A stupid question from the "newbie"

Mike
Mike
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What is the meaning of the

What is the meaning of the "Arecibo power spectrium" graph in the screen saver as relating to the bars turning from gray color to a white color on 2 or more bars?

Mike Hewson
Mike Hewson
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RE: What is the meaning of

Message 99072 in response to message 99071

Quote:
What is the meaning of the "Arecibo power spectrium" graph in the screen saver as relating to the bars turning from gray color to a white color on 2 or more bars?


Power spectrum refers to the energy received ( in a given time ) across some spread of frequencies. The signals are received initially as a fluctuation in ( for instance ) a voltage in the receiver circuitry. This changes from moment to moment, but when looked at over some time interval can be analysed as a summation of signals of different frequencies. The graphic is showing the relative contributions from different frequencies.

Aside : Our ears do this automatically without us knowing it. Sound, which is the pressure of air molecules, hits our eardrums ( or for low frequencies transmits via our body tissues, mainly bones, to the ear area ) and is converted by a special gadget ( our cochlea, one per ear ) into frequency encoded signals that go via nerves to the hearing part of our brain. Mathematically the cochlea performs a Fourier Transform that decides how much ( soft .... loud ) of each particular frequency was present. So ( opera ) singers are classified as baritone, tenor, soprano etc on the basis of what band of frequencies their voices predominantly produce.

So our new famous pulsar PSR J2007+2722 has a big peak in it's power spectrum at 40.8 Hz ( listen to it here ), which comes across as a low frequency hum.

Cheers, Mike.

( edit ) The ABP workunits do the Fourier analysing on about 4.5 minutes of signal from Aricebo, removing known sources of interference ( eg. radars and radio stations ), while also trying to match signal 'templates' that are educated guesses as to what type of pulsar emissions we will probably receive. This has clearly worked! The PSR J2007+2722 signal sky position and characteristics discovered by E@H were forwarded to Green Bank observatory - look here and listen for that - as an independent confirmation. So the discovery also validated the whole setup, the signal processing 'pipeline', that E@H is a major part of.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

paul milton
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RE: RE: The odd number

Message 99073 in response to message 99070

Quote:
Quote:

The odd number of 758MB ram points to a mainboard with onboard graphic. Usually they allocate the (shared) ram dynamically. So it really depends on other tasks (virus scanner, spam-filters etc) and services, the screen resolution, colour depth and eventually loaded graphic filters, whether or not enough ram is available for two tasks.

This can be reduced via BIOS settings. Onboard graphics are no good for 3D games anyway, and I guess 128MB for 2D desktop should be enough.

Michael

i have mine "locked" at 256MB's i have no problem with windows aero, and "some" 3d games such as "planeshift" im not sure about 128MB's my options are only 8MB - 256MB or "dynamic" YMMV

seeing without seeing is something the blind learn to do, and seeing beyond vision can be a gift.

Mike
Mike
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Whats awesome thank you, any

Message 99074 in response to message 99072

Whats awesome thank you, any way to heat that while E@H project is working?

Quote:
Quote:
What is the meaning of the "Arecibo power spectrium" graph in the screen saver as relating to the bars turning from gray color to a white color on 2 or more bars?

Power spectrum refers to the energy received ( in a given time ) across some spread of frequencies. The signals are received initially as a fluctuation in ( for instance ) a voltage in the receiver circuitry. This changes from moment to moment, but when looked at over some time interval can be analysed as a summation of signals of different frequencies. The graphic is showing the relative contributions from different frequencies.

Aside : Our ears do this automatically without us knowing it. Sound, which is the pressure of air molecules, hits our eardrums ( or for low frequencies transmits via our body tissues, mainly bones, to the ear area ) and is converted by a special gadget ( our cochlea, one per ear ) into frequency encoded signals that go via nerves to the hearing part of our brain. Mathematically the cochlea performs a Fourier Transform that decides how much ( soft .... loud ) of each particular frequency was present. So ( opera ) singers are classified as baritone, tenor, soprano etc on the basis of what band of frequencies their voices predominantly produce.

So our new famous pulsar PSR J2007+2722 has a big peak in it's power spectrum at 40.8 Hz ( listen to it here ), which comes across as a low frequency hum.

Cheers, Mike.

( edit ) The ABP workunits do the Fourier analysing on about 4.5 minutes of signal from Aricebo, removing known sources of interference ( eg. radars and radio stations ), while also trying to match signal 'templates' that are educated guesses as to what type of pulsar emissions we will probably receive. This has clearly worked! The PSR J2007+2722 signal sky position and characteristics discovered by E@H were forwarded to Green Bank observatory - look here and listen for that - as an independent confirmation. So the discovery also validated the whole setup, the signal processing 'pipeline', that E@H is a major part of.

Mike Hewson
Mike Hewson
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RE: Whats awesome thank

Message 99075 in response to message 99074

Quote:
Whats awesome thank you, any way to heat that while E@H project is working?


I think you meant 'hear' not 'heat' ...... well the computer is doing that anyway :-)

But alas no sounds are emitted during signal processing. At the LIGO interferometers though ( gravitational waves now ) the operators do hook up the signal output to speakers - they hear all sorts of creaks, groans, whistles etc - none of which we have as yet attributed to any gravitational waves.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

Bikeman (Heinz-Bernd Eggenstein)
Bikeman (Heinz-...
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RE: At the LIGO

Message 99076 in response to message 99075

Quote:
At the LIGO interferometers though ( gravitational waves now ) the operators do hook up the signal output to speakers - they hear all sorts of creaks, groans, whistles etc - none of which we have as yet attributed to any gravitational waves.

I didn't know that...very cool. I can see Jodie Foster in that control room, like in Contact...in "LIGO, the movie". If Roland Emmerich will direct that, of course the GW is a precursor to something that will blow the planet to pieces...

CU
HB

transient
transient
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In the context of movies you

In the context of movies you might like another medium, books. A SF book called The Ring of Charon, by Roger MacBride Allen. It starts of with a gravity wave detector orbiting Pluto or Charon, Pluto's moon. This was written at a time Pluto was still considered a planet. :D

Mike Hewson
Mike Hewson
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RE: I didn't know

Message 99078 in response to message 99076

Quote:
I didn't know that...very cool. I can see Jodie Foster in that control room, like in Contact...in "LIGO, the movie". If Roland Emmerich will direct that, of course the GW is a precursor to something that will blow the planet to pieces...


Well let's hope that Arnie's not in it, nor directs it. We'd have aliens and/or robots jumping out of the anti-symmetric port. Sam Neill would be excellent - 'I would have liked to have seen Montana'. He also did the spooky sci-fi/horror Event Horizon .... :-)

Cheers, Mike.

( edit ) Aside : If you ever get to read up on the cochlea, go for it! It's a thing of beauty, working and looking like like a French horn in reverse. The vibrations go up into/within the spiral ( one of those classic mathematical ones, like on flowers and such ) and a given frequency will resonate at a certain diameter ( diminishing as you go further in ). Small hairs at each location then convert vibration to an electrical impulse, but then the information for amplitude at that frequency is encoded in the repetition rate of impulses up the relevant nerve. It's not quite one nerve fibre per frequency but close to it ( a multichannel analyser comes to mind ), but a Fourier transform occurs none-the-less. To really top it off the encoding follows the logarithm of the power, in effect giving an enormous dynamic range a narrower representation. Thus giving the effect that : a multiple in perceived sound intensity being really an exponent of received power. To really blow your mind, the auditory nerves also have 'post-processing' capability, roughly like a graphic equaliser that can selectively boost frequencies one over another ( so not amplifying all frequencies equivalently ). So my dog Rusty can hear cars approaching miles off when I don't, because (a) he's a dog, (b) his ears catch sound better and (c) his algorithms are superior.

( edit ) BTW the Wikipaedia on the cochlea is misleading in many respects ... the frequency response is higher the further you go into the spiral, it's not the stiffness of the basilar membrane determining response but it's excitation. The articles quoted as the sources for the Wiki page are comparative studies on mammals with deduced correlates/modelling, not actual physiological studies.

I have made this letter longer than usual because I lack the time to make it shorter ...

... and my other CPU is a Ryzen 5950X :-) Blaise Pascal

DanNeely
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RE: But the price doubled

Message 99079 in response to message 99067

Quote:

But the price doubled in the last year or so. I upgraded from 2GB to 6GB, because at that point the 4GB(2x2GB) DDR2 were cheap. I think I payed only 40€.

Sascha

A supply glut can temporarily force prices below manufacturing cost; but it can't hold them there. This is just another round in the DRAM boom/bust cycle.

Fred J. Verster
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***[Snip]*** RE: So

Message 99080 in response to message 99079

***[Snip]***

Quote:


So our new famous pulsar PSR J2007+2722 has a big peak in it's power spectrum at 40.8 Hz ( listen to it here ), which comes across as a low frequency hum.

Cheers, Mike.

Can you 'translate' that in the 40.8 times a second, this Pulsar is spinning? Quite a fast one.

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