Radio transmission range into space?

[STARNIGHTER]

There may not be a definite answer to this, but I would appreciate any guesses!

A lot of people have wondered if basic radio or tv transmissions could be detected from other star systems, if one might assume that there is someone out there to pick up the signals. Obviously, with the vast light year distances, the odds of any conventional signal from earth being detected from even the nearest star systems, would be highly unlikely.

However, my question is specific. How far from earth could a spacecraft,carrying our best radio/dish receiving technology, still be capable of picking up signals from conventional radio/tv transmissions? Not the traditional frequencies used by Nasa, but regular civilian transmissions. That is, if someone had no limits to the expense or size of a spacecraft's payload(and could carry the very best and most powerful equiptment known to technology), just how far from earth could one expect to be able to still detect such signals. Or, if a giant radio dish receiver could be built on some planet surrounding a nearby star, would it be unrealistic to receive any radio frequencies from earth?

May be a silly question, but at least I'm not suggesting that beings in other systems might have already gone to cable, and not rely on transmissions(haha).

[selden]

Current ground based technology is capable of detecting Earth-style commercial radio emission leakage to a distance of about 20 LY.

See http://arxiv.org/abs/astro-ph/0610377

[STARNIGHTER]

Thanks, Seldon! Very interesting link, to know that such transmissions could be detected up to 20 light years.

Now, among the garble and chatter contained within the radio leakage from earth, one wonders if any specific frequency (and thus specific broadcast transmission) could be picked out and understood?

Again, thank you so much for the info, and answering my question!

[guest jo]

A very interesting Article can be found here about the distances you could reach using microwaves.

I??m afraid it is only in german...

http://www.amsat-dl.org/go-mars/pdf/int ... kation.pdf

Karl Meinzer was project leader in several satelite projects of Amsat DL and is also involved in communication with satelites. He also is Ham Radio Amateur.

[STARNIGHTER]

Thanks, "Guest Jo", but I'm afraid I don't speak or read german. Could you tell me roughly what distances (using microwaves) they suggest?

[guest jo]

Ok I??ll try but there are lots of details concerning antenna sizes, used wavelenght and he??s not only writing about whats possible but also whats relistic. Example for that is the question: What transmission power would other civilisations use ? If we look at ourselves we should suppose: not much to be precise: zero ( concerning directional emissions)
But now some statements he does:

- technical civilisations (thats us ) and their normal radio transmissions are absolutely unhearable in a few lightyears distance (below 5 surely)

-actual SETI-project is using the wrong suboptimal frequencys, the "aliens" would have to use about 150 Gigawatts transmission power for 12 lightyears distance. ( diam.100meter Antenna on our side, non-directional beacon on their side)
Assuming extremely high efforts at decoding the signals about 1 Gigawatt would work.

- solution: high gain one-direction antennas on both sides on the right wavelength, diam. 100 meter movable antennas on both sides, distance 12 lightyears -> power needed 2500 watts.

- in general roundabout 20 lightyears are possible

-in a second (older) article under the same link the maximum distance is about 1000 ly. But this needs even shorter wavlengths that can only be used with antennas outside of the athmosphere. In this case diam. 90 meters for distance given. But he dropped this thought in the newer article due to the unexpected slower development of low price space-missions.

So I hope that even with my bad english I could sum it up a bit.
Don??t be too harsh with me...

[LordFerret]

STARNIGHTER, you may want to talk to some people at ARRL, the Amateur Radio Relay League. I'm sure you'll find a wealth of information about radio wave-propagation and distances vs. power etc within their resources.

http://www.arrl.org/

[eburacum45]

Looking at Selden's .pdf link, the proposed Square Kilometer Array could apparently detect the military radars used on Earth (Ballistic Missile Early Warning Systems) from a hundred parsecs or more.

I find that interesting, as I live about thirty miles from one of the most powerful phased-array BMEWS on the planet (at Fylingdales). Interesting to think that transmissions from that array might reach detectors more than three hundred light years away. Yorkshire is emitting energy on an interstellar scale....

[STARNIGHTER]

Thanks, "Guest Jo", for translating. It is I who should apologize for not being able to read the link you gave me in German. It's outstanding that you can translate from other languages, especially such extensive scientific info.

Also, thanks to "eburacum 45", and "LordFerret" for your replies. This information has been very helpful, and I'm grateful to all for responding to a subject matter that most would consider to obscure to debate.

I'm always believed in looking at issues from all sides, including putting myself as being the person on another star system, wondering if long lost radio transmissions from earth could be detected. It appears that strong emissions could be detected up to around 20 light years distance, and less powerful transmissions become obscure in far less distance. Just gets one wondering, how far our technology could receive signals....that is, have we reached a limit, or will future technolgy push the limit a bit farther?!

Thanks, to all, very much!

[STARNIGHTER]

STARNIGHTER, you may want to talk to some people at ARRL, the Amateur Radio Relay League. I'm sure you'll find a wealth of information about radio wave-propagation and distances vs. power etc within their resources.

http://www.arrl.org/

LordFerret, one of my hobbies/interests is radio, and I've had the pleasure of monitoring hams on shortwave, and corresponded with many. They certainly know their business as far as radio transmissions, propagation patterns, etc., but then again, they depend on radio bouncing around the atmosphere, and not off into space. Still, I'll recontact some I know, and perhaps one just might have opinions about the endurance of radio transmissions (in even that frequency range) if purposely directed outward. I do recall one "ham" who was into bouncing signals off the moon, so he may be the first one I'll contact. Thanks again!

[LordFerret]

You're welcome!

Of hams, DX'ers, I too believe the same - they certainly know their business as far as radio. My father happens to be a ham operator and has been one for many years (WAS and WAC), currently involved with ARRL, JSARS and RACES, as well as local emergency management (tied to FEMA and the Red Cross). It was his interest in amateur radio which spurred my first attempt at modeling a spacecraft addon for Celestia - an incomplete attempt thus far (I'm not a very good 3D modeler )... I'm attempting to create Oscar I and Oscar II, the first and second amateur-built satellites.

Good luck with your research!

[STARNIGHTER]

You're welcome!

Of hams, DX'ers, I too believe the same - they certainly know their business as far as radio. My father happens to be a ham operator and has been one for many years (WAS and WAC), currently involved with ARRL, JSARS and RACES, as well as local emergency management (tied to FEMA and the Red Cross). It was his interest in amateur radio which spurred my first attempt at modeling a spacecraft addon for Celestia - an incomplete attempt thus far (I'm not a very good 3D modeler )... I'm attempting to create Oscar I and Oscar II, the first and second amateur-built satellites.

Good luck with your research!

Thanks, LordFerret! A lot of people dismiss amateur radio, but they don't realize that it can mean all the difference in the world for communicating, even when satellites, cell phones, or internets are down! Your background and experience is impressive, and if possible, please email me or IM me sometime about this satellite project you're working on!

I did contact the AARL, but haven't heard back yet.

Radio waves, of any various wavelengths, are fascinating to ponder reaching outward into our universe. If someone is out there, I's say they will most likely receive an old radio transmission instead of our communications on the cell phone or internet(haha).

[LordFerret]

There isn't much to tell about the satellite I'd been working on. I have other 'projects' which compete for time, sorry to say, so I didn't get very far with it. I'm not very good at 3D modelling either... I'd been using Blender, or rather struggling with Blender lol.

Being Oscar 1 and 2 are identical, only one model will be required to create them both. There are not many resources that I'd found for Oscar other than the following:

http://en.wikipedia.org/wiki/OSCAR
The image posted at Wiki is a model, all prettied-up at that.

http://www.projectoscar.net/
The images at the Project Oscar Gallery Archives are more accurate, showing Oscar's creator with the actual satellite. It is from these pictures that I'd taken measurements and drafted 2D scale drawings of it on paper, which I then worked into Blender. I've gotten as far as creating the curved box. I still need to create the antenna and coil and screws, and suppliment with color the areas of thermal-tape. My biggest problem is that I don't know how to 'attach' each of the components to the box LOL!

If I ever do get to finish it, I'll then need to hunt down some orbital data (for both of them) from NASA. I've got some links saved for this already (somewhere I think). I'd written (emailed) the Project Oscar folks to see if they could supply information about the intended rotation (of both 1 and 2), but I never got an answer. However, I did read in one of the articles about some variable data transmission rates of the 'HI' message it sent (Oscar 1), and the indicated speculation about that being caused by solar heating/cooling of the satellite's surfaces as it rotated (the temperature changes affecting its electronics). I'm thinking an approximate rotational period could be derived from that data? Of course I'm getting way ahead of myself here!

Ultimately it would be really nice to see every AMSAT in existance available in Celestia... both for educational, training, and tracking purposes.

[STARNIGHTER]

Thanks, LordFerret! Very impressive project you're involved with! Your enthusiasm is excellent, and that will carry you through!

By the way, I got a great reply from the AARL, regarding radio range. They of course ran a formula based on basic ham freuqncies, as well as antenna gain formulations for receive. There conclusion, a range of only a few hundred Kilometers.....well, not far! Still, I'm sure that if huge dish receivers and highly advanced receiving equpitment were in play, the range would have been much greater. Nevertheless, the AARL were professional and kind to provide their input!