Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Jeremy Nichols]

That is a good suggestion, Dana. My Prologix GPIB-to-Ethernet adapter is
made in a plastic case, so it certainly could radiate if it chose to do so.
I'll have to sniff around sometime while it's operating.

Jeremy

On Sat, Nov 18, 2017 at 5:27 PM, Dana Whitlow  wrote:

> Beware-
>
> Many GPIB-to-Ethernet adapters are also very prolific RFI generators-
> learned the hard way at Arecibo.
>
> Dana
>
>
> On Sat, Nov 18, 2017 at 5:03 PM, Bob Bownes  wrote:
>
> >
> > All GPIB to Ethernet adapters are not created equal.
> >
> > The NI GPIB-E is no longer supported for example, only the 100 & 1000.
> >
> > Which is very annoying to those that have one.
> >
> > Bob
> >
> >
> >
> > > On Nov 18, 2017, at 17:45, Bob kb8tq  wrote:
> > >
> > > Hi
> > >
> > > Given all the nonsense with USB drivers / “fake" serial chips / OS
> > restrictions ….
> > > The ethernet solution makes a lot of sense.
> > >
> > > Bob
> > >
> > >> On Nov 18, 2017, at 4:45 PM, jimlux  wrote:
> > >>
> > >> On 11/18/17 11:04 AM, Attila Kinali wrote:
> > >>> Hi,
> > >>> I have a need for a GBIP adapter that I can use with Linux.
> > >>> It shouldn't be too expensive, but I rather spend a few bucks
> > >>> more for ease of use. Where "ease of use" means I don't have
> > >>> problems with weird drivers on Linux (Windows doesn't matter at all).
> > >>> I do not mind writing my own read-out software (that's quickly and
> > >>> easily done). What would people here recommend?
> > >>
> > >> I use the Prologix GPIB to Ethernet converters.
> > >>
> > >> Makes it "platform independent" since it's just an IP socket to the
> > outside world
> > >> ___
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> > >> and follow the instructions there.
> > >
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Dana Whitlow]

Beware-

Many GPIB-to-Ethernet adapters are also very prolific RFI generators-
learned the hard way at Arecibo.

Dana


On Sat, Nov 18, 2017 at 5:03 PM, Bob Bownes  wrote:

>
> All GPIB to Ethernet adapters are not created equal.
>
> The NI GPIB-E is no longer supported for example, only the 100 & 1000.
>
> Which is very annoying to those that have one.
>
> Bob
>
>
>
> > On Nov 18, 2017, at 17:45, Bob kb8tq  wrote:
> >
> > Hi
> >
> > Given all the nonsense with USB drivers / “fake" serial chips / OS
> restrictions ….
> > The ethernet solution makes a lot of sense.
> >
> > Bob
> >
> >> On Nov 18, 2017, at 4:45 PM, jimlux  wrote:
> >>
> >> On 11/18/17 11:04 AM, Attila Kinali wrote:
> >>> Hi,
> >>> I have a need for a GBIP adapter that I can use with Linux.
> >>> It shouldn't be too expensive, but I rather spend a few bucks
> >>> more for ease of use. Where "ease of use" means I don't have
> >>> problems with weird drivers on Linux (Windows doesn't matter at all).
> >>> I do not mind writing my own read-out software (that's quickly and
> >>> easily done). What would people here recommend?
> >>
> >> I use the Prologix GPIB to Ethernet converters.
> >>
> >> Makes it "platform independent" since it's just an IP socket to the
> outside world
> >> ___
> >> time-nuts mailing list -- time-nuts@febo.com
> >> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> >> and follow the instructions there.
> >
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Leo Bodnar]

USB Prologix works fine with pyvisa on both Mac and Windows for me - 
http://pyvisa.readthedocs.io/en/stable/
I am still trying to shake off memories of NI VISA - even python is better.
Leo

On 18 Nov 2017, at 16:14, time-nuts-requ...@febo.com wrote:
> From: Tim Lister
> As mentioned by others the Prologix works fine in e.g. Timelab but is not 
> supported by NI VISA code or things like the linux-gpib code.
> Tim

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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Bob Bownes]

All GPIB to Ethernet adapters are not created equal. 

The NI GPIB-E is no longer supported for example, only the 100 & 1000. 

Which is very annoying to those that have one. 

Bob



> On Nov 18, 2017, at 17:45, Bob kb8tq  wrote:
> 
> Hi
> 
> Given all the nonsense with USB drivers / “fake" serial chips / OS 
> restrictions …. 
> The ethernet solution makes a lot of sense.
> 
> Bob
> 
>> On Nov 18, 2017, at 4:45 PM, jimlux  wrote:
>> 
>> On 11/18/17 11:04 AM, Attila Kinali wrote:
>>> Hi,
>>> I have a need for a GBIP adapter that I can use with Linux.
>>> It shouldn't be too expensive, but I rather spend a few bucks
>>> more for ease of use. Where "ease of use" means I don't have
>>> problems with weird drivers on Linux (Windows doesn't matter at all).
>>> I do not mind writing my own read-out software (that's quickly and
>>> easily done). What would people here recommend?
>> 
>> I use the Prologix GPIB to Ethernet converters.
>> 
>> Makes it "platform independent" since it's just an IP socket to the outside 
>> world
>> ___
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> 
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Bob kb8tq]

Hi

Given all the nonsense with USB drivers / “fake" serial chips / OS restrictions 
…. 
The ethernet solution makes a lot of sense.

Bob

> On Nov 18, 2017, at 4:45 PM, jimlux  wrote:
> 
> On 11/18/17 11:04 AM, Attila Kinali wrote:
>> Hi,
>> I have a need for a GBIP adapter that I can use with Linux.
>> It shouldn't be too expensive, but I rather spend a few bucks
>> more for ease of use. Where "ease of use" means I don't have
>> problems with weird drivers on Linux (Windows doesn't matter at all).
>> I do not mind writing my own read-out software (that's quickly and
>> easily done). What would people here recommend?
> 
> I use the Prologix GPIB to Ethernet converters.
> 
> Makes it "platform independent" since it's just an IP socket to the outside 
> world
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[jimlux]

On 11/18/17 11:04 AM, Attila Kinali wrote:

Hi,

I have a need for a GBIP adapter that I can use with Linux.
It shouldn't be too expensive, but I rather spend a few bucks
more for ease of use. Where "ease of use" means I don't have
problems with weird drivers on Linux (Windows doesn't matter at all).
I do not mind writing my own read-out software (that's quickly and
easily done). What would people here recommend?


I use the Prologix GPIB to Ethernet converters.

Makes it "platform independent" since it's just an IP socket to the 
outside world

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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Tim Lister]

On Nov 18, 2017 11:05, "Attila Kinali"  wrote:

Hi,

I have a need for a GBIP adapter that I can use with Linux.
It shouldn't be too expensive, but I rather spend a few bucks
more for ease of use. Where "ease of use" means I don't have
problems with weird drivers on Linux (Windows doesn't matter at all).
I do not mind writing my own read-out software (that's quickly and
easily done). What would people here recommend?


As mentioned by others the Prologix works fine in e.g. Timelab but is not
supported by NI VISA code or things like the linux-gpib code.

Tim



Attila Kinali
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Adrian Godwin]

The Galvant adapter appears to use a very similar protocol to the Prologix,
but I'm unsure if it's exactly compatible.

There have been large numbers of HP adapters on ebay - they're generally
thought to be clones of varying quality.

http://www.galvant.ca/#!/store
http://www.eevblog.com/forum/testgear/flood-of-new-agilent-82357b-gpib-usb-adaptors-on-ebay-the-real-deal/150/

On Sat, Nov 18, 2017 at 8:16 PM, Hal Murray  wrote:

>
> att...@kinali.ch said:
> > I have a need for a GBIP adapter that I can use with Linux. It shouldn't
> be
> > too expensive, but I rather spend a few bucks more for ease of use. Where
> > "ease of use" means I don't have problems with weird drivers on Linux
>
> I've been happy with the Prologix.  It may not be as low cost as you would
> like.
>
> It uses one of the common USB-Serial chips, so there is no problem with
> drivers on Linux.
>
> It needs hardware flow control or long-enough pauses in the right places.
> That was the only problem I had getting started.
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Hal Murray]

att...@kinali.ch said:
> I have a need for a GBIP adapter that I can use with Linux. It shouldn't be
> too expensive, but I rather spend a few bucks more for ease of use. Where
> "ease of use" means I don't have problems with weird drivers on Linux

I've been happy with the Prologix.  It may not be as low cost as you would 
like.

It uses one of the common USB-Serial chips, so there is no problem with 
drivers on Linux.

It needs hardware flow control or long-enough pauses in the right places.  
That was the only problem I had getting started.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Gerhard Hoffmann]

I have bought a Prologix GPIB/USB controller. There is a LAN version also.

The German distributor is stantronic.de.

You can get mine for a limited time to see if it fits. I was able to solve

my own problem via LAN w/o adapter.

regards, Gerhard




Am 18.11.2017 um 20:04 schrieb Attila Kinali:

Hi,

I have a need for a GBIP adapter that I can use with Linux.
It shouldn't be too expensive, but I rather spend a few bucks
more for ease of use. Where "ease of use" means I don't have
problems with weird drivers on Linux (Windows doesn't matter at all).
I do not mind writing my own read-out software (that's quickly and
easily done). What would people here recommend?


Attila Kinali


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Re: [time-nuts] Recommendation for cheap GBIP adapter for Linux

[Bob Albert via time-nuts]

 Someone has been selling one of these at a reasonably low price on ebay but I 
don't know anyone who has used it.
Bob
On Saturday, November 18, 2017, 11:05:09 AM PST, Attila Kinali 
 wrote:  
 
 Hi,

I have a need for a GBIP adapter that I can use with Linux.
It shouldn't be too expensive, but I rather spend a few bucks
more for ease of use. Where "ease of use" means I don't have
problems with weird drivers on Linux (Windows doesn't matter at all).
I do not mind writing my own read-out software (that's quickly and
easily done). What would people here recommend?


            Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                -- Miss Matheson, The Diamond Age, Neil Stephenson
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[time-nuts] Recommendation for cheap GBIP adapter for Linux

[Attila Kinali]

Hi,

I have a need for a GBIP adapter that I can use with Linux.
It shouldn't be too expensive, but I rather spend a few bucks
more for ease of use. Where "ease of use" means I don't have
problems with weird drivers on Linux (Windows doesn't matter at all).
I do not mind writing my own read-out software (that's quickly and
easily done). What would people here recommend?


Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
 -- Miss Matheson, The Diamond Age, Neil Stephenson
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Bob kb8tq]

Hi


> On Nov 18, 2017, at 5:38 AM, Magnus Danielson  
> wrote:
> 
> Hi,
> 
> On 11/18/2017 02:16 AM, Hal Murray wrote:
>> kb...@n1k.org said:
>>> Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk�
>>> accuracy with a GPSDO. Much easier to obtain and set up in a school
>>> environment. The key will be orbit estimation for the +/- doppler part of
>>> it.  Orbit estimation is not quite a slam dunk sort of thing. The GPSDO
>>> would also give accurate location. Even with good orbit data, the solution
>>> still requires a good location estimate.
>> What is the orbital period?  It would be fun to plot the Doppler over time
>> and see if you can get something that looks like a big chunk of an orbit.
>> Ugh.   What is the Doppler due to the Earth's rotation?
> 
> You need to compensate for your position, because it would lower due to 
> longitude naturally.
> 
> Yeah, and then the moon isn't in perfect circular orbit either.

Effectively you have multiple things spinning around in various ways. The 
“orbit” isn’t a single thing
in this case. Earth gravity “lumps and bumps” impact GPS orbits. There are a 
lot of things to have
lumps and bumps in this caae. Depending on the orbit relative to this and that, 
you may have a fairly 
limited observation time on each pass. This and that accumulate on the “dark” 
part of the orbit, but 
you can’t observe it as it happens. You simply see a jump (versus prediction) 
at the start of the next
pass.

Bob

> 
> The sat is also in a not so perfect orbit, so it would also needed to be 
> measured and characterized.
> 
> Fun problem.
> 
> I realized that my on the fly least square algorithms would be nice to adapt 
> to this problem.
> 
> Cheers,
> Magnus
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Tim Shoppa]

Orbital determination from Doppler shift is, IMHO, a far more interesting
and fun STEM project than measuring an absolute frequency. And it does not
require MASERs, it only requires low-grade amateur equipment.

Amateur "Crowdsourcing" of orbital data goes at least as far back to ARRL
collecting Sputnik reception reports both by traffic nets and audio tape.

Doppler shift for a VHF transmitter in low earth orbit is several 10's of
kHz over a period of minutes and this pass-information is incredibly useful
for orbit determination.

And science and technology students have been participating in these
determinations for decades too. A very nice review of the work done 25
years ago by students, was published in QST by N6XT:
http://www.setileague.org/articles/ham/kepler.pdf

Tim N3QE
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Re: [time-nuts] Interpreting and Understanding Allen Deviation Results

[Magnus Danielson]

Hi Randal,

On 11/15/2017 05:12 PM, CubeCentral wrote:

The results are shown here:  [ https://i.imgur.com/0sMVMfk.png ]  The
associated .TIM files are available upon request.


As mentioned before, the preferred way of doing this is to do a time 
interval measurement between a start and a stop signal.


Typically you trigger on the GPSDO PPS output as a start signal and then 
stop with another signal. That way the time-base for re-trigger does not 
care as long as it is shorter than a PPS period.



So, now we get to the heart of the matter and the questions this test and
results have raised.
I am trying to understand what the data is telling me about the test, and
therefore the character of the counter.

1)  Why are the plots a straight line from ~0.25s until ~100s?


The straight line slope, we call it 1/tau slope, is typically due to 
white phase noise and the counter time-quantization. Without going into 
details about how they mix, you often find that slew-rate limiting and 
non-ideal trigger-point can push this limit upwards. One reason for 
slew-rate limiting is low amplitude while the trigger point should be 
somewhere with a high slew-rate, that is quick change of voltage per 
time unit.


The starting-point of ~0.25 s is due to time-base setting in your setup, 
and it would not surprise me if the different levels is due to slight 
different time-base settings. Avoid using the time-base like that using 
the trick above.


Also, one should make sure that one get all the samples, they can play 
havoc with you.


The slope ends when other noise-formms become strong enough to reach 
over the slope. We try to use better counters to push this slope 
downwards, such that we can see the other noises for shorter 
time-intervals. If you don't really care about ADEV until 100 s or so, 
you are fine.



2)  Why, after falling at the start, do the plots all seem to go back up
from ~100s to ~1000s?


That's where thermmal of A/Cs, house heating etc. starts to come in.
Also, the top part of the plot should not be too much trusted, it needs 
to run for a time to average out other noiseforms that obstruct the 
reading of a particular tau. Another way of saying this is that the 
confidence interval is very high for the top taus, and decreases.



3)  What do the "peaks" mean, after the plot has fallen and begin to rise
again?
4)  Why is the period from ~1000s to ~1s so chaotic?


These probably is a combination of thermal and lack of convergence 
effects. I would try to redo the measurement as described above, you 
should get more consistent results.



5)  The pattern "Fall to a minimum point, then rise to a peak, then fall
again" seems to be prevalent.  What does that indicate?


Cyclic disturbances such as a house heater or A/C can create such patterns.


6)  Why does that pattern in question (5) seem to repeat sometimes?  What is
that showing me?


You should be looking at the phase-plot, I expect you to see a few 
cycles of some pattern there. As you look at different distances they 
self-correlate or not at different multiples of time, as cyclic or 
semi-cyclic patterns tend to do. ADEV was never made to handle such 
systematic noises, so you need to cancel them out as they form an 
disturbance to your measurement.



And finally, some general questions about looking at these plots.
a)  Would a "perfect" plot be a straight line falling from left to right?
(Meaning a hypothetical "ideal" source with perfect timing?)
b)  Is there some example showing plots from two different sources that then
describes why one source is better than the other (based upon the ADEV
plot)?


You can expect a 1/tau slpoe from the source, to can expect it to 
flatten out and you can expect an sqrt tau slope up before hitting the 
tau slope, which often is obstructed by the tau slope from linear drift 
of oscillator. The later usually settles down.


The amplitude of these slopes represents the noise level of different 
noise types, but can only be seen once systematics have been reduced to 
negligable.



c)  I believe that if I understood the math better, these types of plots
would be more telling.  Without having to dive back into my college Calculus
or Statistics books, is there a good resource for me to be able to
understand this better?


The math behind these is kind of difficult if you are somewhat out of 
tune, but look at the Allan deviation wikipedia article, I tried to give 
some clues there.



Lastly, thank you for your patience and for keeping this brain-trust alive.
I am quite grateful for all the time and energy members pour into this list.
The archives have been a good source of learning material.


As it should be. Be patient, try to learn from mistakes and you will 
pick up and learn tricks of trade. What you have in toys suffice to 
learn a lot useful stuff and get hands on practice.


Cheers,
Magnus
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Re: [time-nuts] How good is your ADEV at 10E7 seconds? :)

[Magnus Danielson]

On 11/18/2017 12:16 PM, Attila Kinali wrote:

On Fri, 17 Nov 2017 17:54:51 -0800
Hal Murray  wrote:


LIGO only works for roughly the audio spectrum.  At the low and high ends,
the noise goes up.  Lots of people are working on how to build gear that will
work at other wavelengths.


I was wondering about those limits, when i saw the plots.
Though, is it really the time/frequency source that defines
the detection limit?


If your laser bounces 10 times in a 4 km tunnel to detect things, 
speed of light will limit the effective bandwidth.


Thermal noise plucking the silica fibre suspension creates a noise floor.

There is no cesium or H-maser at LIGO, they use GPS, we sure asked.

Cheers,
Magus
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Attila Kinali]

On Fri, 17 Nov 2017 13:26:18 -0800
Patrick Barthelow  wrote:

>  I am a member of  Team Alpha Cubesat.  We and some other teams are in the
> NASA CUBEQUEST challenge.  Launching next year a 6u  cubesat to lunar
> orbit.  I am not an expert at the freq measurement aspect of this, so, I am
> a Newbie. With tons of questions, but  I was surprised how quickly a check
> of the world's Hydrogen line MASERS got many to offer to come on board.
> MASER is overkill, but that is OK.  The Chief Scientist of the project is
> in the USA and wants to make measurements to the HZ level, at 437 mhz so
> with MASERS and Cesium, Rubidium we are overkill but it could generate
> STEM/Citizen Science participation.  That is what we are doing.  So the
> satellite will be on 437.5 mhz  plus  minus doppler.

Is there a scientific experiment behind this? Or is it just a cool
thing to show?


> I was surprised
> they did not just say go away... a half million dollar MASER is, or should
> be busy with similar but necessary measurements from paying customers.

It's not like you are taking away maser-time from someone else.
At most you are using one of the free output ports of the distribution
amplifier.

> This is like a modern day Frequency Measurement Test that ARRL did years
> ago.  I will in fact call ARRL to see if they want to play in this.

They are still running those. And quite a few get within 1Hz under more
difficult conditions than measuring a satellites frequency.

> And now know a school in Europe a Technical Instrumentation
> school, that offers a project to build a Hydrogen Line Maser using modern
> simpler, cheaper methods and hardware.

Oh? Really? Which school is that? And is the documentation to this
project available somewhere?


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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Re: [time-nuts] How good is your ADEV at 10E7 seconds? :)

[Attila Kinali]

On Fri, 17 Nov 2017 17:54:51 -0800
Hal Murray  wrote:

> LIGO only works for roughly the audio spectrum.  At the low and high ends, 
> the noise goes up.  Lots of people are working on how to build gear that will 
> work at other wavelengths.

I was wondering about those limits, when i saw the plots.
Though, is it really the time/frequency source that defines
the detection limit?

> One proposal is to monitor pulsars.  There might be stuff leftover from the 
> big bang with a period of a year or so.  If you can get good timing from a 
> pulsar, you might be able to see it.  I suspect that will take "good" timing 
> to a scale that would astonish most time-nuts.

I think going with a 2-4 5071s and a Cs or Rb fountain to keep them
on frequency would be the easier thing to do. For additional short
term performance, throw in an active H-maser.

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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Re: [time-nuts] How good is your ADEV at 10E7 seconds? :)

[Jim Palfreyman]

Approximately 6% of pulsars "glitch" and yes these (typically young)
pulsars are poor time standards. The glitching is most likely caused by
unpinning of vortices in the superfluid outer core. This causes a momentum
transfer from the core to the crust - and a speed-up. The Vela pulsar (freq
of ~11 Hz) is the most famous of the glitching pulsars as it glitches
regularly (approximately every three years). The last glitch of Vela (Dec
2016) had a deltaF/F of about 1.4E-6.

However millisecond pulsars are completely different. They spin at hundreds
of Hz, typically don't glitch, and PSR J0437-4715 will give many atomic
clocks a run for their money. It has an error in its period (5.75 ms) of
9.9E-17 and an error in its period derivative of 9E-26. The idea was to
monitor an array of millisecond pulsars and use this to detect
gravitational waves. For many years it was a race between LIGO and the
pulsar array to find GW. LIGO won.

Incidentally, LIGO has looked for GW coming from a pulsar. Vela was chosen
as its frequency is in the LIGO sweet spot. Nothing was found however (
https://arxiv.org/pdf/1104.2712.pdf) - but this was 7 years ago.


Jim





On 18 November 2017 at 13:24, Bob kb8tq  wrote:

> Hi
>
> There are a number of papers on pulsars as time standards. The gotcha
> in the observed data (that has been measured over long time periods) has
> been random frequency jumps. Put another way, 10 million seconds and
> beyond *is* the problem. It’s going to take a *lot* of monitoring for a
> very long
> time to convince people that a specific pulsar is a good idea.
>
> Bob
>
> > On Nov 17, 2017, at 8:54 PM, Hal Murray  wrote:
> >
> >
> > Context is the what-next portion of a recent LIGO talk.  For those of you
> > that missed it (or didn't pay enough attention), on Aug 17th, they got
> good
> > data from a pair of neutron stars.  1.7 seconds later, the Fermi
> satellite
> > got a gamma ray burst.  Within a day, the optical guys had found a new
> spot.
> > Over the next days and weeks, they got data over the whole spectrum,
> radio to
> > X-rays.  (There were 70 observatories lined up to pounce.  Everybody
> wanted
> > in on the action.)
> >
> > LIGO only works for roughly the audio spectrum.  At the low and high
> ends,
> > the noise goes up.  Lots of people are working on how to build gear that
> will
> > work at other wavelengths.
> >
> > One proposal is to monitor pulsars.  There might be stuff leftover from
> the
> > big bang with a period of a year or so.  If you can get good timing from
> a
> > pulsar, you might be able to see it.  I suspect that will take "good"
> timing
> > to a scale that would astonish most time-nuts.
> >
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
> > ___
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>
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Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

[Magnus Danielson]

Hi,

On 11/18/2017 02:16 AM, Hal Murray wrote:


kb...@n1k.org said:

Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk�
accuracy with a GPSDO. Much easier to obtain and set up in a school
environment. The key will be orbit estimation for the +/- doppler part of
it.  Orbit estimation is not quite a slam dunk sort of thing. The GPSDO
would also give accurate location. Even with good orbit data, the solution
still requires a good location estimate.


What is the orbital period?  It would be fun to plot the Doppler over time
and see if you can get something that looks like a big chunk of an orbit.

Ugh.   What is the Doppler due to the Earth's rotation?


You need to compensate for your position, because it would lower due to 
longitude naturally.


Yeah, and then the moon isn't in perfect circular orbit either.

The sat is also in a not so perfect orbit, so it would also needed to be 
measured and characterized.


Fun problem.

I realized that my on the fly least square algorithms would be nice to 
adapt to this problem.


Cheers,
Magnus
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