[time-nuts] Remote GPS Oscillator Steering

[Iain Young]

Hi Everyone,

Recently, I have acquired a HP Frequency Counter and Signal Genny, and
have set up a small "lab" in the house. This is great, but I'd like to
hook it into my 3816A, which is 70 ft away in an outhouse, along with
all my radio gear, to at least compare it to the 10811 in the Frequency
Counter.


I'd rather not drill a hole and run a cable (There are other issues
with that as well as the hole, the outhouse is the other side of the
garden path from the lab!)

I do have fibre to the house for N/W  connectivity, and (unshielded)
CAT6 from the patch panel to the "lab".

Two problems here. One the patch panel is the other side of the house
from the lab (so running a dedicated piece of coax is out without
taking up the floors..), and Two, 10MHz over unshielded CAT6 is not
good practice, to say the least, and simply not going to happen.

So I started looking at other possibilities. It seems a lot of GPSDOs
steer the Oscillator by using the PPS. Is that right ? 1 Hz over UTP is
a bit more reasonable than 10 MHz, but I did not find many 10MHz
oscillators with a PPS input.


I thought of using a Z3801 instead of the Z3816, but patching out from
the EFC SBM connector, then (optionally) converting that to fibre,
sending it up the garden to the house, converting back to copper, then
the CAT 6 to the Lab where a second Z3801 would sit

I would rather fibre between the house and outhouse for EMC and
grounding reasons. My hope is that thee 10MHz Osc would then be steered
from the remote Z3801, although the lab Z3801 itself would complain
bitterly about no lock no doubt.


Does anyone have any comments on this madhat scheme ? Or have other
suggestions of how I might go about getting that 10MHz signal
converted to fibre, and back again to send into the "lab" equipment ?
What are other people's experience with similar issues ?

What do the "big boys" like NIST and NPL do to manage this ? I know
they transfer time over large distances, and I know NPL transfer
frequency as well to certain customers, so I guess other similar
institutions do as well


[Note, for me, plug and play is better. Soldering irons do not like me,
and I wouldn't trust myself with one anywhere near anything like a
precision instrument :), although putting pre-built modules in a metal
box I'm okay with, but plug-and play preferred.]

(Googling for fibre converters or similar these days brings up such
a noise floor of Ethernet, Any suggestions on the best terms
or part numbers to use to find raw (assembled) fibre transmitter /
receiver modules that might be suitable would be gratefully received)


Best Regards

Iain