From what I have read, most of this SETI data processing involves very long FFT to channelize down to 1 Hz BW. However, assuming any alien signals would be like our digital comms, those signals are pseudo noise like, so using very narrow bandwidths just reduces the signal too. These narrow bandwidths would only be good for CW signals?
If I recall my EE schooling correctly, the 1Hz resolution bandwidth significantly reduces the noise floor of the receiver, and this allows you to resolve smaller signals from the noise. Also, assuming it is sweeping, having a digital signal with greater bandwidth is no problem to find.
Yes, EE here too, but if the signal you're trying to detect is also noise like (pseudo random), it is averaged out with the noise. That's why I'm thinking that any moderately complex signal won't be detectable. We'd have to detect a signal that aliens purposely sent out at a very narrow bandwidth; essentially seconds per bit, or even narrower.
And that they didn't bother to compress to save on bandwidth.
To me that's the kicker. There's only a 100 year or so window during which you can catch a civilization's transmissions un-encrypted and un-compressed. After that it might as well be noise.
Even after they have switched to encrypting and compressing their transmissions, they might still have have unencrypted, uncompressed station identification messages transmitted periodically.
I've always thought that this was the most likely reason for our simulation, and the most telling evidence for it:
In a universe where intelligent life is common throughout the galaxy, there'd be no way to tell what our species would have become left to its own devices. What discoveries we would have made, what cultures we would have created, what our destiny might have been.
The only way to discover it would be to simulate human life on a planetary scale in a universe where other intelligent life is mysteriously absent. Which is exactly the situation we find ourselves in.
We've been transmitting for less than 150 years, our species has been around for what is now believed to be 250k or so years, life on earth is about 4 bln years old.
Even if we continue to survive as a technological species for another 1000-5000 years and not push ourselves to extinction even if we go 10,000 years it's still a spec on the timeline of our galaxy not to mention our universe.
It's very likely that life is very common, technological species might also be common but this is on universal time scales it's also pretty likely that because species and entire planets go extinct all the time that the they simply do not overlap on universal time scales.
"The Green Bank Telescope searched for these signals using its “L-band” receiver, which gathers data in frequencies ranging from 1.1 to 1.9 GHz ... they conducting three five-minutes observation periods, while also conducting five-minute observations on a set of secondary targets"
Does this seem like a really short timescale to anyone else?
Of course, anything on human timescales is but the blink of an eye on geological, never mind astronomical timescales, but it still fells like you'd have to get awful lucky to catch something in just the 5 to 15 minutes you happened to be listening on a narrow range of radio frequencies.
Yeah, I have read to detect a transmission from several light years, it would take a transmitter like Aeroceibo. Also must assume the alien politicians would fund it long enough.
I thought this may have been NIROSETI but it isn't I wonder how NIROSETI is doing they search by looking at near infrared signals.
Here is what they do:
>Near-infrared Optical SETI (NIROSETI) has the advantage that light at infrared wavelengths is less affected by interstellar gas and dust; an infrared signal can be seen at greater distances than an optical signal at shorter wavelengths. Also, it takes less energy to send the same amount of information with an infrared signal than at shorter, optical wavelengths.
The data is analyzed on a distributed network. You can download the app and have it run in the background or as a screensaver. If ET is found, they promise to credit the computer owner that actually finds it. Just think, you might be the one!
