On 3/20/19 11:42 PM, Warren Kumari wrote:
On Thu, Mar 21, 2019 at 7:05 AM Anders Wallin <[email protected]>
wrote:
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/
And if you want a "ready made" solution instead of making the board
yourself, etc there is
http://shop.sysmocom.de/t/development-boards/sfp
I have some on order to play with, but am traveling, and so cannot play
with them yet.
W
This is very interesting stuff...
There have been times I was thinking "what I really need here is a
optical link for the 10 or 100 MHz".. But "hundreds of dollars" was a
bit steep. This is starting to get more reasonable (still, about $200
for a link, by the time you buy/assemble adapter boards, the $7 modules,
and some fiber).
As far as the reprogramming goes (another comment on the list) - I
understand that is to make the unit have some particular flavor
SFP-wise. If you were plugging them into a Cisco switch and all you had
was ones configured for Juniper switches, then you'd want to do that. At
the multikilobuck level to do this, you'd need a LOT of them to make it
worthwhile. The folks building radio telescope arrays with hundreds of
cables probably fit in that use case. A devoted time-nut using it to
distribute their reference around the house or lab, probably not.
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
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