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Radio Astronomy Help Needed For Story

Loss Leader

I would save the receptionist., Moderator
Loss Leader
Joined
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Gearheads:

I want to write an SF story where a private company leasing time on a radio telescope receives a large file from space which is, essentially, a pdf (or other book format). It would be about 800,000 pages of text and diagrams.

My question is how this could happen. Forgetting the speed of light and when the message was sent:

1. Can a private company lease time on a radio telescope?

2. Can they do it in such a way that only they receive the information?

3. What would the actual recording sound like? I assume it would be a very fast modulation between two pitches to represent 1's and 0's.

4. How would the radio astronomers be able to decode it to realize it was a file they could just open with current technology?

5. How long would such a process take?

6. Is there any way the radio signal downloads such that it resides in the computer memory as an actual file?

Much of this may be caught up with how the internet is perceived by personal satellite dishes now. Certainly, if my satellite provider is also my internet provider, I'm getting some sort of signal that my dish is reading as hypertext and showing me on my screen. I can also receive an email with an attached executable or readable file in one form or another which the computer detects and opens with the right player.

As such, would it just be easier if they received an email overnight?

I'd like some drama in the realization that they just got a damn book from space with enough actual science that I don't sound like an idiot.

My own research in the area has been frustrating in that it is either aimed way above my head or not aimed at all. For instance, I've been trying to book time on various radio telescopes around the world and they don't seem to be upfront about how to do that.

Thanks for any science you can science for me.
 
Loss Leader said:
Gearheads:

I want to write an SF story where a private company leasing time on a radio telescope receives a large file from space which is, essentially, a pdf (or other book format). It would be about 800,000 pages of text and diagrams.

My question is how this could happen. Forgetting the speed of light and when the message was sent:

1. Can a private company lease time on a radio telescope?
Click to expand...
If you write it in the future, even the near future, just write this in.

2. Can they do it in such a way that only they receive the information?
Click to expand...
Sure, who else has that big of an array?

3. What would the actual recording sound like? I assume it would be a very fast modulation between two pitches to represent 1's and 0's.

4. How would the radio astronomers be able to decode it to realize it was a file they could just open with current technology?

5. How long would such a process take?

6. Is there any way the radio signal downloads such that it resides in the computer memory as an actual file?

Much of this may be caught up with how the internet is perceived by personal satellite dishes now. Certainly, if my satellite provider is also my internet provider, I'm getting some sort of signal that my dish is reading as hypertext and showing me on my screen. I can also receive an email with an attached executable or readable file in one form or another which the computer detects and opens with the right player.

As such, would it just be easier if they received an email overnight?

I'd like some drama in the realization that they just got a damn book from space with enough actual science that I don't sound like an idiot.

My own research in the area has been frustrating in that it is either aimed way above my head or not aimed at all. For instance, I've been trying to book time on various radio telescopes around the world and they don't seem to be upfront about how to do that.

Thanks for any science you can science for me.
Click to expand...
I don't see the problem with this as far as credibility goes. Readers don't need the details, in fact, too many details might be a turn off.

Just make the technology up. I bounce ideas off my son when it comes to the technology (my sci-fi book is in its last editing stage). If you don't get enough info here, don't forget the Cosmo (Universe Today/Bad Astronomy) forum, those geeks know everything about technology.
 
Do the private company need to rent time? Maybe a scenario whereby a telescope needs an upgrade, and various sub-contractors are called in to do different aspects of the work. The systems guy could be a former employee of a space agency, now freelancing. Doing final checks before handover, they point at a well known radio source, but the alignment is slightly off. Before fixing the problem, our guy notices his screens suddenly filling up with apparent gibberish..............I'll let you write the rest :)
 
jonesdave116 said:
Do the private company need to rent time? Maybe a scenario whereby a telescope needs an upgrade, and various sub-contractors are called in to do different aspects of the work. The systems guy could be a former employee of a space agency, now freelancing. Doing final checks before handover, they point at a well known radio source, but the alignment is slightly off. Before fixing the problem, our guy notices his screens suddenly filling up with apparent gibberish..............I'll let you write the rest :)
Click to expand...

Or minor variation, astronomers find a strange signal from space. They give it to someone to decode, which they do.
 
rjh01 said:
Or minor variation, astronomers find a strange signal from space. They give it to someone to decode, which they do.
Click to expand...

like seti@home or some other BOINC , maybe a version with just a little larger distributed packet or the whole file fractally compressed and the company finds the encoding
 
Loss Leader said:
Gearheads:

I want to write an SF story where a private company leasing time on a radio telescope receives a large file from space which is, essentially, a pdf (or other book format). It would be about 800,000 pages of text and diagrams.

My question is how this could happen. Forgetting the speed of light and when the message was sent:

1. Can a private company lease time on a radio telescope?

2. Can they do it in such a way that only they receive the information?
Click to expand...

No idea but I would wager : not.

3. What would the actual recording sound like? I assume it would be a very fast modulation between two pitches to represent 1's and 0's.
Click to expand...

Pretty much random. PDF and similar format are highly entropic, so you won't have nice repartitions of 1 and 0. What you would get with a radio telescope are signals within the 400 Mhz up to a few GhZ. Even if you had two disticnt signal you transformed into some audible frequencies, the 1 and 0 would be pretty much random and you would get a mess, probably to human ear a superposition of the two signal unable to hear the zero and 1 (unless the download rate is abysmal).

4. How would the radio astronomers be able to decode it to realize it was a file they could just open with current technology?
Click to expand...

You would have to detect how the transmission parity is , error correction, and unit for the "byte" of info : on earth we decided for 8 but why should it be so unless intentional. Count practically 9 bits for each byte.

Once you detect that and the signal is repeated, it is trivial to have a spectra analyzer or a programs on a PC which read the frequencies, decide if it is one or zero then concatenate it into bytes.

Afterward what you could do is pretend that some guy copying the file, get an "helpful" hint of the OS of "recognized file format" and realize by accident that the file format is indeed terrestrial.

5. How long would such a process take?
Click to expand...

Depends on your bandwidth for the transmission. Imagine those 800000 pages have a bit of pictures and text, they are each 100 Kb. So the total transmission is 80 Gb.

I would wager that your bandwidth cannot be of the order of magnitude of the signal frequencies, (theoretically freq/4 is the minimum I think ?) but more probably for a noisy interstellar signal you would take a sure speed of less than 10MHz so that the zero and 1 are pretty clear. Let us say 8MHz, that means 1 cycle of transmitting the file is 10000 seconds or 3 hours about.

Then many cycle would have to be repeated before somebody "catch" this is a repeated signal.

Once you can transform the frequencies 1 to 0 , it is a matter of minutes to get a file.

6. Is there any way the radio signal downloads such that it resides in the computer memory as an actual file?
Click to expand...

From the size spoken ? Doubtful. But segments of it can stays as long as the memory is not required by other process - for a idle computer but the OS nowadays are clever enough to offload data on disk and get back memory unused for a time. In a functioning radio telescope in practice I would bet this does not happen as it would be constantly shifting data.

Much of this may be caught up with how the internet is perceived by personal satellite dishes now. Certainly, if my satellite provider is also my internet provider, I'm getting some sort of signal that my dish is reading as hypertext and showing me on my screen. I can also receive an email with an attached executable or readable file in one form or another which the computer detects and opens with the right player.

As such, would it just be easier if they received an email overnight?

I'd like some drama in the realization that they just got a damn book from space with enough actual science that I don't sound like an idiot.

My own research in the area has been frustrating in that it is either aimed way above my head or not aimed at all. For instance, I've been trying to book time on various radio telescopes around the world and they don't seem to be upfront about how to do that.

Thanks for any science you can science for me.
Click to expand...

Not sure if I am helpful or not.
 
If you want to send a picture to someone who has no idea how to decode it then you have the number of pixels height and width prime numbers. Like 7 and 11. This makes the total number of pixels used is 77. The receiver can note the product of the primes (hard but possible) and so work out the dimensions. Of course the prime numbers would be much larger.
You would also need error correction. Here is a Youtube on how this can be done https://www.youtube.com/watch?v=EBy7IYtJRKs
 
I'd suggest reorienting the story to aliens receiving the information from earth.
 
Identifying something as a modern file format is generally fairly simply. There is a fixed string of characters at the beginning that identify the file format.

For example, a pdf file will begin with something like: %PDF-1.3.%

The % symbol means what follows is a comment. The first comment specificies the PDF version number. These would be the first few characters found in all pdf files (with the version digits differing accordingly).

All file formats from .jpg to .gif all have a unique header that makes identifying them simple.

The hard part with the radio signal would be identifying the appropriate bit-rate, and encoding used. Is it ASCII? Is it Big-endian or Little-endian? Is it using frequency modulation or amplitude modulation? Is it in a compressed format? Did you catch the entire signal from start to finish and can clear identify where the header begins?
 
Last edited:
Molinaro said:
Identifying something as a modern file format is generally fairly simply. There is a fixed string of characters at the beginning that identify the file format.

For example, a pdf file will begin with something like: %PDF-1.3.%

The % symbol means what follows is a comment. The first comment specificies the PDF version number. These would be the first few characters found in all pdf files (with the version digits differing accordingly).

All file formats from .jpg to .gif all have a unique header that makes identifying them simple.

The hard part with the radio signal would be identifying the appropriate bit-rate, and encoding used. Is it ASCII? Is it Big-endian or Little-endian? Is it using frequency modulation or amplitude modulation? Is it in a compressed format? Did you catch the entire signal from start to finish and can clear identify where the header begins?
Click to expand...


Great help. Thanks.
 
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