We've tinkered with SFP-to-SMA adapter boards like this: https://github.com/aewallin/SFP2SMA_2018.03 http://www.anderswallin.net/2018/04/500-mhz-sfp-board-v4/
although designed for 1 Gbit (1.25 GHz, or 800 ps 'bits') they work down to 10 MHz (and 5 MHz IIRC). With a decent interface-board and a short bit of fiber the ADEV noise floor is very close to what is measurable with a 3120A (aka TimePod). IIRC a rough rule-of-thumb is that the fiber can add around 1e-16/meter. So add 1km of fibre and you can expect fluctuations at 1e-13 level - roughly... AW On Thu, Mar 21, 2019 at 6:06 AM jimlux <jim...@earthlink.net> wrote: > While researching this for a radio telescope, I found amazingly > inexpensive (<$10) fiber optic transceivers for 1Gbps sorts of rates.. > > They take a standard singlemode duplex fiber and have a pinout suitable > for plugging into a Cisco, etc. switch. Apparently, there's some > internal programming which sets the hardware for the kind of switch, > rates, etc.. fs.com has a generic ASIC inside the adapter which can be > reprogrammed for whatever formatting, compatibility etc is needed. The > astronomers were saying that at Berkeley, they bought a box for a few k > which allows them to reconfigure the transceivers. > > > Something like this: > https://www.fs.com/products/12622.html > > Data sheet here: https://img-en.fs.com/file/datasheet/sfp1g-lx-31-10km.pdf > > and a 10 meter patch cable is $5 > https://www.fs.com/products/40203.html > > This is sort of "old news" in the networking world (the SFP form factor > was defined in 2001) > > > It seems like you could probably figure out how to interface to these > things and use them to distribute timing signals. > > I'll be talking to the radio astronomers tomorrow again, and I'll see > what I can find out about interfaces. I suspect they do NOT use them for > conventional networking - they're all about running lots of bits from > antennas into large multichannel correlators/beamformers. > > They're buying these things by the dozen. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.