Human electrical transmission & detecting aliens


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Message 1047341 - Posted: 10 Nov 2010, 6:41:35 UTC
Last modified: 10 Nov 2010, 7:31:41 UTC

Human electrical transmission & detecting aliens
One of the current popular topics in SETI, Astrobiology and planet hunting is what "signature" should we be looking for when we look and listen for other life in the universe.

In SETI searches, we "listen" for possible radio signals from intelligent aliens, usually around the 1.42 GHz frequence or the Hydrogen Line. We might also watch for "optical laser" transmissions that aliens might transmit.

In planet hunting circles, astronomers look for wobbles in stars to detect planets. But in theory they might then look closer at a planets "gas signature" in its atmosphere to detect possible methane or oxygen that might give rise to simple living creatures.

But this is my latest thought guys! In SETI circles we often say that aliens might detect us humans and pick up the very first "I love Lucy" TV transmissions that we transmitted from satellite dishes out into space. These "I love Lucy" transmissions would be incredibly weak and very hard to detect!!!

Here is the twist....... The way i see it from an electrical engineering point of view, mankind's most powerful radio transmission is our simple use of electricity!!!!

In every country on earth, for the last hundred or more years, we wire up our cities with electrical transmission grids that use A.C. (Alternating current) electricity at 50Hz or 60Hz depending on what country you live in.

Now high voltage, high current electrical transmission lines that you see criss crossing the countryside as you drive along the road really act as massive radio transmission antenna's. Completely unaware to the vast majority of people, mankind's electrical power transmission lines are the most powerful "signature of intelligent life" that mankind transmits!!! In every country in the world, our use of electricity through these massive H.V. electrical grids is a massively powerful radio transmission that travels out from planet earth in all directions simultaneously. If aliens want to detect us here on planet earth from far away, our transmission's at 50Hz and 60Hz would stand out way above any background radio noise or "I love Lucy" signal.

Now one thing i have learned over the years is that there is a dam good electrical engineering reason why our electrical grids use 50 or 60 Hz and not 10Hz or 100Hz or 1,000Hz or 1 million Hz. We use 50 to 60Hz A.C. electricity because this range is the most economical way to transmit massive amounts of electricity, through copper wires, by stepping up the voltage through electrical transformers, then we step down the voltage at the other side. The electrical science fact is that transformers work best at 50 to 60Hz. Also, A.C. electrical motors physically work best in the 50 to 60Hz range. Also generating electricity with very large turbines and generators is very efficent at 50 to 60 Hz.



Whats the point i am making here????

The point i am making is that the electrical science i just explained here is universal!! Exactly the same electrical science will apply to any intelligent alien on any planet, no matter how technologically advanced you are. To transmit electrical energy through electrical grids, and to convert electrical energy to mechanical energy in motors, 50 to 60Hz is the best frequency to do it.

Its mankind's most powerful radio transmission out into space. If aliens want to detect us, they should listen for planets transmitting radio at 50 to 60Hz. And vise versa, if we want to detect intelligent aliens, there "signature" will be planets that "hum" of radio waves at 50 to 60Hz. The frequency range should be universal to any intelligent alien. This frequency range is called "SLF" or "Super low frequency radio". Even if an intelligent alien is using super conductors for electrical transmission, electricity to power motors still works best at 50 to 60Hz.

The catch!

It would be difficult to build a detector that could block out the 50 to 60Hz earth signal allowing you to detect that same signal from part of the sky. But its funny, its not impossible either! You could use "directional antenna's" so you only pick up signals from a particular source like a point in the sky. Its also very easy to block or shield background interference at 50 to 60 Hz.

Further reading;

SLF, Super low frequency radio;
http://en.wikipedia.org/wiki/Super_low_frequency
Electric power transmission;
http://en.wikipedia.org/wiki/Electric_power_transmission

John in Ireland.
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Message 1047347 - Posted: 10 Nov 2010, 8:30:27 UTC
Last modified: 10 Nov 2010, 8:41:38 UTC

Another point i forgot to mention;

To detect intelligent aliens that are using electricity at 50 or 60Hz, it can easily be distinguished from natural astronomical radio noise because it will always be transmitter in 3 angular phases. Why???

Because to convert electrical energy to mechanical energy in an electrical motor, it works best with 3 windings. Thats why we we generate electrical power as "3-Phase A.C. electricity". Its to make motors and transformers work efficiently! Its not as efficient with 2 phases or 1 phase winding.

So the 50Hz signal will always be 3 phases separated by 120 angular degrees. Or 6 phases separated by 60 angular degrees. Or 9 phases separated by 40 angular degrees. This would make the signal easy to distinguish from natural astronomical radio noise.

Image of the phase rotation of 3 phase A.C. electricity;



In a domestic residential nebourhood, each house gets 1 of these phases from the supply transformer. In american homes, i believe the voltage is 110 volts at 60Hz. In the UK and Ireland, we get 230 or 240 volts at 50Hz. Its one of the phases.

John.

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Message 1047438 - Posted: 10 Nov 2010, 16:55:02 UTC

Some interesting outside the box thinking. I foresee a few problems, though. First, any practical antenna at these frequencies is extremely inefficient. This would seem to be of particular concern in detecting emissions at stellar distances. Second, Earth's atmosphere forms a barrier to the passage of EM emissions at these frequencies. Space based receivers with antennas approximating a half wavelength (a few thousand km) would be more likely to work, though they would provide no appreciable gain, as a large parabolic dish antenna does. If the transmitting planet had a similar ionosphere to Earth, the emissions would apparently be confined to that planet. Michael

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Message 1047442 - Posted: 10 Nov 2010, 17:26:18 UTC - in response to Message 1047438.
Last modified: 10 Nov 2010, 17:35:19 UTC

Some interesting outside the box thinking. I foresee a few problems, though. First, any practical antenna at these frequencies is extremely inefficient.

What i am saying Michael is that the H.V. electrical transmission lines that criss cross every country on Earth ARE one massive transmission antenna. We have already built them and any intelligent alien's will have them too. They are very efficient and its the strongest electromagnetic signature being transmitted from this planet, by many multiples over any directional parabolic transmission dish. Mankind's loudest noise in space is our use of electrical A.C. transmission grids.

This would seem to be of particular concern in detecting emissions at stellar distances. Second, Earth's atmosphere forms a barrier to the passage of EM emissions at these frequencies.

That's just not science fact. All the H.V. electrical transmission lines on earth run for 10's or hundreds of kilometres in straight lines, parallel to the atmosphere above. They work as perfect antenna's and the 50Hz signal is NOT blocked by the atmosphere or the ionosphere. The ionosphere will bounce a certain amount of EM radiation back down but in general most of the 50/60Hz signal just leaks out into space.


Space based receivers with antennas approximating a half wavelength (a few thousand km) would be more likely to work, though they would provide no appreciable gain, as a large parabolic dish antenna does. If the transmitting planet had a similar ionosphere to Earth, the emissions would apparently be confined to that planet. Michael

As mentioned, the ionosphere does NOT block or mask the fact that we have massive electrical transmission grids in every country.

John.
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Message 1048586 - Posted: 15 Nov 2010, 13:48:14 UTC

Nice idea, but the background 50-60Hz level is "quite high" so separating any signal coming from space from the "home grown" signal would be a bit of a challenge as these low frequencies are real pigs to shield. Now if you put the receiver on the dark side of the moon you might stand a better chance.
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Message 1048587 - Posted: 15 Nov 2010, 14:13:31 UTC - in response to Message 1048586.

Disregarding other potential problems, it might be useful to think about very narrow tuning in and around the range of 50-60 Hz. The chances of an extraterrestrial power system happening to be at exactly 50 or 60 Hz seems very small. As far as I know, anywhere in or near that range would serve as well. The selection of these specific frequencies seems to have been based on even, 'round' numbers in our base ten number system, and the length of the second, which are presumably unique to this planet. Finding weak emissions at, say, 47.3, 54.7, or 61.2 Hz might be indicative of an extraterrestrial power system, all other explanations having been ruled out. Michael

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Message 1048650 - Posted: 15 Nov 2010, 19:25:08 UTC - in response to Message 1048587.
Last modified: 15 Nov 2010, 19:40:32 UTC

Another thing, any kind of modulating, these Very Low Frequencies, is almost impossible. No matter if using Frequency-- or Amplitude-Modulation or any other way of modulating this 'signal'.

The wave lenght would be ULTRA LONG.
Things like Doppler-shift and harmonics are very difficult to 'detect', let alone an effective "Antenna" for these wavelenghts!
And the Kennely-Heaviside layer would reflect these wavelenghts, anyway.

Probably more efficient, is to modulate light, L.A.S.E.R. Also DE-Modulate if a
signal is picked up. Dark-side of the moon, would be apropiate for this :)
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Message 1048984 - Posted: 17 Nov 2010, 5:19:40 UTC - in response to Message 1047341.

any way of detecting ET radio signals by using the infrared spectrum, can microlensing be used for the detection of ET radio transmissions and ET laser signals

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Message 1049284 - Posted: 18 Nov 2010, 9:40:45 UTC
Last modified: 18 Nov 2010, 9:43:08 UTC

Michael Watson,
Your right, an alien electrical grid might be 39.4Hz or 62.31Hz or whatever, they probably would not use our decimal number system. But what i am saying is that the frequency range between about 30Hz and about 150Hz will be universal, it will apply to any planet anywhere. Why??? Because its the best frequency range to get an electrical motor type device to physically turn. Especially with massive electrical motors and generators.

Fred J. Verster,
Your right, The wave length would be ULTRA LONG.

The essential point i am making here is this 50/60Hz radio hum we are transmitting from earth is accidental. Its the result of our technological use of electricity on a massive scale. We are leaking out this signal whether we like it or not! And intelligent aliens can listen for it. But aliens will also be leaking out this signal if they use large amounts of electricity.

C Olival,
Yes, there are a tonne of other good ways to detect aliens, we're just discussing this one.

John.
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Message 1049290 - Posted: 18 Nov 2010, 10:17:15 UTC

60 cycle power doesn't transmit very well or very far. You don't hear it unless it rides in on your power system. In the good old days the heaters on vacuum tubes would drive us HI-FI mavens nuts. I used to put DC on my heater circuits with very low ripple to lower my noise problem.

With velocity =frequency times wavelength

Figure out how long the antenna would have to be --about 50,000 miles for a quarter wavelength.

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Message 1049311 - Posted: 18 Nov 2010, 12:52:18 UTC - in response to Message 1049290.
Last modified: 18 Nov 2010, 12:53:39 UTC

60 cycle power doesn't transmit very well or very far. You don't hear it unless it rides in on your power system. In the good old days the heaters on vacuum tubes would drive us HI-FI mavens nuts. I used to put DC on my heater circuits with very low ripple to lower my noise problem.

With velocity =frequency times wavelength

Figure out how long the antenna would have to be --about 50,000 miles for a quarter wavelength.

Yes, at 30Hz, the antenna would be 10,000 kilometres long, i admit its a problem! http://en.wikipedia.org/wiki/File:Light_spectrum.png

But as you say, you can build a detector with a shorter antenna that just detects part of the wave.

John.
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Message 1049833 - Posted: 20 Nov 2010, 6:19:13 UTC

A more practical alternative way to look might be optical.

Seen the nasa picture "earth lights"?

Of course our optics are no where near good enough to detect most planets, let alone light from them. But some day maybe.
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Message 1050222 - Posted: 21 Nov 2010, 13:41:56 UTC - in response to Message 1049833.
Last modified: 21 Nov 2010, 13:44:45 UTC

A more practical alternative way to look might be optical.

Seen the nasa picture "earth lights"?

Of course our optics are no where near good enough to detect most planets, let alone light from them. But some day maybe.

I think your missing the point.

ET's loudest accidental noise is not going to be lights or radio transmissions, its going to be their use of A.C. electricity, for the reasons mentioned below. The noise will be louder and easier to detect than anything else, by many multiples.

Yes, there are lots of other ways to listen for ET including the method currently used by SETI@home. There just always going to be more difficult to detect.

John.
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Message 1050533 - Posted: 23 Nov 2010, 9:13:47 UTC
Last modified: 23 Nov 2010, 9:18:26 UTC

Johnny, my son,

Don't think that AC power will transmit very far; thats why we use wires to carry it.. The wires that carry the current act as a wave guide and hence very little power "leaks" out to be "Broadcast". What you hear when you are listening to AM radio near a power line are harmonics and noisy brushes on the generators. They are easily drowned out at a few hundred yards by the weakest radio stations, say, of 5000 watts transmitted power that are many miles away. Conversely a very high percentage of the power is transmitted at radio frequencies (compared to 60 cycle current where almost zero power is "transmitted".

The 60 cycle current is up-converted , in a sense, to very high frequency when it is used for lighting. Detectors for light involve the eye and photodetectors as well as lenses and film.

Microwaves, (where we are looking for ET-e.g.) do very well where low power serves to communicate satellite TV to earth over a thousand miles with maybe 10 watts of power and it requires a crappy, toy antenna of only a few inches. hence very efficient for communicating long distances with modest power.

I think that radar and high power TV and short wave are the best that we can look for other than an intentional broadcast on the LYMAN hydrogen line or pi times this frequency.

Regards,

Daddio

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Message 1050615 - Posted: 23 Nov 2010, 20:25:28 UTC - in response to Message 1050533.
Last modified: 23 Nov 2010, 20:33:24 UTC

Bill, my friend,
I have to correct you. Copper wires are not used as a wave guide. Copper wires "carry" the flow of electrons efficiently, thats all, they are "electron guides". In the word "electromagnetic", its the "magnetic" bit that is the carrier of the transmitted signals in radio transmission. The theoretical photon is the signal carrier for electromagnetic radiation. Not the electron. The photon is the theoretical carrier for magnetism.

It does not matter how small a frequency you use when you generate A.C. electricity, you still generate a moving magnetic field..... Thats electromagnetic radiation or a radio wave. At 50/60Hz, its called SLF, Super low frequency radio. Nicola Tesla experimented a lot with transmitting electricity through thin air. Tesla's idea works fine, but it has big losses. The problem is people stealing the electricity your generating. But from a SETI point of view, the losses are detectable electromagnetic radio signals.

Any electromagnetic dipole with electrons alternating back and forth will generate a magnetic field, and hence, radio waves.

John.
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Message 1050941 - Posted: 25 Nov 2010, 2:23:40 UTC - in response to Message 1050615.

What you say is true about an Electomagnetic field . But in electric wires the energy is delivered by the wires--very very little escapes as broadcast noise.
Electric circuit theory and field theory are inter-changeable.

Take your radio near the power lines and you will see what I am talking about--move a few hundred yards away and all of the higher frequency hiss will be gone. You will hear the radio station loud and clear. On the other hand tune your TV to an off station and listen to the hiss --part of which is leftover from the big bang. At TV frequencies, tranmitted energy travels very well.

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Message 1051030 - Posted: 25 Nov 2010, 6:38:25 UTC - in response to Message 1050941.

What you say is true about an Electomagnetic field . But in electric wires the energy is delivered by the wires--very very little escapes as broadcast noise.
Electric circuit theory and field theory are inter-changeable.

Take your radio near the power lines and you will see what I am talking about--move a few hundred yards away and all of the higher frequency hiss will be gone. You will hear the radio station loud and clear. On the other hand tune your TV to an off station and listen to the hiss --part of which is leftover from the big bang. At TV frequencies, tranmitted energy travels very well.

But my radio doesn't tune to 50-60 Hz. If it did I doubt I could find a spot on the planet that is quiet. Maybe the back side of the moon.

Take your typical power transmission line. It is many many miles long so it makes a pretty good antenna at 50-60 Hz. Three Gorges Dam is supposed to have 22.5 giga watts of generation. At about 500Kv that is about 450,000 amps. As the magnetic field depends on the current carried a lot of stuff is going to get radiated into space. Clearly the power grid is the largest radiator on the planet.

However for the ET perspective, a lot of natural processes make a lot of noise in the 50-60 Hz range. That makes picking a signal out very hard. Much easier where it is quiet like the microwave band. That why I think RADAR is likely to be the easiest thing for ET to see coming from us.

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Message 1051053 - Posted: 25 Nov 2010, 8:52:45 UTC - in response to Message 1051030.

My point is that even the higher frequencies associated with power generation--mostly brush noise from generators- goes very little distance. I did some work 45 years ago with 3000 cycle lighting and the subway transformers use 25 cycles. 3000 cycle was much noisier as far as electromagnetic emissions than any 60 cycle power.

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Message 1051063 - Posted: 25 Nov 2010, 10:13:46 UTC


To paraphrase Johnney's central posit: the question is do power transmission lines actually transmit an EM signature detectable at interstellar distances; particularly at around 50-60Hz?

I rephrase it this way so I can answer it, sort of. I have used a (ground-based) survey instrument that detects the secondary (induced) EM field in rocks. The earth is criss-crossed as Johnney notes with transmission lines which in my rock world also behave (annoyingly) as primary transmitters which swamp the secondary fields I want to measure; however the surveys capture/measure the fields generated by these transmission lines too.

For clarity, the survey instrument has a frequency tuning range between 15kHz to 30kHz - so it is a VLF and not SLF field detector. The unit measures total field strength, total dip (in-phase), and the vertical quadrature (out-of-phase) components of the EM field.

A major >1,000km transmission line (230kV) is detectable in the 15kHz to 30kHz range up to 250 meters either side of the line. So what I see in measured VLF data is a detectable effect from transmission lines out to say 500 meters diameter centered on the line. This is consistent with car radio 'interference' distances. It is not consistent with interstellar distances. Note that this method doesn't measure magnitude of energy transmission; it just shows how far from the transmitter an effect is detectable - considering the detection limit of the instrument.

I leave the science and form of EM energy propagation to you guys - who know a lot more about it than I. In practical terms though, with the VLF equipment I use, the transmission lines are invisible to detection about a half-km away. This suggests to me that the boys on Tau Ceti at >10 LY will have a hard time figuring out we have coal-fired electricity and not lightning storms. And vice versa for us.


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Message 1051073 - Posted: 25 Nov 2010, 11:50:34 UTC - in response to Message 1051063.
Last modified: 25 Nov 2010, 11:59:59 UTC

The 50 or 60 Hz (cycles per second) frequencies are especially chosen, cause
they're easy to generate, (triple-fase) and transform to a high voltage.
In Europe, 3 x 380KV is used for long-distance distribution.

Another reason, losses are minimal, cause 'radiation' is almost zero and no capacitive loss in underground cables, only transformers need a huge ferro-magnetic 'core'.

Computer PSU.
Modern computer PSU's, do use a much higher, ~30-40KHz, frequency in order to use small ferrite core and thick wirering.

Only 'down-side' to 50 or 60Hz, is the effect on men and animals, this is the most dangerous frequency for heart failliar/disturbance.

In order to 'leave the planet', instead of being 'reflected' by a magnetic layer,
Kennely-Heaviside, frequency has to be higher then `50MHz, wavelenght 6 meter'.

Lower frequencies are reflected between this layer and the earth, itself.
(That's why, you can receive 'shortwave radio', from the otherside of the earth!)
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