Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

I can't recall what I said before, but it *has* been done in the backyard
before. There's good news and bad news. The good news is that all the
software for processing your data: coherent dedispersion, folding, moving
all arrival times to the solar system barycentre, Einstein delay, Shapiro
delay, fitting, analysis etc is open source. You need DSPSR, PSRCHIVE, and
TEMPO2 and a unix machine to run them on.

The bad news:

Vela had a declination of -45 10 35 which means it's not visible very often
for you northerners. The second brightest pulsar has a similar declination.
After that, forget it - they are too faint.

Observing of individual pulses requires around a 20+ m radio telescope with
a receiver cooled to 20K (at ~1400 MHz). However using the above software
you can fold your data on the latest pulse period (which I can provide if
needed) and this then brings things down to a possible level:

You'll need a dish that can track. One that is 2 m across might just work.
Frequency choice is important. The lower the frequency the stronger the
pulse, but also multipath scattering smears the pulse out. Around 1400 MHz
is a good choice for removing the scattering, but may be too faint for
small dishes. If you went with ~600 MHz that could work - but do check any
local RFI.

If you didn't track, but just waited for the pulsar to pass through the
beam, you'd get about 2 minutes of data. That *might* be enough to fold and
get a signal.

It'd be a long, but awesome, project to work on.

The really cool part is that Vela glitches (speeds up) in rotation ~3 years
by around deltaf/f =10^-6 and you could measure that. It just glitched in
December (and I was observing at the time!), so you have another 3 years to
get building.

As to timing, any half decent GPSDO would be fine.

Oh, almost forgot, you'd also need a sampler.


Jim Palfreyman



On 26 January 2017 at 13:58, Tom Van Baak  wrote:

> > What can I do at home, to observe such processes? Or is it way beyond
> > any imagination to participate in any such experiments?
> >
> > Volker
>
> LIGO is a billion dollar experiment, involving thousands of PhD's so it
> will be some time until you can do that sort of stuff alone at home, or
> with your family.
>
> Jim Palfreyman has mentioned before what it would take to do Pulsar
> measurements as a home experiment. Search for the old threads or he can
> jump in to remind us why it can't or hasn't been done yet. See also the
> thread a month ago about a DIY H-masers since you'll want some of them on
> hand before you start.
>
> It's worth spending time reading anything about LIGO. The experiment is
> out-of-this-world clever, complex, sensitive. And it actually works! Unlike
> the particle physics tree, which seems to be nearing the end of bearing
> fruit, LIGO is at the very beginning of an entirely new way to study the
> universe.
>
> /tvb
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Re: [time-nuts] How good is the left end of your ADEV curve?

[jimlux]

On 1/25/17 6:58 PM, Tom Van Baak wrote:

What can I do at home, to observe such processes? Or is it way beyond
any imagination to participate in any such experiments?

Volker


LIGO is a billion dollar experiment, involving thousands of PhD's so it will be 
some time until you can do that sort of stuff alone at home, or with your 
family.

Jim Palfreyman has mentioned before what it would take to do Pulsar 
measurements as a home experiment. Search for the old threads or he can jump in 
to remind us why it can't or hasn't been done yet. See also the thread a month 
ago about a DIY H-masers since you'll want some of them on hand before you 
start.

It's worth spending time reading anything about LIGO. The experiment is 
out-of-this-world clever, complex, sensitive. And it actually works! Unlike the 
particle physics tree, which seems to be nearing the end of bearing fruit, LIGO 
is at the very beginning of an entirely new way to study the universe.



I wonder if there are ways to do this kind of science in a massively 
parallel way.. rather than the "one big awesomely high performing 
instrument" you have a million mediocre instruments...


Of course, I know that doesn't always work, otherwise we could just buy 
1000 cheap crystals and tell the maser folks to peddle their wares 
elsewhere 


But, as in many other endeavors, there's a limit to "how big/fast/good" 
a single device can be, and you have to go to multiple devices - there's 
always complexity and a learning curve, but eventually there is success:



One big power grid tube is better than many smaller ones, but 
eventually, you hit the maximum size tube, and if you need more power 
there's nowhere else to go but multiples.


Scientific computation hit the "single processor" wall, ultimately 
resulting in the development of modern Beowulf cluster computers, which 
in turn forced the development of new algorithms and reformulating the 
underlying problem to allow such large clusters to be useful (Amdahl's 
law, and all), and now things like exascale computing are becoming reality.



I've thought about whether one could do amateur radio Venus bounce or 
Mars bounce, with a distributed transmitter/receiver system, timed by 
GPS, so that you can do coherent processing.



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Re: [time-nuts] How good is the left end of your ADEV curve?

[Tom Van Baak]

> What can I do at home, to observe such processes? Or is it way beyond 
> any imagination to participate in any such experiments?
> 
> Volker

LIGO is a billion dollar experiment, involving thousands of PhD's so it will be 
some time until you can do that sort of stuff alone at home, or with your 
family.

Jim Palfreyman has mentioned before what it would take to do Pulsar 
measurements as a home experiment. Search for the old threads or he can jump in 
to remind us why it can't or hasn't been done yet. See also the thread a month 
ago about a DIY H-masers since you'll want some of them on hand before you 
start.

It's worth spending time reading anything about LIGO. The experiment is 
out-of-this-world clever, complex, sensitive. And it actually works! Unlike the 
particle physics tree, which seems to be nearing the end of bearing fruit, LIGO 
is at the very beginning of an entirely new way to study the universe.

/tvb
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Bob Camp]

> On Jan 25, 2017, at 12:15 AM, Hal Murray  wrote:
> 
> way way way left.
> 
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In case 
> you don't recognize the name, he is one of the leaders of the LIGO project 
> that detected gravity waves about a year ago.
> 
> He's a good speaker with a neat topic.  He spent a lot of time giving credit 
> to other people.
> 
> One of the far-out future ideas he mentioned was collecting data on lots of 
> pulsars.  If you could get good enough data, maybe you could see gravity 
> waves wandering around the universe.  (Maybe leftover from the big bang.  I 
> didn't catch that part.)
> 
> The time scale is months or years.  Micro Hertz.  The unit for wavelength 
> would be light-years.

….. errr … would not that be the *right* end of the ADEV curve? …..:)

Back in the 1980’s these guys were after sub 1x10^-15 bumps over path 
distances like Earth to Jupiter. Not sure what they are after these days. 

Bob

> 
> How long will it be before we need a gravity-nuts list?
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] How good is the left end of your ADEV curve?

[Volker Esper]

What can I do at home, to observe such processes? Or is it way beyond 
any imagination to participate in any such experiments?


Volker


Am 25.01.2017 um 06:15 schrieb Hal Murray:

...

How long will it be before we need a gravity-nuts list?



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Re: [time-nuts] How good is the left end of your ADEV curve?

[Jim Palfreyman]

First, a picky - but important - point. There is a difference between
"gravity waves" and "gravitational waves". When you go to the beach and
watch the waves crash on the shore, that's an example of a gravity wave.

Now, onto the far more interesting topic of gravitational waves and my pet
topic, pulsars.

Pulsars most likely give off gravitational waves. The rotate at a rate
anywhere from 1/12 Hz to 716 Hz. The brightest (in a radio sense) and one
of the closest pulsars is the Vela pulsar which rotates at 11.18677266 Hz
(as of a few days back). This frequency is in the sensitivity bands of
Advanced LIGO and Advanced VIRGO, but the gravitational waves from Vela are
probably too "faint" to be detected. But there is still no harm in trying.


Jim Palfreyman



On 25 January 2017 at 16:15, Hal Murray  wrote:

> way way way left.
>
> Ray Weiss was the speaker at the Stanford Physics Colloquium today.  In
> case
> you don't recognize the name, he is one of the leaders of the LIGO project
> that detected gravity waves about a year ago.
>
> He's a good speaker with a neat topic.  He spent a lot of time giving
> credit
> to other people.
>
> One of the far-out future ideas he mentioned was collecting data on lots of
> pulsars.  If you could get good enough data, maybe you could see gravity
> waves wandering around the universe.  (Maybe leftover from the big bang.  I
> didn't catch that part.)
>
> The time scale is months or years.  Micro Hertz.  The unit for wavelength
> would be light-years.
>
> How long will it be before we need a gravity-nuts list?
>
> --
> These are my opinions.  I hate spam.
>
>
>
> ___
> time-nuts mailing list -- time-nuts@febo.com
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> mailman/listinfo/time-nuts
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>
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Re: [time-nuts] Autodesk Eagle -- maybe they're listening

[Dan Kemppainen]

Hi,

OK, maybe off topic for this list. It'll be my first and last post on this.

Spent some time on the phone with autodesk. Something interesting came 
out of the conversation. The autodesk rep said that he hasn't heard 
anything but positive feedback about the subscription licensing. (Yeah, 
Yeah, I know...)


He said they have an email address that can be used for feedback. And 
that if anyone is unhappy, they should let them know what their concerns 
are.


support.ea...@autodesk.com

So, please let autodesk know. And foreword this out to other lists and 
people who can also send out a quick note. Autodesk really needs to hear 
how we all feel.


Thanks!

Dan



On 1/24/2017 2:06 AM, time-nuts-requ...@febo.com wrote:

Message: 3
Date: Mon, 23 Jan 2017 17:24:52 -0600
From: "Graham / KE9H" 
To: Discussion of precise time and frequency measurement

Subject: Re: [time-nuts] Autodesk Eagle -- maybe they're listening
Message-ID:

Content-Type: text/plain; charset=UTF-8

Hi John:

It is still an effective tripling or quadrupling of the cost.

I purchased a "non profit" license several years ago for $129.  "Non
commercial, 4 layers, up to 160 sq cm., all functionality enabled."
They converted this to a "standard" license over time.
A license was good for the life of a major version, such as 5 or 6.
When 7 came out, I had to buy a new license for 7, but it was at the
existing customer upgrade price, which was $69.

So $129 initially, then $69 every two or three years or so, as new major
versions came out.
Now they want $100 per year.

--- Graham

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Re: [time-nuts] 5 Mhz NBS Frequency Computers for Sale

[paul swed]

Perry,
I remember those. NBS actually sold them to cal labs. The Navy had one at
the Oakland Ca Naval Air station and they used them to set the AN/URQ10
frequency reference we used on the ship.
There you go 1970s technology.
Regards
Paul
WB8TSL

On Wed, Jan 25, 2017 at 2:23 PM, Perry Sandeen via time-nuts <
time-nuts@febo.com> wrote:

> List,
> I'm culling my too extensive test equipment inventory.
> I have two NBS System 358 Frequency Measurement Computers for sale
> It works like this:  You have a 5 MHz "A" input for your standard and a 5
> MHz "B" input for the DUT.
> The computer has a "B" offset output that multiplies the error to 3000 x
> 10^ -11.
> The person who acquired them from NBS surplus sale was the late Clyde
> Still of Colorado Springs CO who ran a local frequency calibration and
> measuring service on the side as he was a shift transmitter engineer for a
> local TV station on top of Pikes Peak.
> I acquired them from a third party. They were originally sold at the NBS
> excess inventory sale in Ft. Collins, CO as working units, but I haven't
> had the round-to-it's to use them.
> The PS has a number of small electrolytic caps that should probably we
> replaced before using. I have no schematics or data for them.
> They measure about 12 inches long by 9 1/2 inches wide and 2 1/2 inches
> thick and weigh about 6 pounds each.
> Asking $70 each PLUS shipping from 92220 or $120 for both plus shipping.
> Please contact me off list.
> Regards,
> Perrier
>
>
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[time-nuts] 5 Mhz NBS Frequency Computers for Sale

[Perry Sandeen via time-nuts]

List,
I'm culling my too extensive test equipment inventory.
I have two NBS System 358 Frequency Measurement Computers for sale
It works like this:  You have a 5 MHz "A" input for your standard and a 5 MHz 
"B" input for the DUT.
The computer has a "B" offset output that multiplies the error to 3000 x 10^ 
-11.
The person who acquired them from NBS surplus sale was the late Clyde Still of 
Colorado Springs CO who ran a local frequency calibration and measuring service 
on the side as he was a shift transmitter engineer for a local TV station on 
top of Pikes Peak.
I acquired them from a third party. They were originally sold at the NBS excess 
inventory sale in Ft. Collins, CO as working units, but I haven't had the 
round-to-it's to use them.
The PS has a number of small electrolytic caps that should probably we replaced 
before using. I have no schematics or data for them.
They measure about 12 inches long by 9 1/2 inches wide and 2 1/2 inches thick 
and weigh about 6 pounds each.
Asking $70 each PLUS shipping from 92220 or $120 for both plus shipping.
Please contact me off list.
Regards,
Perrier


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Re: [time-nuts] [No sat positions in LH with Trimble NTBW50AA? SOLVED!

[Brad Dye]

Gents: I really enjoy reading the postings from this group. It’s like going 
back to school sometimes. I am a longtime user of Lady Heather with a Trimble 
Thunderbolt and recently updated the program to V5.00.

For some unknown reason I am not receiving time or sat location info. LH does 
appear to be talking to the Thunderbolt since some of the info is in white 
letters. I have tried lots of commands with no joy. Computer is the same laptop 
I have always used running Win. 7.

I have tried a second Thunderbolt and a second antenna — still no luck — since 
it looked like the GPS receiver portion of the GPSDO isn’t working.

Does anyone have any suggestions to help out an “OM” with emphasis on the “O.” 

Here is my setup: http://www.braddye.com/gps_do.html

73

Brad Dye, K9IQY
ex KN9IQY, KN4BK, KM5NK, WB4JCF, ZP5TQ, WA4VXU, WA9RVL, HH2FJ /TI2, /9Y4, /6Y5, 
/KP4
60 years as a licensed amateur radio operator
43 years since licensed as a First Class Commercial radio operator/engineer

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[time-nuts] HP 58503A GPS time and frequency receiver - How do I determine why the ALARM LED is on?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

I've got an HP 58503A purchased from China a couple of years ago. It has a
bit of a hard life, having been in water at some time. But it seems to work
ok, as far as I can tell. Today there was a power failure for 5 minutes or
so. The red ALARM LED is on. It is not clear to me why, although of course
I'm aware there was a power outage, which almost certainly caused this,
although I can't be 100% sure.

Could it be that the log is full? I had a program running trying to get the
position multiple times in a loop, to get some sort of average, so I can
well believe I filled the log up. But this was a few weeks ago. The log is
clearly full .

scpi > diag:log:read:all?
Log status: Full

Log 001:19970504.00:00:00:  Log cleared
Log 002:19970504.00:00:00:  System preset
Log 003:19970504.00:00:00:  Power on

Log 219:20170107.05:30:17:  Position hold mode started
Log 220:20170107.05:30:57:  Holdover started, not tracking GPS
Log 221:20170107.05:31:03:  Survey mode started
Log 222:20170107.05:33:04:  GPS lock started

Nothing has been logged since 7th January. I know for a fact there was a
power outage on the 19th and today (25th), so I suspect the log being full
has NOT caused the ALARM light to come on. A fault, that is not logged, has
caused it.

scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION . [ Outputs
Valid ]
SmartClock Mode ___   Reference Outputs
___
>> Locked to GPS  TFOM 3
FFOM 0
   Recovery   1PPS TI +9.5 ns relative to
GPS
   Holdover   HOLD THR 1.000 us
   Power-up   Holdover Uncertainty

  Predict  432.0 us/initial 24
hrs

ACQUISITION  [ GPS 1PPS
Valid ]
Tracking: 6    Not Tracking: 1    Time

PRN  El  Az   SS   PRN  El  AzUTC  15:03:50 25 Jan
2017
  5  23 186   7324  21 252GPS 1PPS Synchronized to UTC
 13  84 110   81  ANT DLY  0 ns
 15  59 289   94  Position

 20  45 245   96  MODE Hold
 28  51  76  104
 30  27  68   83  LAT  N  51:39:04.155
  LON  E   0:46:36.381
ELEV MASK 20 deg  HGT   +45.55 m
(MSL)
HEALTH MONITOR .. [
ERROR ]
Self Test: Err   Int Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi >


The self-test shows an error, but no indication what the error was, as the
log was full.

I have a fairly good idea what may have happened. Sometimes when the unit
is powered on, the voltages on the PSU appear to go out of spec. I'm not
convinced this is really happening, as a multimeter on peak hold could not
catch any glitch, but I have not tried a fast scope.

I'm just wondering if there's anything else I can do to see what caused the
LED to come on. I suspect if I execute the self-test, it will pass and the
light go out, but I'd rather find the reason before doing that.

Dave
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Re: [time-nuts] Thermal effects on cables

[REEVES Paul]

Hi Attila,

I quite agree, I should have remembered that but I tend to use fairly small 
coax anyway at those frequencies as a matter of course and it didn't register 
as something that needed saying. My fault!
It can be quite difficult to get people to notice the difference between SMA 
and 3.5mm - I have often had to repeatedly remind some of our test technicians 
of the difference as they tend to think they are interchangeable with the 
unfortunate results you describe :-(It is just as well that the 3.5mm cal 
kit for the HP8510 (still a fine VNA, if lacking a few of the new bells and 
whistles) is a work of art with DTIs for checking the mechanical setup of the 
connectors - they are not just for show!

Regards,

Paul Reeves

-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Attila Kinali
Sent: 23 January 2017 19:33
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thermal effects on cables

On Mon, 23 Jan 2017 15:13:39 +
REEVES Paul  wrote:

> Surely the impedance of the cable is only affected by the ratio of the 
> inner conductor and outer conductor diameters modified by the internal 
> dielectric constant, nothing to do with the frequency of operation. 
> You might well have problems converting the larger diameters down to a 
> suitable size for the connectors at the higher frequencies though

If you are only looking at the impedance, then yes. But once you get to high 
frequencies, you get also multi-mode behaviour of the coax cables and 
connectors, which leads to dispersion. That's why people hardly use N 
connectors for GHz frequencies, even though the connector itself would allow 
it. For VNAs where even small phase shifts/instabilities due to multi-mode 
behaviour/dispersion are a no go, the connectors are usually 3.5mm (basically a 
precise version of the SMA), 2.9mm, 2,4mm etc and go down to even 1.0mm which 
can be spec'ed up to 110GHz.

BTW: the 3.5mm connector is one that you will find on many instruments that go 
beyond 1-2GHz. Unfortunately it looks exactly the same as an SMA connector and 
will mate with one. Even more unfortunately, mating it with an SMA connector 
will scar the connector and most likely move it out of spec (ie degrade it to a 
simple SMA connector). If it's just an adapter, you've only lost a bit of money 
(in the order of a few €100).
If it was the connector of your VNA/oscilloscope/..., you might need to send it 
in for an expensive repair.

Attila Kinali

--
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to fit the 
views, which can be uncomfortable if you happen to be one of the facts that 
needs altering.  -- The Doctor ___
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