Hi all,
In the old days the biggest problem was the very limited dynamic range of
fiber optic receivers. If you are thinking of using analog links you shoud
check if this is still true and if it isn't, what tricks have been used to
circumvent it.
Otherwise all the different standards are a big mess, but if you know
basic optics almost anything can be done. For example the operators
routinely connect multimode and singlemode equipment by using inexpensive
attenuators. Our 10 Gbps link uses dwdm in one end and inexpensive
10Gbase-ZR on the other, never had a problem.
Using optics for high-speed digital links is surprisingly easy, I guess
analog links are easy too if the signal strength is constant which is true
for radio links, not true for radio astronomy.
Please correct me if you think otherwise.
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 Fri, 18 Dec 2009, Justin Jonas wrote:
Alan reminded me I should have given the link to the supplier:
http://www.foxcom.com/index.aspx?id=2510
J
On 18 Dec 2009, at 12:53 AM, Tom Kuiper wrote:
John Ford wrote:
We've decided (Maybe prematurely?) that wide-band analog links are not the
way to go, for single-dish, at least. The stability we need was not there
the last time I looked, when you factor in the twisting of the fibers, the
diurnal temperature variations, etc. Can you give me more info on these
wideband analog links? It would be much easier for us if they really
worked well at these bandwidths of ~10 GHz.
Glenn is in Green Bank, I believe, but when he sees this thread he may have
something to says about stability concerns at DSS-28 due to the fibers from
receiver at the base of the dish and the DSP electronics in the antenna
pedestal.
In any case, I agree with Jouko that you should bury as many fibers as you
have money for. The cost of the WDM systems far overshadows the cost of
fiber at 500 meters. If you were trying to reuse existing infrastructure,
it would be a different story.
We don't even have to bury the fiber bundle. It just gets strung alongside
all the other cables that are already there.
Cheers
Tom
Justin Jonas
j.jo...@ru.ac.za
