Hi Tom,
In my earlier life I designed some of the biggest fiber optic networks in
the world, before going into radio astronomy.
In your case, fibers are really cheap, digging costs a lot more. Cable
cost is insignificant.
For those lenghts I would use a 48 or 98- single mode fiber cable, forget
the switches if they are not essential. Use the 10Gbase-LR or something
similar, we use ZR for 50 kilometers. My knowledge might be outdated,
anyway get the cable with as many fibers you can get, light armoring
is usually needed.
All the wavelength-division-multiplexing schemes are not cost-effective at
that range, start to be at 1000 miles distance.
Sorry for the short answer, will be glad to help privately without
bothering other people on the list.
Cheers,
Jouko
"Life is pretty simple: You do some stuff. Most fails. Some works. You do
more of what works. If it works big, others quickly copy it. Then you do
something else. The trick is to do something else."
On Thu, 17 Dec 2009, Tom Kuiper wrote:
During the upcoming Goldstone 70-m down-time, we have an opportunity to put
fibers dedicated to radio astronomy in the antenna. The receiver we envision
would, when fully built up, have 40 2-GHz ADCs. To be able to use our signal
processing equipment with other antennas as well, we would want to put it in
the Signal Processing Center, which is about 0.5 km away from the receiver.
I assume that we would have a 10 GBe switch in the antenna. Could someone
give me an estimate of how many fibers of what kind would best serve our
needs?
An alternative scheme would be what GAVRT DSS-28 does, which would be to
bring 40 IFs to the SPC and digitize there. That way the ADCs could serve
other antennas. However, this appears to me to be more expensive and more
problem prone, and ADCs are cheap.
Thanks and regards
Tom
