Offline SteelyBob

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Ring laser gyros
« on: September 07, 2021, 08:13:31 PM »
I noticed that wiki is somewhat brief in its look into RLGs - the data comes from an experiment conducted in the early 20th century, a very early commercial RLG in the the early 1990s, and a MEMs gyro (like the one you would find in a phone, which work on coriolis and not lasers).

I thought people might be interested in this one: https://iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf, which is a large, ultra precise RLG capable of measuring tiny variations in the rotation, as well as the rotation itself.

Given that the wiki rejects the notion of a grand-scale conspiracy (in favour of a smaller space-travel one), are the scientists who wrote this paper and who worked on the device wrong?

Re: Ring laser gyros
« Reply #1 on: September 08, 2021, 02:47:30 AM »
Given that the wiki rejects the notion of a grand-scale conspiracy (in favour of a smaller space-travel one)

In favor of a smaller one that does not involve the shape of the earth.

Quote
are the scientists who wrote this paper and who worked on the device wrong?

Yes, of course - about lots of stuff.  That's just the way human knowledge is, perhaps most notably in science.

Interferometery is very interesting, well worth studying, and somewhat relevant to this subject.

The presumed rotation can be measured with a simple pendulum, as well as any mechanical gyroscope (including the mems, which is not a gyroscope even in a figurative/metaphorical sense)

The rlg works, it just does not work the way the modern scientists imagine it does (they should study its invention, and its inventor) and it does not measure what they presume it does.

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Offline stack

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Re: Ring laser gyros
« Reply #2 on: September 08, 2021, 03:48:24 AM »
The rlg works, it just does not work the way the modern scientists imagine it does (they should study its invention, and its inventor) and it does not measure what they presume it does.

It appears that a fellow named Clifford Heer was the first guy to come up with the RLG concept back in 1961:

Modern Inertial Sensors and Systems
By AMITAVA BOSE, SOMNATH PURI, PARITOSH

"In Chapter 11 we defined the ring laser gyroscope (RLG) as a type of active resonator gyro. Clifford Heer conceived the RLG in 1961 [1]; he saw that the properties of the laser, recently invented by Schawlow and Townes, could be exploited to measure rotation."

How does it "...not measure what they presume it does," if not rotation as originally intended? What's your evidence for such a statement? Or is this just your opinion?

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #3 on: September 08, 2021, 03:57:26 AM »
I noticed that wiki is somewhat brief in its look into RLGs - the data comes from an experiment conducted in the early 20th century, a very early commercial RLG in the the early 1990s, and a MEMs gyro (like the one you would find in a phone, which work on coriolis and not lasers).

I thought people might be interested in this one: https://iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf, which is a large, ultra precise RLG capable of measuring tiny variations in the rotation, as well as the rotation itself.

Given that the wiki rejects the notion of a grand-scale conspiracy (in favour of a smaller space-travel one), are the scientists who wrote this paper and who worked on the device wrong?

I don't think you've read through everything in the Wiki on this. The very paper you linked to is cited on the second Ring Laser Gyroscope page in the section 'Fluctuating Earth Rotation Rate'.

The bottom of this page:

https://wiki.tfes.org/Ring_Laser_Gyroscope

continues onto a second page:

https://wiki.tfes.org/Ring_Laser_Gyroscope_-_Seismology
« Last Edit: September 08, 2021, 04:02:00 AM by Tom Bishop »

Offline SteelyBob

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Re: Ring laser gyros
« Reply #4 on: September 08, 2021, 02:51:13 PM »

I don't think you've read through everything in the Wiki on this. The very paper you linked to is cited on the second Ring Laser Gyroscope page in the section 'Fluctuating Earth Rotation Rate'.

The bottom of this page:

https://wiki.tfes.org/Ring_Laser_Gyroscope

continues onto a second page:

https://wiki.tfes.org/Ring_Laser_Gyroscope_-_Seismology

You're absolutely right - I hadn't spotted the reference to that paper in the seismology page. My apologies. That said, it doesn't really flow as a 'second page' - it's just one of several links in the article.

Reading the seismology page, and indeed the RLG main page, is a fascinating journey into the bizarre analysis that runs through most of the wiki. I'm still not clear if you have wilfully misrepresented, or just completely misunderstood what is being discussed in the various papers. That one that I linked to above, for example, is describing a new gyro with a sensitivity of below ∆ΩE x 10-8. They aren't talking about being able to measure the earth's rotation - they are interested in parts per million of it. The earth's rotation is so ridiculously, stunningly obvious, and so easy to detect - they are way, way past that.

There's a great deal that's wrong within the wiki. Here's a few:

Quote
The Ring Laser Gyroscope (RLG) is a consumer device version of the Michelson-Gale-Pearson Experiment (MGP)

Not really. RLG's are expensive, and accurate ones are even more so. They aren't really consumer products. MGP didn't have access to lasers, or the optical technology required for a RLG. The Canadian paper you cite in the wiki was specifically looking at a low cost model, with associated reductions in accuracy. The Honeywell GG1320AN, which seems to be the industry standard model, has far better specs - a quoted bias drift, for example, of 0.0035 deg/hr, compared to the cheaper/older model used in your paper, which had bias drifts measuring in the low single digit degrees/hr.

Quote
Essentially the tests saw wild results. There was almost no change to light's velocity in one test, and then a lot of change in another test. It is perplexing that the rotation of the earth would start and stop when tested at different times. Only through the statistics was it claimed that the experiment saw the rotation of the earth. The inconsistent results were ambiguous in nature and could offer no evidence of the shift in the phase of the light beams. As stated above, the results of the Michelson-Gale-Pearson experiment were inconsistent and an algorithm was applied to get the desired result.

Again, not really. MGP were working with relatively primitive equipment - it is extremely hard to measure fringe distance manually like that, especially when the apparatus would have been hugely sensitive to changes in temperature and any local vibration. There is absolutely nothing wrong with taking a statistical approach - their data shows a clear normal distribution shape with the mean centred on almost precisely the fringe separation one would expect for the apparent rotation at their latitude. Taking multiple samples and applying statistical techniques to them is basic science - if you are rejecting that then there's little point in doing any science at all. If their data showed an equal chance of getting different results, that would be a very different thing. But it doesn't.

Quote
If we are to say that the Ring Laser Gyroscope is the same device, then the same criticism would apply.

But we aren't to say that, are we? Because we are nearly a century on, and we are talking about technology with accuracy that MGP could only have dreamed of.

Quote
It is further seen that, like the original MGP experiment, the raw results of the gyroscopes are inconsistent[2] and dwarf the results from rotation.

None of what follows after this sentence shows that in the context of RLGs. You've had to dig out an experiment using MEMS sensors, which are far, far less accurate than RLGs, which is why you won't find them in navigation equipment. The experiment is really interesting - they are using various statistical techniques to try to pull out the earth rate from the noise - but it is nothing to do with RLGs, although they do actually still manage to measure the earth rate nevertheless, which is very impressive.

The graphs you show from the Canadian test of the Honeywell device show absolutely no comparison of the noise with the signal caused by earth's rotation - it's not in there at all. They essentially ran a series of tests using their calibrated bench test system, some with the device orientated to remove the earth rotation component and some with it not, but the rotation rate itself isn't shown - they were only interested in the measured rate versus the accurately calibrated forced rate. None of your graphs show the actual measurement of the earth's rotation. They just show various noisy signal plots, which is hardly surprising given the nature of the device.

The seismology page takes it to whole new level of oddness.

Quote
Researchers have used these sensitive devices to detect patterns in the background microseismic noise, where certain features are interpreted to be caused by the earth's rotation. The feature of the background noise assumed to be an effect of the earth's rotation is called the "Earth line," and is admitted to be of unknown origin and cause.[2]

This is just utter nonsense, I'm afraid. Seismic activity presents itself as disturbances to the measured earth rate. The earth rate isn't extracted from the noise. The output from an accurate RLG is nothing like the MEMS graphs you showed - the noise is low ppm compared to the signal - measuring several degrees per hour (unless you are on the North Pole, or you orientate your RLG to the earth's rotation axis, you will measure < 15 / deg/hr) is trivial and accurate. High end, large installed RLGs like Gross-ring or GINGER are now able to resolve tiny variations in earth rate - see https://www.sciencedirect.com/science/article/pii/S1631070514001406

Quote
It is unclear whether those types of RLGs in airplane guidance systems claim to be able to detect the earth's rotation.

It's not unclear at all - they absolutely do, and they have to be corrected for it. As I've shown before, with you failing to respond (eg https://forum.tfes.org/index.php?topic=17396.msg227601#msg227601), even older mechanical directional gyros have to be compensated for drift, either by a bench-adjusted drift nut for short range aircraft, or via a latitude scale set in the cockpit. Something like a GG1320AN, with a bias of around 0.0035 deg/hr, will absolutely drift if earth rate isn't compensated for. It's equally true of mechanical gyro systems and laser based ones (RLGs, of course, aren't actually gyros - they are angle rate sensors). Here's one about marine systems: https://www.hydro-international.com/content/article/how-does-inertial-navigation-work)

Overall, I'm shooting for sophistry, rather than misunderstanding, but I could be wrong.



Offline SteelyBob

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Re: Ring laser gyros
« Reply #5 on: September 08, 2021, 02:54:45 PM »

The rlg works, it just does not work the way the modern scientists imagine it does (they should study its invention, and its inventor) and it does not measure what they presume it does.

I would echo Stack's comment. Don't be so mysterious...if not rotation, what then does a RLG measure? Bear in mind you can put them in a test rig and measure their accuracy very easily (see the Canadian paper in the wiki). So if you've got a system that is proven to be accurate when you rotate it at a known rate, and then it measures a rate of (15 deg / h) x (sin latitude) when you put it flat on a table, what exactly is it measuring, if not the rotation of the table, and therefore the earth?

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #6 on: September 08, 2021, 07:11:59 PM »
Quote from: SteelyBob
There's a great deal that's wrong within the wiki. Here's a few:

Quote
The Ring Laser Gyroscope (RLG) is a consumer device version of the Michelson-Gale-Pearson Experiment (MGP)

Not really. RLG's are expensive, and accurate ones are even more so. They aren't really consumer products.

Incorrect. Businesses are consumers.



Quote
The Canadian paper you cite in the wiki was specifically looking at a low cost model, with associated reductions in accuracy.


Incorrect:

"The gyroscope demonstrated excellent high-rate
performance although significant scale factor deviations
were noted during temperature variations."

"Results of the testing showed that instrument
performance at high angular rates was better than
specifications although significant scale factor deviations
were noted during temperature variations. "



Quote
Again, not really. MGP were working with relatively primitive equipment - it is extremely hard to measure fringe distance manually like that, especially when the apparatus would have been hugely sensitive to changes in temperature and any local vibration. There is absolutely nothing wrong with taking a statistical approach - their data shows a clear normal distribution shape with the mean centred on almost precisely the fringe separation one would expect for the apparent rotation at their latitude.

If it's measuring variation it is not directly measuring the phenomenon. They are measuring some sort of variation and are using statistics to make indirect conclusion. There are multiple phenomena involved, which muddies the conclusions.

Quote
But we aren't to say that, are we? Because we are nearly a century on, and we are talking about technology with accuracy that MGP could only have dreamed of.

It appears that the raw results from the Honeywell Gyro are also inconsistent.

Quote
The graphs you show from the Canadian test of the Honeywell device show absolutely no comparison of the noise with the signal caused by earth's rotation - it's not in there at all. They essentially ran a series of tests using their calibrated bench test system, some with the device orientated to remove the earth rotation component and some with it not, but the rotation rate itself isn't shown

The raw tests with the earth's rotation from the Honeywell Gyro shows that the signal is inconsistent and noisy.

Quote
The output from an accurate RLG is nothing like the MEMS graphs you showed

Citation needed. The raw tests from the Honeywell gyro looks very noisy.

Quote
measuring several degrees per hour (unless you are on the North Pole, or you orientate your RLG to the earth's rotation axis, you will measure < 15 / deg/hr) is trivial and accurate.

Citation needed. Where are the raw results showing this?

Quote
High end, large installed RLGs like Gross-ring or GINGER are now able to resolve tiny variations in earth rate - see https://www.sciencedirect.com/science/article/pii/S1631070514001406

Irrelevant if you can't demonstrate what the earth rate actually is in these studies. These studies seem to imply that it's a seismic phenomenon, as seen on the Ring Laser Gyroscope seismology page in the Wiki.

Quote
It's not unclear at all - they absolutely do, and they have to be corrected for it. As I've shown before, with you failing to respond (eg https://forum.tfes.org/index.php?topic=17396.msg227601#msg227601), even older mechanical directional gyros have to be compensated for drift, either by a bench-adjusted drift nut for short range aircraft, or via a latitude scale set in the cockpit. Something like a GG1320AN, with a bias of around 0.0035 deg/hr, will absolutely drift if earth rate isn't compensated for. It's equally true of mechanical gyro systems and laser based ones (RLGs, of course, aren't actually gyros - they are angle rate sensors). Here's one about marine systems: https://www.hydro-international.com/content/article/how-does-inertial-navigation-work)

Citation needed for the adjustment for Ring Laser Gyroscopes. Your links are talking about mechanical gyroscopes.

About the latitude nut:

From a video demonstrating the Latitude Nut: https://www.youtube.com/watch?v=xNYW8JWMVOY&ab_channel=fromjesse

04:22 "over here on the other side this is your latitude nut right there that can induce you can move that in or out and you can induce some a drift clockwise or counter clockwise on the you know east or west on the whatever you want to call it the scale here"

If you can induce the rotation by rotating a nut, how do you know if you're introducing it or removing it by adjusting the nut?

14:22 "the earth's rotation would then be added or subtracted from the existing drift of the gyroscope"

Oh, so now there is "existing drift" that the earth's rotation is added or subtracted from to get the "true drift".

Very scientific evidence there for the validity of this nut.

Clearly, more evidence is needed on this beyond these assumptions and appeals.


« Last Edit: September 08, 2021, 08:27:17 PM by Tom Bishop »

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #7 on: September 08, 2021, 07:42:24 PM »
A test was done with a mechanical gyroscope in a terrestrial environment and no "latitude nut" was needed. The earth didn't move.



An airplane gyro and other gyros are tested here, showing that there is no drift:



On the Latitude Nut:

To know how much you need to adjust it you need to know multiple variables.

https://books.google.com/books?id=6VTzCQAAQBAJ&pg=SA2-PA37&lpg=SA2-PA37&source=bl&ots=rUQ9gIz_q5&sig=ACfU3U0_8LNHps7CCyyOkxNGsE-mz643Rw&hl=en&sa=X&ved=2ahUKEwjgvOOlkvDyAhXSElkFHe7nD14Q6AF6BAg8EAM#v=onepage&q&f=false



Alternatively, you know, the earth was not rotating and this complex compensation is not needed and there was simply a wander of some particular amount during a particular journey.

Can you see how uncontrolled wander invalidates this latitude nut proof of yours?
« Last Edit: September 08, 2021, 08:28:10 PM by Tom Bishop »

Offline SteelyBob

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Re: Ring laser gyros
« Reply #8 on: September 08, 2021, 08:59:21 PM »
Incorrect. Businesses are consumers.

I can't get too excited about this one. My point was that your phrase suggested that RLGs are cheap. They aren't. Hence my point about your MEMS example - you find that kind of tech in all sorts of everyday items, not least our phones, for example. The closest most people get to an RLG is the cockpit of the aircraft that takes them holiday.

Quote
The Canadian paper you cite in the wiki was specifically looking at a low cost model, with associated reductions in accuracy.


Incorrect:

"The gyroscope demonstrated excellent high-rate
performance although significant scale factor deviations
were noted during temperature variations."

"Results of the testing showed that instrument
performance at high angular rates was better than
specifications although significant scale factor deviations
were noted during temperature variations. "

That doesn't change the fact that the whole point of the model in question is to make it cheap. The materials used and other specs are way lower than their normal products. Yes, the device performed well, but the bias, amongst other stats, is way, way worse than, say, a GG1320.

Quote
Again, not really. MGP were working with relatively primitive equipment - it is extremely hard to measure fringe distance manually like that, especially when the apparatus would have been hugely sensitive to changes in temperature and any local vibration. There is absolutely nothing wrong with taking a statistical approach - their data shows a clear normal distribution shape with the mean centred on almost precisely the fringe separation one would expect for the apparent rotation at their latitude.

If it's measuring variation it is not directly measuring the phenomenon. They are measuring some sort of variation and are using statistics to make indirect conclusion. There are multiple phenomena involved, which muddies the conclusions.

Are you contesting that fringe separation is a function of rotation rate? Or not? MGP were trying to measure fringe separation. It's not easy. But they did it. And the shape of the stats proves that it is highly unlikely to be a fluke, because far more results occurred around the mean than around the extremes.

It appears that the raw results from the Honeywell Gyro are also inconsistent.

Really? I thought you said it performed well? If you're confused by the noise on the graphs then you clearly don't understand electronics, or indeed how RLGs work.

The raw tests with the earth's rotation from the Honeywell Gyro shows that the signal is inconsistent and noisy.

All of the tests show similar noise levels. If you think the earth is flat, then you presumably don't think the change of angle used to eliminate the earth's rotation from the test would have had any effect, though, right?

Quote
The output from an accurate RLG is nothing like the MEMS graphs you showed

Citation needed. The raw tests from the Honeywell gyro looks very noisy.
'Looks very noisy'...how much noise would it take for you to say that it wasn't noisy? Do you even understand what the noisy signal is? Do you understand the relative amount of noise in the MEMS example, versus the Honeywell gyro in the experiment, versus a more advanced Honeywell gyro, versus something like the large, fixed devices mentioned in the other papers...the ones that can measure changes in rotation rate down to 10-8? Citation needed? The one you've cited works nicely - https://iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf

Quote
measuring several degrees per hour (unless you are on the North Pole, or you orientate your RLG to the earth's rotation axis, you will measure < 15 / deg/hr) is trivial and accurate.

Citation needed. Where are the raw results showing this?

Bob Knodel did quite a nice job, didn't he?!

About the latitude nut:

Lattitude Nut



04:22 "over here on the other side this is your latitude nut right there that can induce you can move that in or out and you can induce some a drift clockwise or counter clockwise on the you know east or west on the whatever you want to call it the scale here"

“This is your latitude nut. You can move it in or out and induce some drift clockwise or counter-clockwise, east or west”

If you can induce the rotation by rotating a nut, how do you know if you're introducing it or removing it by adjusting the nut?

Because when you build the device you design so that, without the gyro spinning, the device is balanced with the nut in the neutral position. All the nut does is move in and out, tipping the scales as it were, and via precession inducing a clockwise or anti-clockwise rotation to oppose the drift.

The test was done with a mechanical gyroscope in a terrestrial environment and no "latitude nut" was needed. The earth didn't move.



Clearly, more evidence is needed on this beyond these assumptions and sourceless appeals.

That video is more fakeable than anything NASA might put out. There's no actual way of figuring out if the gyro is spinning while the video runs, nor is there any way of knowing whether or not he's simply constrained the gyro. If anything, it's too perfect, as most gyros have some inherent drift due to friction and other intolerances.

Offline SteelyBob

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Re: Ring laser gyros
« Reply #9 on: September 09, 2021, 08:58:00 AM »

Alternatively, you know, the earth was not rotating and this complex compensation is not needed and there was simply a wander of some particular amount during a particular journey.

Can you see how uncontrolled wander invalidates this latitude nut proof of yours?

So every avionics manufacturer is wrong? Every single flight manual, ATPL ground school exam, every military and civilian training course the world over is wrong? Look at this video: https://www.youtube.com/watch?v=t2yzsc3y1R8

Earth rotation is a fundamental part of the align process. These people do this for a living, but they are wrong? The align process takes longer at extreme latitudes than at the equator because....why exactly?

If it's RLG testing you want...this guy is all over it. https://www.repairfaq.org/sam/laserlia.htm#liarlghr

Scroll down to the bit where he tests the GG1320AN:
Quote
If the GG1320 were sitting on a table at the North pole, the Sagnac frequency δf due to the Earth's rotation would be around 3.38 Hz. At the latitude here of 39.95°, δf drops to 2.17 Hz. Multiplying by 4 for the GG1320 X4 resolution results in 8.68 counts/second, which is consistent with the observed count rate. It's comforting to know that the Earth is still spinning correctly as advertised. ;-) The larger than expected change from 9 to 10 seconds when the GG1320 is supposed to be stationary is almost certainly because I was touching it. And as further confirmation that the slow counting is indeed due to the Earth's rotation, with the GG1320 tipped at around 40 degrees away from true North, the counting slows to a virtual stand-still with just some randomness in the LSB due to vibrations, and reverses direction when tipped beyond 40 degrees. When tipped the other way up to 50 degrees towards North, the counting is most rapid. Isn't Physics wonderful? ;-)

And if you want another example of drift correction due to latitude, how's about the AHRS system on a Hawk T1 training jet? This is a mech gyro based system, with a cockpit selectable latitude scale that is used to ensure the correct earth rate correction is applied. This simulator manual has quite a good overview: https://cdn.cloudflare.steamstatic.com/steam/apps/1478120/manuals/aerofly_fs_2_just_flight_hawk_t1a_manual.pdf?t=1605888346

See page 15 for the control panel (note the 'LAT' control) and page 48/49 for the description.



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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #11 on: September 10, 2021, 09:35:20 AM »
Quote from: SteelyBob
I can't get too excited about this one. My point was that your phrase suggested that RLGs are cheap.

Does it? Consumer device means that a company is making it for sale. It doesn't mean that it's cheap.

Rich people are also consumers and have industries tailored around selling expensive things to them. They are called consumers, FYI. Same with businesses.

Quote from: SteelyBob
That doesn't change the fact that the whole point of the model in question is to make it cheap. The materials used and other specs are way lower than their normal products. Yes, the device performed well, but the bias, amongst other stats, is way, way worse than, say, a GG1320.

You haven't provided raw results from that gyro.

You are ignoring that the specs show that the resolution on this Honeywell gyro is above that necessary for the 15 deg/hr.



Quote from: SteelyBob
Really? I thought you said it performed well? If you're confused by the noise on the graphs then you clearly don't understand electronics, or indeed how RLGs work.

Then you should explain to us how it works. Where is the Earth's rotation in the raw output of the Honeywell gyro:

https://apps.dtic.mil/dtic/tr/fulltext/u2/a266418.pdf

2.3 GRAPHICAL REPRESENTATION

  “ Figure 2-2 shows graphical representations of typical raw gyro outputs. The family of graphs (a) thru (e) illustrate the RLG counts and analog parameters for a bias drift test that includes local Earth rate with strobing at a nominal 10 seconds.”



Quote from: SteelyBob
All of the tests show similar noise levels. If you think the earth is flat, then you presumably don't think the change of angle used to eliminate the earth's rotation from the test would have had any effect, though, right?

What are you talking about? If the earth is rotating then it should appear somewhere in the raw output. So show us where it is.

Quote from: SteelyBob
'Looks very noisy'...how much noise would it take for you to say that it wasn't noisy? Do you even understand what the noisy signal is? Do you understand the relative amount of noise in the MEMS example, versus the Honeywell gyro in the experiment, versus a more advanced Honeywell gyro, versus something like the large, fixed devices mentioned in the other papers...the ones that can measure changes in rotation rate down to 10-8? Citation needed? The one you've cited works nicely - https://iopscience.iop.org/article/10.1088/1742-6596/723/1/012061/pdf

I just see a bunch of seismic related stuff in that link:



So is this stuff in black the rotation of the earth? It says that it's the rotational signal.

With the rotational signal in black I see that the time other than the earthquake the Earth is wobbling, + and -, sort of like the Honeywell gyro.

Here is a definition of rad/s:

« Last Edit: September 10, 2021, 10:07:56 AM by Tom Bishop »

Offline SteelyBob

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Re: Ring laser gyros
« Reply #12 on: September 10, 2021, 10:15:46 AM »




Quote
Really? I thought you said it performed well? If you're confused by the noise on the graphs then you clearly don't understand electronics, or indeed how RLGs work.

Then you should explain to us how it works. Where is the Earth's rotation in the raw output of the Honeywell gyro:

https://apps.dtic.mil/dtic/tr/fulltext/u2/a266418.pdf


It's staring you in the face, if you understand what you're looking at.

The RLG counts for the graphs you've shown there are strobed at 10 seconds, so the line at roughly 10 counts means around 1 count per second. As per the specs you've quoted, the scale factor is 116000 counts per revolution, so the gyro is indicating a rotation of 1 / 116000 = 8.62 x 10-6 revs / sec

Convert that into degrees per hour and you get 11.2. I don't see a lat/long or address for the lab in the paper, but I'm guessing it's southern Canada, around 49 degrees North. 11.2 / sin 49 = 14.8 degrees per hour.

Pretty good, although clearly you'd need to average out the line with a bit more precision, and to locate the lab better than my rough guess.

So yes, the device can and does detect earth rate, and your graphs show it quite clearly. Thanks for sharing.

 Worth pointing out that the specs on RLGs can be a bit misleading - early / cheaper ones struggled with slow rotation rates due to 'locking', which prompted the use of dither - this adds to the noise but improves low rotation rate performance.

Quote

I just see a bunch of seismic related stuff in that link:



So is this stuff in black the rotation of the earth?

In black I see that the time other than the earthquake the Earth is wobbling forward and backward, + and -, sort of like the Honeywell gyro.

Here is a definition of rad/s:



I'm well aware of what a radian is, thanks. No, the stuff in black isn't earth rotation. You wouldn't see it on that scale - earth rate is 0.000072 rad/s.

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #13 on: September 10, 2021, 10:38:03 AM »
Quote from: SteelyBob
I'm well aware of what a radian is, thanks. No, the stuff in black isn't earth rotation. You wouldn't see it on that scale - earth rate is 0.000072 rad/s.

So there is noise that is dominating the results, and the earth rate is interpreted indirectly. I see. Well, isn't that a downer for your argument.

Quote from: SteelyBob
So yes, the device can and does detect earth rate, and your graphs show it quite clearly. Thanks for sharing.

Really, where in the wiggly line graph is the rotation of the earth? Can you point it out to us in a photo editor please?

Offline SteelyBob

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Re: Ring laser gyros
« Reply #14 on: September 10, 2021, 10:46:24 AM »
Quote from: SteelyBob
I'm well aware of what a radian is, thanks. No, the stuff in black isn't earth rotation. You wouldn't see it on that scale - earth rate is 0.000072 rad/s.

So there is noise that is dominating the results, and the earth rate is interpreted indirectly. I see. Well, isn't that a downer for your argument.


Errrr....not really. That's an earthquake you're looking at there, so yes, the noise (ie the earthquake) is dominating the results, which is as you'd expect. When it's not earthquaking, it measures the earth rate very well, indeed far better than the Honeywell one...

Quote

Really, where in the wiggly line graph is the rotation of the earth? Can you point it out to us in a photo editor please?

On all three of the graphs you've shown the left hand y-axis is 'RLG CNTS' - the line averages around 10 after the warm up. As I've shown, that works out pretty much bang on what you'd expect for earth rate. It's not hugely precise, but then it's not really intended for that purpose and it is, as I explained earlier, relatively cheap compared to the far more precise GG1320 - a similar trace from a 1320 would have far less 'wiggle'.

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #15 on: September 10, 2021, 11:05:30 AM »
Oh, so the only diagram of raw results in the article you posted is flawed because there's an earthquake.

Here is another paper on GINGERRINO which has some angular rotation rate graphs. Nothing about an earthquake appears to be mentioned here:

https://www.frontiersin.org/articles/10.3389/fspas.2020.00049/full

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Figure 8. (A) The data utilized in the present analysis (30 days from June 15, 2018), ωs0 with mean subtracted, and the data after around day 20 have been removed since GINGERINO was in split mode. (B) ωs, mean subtracted, evaluated with the model of the laser systematic. The data have been decimated down to 1,800 s. Since GINGERINO is a single-ring gyroscope, with an ~45° inclination with the Earth axis, it is impossible to distinguish rotations and inclinations. On the right, the sensitivity is expressed in change of the relative angle with the Earth rotation axis, showing that the orientation of the apparatus of GINGERINO is stable at the level of a few μ rad.

The units are nrads and μrads now. Maybe the rotation of the earth is in this graph somewhere? Can you point it out to us?

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On all three of the graphs you've shown the left hand y-axis is 'RLG CNTS' - the line averages around 10 after the warm up. As I've shown, that works out pretty much bang on what you'd expect for earth rate. It's not hugely precise, but then it's not really intended for that purpose and it is, as I explained earlier, relatively cheap compared to the far more precise GG1320 - a similar trace from a 1320 would have far less 'wiggle'.

I'm not sure I can see what you're talking about without an image. Can you use an image editor to point out the earth's rotation in one of the graphs?
« Last Edit: September 10, 2021, 11:32:03 AM by Tom Bishop »

Offline SteelyBob

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Re: Ring laser gyros
« Reply #16 on: September 10, 2021, 12:02:14 PM »
Oh, so the only diagram of raw results in the article you posted is flawed because there's an earthquake.

I wasn't really referring to the diagram, more the text itself. The whole point is the incredible accuracy of the system - down to 10-8. If it's a diagram you want, then there's the ∆Ω/Ω graph just above the one you posted. You seem to be demanding that these papers have a section called 'we measured the earth rate and here's what we found it to be' - they aren't going to do that, as they are way, way past that and ΩE itself isn't really of interest - they are interested in tiny, tiny variations in it, hence the article.

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Here is another paper on GINGERRINO which has some angular rotation rate graphs. Nothing about an earthquake appears to be mentioned here:

https://www.frontiersin.org/articles/10.3389/fspas.2020.00049/full

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Figure 8. (A) The data utilized in the present analysis (30 days from June 15, 2018), ωs0 with mean subtracted, and the data after around day 20 have been removed since GINGERINO was in split mode. (B) ωs, mean subtracted, evaluated with the model of the laser systematic. The data have been decimated down to 1,800 s. Since GINGERINO is a single-ring gyroscope, with an ~45° inclination with the Earth axis, it is impossible to distinguish rotations and inclinations. On the right, the sensitivity is expressed in change of the relative angle with the Earth rotation axis, showing that the orientation of the apparatus of GINGERINO is stable at the level of a few μ rad.

The units are nrads and μrads now. Maybe the rotation of the earth is in this graph somewhere? Can you point it out to us?


No, I can't because if you read the text you've quoted it clearly says 'with mean subtracted' - they aren't interested in the absolute figure, they are interested in the delta. And the delta being measured is absolutely tiny - nano rad/s, or 10-9.

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I'm not sure I can see what you're talking about without an image. Can you use a photo editor to point out the earth's rotation in one of the graphs?

How's this? The average RLG counts are just under 10, I'd say. That's your earth rate, as I showed in the earlier calculations.


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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #17 on: September 10, 2021, 12:27:28 PM »
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I wasn't really referring to the diagram, more the text itself. The whole point is the incredible accuracy of the system - down to 10-8. If it's a diagram you want, then there's the ∆Ω/Ω graph just above the one you posted. You seem to be demanding that these papers have a section called 'we measured the earth rate and here's what we found it to be' - they aren't going to do that, as they are way, way past that and ΩE itself isn't really of interest - they are interested in tiny, tiny variations in it, hence the article.

So now you are arguing that the papers aren't about showing the earth rotation and are just about a series of higher level assumptions. They are "way way past that". Why are you posting these papers of higher level assumptions as proof if it's not about that then?

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No, I can't because if you read the text you've quoted it clearly says 'with mean subtracted' - they aren't interested in the absolute figure, they are interested in the delta. And the delta being measured is absolutely tiny - nano rad/s, or 10-9.

I'm not interested in the mean of the figures, I'm interested in the Earth's rotation. I don't see it.

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Looks pretty questionable. If that's the Earth's rotation then something is increasing and decreasing it's speed by 30%. Maybe circle back when you figure out why light's speed is constantly increasing and decreasing and which phenomena it's related to and whether it is affecting your assumptions.

Maybe something better than presenting a bunch of noisy garbage and pretending that you know which phenomena is caused by which and why.
« Last Edit: September 10, 2021, 12:43:36 PM by Tom Bishop »

Offline SteelyBob

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Re: Ring laser gyros
« Reply #18 on: September 10, 2021, 01:19:21 PM »

So now you are arguing that the papers aren't about showing the earth rotation and are just about a series of higher level assumptions. They are "way way past that". Why are you posting these papers of higher level assumptions as proof if it's not about that then?

Your inability to comprehend this stuff is not my problem.

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No, I can't because if you read the text you've quoted it clearly says 'with mean subtracted' - they aren't interested in the absolute figure, they are interested in the delta. And the delta being measured is absolutely tiny - nano rad/s, or 10-9.

I'm not interested in the mean of the figures, I'm interested in the Earth's rotation. I don't see it.
And you won't see it. It isn't there to be seen. You posted it, not me.


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Looks pretty questionable.

Based on what? You asked where the rotation was, presumably because you don't understand the data, and now when I show it to you where it is in the data it's too noisy for you? At the start of this I pointed out that this was a cheaper model - it is less accurate, and more noisy - that's the whole point. Measuring earth rate - 15 deg/hour - using a device that's designed for measuring up to 1000 deg / sec is always going to be tricky. If they used a more precise one, it would be less noisy and more precise

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If that's the Earth's rotation then something is increasing and decreasing it's speed by 30%.

If that's how you interpret scientific measurement data then it's no wonder your understanding of the planet is so hopelessly at odds with reality. The data has noise in it, but the trend is clear - it's just shy of 10 counts every 10 seconds, which is exactly what we would expect the earth rate measurement to be at the latitude in question. The noise level is significant, yes - but then the rotation rate is tiny, so it's not surprising. When you put roughly the same noise level on a more substantial rotation rate, like the 100 deg/ sec tests shown in graph (f) you get deviations at the 4th or 5th significant figure. Significant noise:signal ratio at low rotation rates is exactly what you would expect to see in a cheaper device like this one.

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Maybe circle back when you figure out why light's speed is constantly increasing and decreasing and which phenomena it's related to and whether it is affecting your assumptions.

Maybe something better than presenting a bunch of noisy garbage and pretending that you know which phenomena is caused by which and why.

The measured earth rate is bang on what we would expect, and the noise level is exactly what we would expect for the device in question. You didn't understand the data, and are now flailing around for another explanation that might give you an 'out' now you've been shown what it is. The data shows the measurement of earth rate. All of the data aligns perfectly with RE expectations.

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Offline Tom Bishop

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Re: Ring laser gyros
« Reply #19 on: September 10, 2021, 01:44:11 PM »
You claim that there are more accurate devices, but refuse to provide raw graphs, data, and provide only claims and assumptions. Maybe the 'more accurate' devices create bigger spikes compared to the baseline like the last GINGERRINO graphs did.

You think that a trend is proof, yet refuse to acknowledge that there are many diurnal phenomena above and around us beyond the supposed rotation of the earth.

You see that the data is tainted with phenomena which are not the rotation of the earth, yet refuse to acknowledge that the presence of unmitigated effects invalidates the assumptions involved.

How often are inconsistent experiments with unknown effects and a series of assumptions accepted in hard sciences like chemistry or biology? I'll answer for you: Hardly ever. We can test and control and address most of the elements those sciences, but not when measuring something large and outside of our control like in this experiment. The quality is better there. In this case it's basically a dilapidated road with potholes that need to be filled with assumption.

You post various papers and then later dismiss them as being "way, way" beyond what we're talking about and position them as higher level assumptions.

Are we done here? This is just a load of assumptions and very little in the way of tangible evidence. You might think that this is asking for too much, but in other sciences mystery inconsistencies and experiments tainted with unknown effects and 'oh well, let's just assume' just doesn't cut it. The presence of other things affecting the experiment pretty much invalidates it all. The affecting elements have not been properly removed from the experiment by the experimenter to allow for a determinable conclusion.
« Last Edit: September 10, 2021, 02:23:44 PM by Tom Bishop »