
purposes: both attenuating the signal, and terminating it.  In which case
it's a win-win.

If need be, the resistive divider can add a small DC offset, say if you
need to drive 1.8V logic and the OCXO's Vol isn't low enough.

Instead of a resistive divider, you might use a schottky switching diode to
limit the positive swing.  Then you get close to a replica of the OCXO's
signal through the switching range of the input pin, with attenuation
kicking in only when the voltage starts going too high.

I don't know if these devices are still popular, but there are passive FET
signal 'limiters' that work in a similar way; the signal passes through
unchanged until the instantaneous voltage reaches 3V or so, and then the
FET eases off and doesn't pass higher voltages.  Some years ago they were
popular for making 5V/3.3V signal transitions.  They are supposed to have
negligible delay (well, you know) when the FET is on, they are
bidirectional (not that it matters to you here), and they consume no
power.  I think the name Quickswitch was one of the brand names, and
Pericom and IDT were two of the manufacturers.

Regards,
Andy
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Re: [time-nuts] Have some Leica/AeroAntenna Tech Inc Choke Ring antennas for sale

[Andy Bardagjy]

Hi Pete, I'd like to tentatively speak for one. Thanks!

Andy ◉ Bardagjy.com ◉ +1-404-964-1641

 On Sep 13, 2014, at 5:13 PM, Pete Lancashire p...@petelancashire.com wrote:
 
 Forgot .. I'm in Portland, Oregon 97217
 
 -pete
 
 On Sat, Sep 13, 2014 at 5:00 PM, Pete Lancashire p...@petelancashire.com
 wrote:
 
 I've acquired a few new in the box Leica/AeroAntennas. Some boxes have
 been opened.
 
 
 https://plus.google.com/u/0/photos/111617808980322733757/albums/6052074218781475313
 
 The complete assemble is Leica P/N 10147
 
 The 'puck' antenna is P/N 10160
 
 I would like to have Time-Nuts get first dibs
 
 Does $100 + shipping sound reasonable ?
 
 The box is 16 x 16 x 16 and weighs 11 lbs.
 
 -pete
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Re: [time-nuts] One man's noise is another man's signal...

[Andy Bardagjy]

One of my favorite alternate GPS applications is using the visibility of the 
satellites like tomographic beams to reconstruct the 3D geometry of buildings

http://www.kihwan23.com/papers/ISWC08/GPSRAY_ISWC08_short_final.pdf

Andy Bardagjy
bardagjy.com

On Aug 14, 2014, at 5:18 AM, Collins, Graham coll...@navcanada.ca wrote:

 
 This is an interesting use of GPS, I had never considered the Aurora or solar 
 storm angle before.
 
 However, I am aware of the use of ionospheric scintillation and TEC 
 measurements for ionospheric research and also for the study and detection of 
 earthquakes.
 
 Canadian High Arctic Ionospheric Network  (CHAIN) uses this technology
 
 http://chain.physics.unb.ca/chain/pages/gps/
 
 and a couple of links about the earthquake angel:
 
 http://demeter.cnrs-orleans.fr/dmt/doc/workshop2011/10_Vishal_Chauhan.pdf
 
 http://demeter.cnrs-orleans.fr/dmt/doc/workshop2011/12_O.P.%20Singh_Agra.pdf
 
 I have been pondering how I could use as is or modify one of my GPS receivers 
 to make these sorts of measurements. The CHAIN gps receivers use a OCXO but 
 haven't figured out how to apply that to one of the GPS receivers I currently 
 have or even if I could.
 
 I have also been pondering whether I could approach from a different angle by 
 using the range correction values provided Differential GPS (DGPS) radio 
 beacons which broadcast range correction values for use with DGPS capable 
 receivers. Seems to me that the Ionospheric effects on the GPS signal is 
 reflected in the range correction values and it should be a matter of working 
 backwards.
 
 Cheers, Graham ve3gtc
 
 
 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On 
 Behalf Of Hal Murray
 Sent: August-14-14 4:32 AM
 To: time-nuts@febo.com
 Cc: Hal Murray
 Subject: [time-nuts] One man's noise is another man's signal...
 
 Tue evening, I went to a talk on Auroras and Solar Storms.  It was targeted 
 as the general public so they didn't get into any technical details.
 
 One of the pictures showed a GPS setup.  They were using it to measure free 
 electrons in the ionosphere.
 
 
 A friend found this in case anybody wants gory details:
  http://www.navipedia.net/index.php/Ionospheric_Delay
 
 
 --
 These are my opinions.  I hate spam.
 
 
 
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Re: [time-nuts] 2014 Million £ Longitude Prize

[Andy]

Brooke Clarke wrote:

A million pounds is about 16.8 million dollars.

That doesn't seem right.

The prize is 10 million British pounds, so your U.S. dollar equivalent is
about right but not in the way you stated it.

Andy
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Re: [time-nuts] optically excite a quartz crystal?

[Andy Bardagjy]

When this question was first posed, AOM's first jumped to my mind. An AOM 
(sometimes AOD) is an Acousto-Optic Modulator that works by setting up an 
acoustic wave in a crystal. When a laser is directed through (or reflected by) 
an AOM, it is deflected. 

One way to think about this is the crystal lattice deforms with the period of 
the acoustic wave. The lattice deformations form a grating of regions of 
varying indices of refraction which produce varying phase delay. This steers 
the beam just as a grating would. 

Another way of thinking about it is the 'phonon's' momentum and the photon's 
momentum add producing a deflection (like two billiard balls colliding). This 
might seem impossible, but the math works out exactly..

Another nice thing is, if you recall, the EM field produced in the far-field of 
a coherent EM wave impinging on a grating is the Fourier Transform of the 
grating itself. In something like a CD, the grating has hard edges, producing 
lots of harmonic content. AOMs look like sine waves, most of the energy ends up 
in the deflected beam. 

AOMs are often constructed using quartz crystals because they are fairly 
broadband (optically) and piezoelectric. The piezoelectric properties make it 
easy to set up the acoustic wave in the crystal.

The key difference is, AOMs are typically designed to absorb as little power as 
possible (power absorption is their primary failure mechanism). Depending on 
your laser, you might want to find an AOM that is less transparent in your 
excitation regime.

That said, you can get a lot of energy out of lasers these days. Megawatt 
pulses are not impossible with something like a Kerr-lens mode locked laser. 
This results in extremely high electric fields (MW pulse in 0.1 mm^2).

Andy Bardagjy
bardagjy.com

On Apr 21, 2014, at 6:47 AM, Magnus Danielson mag...@rubidium.dyndns.org 
wrote:

 
 On 04/21/2014 03:18 PM, Attila Kinali wrote:
 On Mon, 21 Apr 2014 14:54:12 +0200
 Magnus Danielson mag...@rubidium.dyndns.org wrote:
 
 They used a 10mW HeNe laser, modulated with 1kHz to 1MHz on
 various quartz cuts (X+5°, DT, AT) and could measure oscillations
 of the quartz using metal electrodes.
 The mechanism of exitation was photothermal
 
 10 mW laser is reasonable.
 
 What levels of signal where they getting?
 
 6.2mV, with an real laser incident power of 5mW (the AOM ate half of the 
 power)
 
 Cool. Today we use semiconductor lasers that we can modulate directly, so no 
 need for the AOM on the NeHe laser.
 
 Cheers,
 Magnus
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Re: [time-nuts] Looking for WWVB digital wall clock with digital 24 hour UTC display

[Andy]

Rick wrote:

  Thanks for the suggestions, but the MFJ121 does not
   display the date

The MFJ-121 might not include the date, but some of their other large WWVB
clocks do.  Go to
http://www.mfjenterprises.com/Categories.php?sec=226(clock products)
and click on the ones that say ATOMIC.  I am not sure if
they all can be set to UTC but some of them say they can.  MFJ products are
made for radio amateurs, many of whom use UTC for 'talking around the
world'.

Be aware that MFJ has mixed reviews ... some of their products that they
themselves assemble in Mississippi can have QC issues.  Cold solder joints
is the one I hear most often.  Some people love 'em; others hate 'em.  They
are a successful business for 40+ years so I'd have to guess the lovers
outweigh the haters.

Andy
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Re: [time-nuts] Looking for Dual-Time Atomic Clock

[Andy]

Richard wrote:

The 121B will only offset the 5 NA Time Zones.

And Zulu too, right?

So aside from the size, it meets your requirements, right?

I guess you would have to change its time zone when the rest of the
country changes to/from Daylight Saving time, but that's probably true
of most of them.

Andy
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Re: [time-nuts] Looking for Dual-Time Atomic Clock

[Andy]

Dick asked,

What I am looking for is a way to display Local Time (MST) and Zulu (GMT)
 time in a small (6 X 8 or similar) package. There must be two displays
 and
 both lock up to NBS.

 Has anyone seen such a thing ?


Might not meet all your specs, but MFJ may have something:

http://www.mfjenterprises.com/Product.php?productid=MFJ-121B  (too big?)
http://www.mfjenterprises.com/Product.php?productid=MFJ-133RC  (shows only
one zone at a time?)
Andy

(I replied earlier but forgot to use the right address.)
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Re: [time-nuts] Making a Raspberry Pi NTP server without soldering

[Andy Bardagjy]

The networking adapter on the Pi is connected to the SoC via USB while on
the BeagleBone the MAC is native. I suspect this might affect timing.

Andy Bardagjy
bardagjy.com


On Tue, Oct 22, 2013 at 11:36 AM, Chris Albertson albertson.ch...@gmail.com
 wrote:

 On Tue, Oct 22, 2013 at 7:13 AM, Collins, Graham coll...@navcanada.ca
 wrote:

 
 
  How you done anything with or have compared the PI to the Beaglebone
 Black?


 If your only use of the device is to have an NTP server then why pay more
 for the  Beaglebone?  The Pi based server seems to be better than required.
  better in this case meaning that it keeps time better then it can
 transfer it over your network.

 If you need a lower cost Linux server, you can repurpose a PogoPlug.  These
 are roughly the same specs ARM process and a little bit of RAM but come
 with a case and power supply all for under $20.  You can re-flash them with
 a general purpose Linix-ARM distribution.  But no good place to attach a
 PPS input except for using a USB-Serial dongle.   Well there is a serial
 port header inside the box but I've not tried it.

 Chris Albertson
 Redondo Beach, California
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Re: [time-nuts] Article on linear regulator noise reduction methods

[Andy Bardagjy]

Worth also reading the very good (cited) article from Wenzel

http://www.wenzel.com/documents/finesse.html

Andy Bardagjy
bardagjy.com


On Thu, Oct 17, 2013 at 11:24 AM, Robert LaJeunesse 
rlajeune...@sbcglobal.net wrote:

 FYI. Addresses LM317 noise in a simple implementation, how to reduce it,
 and how it relates to other approaches and parts. Numerous graphs of noise
 voltage versus frequency can prove enlightening.

 http://www.edn.com/Home/PrintView?contentItemId=4422750
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Re: [time-nuts] Low cost GPS for model aircraft

[Andy Bardagjy]

There are quite a few off the shelf model aircraft controllers. As you can
imagine, those based on GPS and/or MEMS IMUs are not terrifically high
performing. That said, I have seen very promising results from thermopile
based systems - good discussion in the link below

http://paparazzi.enac.fr/wiki/Sensors/IR

They do tend to break down on overcast or cloudy days when the contrast
between the sky and the ground is minimal.

Andy Bardagjy
bardagjy.com


On Mon, Aug 5, 2013 at 10:14 AM, J. Forster j...@quikus.com wrote:

 This chatter about model aircraft GPS got me to wondering if there now
 off-the-shelf flight control systems for model planes that will do nav
 and/or attitude control? I know there are mini-gyros, but I think they are
 only good enough for attitude control.

 Last time I was into this, if you lost radio contact the model was gone or
 had crashed..

 -John

 



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Re: [time-nuts] Lead acid battery noise levels

[Andy Bardagjy]

The SRS 560 and 570, low noise voltage and current preamplifiers
respectively, both use bog standard sealed lead acid batteries.

Andy Bardagjy
bardagjy.com


On Tue, Jul 9, 2013 at 9:26 AM, J. Forster j...@quikus.com wrote:

 EGG Princeton Applied Research made a very low noise preamp unit, the
 113, which was pretty much the industry leader for years. It was often
 used with Lock-In amplifiers. The unit used NiCds, I believe for that,
 among other, reasons. I'd expect Ithaco and SAE have similar products.

 -John

 ===


  David Kirkby wrote:
  On 9 July 2013 04:52, Mark Spencermspencer12...@yahoo.ca  wrote:
 
  Hello, I've just reviewed the thread from earlier this year regarding
  low noise power supplies and some related information about the noise
  levels of certain batteries.Has anyone ever come across any data
  pertaining to the noise levels of common gelled lead acid storage
  batteries ?
 
  Have you come across the volt-nuts list?
 
  https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
 
  I see a bizzare review of an HP 3457A meter on utube
 
  http://www.youtube.com/watch?v=HfxpJCdgVwc
 
  where the guy determines the noise level of the 6.5/7.5 digit meter by
  measuring the voltage of what he describes as a general purpose lab
  power supply. Is it me, or is it a bit dumb to try to measure the
  noise level of a laboratory multimeter by using a general purpose lab
  power supply.
 
  I must admit, I thought that using a battery would have been stable at
  least short term, but it seems there is noise on a battery - something
  I was not aware of until today.
 
  Dave
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  A battery is noisest when current is flowing in the battery.
  With no current flow (or electrolyte disturbance) the noise is very low.
  NIST has measured the noise of unloaded NiCd cells for example and it is
  extremely low.
 
  Bruce
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Re: [time-nuts] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?

[Andy Bardagjy]

I've had my eye on the Stanford Research SG 380 for some time - they boast
-116dBc/Hz phase noise

http://thinksrs.com/products/SG380.htm

They use a pretty interesting rational approximation frequency synthesis
which they discuss in detail in their operating manual. This allows them to
drive down the phase noise.

Too bad it's nearly $4000...

Andy Bardagjy
bardagjy.com


On Mon, Jul 8, 2013 at 10:55 AM, Ed Palmer ed_pal...@sasktel.net wrote:

 In 2002, this document:

 THE CRYSTAL OSCILLATOR CHARACTERIZATION FACILITY AT THE AEROSPACE
 CORPORATION
 http://www.pttimeeting.org/**archivemeetings/2002papers/**paper32.pdfhttp://www.pttimeeting.org/archivemeetings/2002papers/paper32.pdf

 stated:

 The Programmed Test Sources, Inc. PTS model #250M6NIGSX-51 low-noise
 frequency synthesizer is
 used to offset the frequency reference to obtain the desired beat
 frequency. In our previous system, we
 used a Fluke 6160B frequency synthesizer, since the Fluke 6160B frequency
 synthesizer had the lowest
 noise contribution of all the frequency synthesizers on the market at that
 time.  The reason for having the
 low-noise frequency synthesizer is the synthesizer  noise contributions to
 the system noise-floor.
 Unfortunately, Fluke has discontinued manufacturing and maintaining this
 synthesizer. Therefore, we
 looked at the new synthesizers on the market and found that the PTS
 synthesizer was the closest to the
 Fluke 6160B frequency synthesizer in terms of noise floor. 

 Sounds like a working 6160B would be a nice thing to have. Unfortunately,
 it's too large for my already overcrowded lab. :-(

 Ed



 On 7/8/2013 3:44 AM, Anders Time wrote:

 I have been looking around for a very stable synthesizer(E-12 at 1s
 adev).
 The only really good information that I have found is febo.com´s
 measurements on the PTS synthesizers(http://www.febo.**
 com/pages/pts_synth/ http://www.febo.com/pages/pts_synth/).
 Is there any other really good alternatives to the PTS synthesizers? DDS?
 HP?
 Best Regards
 Anders

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Re: [time-nuts] Cheap 9.8Mhz Sa.22c's

[Andy Bardagjy]

Bob, are you referring to a particular GPSDO (for $120)? Which is it? Can
you provide a link?

Andy Bardagjy
bardagjy.com


On Sun, Jun 2, 2013 at 4:30 PM, Bob Camp li...@rtty.us wrote:

 Hi

 Far cheaper to spend the $120 on the GPSDO that does the 9.8304 to 10 MHz
 conversion than to send the Rb back to the factory.

 Bob

 On Jun 2, 2013, at 4:24 PM, Ed Palmer ed_pal...@sasktel.net wrote:

  Glutton for punishment, aren't you Mark!  :)
 
  There's probably no way to get to 10 MHz.  I have two of these that I
 picked up just to play with.  Another purchaser contacted Symmetricom and
 actually got some information out of them.  The oscillator in these runs at
 58.9824 MHz.  The default output is 9.8304 MHz.  The output can be changed,
 but only in submultiples of the 58.98 MHz.  e.g. 58.98 divided by 6 equals
 9.8304.  You can change  the '6' to various integers as documented in the
 manual.
 
  To move the output to 10 MHz you'd have to change the crystal back to
 the standard 60 MHz so that you could divide it by 6.  But then you'd mess
 up the multiplier that takes the crystal frequency up to the Rb frequency.
  You'd have to change the synthesizer that controls that side of the
 system.  There's no way to tell if that would require a completely new
 firmware load or if, just maybe, there could be an undocumented (maybe
 protected) command to modify it.  You might be able to send it back to
 Symmetricom to get it changed but, based on my experience, you couldn't
 afford it.
 
  Ed
 
  On 6/2/2013 11:52 AM, Mark C. Stephens wrote:
  These are 9.8304Mhz, is possible to move them to 10Mhz?
 
 
 http://www.ebay.com/itm/Symmetricom-SA-22c-9-8304MHz-Precision-Rubidium-Oscillator-5V-and-15V-NICE-/261223397404
 
 
  -marki
 
 
  Kind Regards,
  Mark Stephens
 
  Mark Clemens Stephens | Customer service engineer | Non-Stop Computer
 Ltd
  * +61 2 9011 8186 | ( +61 428 256 334 | * ma...@non-stop.com.aumailto:
 ma...@non-stop.com.au
 
  Non-Stop Computer PTY LTD
  79 Devon St
  North Epping
  NSW 2121
  Australia
  Timezone: AEST (UTC +10)
 
  Email: serv...@non-stop.com.aumailto:serv...@non-stop.com.au
 
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Re: [time-nuts] Net4501's cheap...

[Andy Bardagjy]

The net4501s went way up in price, but there is a seller offering a lot of
five net4521 boards plus five 64MB CF cards for $80 - and he is willing to
accept less if you make an offer. Try lot 320744604969.

They seem to be the same as a net4501 but with two PCMCIA slots. I was
gonna try to run NTPd on it for a work project, though I've also got a few
BeagleBone Blacks hanging around.

Andy Bardagjy
bardagjy.com


On Thu, May 23, 2013 at 1:14 AM, mike cook mc235...@gmail.com wrote:



 Le 23 mai 2013 à 03:31, Jim Sanford a écrit :

  Do you have any documentation on how to use them?  I have one that I
 bought to be an internet access point with a verizon card, failed due to
 verizon not complying with the RFCs.  Love the device, but no information
 on ports, etc.  Might want to play with it, or could make it available.
 

   User manuals, firmware etc from the Soekris.com site and there is plenty
 of OS installation/admin doc visible on the web. They marry with PCI or
 mini-PCI wifi cards that can be found cheaply. Mine were running FreeBSD
 but there are other flavors that support it. I say were because their power
 supplies failed after around 5years 24/24. The 4801s of the same vintage
 are still going.
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Re: [time-nuts] Time Nut Pickens at the MIT Flea ?

[Andy Bardagjy]

Plenty of good stuff in the area; Flour, Area Four, Catalyst, Friendly
Toast, Blue Room, CBC, and so on.

I live in the area - recent MIT graduate - and would be happy to set
something up (though I think my gf's birthday is that day, so maybe not)

Andy Bardagjy
bardagjy.com


On Mon, May 20, 2013 at 8:34 AM, J. Forster j...@quikus.com wrote:

 There are cafe/pizza options in the Strattion Student Center, although
 seating is somewhat limited. But there are other places in the same
 building.

 It's a short walk from the flea site (Mass Ave at Vasser Street) Bldg W-20

 -John

 


  I was there as well, but did not see much of interest. That might be
  because Paul Swed scooped up the good stuff before I could finish the
  first pass :) Nice find Paul, hope they settle down for you. Would love
 to
  see a post-flea get together and put some faces with names, but I don't
  know of any places nearby.
 
  Paul - K9MR
 
  On May 19, 2013, at 10:22 PM, paul swed wrote:
 
  Good news at least the first EGG RB fired up and after adjusting the
  synthesizer is locked very nicely. Letting it bake and figuring out the
  dip
  switches. They were wrong or purposely offset. Hard to say. Lamp voltage
  is
  12 VDC I suspect thats quite a good number if compared to the old FRS and
  FRCs I have down in the 5-6V range. The FRS/C run 12 new.
  Can't really find any documentation, but expected that.
  Regards
  Paul
  WB8TSL
 
 
  On Sun, May 19, 2013 at 10:09 PM, Bob Bownes bow...@gmail.com wrote:
 
  We should plan a Time-Nuts BOF lunch after the next flea.
 
  Saw little TN gear @ Dayton save one Efretom RBI time base for $1800 and
  a
  few 10811s of dubious quality for $50 ea. the dents put me off gambling
  on
  one since I was given or the afternoon before! ;)
 
  On May 19, 2013, at 21:50, paul swed paulsw...@gmail.com wrote:
 
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Re: [time-nuts] 10Mhz Sine from Square Wave Synthesizer

[Andy Bardagjy]

Alright, so it seems that it's possible the Symmetricom SA.22c that I've
got might be set to 9.8304MHz. That may be programmable to 10MHz, but it
might require a DDS otherwise.

Nevertheless, if the oscillator is set to 10MHz it seems the consensus is
to construct a LPF.

Luciano, thank you for sharing your design, did you wind your own
inductors? Odd values.. Typically when designing filters I start  by fixing
the inductor values and work backwards...

John, thanks for your input, you reminded me that LFP performance often
depends on source impedance. To the MMIC amplifier, you'd be amazed what
you can do with an opamp these days. I was amazed reading the datasheet for
the LTC6409 a 10GHz GBW, 1.1nV/sqrt(hz) fully differential opamp. With a
gain of one, the frequency response is totally flat out to 1GHz.

http://cds.linear.com/docs/en/datasheet/6409fa.pdf

Perhaps something like a LT6600-15 might be a complete solution for me -
it's a fully differential amplifier with a 15Mhz 4 pole LPF.

http://www.linear.com/product/LT6600-15

Thanks for your input, I'll be sure to keep everyone posted on my project's
progress.

Andy Bardagjy
bardagjy.com


On Mon, May 20, 2013 at 12:03 PM, Luciano Paramithiotti timeok...@gmail.com
 wrote:

 Hi Andy,

 The simplest way is to use a low pass filter with a notch capability for
 the second and third harmonics.
 You can find the schematic and response for 5 and 10 MHz here:

  http://www.timeok.it/files/5_and_10mhz_low_pass_notch_filter.pdf

 ciao,

 Luciano
 timeok

 see: www.timeok.it

 On Mon, May 20, 2013 at 1:30 AM, Andy Bardagjy a...@bardagjy.com wrote:

  Hi folks, I recently picked up a Symmetricom SA.22c rubidium oscillator.
  According to the datasheet, it outputs a square wave with programmable
  frequency (well you can pick among some set of frequencies).
 
  I'd like to build up a small circuit locked to the square wave output
 which
  outputs a 10MHz sine wave for use as my house clock for my various
  instruments (spec an, counter etc). I of course could distribute the
 square
  wave, but am concerned about harmonics, among other things.
 
  The FE-5680A uses a AD9830A DDS to synthesize its output. Is a DDS the
  right way to go - in terms of performance, phase noise and so on?
 
  I suppose I could do this with a tank or some other analog circuit, but..
 
  Andy Bardagjy
  bardagjy.com
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 --
 Luciano
 Timeok
 visit : www.timeok.it
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Re: [time-nuts] Time Nut Pickens at the MIT Flea ?

[Andy Bardagjy]

I grabbed a real nice Leitech distribution amplifier - but I took it home
and it was empty!

I walked back and returned it for a refund, but the seller said he had a
whole stack in his office. I was gonna post to the list when I sort it out
- it was a real bargin, and he said he might be willing to ship them around.

Andy Bardagjy
bardagjy.com


On Sun, May 19, 2013 at 4:42 PM, Stan, W1LE stanw...@verizon.net wrote:

 Anyone  got any Time Nut quality items at the MIT fleamarket today ?

 Stan, W1LE   Cape Cod
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[time-nuts] 10Mhz Sine from Square Wave Synthesizer

[Andy Bardagjy]

Hi folks, I recently picked up a Symmetricom SA.22c rubidium oscillator.
According to the datasheet, it outputs a square wave with programmable
frequency (well you can pick among some set of frequencies).

I'd like to build up a small circuit locked to the square wave output which
outputs a 10MHz sine wave for use as my house clock for my various
instruments (spec an, counter etc). I of course could distribute the square
wave, but am concerned about harmonics, among other things.

The FE-5680A uses a AD9830A DDS to synthesize its output. Is a DDS the
right way to go - in terms of performance, phase noise and so on?

I suppose I could do this with a tank or some other analog circuit, but..

Andy Bardagjy
bardagjy.com
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Re: [time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

A couple of guys have expressed interest in this unit, so I think it is
spoken for.

Hopefully the adoptive home will post up about their experience with this
after they get it running.

-Andy

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Re: [time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

Hi Paul:

It was your reports of the Great Lakes chain that got me interested in
this. I live in St. Paul, Minnesota, so I am hopeful of hearing it here. I
have a couple other LF receivers with which to try to hear Loran C, so I
still have options.

Obviously, before I invest much in this, I want to see that the feds have a
long term interest in maintaining Loran again, and especially the GL chain.

-Andy

On Sat, Mar 3, 2012 at 10:28 AM, paul swed paulsw...@gmail.com wrote:

 That is indeed interesting because the only rcvr I knew that needed a pdp 8
 was the older actual station monitoring units.
 I would strongly believe if you know what the 5000 wants these days its
 very reasonable to emulate the control system.
 That said in the US the only GRI I could monitor was the great lakes chain
 89700.
 It was on and off the air as you might expect for a test.
 Regards
 Paul
 WB8TSL





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[time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

Greetings:

I think this is my first post to this reflector. I have been a subscriber
for some time now. Thanks to everyone for sharing their knowledge.

Recently, a member of this list gave me an Austron 5000 Loran C receiver.
With the recent news about Loran C, I am interested to try to use this
device. But I have some questions:

Is it possible to use this receiver without the PDP-8 computer that it was
generally paired with? If so, how is it done?

Does anyone know where a manual for this receiver can be found?

I appreciate any help.

Thanks

Andy K0AJL

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Re: [time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

Hi again: Thanks for all of the replies so far.

I took a few photos of the unit for Mr. Kimberely. They are a front view, a
rear view and one of the label on the side. Not the greatest shots, but you
can view them here:
https://plus.google.com/photos/110810019489830210559/albums/5715752440279697361?authkey=CM2uhYmH7PnfmgE

As you'll see, interfacing it to something doesn't appear to be simple.
However, I'll look into the emulator links. I appreciate them.

I do not have the full set- only the receiver part. Every online image I
have found looks like it's sitting on the PDP-8

-Andy





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Re: [time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

Thanks to all who replied. I think I'm in over my head with this one. There
are far easier ways for me to try to receive Loran C, and I have no
shortage of projects.

So... Forgive me if this is not allowed on this reflector...

Free to a good home (after shipping): One Austron 5000 Loran C receiver.
Untested. Decent physical condx. See earlier post from me for a link to
photos.

If interested, please contact me off list.

-Andy






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Re: [time-nuts] Questions about Austron 5000 Loran C receiver

[Andy Lokken]

Bill:

No need to apologize. This has all been a positive experience for me. Had I
not taken that receiver, I  might not have learned everything I have
learned about Loran C in the last several weeks. And the other equipment
you gave me is in use and works great, by the way.

This list is a great resource.

Maybe the '5000 finds a new home... or maybe I part it out It's still
all a plus on this end.

Best regards,
Andy





On Sat, Mar 3, 2012 at 10:32 PM, Bill Hawkins b...@iaxs.net wrote:

 Andy, I'm truly sorry this didn't go anywhere, in spite of Forster's
 attempt to hijack the thread. You got more replies from heavy hitters
 than I ever did. (Excuse me, Magnus, if you do not consider yourself
 as a heavy hitter.)

 What you have is a device that has a CRT display and Nixie displays,
 an antenna connection, and several 50 pin connectors. A creative
 bit banger could make a marvelous display from this unit. Truly
 creative bit bangers are hard to find these days.

 Have I challenged anybody here? Andy is one of the good guys.

 Bill Hawkins


 -Original Message-
 From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
 Behalf Of Andy Lokken
 Sent: Saturday, March 03, 2012 10:09 PM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Questions about Austron 5000 Loran C receiver

 Thanks to all who replied. I think I'm in over my head with this one. There
 are far easier ways for me to try to receive Loran C, and I have no
 shortage of projects.

 So... Forgive me if this is not allowed on this reflector...

 Free to a good home (after shipping): One Austron 5000 Loran C receiver.
 Untested. Decent physical condx. See earlier post from me for a link to
 photos.

 If interested, please contact me off list.

 -Andy



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