When I asked about this on another Group a while back, I was told the phase
noise made it an undesirable solution.

Although I never tried it, I would imaging balanced shielded twisted pair
would be a better way to go.  Immune from ground loop problems than can
beset coax distribution and a whole raft of ICs support the medium, from
RS422 to CAN bus drivers and receivers.

Andy
www.g4jnt.com

On Sat, 28 Aug 2021 at 17:51, AC0XU (Jim) James.Schatzman@ac0xu.com wrote:

On 8/28/21 9:51 AM, AC0XU (Jim) wrote:

Take a look at the standard fiber optic modules that plug into a
switch.  They typically have a very simple logic level interface to the
diode.

here's a $27 dollar example - but I think you might want to iterate
around - I recall finding cheaper ones - part of it is which fiber
cable/connector you use, and part of it is what the backside interface
looks like. I can't find it now, but you can get the mating electrical
connector, or you can solder wires.

https://www.fs.com/products/11555.html?attribute=77&id=219732

The OVRO-LWA uses fiber to connect the remote antenna preamp with ~1km
fiber to the receiver at 30-90 MHz  - they use a laser diode on the Tx
end and a receiver on the Rx end. They're pretty cheap. They've done
quite a bit of testing of various schemes, and measuring noise
performance and loss.

dig around here: http://www.tauceti.caltech.edu/LWA/lwamemos.html

In particular memo 12

http://www.tauceti.caltech.edu/LWA/memos/memo12.pdf - gives a couple
part numbers.

If you need Sandy Weinreb's report (from 2019, referenced by Larry
D'Addario in memo 12) - you could probably email him, or I can look for
a copy.

On 8/28/21 9:56 AM, Andy Talbot wrote:

We use fiber to distribute high quality 10 and 100 MHz at JPL. I can
visualize the rack downstairs from my office where the cables terminate,
but I can't for the life of me remember the brand name. It's a 3U card..

DSN does it as well, with obsessive attention to temperature, mechanical
stress, etc.

From 20 years ago:
https://tmo.jpl.nasa.gov/progress_report/42-148/148L.pdf - probably overkill

PTS has a Fiber distribution amp: https://www.ptsyst.com/DA1-100-10-FO-B.pdf

There's this, but Im going to bet it's pricey:
https://emcore.com/products/reference-timing/

Look at Synchronous Ethernet.....

On Sat, 28 Aug 2021, 17:51 AC0XU (Jim), James.Schatzman@ac0xu.com wrote:

I was looking for something similar about 18 months or so ago.  Although I
haven't taken any
action yet, I concluded that one could do a nice job for under $200 per
segment, including the
transmitter and receiver modules and lots of connectorized multimode
fiber.  What I don't know
is what the phase noise performance would be, except that I do know that
the fiber's VF is
materially influenced by temperature.

I was looking primarily at the HFBR-2416 for the fiber receiver, and the
HFBR-1412 (standard
power) or the HFBR-1414 (high power option) for the transmitter  Unlike
most of the available
models, these are fundamentally analog devices, meaning that you can
transmit sinewave
10 MHz through them.  At the time I was looking, Mouser was selling these
for about $20 each.

See the datasheet at
https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
with particular attention to page 21 regarding the HFBR-2416 receiver.

I was also looking at Fiber Instrument Sales for patch cords.  We bought a
lot of fiber stuff from
them at Arecibo, and I was always happy with them.  See:
https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB

Somebody had pointed out yet another source of connectorized fibers ("patch
cords") to me, but I cannot find the name
at the moment.

Dana  K8YUM

On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim) James.Schatzman@ac0xu.com
wrote:

White rabbit seems pretty good for time synced over fiber.  PTP with
enhanced stability profile.  It's a IEEE standard.  It seems to work for
CERN.  Lately I've been looking at Cisco devices that can support it.  It
whould be nice if I could find hardware that'll support it more easily...
Maybe it'll come soon?

If you need optics I highly recommend AMC optics they'll code (Cisco,
Intel, NetApp) SFP+ and QSFP for any vendor you want.  Prices are great and
it's all made the USA no relation to me.  I've been getting into 100G
Ethernet over OM4 fiber.  The new profile for PTP over fiber is legit.

Bill

On Sat, Aug 28, 2021, 12:04 PM Dana Whitlow k8yumdoober@gmail.com wrote:

Hi

With a whole variety of pretty good OCXO’s going for cheap money
on eBay, it’s likely less expensive to do cleanup oscillators on the link
compared to going crazy with low noise optical this or that. Yes, you
will be getting something in the high 150’s for noise, but still pretty good
for $10.

If you need better, spend $50 or so on a 10811. Still less money than
some of the crazy fiber stuff.

With either one, send over a high enough frequency that the loop isn’t
dealing with reference spurs in any significant way. Given the clock rates
Ethernet runs at these days, that part should be fairly straightforward.

This assumes that there is a crossover somewhere practical between
the fiber noise and the noise on the optical gear. You should be able to
work out what it is with some fairly normal phase noise or ADEV testing.

Bob

Bob, my own motivation  for going to fiber was entirely different.  I
simply wanted to
run 10 MHz all over the place from reference sources in disparate
locations in the
house, and I quickly discovered that cable leakage was embarrassingly
severe.  So
I shut down and began contemplating a fiber link.  But then reality set in
and I realized
that running fiber across the house had its own big problems, so I set the
project aside.

Dana

On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq kb8tq@n1k.org wrote:

Hi

Anything you do that has a bunch of 10 MHz cables running out from here or there
will impact your ability to listen to WWV at 10 MHz :)  Other than killing all the sources,
there is no silver bullet.

Bob