I think dish@home as originally conceived could get around the signal to noise ratio problem GentleGiant brought up.
...
I found this link while investigating the NRAO site SARA
Thanks for this, Mark. It certainly simplifies things a bit. A few links from the SARA site, I noticed the SETI League has a beacon on the moon they use for timing.
I also noticed a page related to a more practical question: How Should We Scan?
Without data logging, you (everyone) can only scan in a specific direction, at a specific frequency, for just a small period of time. More participants means it's easier to divide the sky into sections, though. There's quite a selection of data loggers presently available...
After clicking on numerous tangential links from the NRAO page (mentioned above), finally made it back for a more thorough look, and found the following, on VLBI
Quote:
Interferometer systems of essentially unlimited element separation are formed by using the technique of very long baseline interferometry, or VLBI. In a VLBI system the signals received at each element are recorded by broad-bandwidth videotape recorders located at each element. The recorded tapes are then transported to a common location where they are replayed and the signals combined to form interference fringes. The successful operation of a VLBI system requires that the tape recordings be synchronized within a few millionths of a second and that the local oscillator reference signal be stable to better than one part in a trillion. A single magnetic tape capable of recording for several hours can contain one trillion bits of information, which is roughly equivalent to storing the entire contents of a modest-sized library. Hydrogen maser frequency standards are used to give a timing accuracy of only a few billionths of a second and a frequency stability of one part in a billion billion.
As GentleGiant pointed out, networking the TV dishes is analogous the VLBA. But when antennas are spaced more than 100 km apart, there is then the difficulty of providing the local oscillator reference signal – it costs too much to physically connect all the antennas. So the VLBI technique would be required to realize barkster's vision (shared by many, it turns out) of a “giant spherical array”, unless the reference signal can be gleaned from the TV broadcast itself, as Mark points out.
If I understand things correctly then, in either case, some kind of central facility will be needed for each metropolitan-area-VLBA, whose data would then be combined in regional VLBI. So I guess the $64 question is: Can BOINC help with this (e.g. as in a virtual central facility)?
Hey, how about 10,000 old-fashioned TV antennae and 100 PCs? It's called the “Primeval Structure Telescope (PaST)”, and it should allow cosmologists to see all the way back to when the first stars are being born (about 200 million to 1 billion years after the big bang). Even with the new WMAP data, there are still some questions about early ionization of hydrogen gas (e.g., maybe some stars formed and died quickly). There's a good project overview on it at above link. (Additional components include electronics from TV sets and from cell phones, too!)
-And-
They're making good progress with the Allen Telescope Array:
(Click for link to Space.com article on the update)
RE: I think dish@home as
)
Thanks for this, Mark. It certainly simplifies things a bit. A few links from the SARA site, I noticed the SETI League has a beacon on the moon they use for timing.
I also noticed a page related to a more practical question: How Should We Scan?
Without data logging, you (everyone) can only scan in a specific direction, at a specific frequency, for just a small period of time. More participants means it's easier to divide the sky into sections, though. There's quite a selection of data loggers presently available...
After clicking on numerous
)
After clicking on numerous tangential links from the NRAO page (mentioned above), finally made it back for a more thorough look, and found the following, on VLBI
As GentleGiant pointed out, networking the TV dishes is analogous the VLBA. But when antennas are spaced more than 100 km apart, there is then the difficulty of providing the local oscillator reference signal – it costs too much to physically connect all the antennas. So the VLBI technique would be required to realize barkster's vision (shared by many, it turns out) of a “giant spherical array”, unless the reference signal can be gleaned from the TV broadcast itself, as Mark points out.
If I understand things correctly then, in either case, some kind of central facility will be needed for each metropolitan-area-VLBA, whose data would then be combined in regional VLBI. So I guess the $64 question is: Can BOINC help with this (e.g. as in a virtual central facility)?
Hey, how about 10,000
)
Hey, how about 10,000 old-fashioned TV antennae and 100 PCs? It's called the “Primeval Structure Telescope (PaST)”, and it should allow cosmologists to see all the way back to when the first stars are being born (about 200 million to 1 billion years after the big bang). Even with the new WMAP data, there are still some questions about early ionization of hydrogen gas (e.g., maybe some stars formed and died quickly). There's a good project overview on it at above link. (Additional components include electronics from TV sets and from cell phones, too!)
-And-
They're making good progress with the Allen Telescope Array:
(Click for link to Space.com article on the update)