Regarding oscillation modes of the earth, the are various frequencies involved depending of what kind of motion we are talking about. Perhaps this diagram will clarify: http://www.iris.iris.edu/sumatra/LargeImages/Figure1_large.gif
Regarding the relationship between oscillation modes of a body of mass, and detecting impinging gravity waves, its importance depends on how we are trying to detect the waves. If we want to use the body as a detector, we might consider whether gravity wave interaction would make some measurable difference in one of the vibration modes. That is, if the wave excites some ringing of a mode, or if it shifts the frequency a little, there might be something there we could measure. Something like that. Because the Earth's modes have certain directional orientations, they might be more or less sensitive to waves coming from different directions.
Regarding the relationship between oscillation modes of a body of mass, and detecting impinging gravity waves, its importance depends on how we are trying to detect the waves. If we want to use the body as a detector, we might consider whether gravity wave interaction would make some measurable difference in one of the vibration modes. That is, if the wave excites some ringing of a mode, or if it shifts the frequency a little, there might be something there we could measure. Something like that. Because the Earth's modes have certain directional orientations, they might be more or less sensitive to waves coming from different directions.
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I read that after the big 2004 Boxing day quake, the earth resonated for 3 months. I find that astounding - maybe someone has more info on this, or more accurate numbers.
Having lived through the 3/11 Tokyo quake, I know building resonate detectably for about 30 minutes. I was on the 24th floor. Not an experience I would recommend, but if you are going to be in a big quake, Japan is the safest place to be.
I mention this because if you were to use the Earth<>Moon system as a detector, there'd be a lot of things to take into account over and above the ones LIGO currently deals with.
Having lived through the 3/11 Tokyo quake, I know building resonate detectably for about 30 minutes. I was on the 24th floor. Not an experience I would recommend, but if you are going to be in a big quake, Japan is the safest place to be.
I mention this because if you were to use the Earth<>Moon system as a detector, there'd be a lot of things to take into account over and above the ones LIGO currently deals with.
They say a good wine is like sex . . .
Ok, I admit it, another analogy that probably wont work
Are you sure they didn't mean the bottle?
Sorry George, those numbers were inverse frequency in hours I mis-typed.
My source was directly from Saulson's book which included a reference to the literature that the exact instrumentation was not disclosed by Weber. That is the layout and exact nature of his ferro-magnetic sensors.
BTW you can download and play with the raw LIGO data including Python scripts to simulate their filtering and template matching.
Thanks Mark
They are all at mHz and below
Osc. Mode/Period(min)/Freq(Hz)
Toroidal 0T2/44.2/0.000377
Toroidal 1T2/12.6/0.001323
Toroidal 0T3/28.4/0.000587
Spheroidal 0S0/20.5/0.000813
Spheroidal 0S2/53.9/0.000309
Spheroidal 0S3/25.7/0.000649
Any and all of them (*).
A good number of advanced three-axis digital recording seismometers all over the globe working 24/7 for decades has accumulated a vast amount of data, which can be exchanged btn labs and analyzed in anyway they want. They might not need to invest in new instrumentation if they were to use the Earth as a detector. But it seems that the globe is too noisy for that (moon, much less so)
(*) All of these questions are applicable to the case of artificial resonant–mass detectors too. They simply didn’t and still don’t know many things about the interaction of a gravitational pulse and the detector. They haven’t met any of any origin. They don’t know crucial (for the accomplishment of detection) details of the pulse (it’s shape, spectrum, duration). Hopefully they may get such information from LIGO’s captures.
You mean in minutes. It’s OK. I should have thought of that.
I was really surprised to read the analysis on how strong is the effect of every minute detail of sensor pick-up and it’s interface with the bar on the system noise.
https://books.google.ie/books?id=yb...it&source=gbs_toc_r&cad=3#v=onepage&q&f=false
Thanks.
Re Python, have you checked this?
George
You mean in minutes. It’s OK. I should have thought of that.
I was really surprised to read the analysis on how strong is the effect of every minute detail of sensor pick-up and it’s interface with the bar on the system noise.
https://books.google.ie/books?id=yb...it&source=gbs_toc_r&cad=3#v=onepage&q&f=false
Thanks.
Re Python, have you checked this?
George
See I got it wrong twice.
Interesting book did you see his funny recollection about one of Weber's lectures, clearly a character? Notice the need to account for the reciprocity of the transducers, sounds familiar.
Thanks again, I failed to notice the course was free.
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Thus the appellation "Larrikin". Of course in the USA we have Larry, the cable guy.
I suspect that many here who contribute know or care little about highest quality audio. Sure, we can all get along with mid-fi, but just like we could get along with a low cost American car, but isn't there more in driving a BMW, Mercedes, Porsche for example? It is the same with audio. Hi end audio has lots of people in it who hardly know what they are doing, or else tend to overcharge for what they produce, but deliberately ignoring hi end audio entirely, just keeps you down to mid-fi performance. Is this what you want?
BMW in the USA is not really mid market. Perhaps it is in Europe. But that is a quibble. There is cost-effective hi end like some Parasound products, but most here find it too exotic to make any sonic difference. To me, it is like comparing a BMW to a Honda. The BMW is more comfortable, in my experience.
Yes, this is what the great public wants.....reasonable performance and ultra ergonomics, ie system control via Tablet/phone touch screen.
This product is here now, and it's storming out of the retailers and into homes because it satisfies the demand of the 99%.
The traditional arrangement with amplifier/cdp/tuner etc mounted prominently in a rack/stand with cables aplenty, and large loudspeakers dominating the room is real fast becoming so last century.
Wireless connectivity/control is the new standard, and let's face it most of the Sonos/Yamaha etc type systems work impeccably/stunningly well and are available at Mums/Dads prices, EXCEPT for ultimate sound quality/clarity , and THIS is where evolution of home audio will complete.
Let's face it, the distortions performance of modern mass produced audio designs is now way good enough for the job, however it is the noises performance of modern systems that is the let down, and is the current limitation/hindrance to first class sound in every home.
Recent experiment has involved recording a three piece rock/blues band utilising my filters in the stage instruments and the studio recording system.
The resultant 24/96 release sound quality is uniquely/startlingly real/clear/good, and confirms that modern recording techniques/equipment can deliver more than adequate distortions performance.
Frankly Hi-End typically is about reinventing the wheel in new/flashier housings, but most Hi-End stuff is fundamentally flawed, and for the same reasons that Mid-Fi is flawed.
I believe there is a new era in audio reproduction around the corner, and this will complete our quest.
Dan.
The way most people use music has changed. They no longer sit down and attend to listening to a whole album. Instead, they use music in the background while they attend to other things. In that case, quality doesn't matter as much. However, I find that people do appreciate good sound if and when they get an opportunity to try it, and when can give it a little time and attention. Even for people who do like good sound, good systems are still expensive compared to most TV sets and other entertainment devices.
I have to ask, Mark - when did people ever sit down and just listen to recorded music? Sure, there might have been a little niche group of audiophiles (me included) who did. 99.7% of them male - but did most people ever do this? I don't remember it. I have never met a women who would sit down and just listen to recorded music. Certainly a few must exist, but I have not met one.
I used to have one of the best listening rooms on the planet. Getting friends down there to just sit and listen? Not easy. And most people now don't even give TV their full attention. I seem to remember that they did back in the 60s and 70s, but I could be wrong.
Bottom line: Was there ever a significant proportion of the population who sat down to listen to recorded music and nothing else? Outside the audiophile fringe - us.
I used to have one of the best listening rooms on the planet. Getting friends down there to just sit and listen? Not easy. And most people now don't even give TV their full attention. I seem to remember that they did back in the 60s and 70s, but I could be wrong.
Bottom line: Was there ever a significant proportion of the population who sat down to listen to recorded music and nothing else? Outside the audiophile fringe - us.
Yes, back in the 60s and 70s, and before that. People in the music industry are aware of such trends, and they believe listening patterns have changed. Like any other business, it helps to understand how users want to use your products, so you need to pay attention to that in order to help stay competitive
Also, in the much more distant past, families would even sit around the living room listening to the radio, if they had one. Not much else to do, I guess.
Sure, people would listen radio shows like they went on to watch TV. Although I suspect that women rarely sat down to just listen.
I also remember that in the 50 thru the 70s there were people who sat down to simply listen. You know, stacks of LPs, comfy chair, pipe, dog and slippers. But did that ever really exist in significant numbers? Numbers greater than today?
I also remember that in the 50 thru the 70s there were people who sat down to simply listen. You know, stacks of LPs, comfy chair, pipe, dog and slippers. But did that ever really exist in significant numbers? Numbers greater than today?
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