[time-nuts] 10 MHz over optical fiber?

[Lux, James P]

On 12/5/08 3:48 AM, "Neon John" <jgd at johngsbbq.com> wrote:

> On Mon, 24 Nov 2008 17:33:25 -0800, "Tom Van Baak" <tvb at LeapSecond.com> wrote:
>
>>> Yes. I know of several commecial systems. If you only need to do a short
>>> jump, then using fairly basic E/O-O/E equipment should work well
>>> enought. It all depends if you want/can to roll your own or need to buy
>>> a finished product (aka "buy this, and you will be fine!").
>>
>> Magnus, what's the typical noise floor, tempco or drift of cheap
>> (i.e., non JPL-level) fiber distribution systems like this? Is it less
>> than regular coax, or phase stabilized heliax? At 100 m lengths?
>
> OK, tom, you got me with another one.  WTF is phase stabilized heliax?  Is
> that a hunk of ordinary heliax that has been characterized or is it made
> special in some way?


I don't know about heliax, but in the semirigid and flex coax area, getting
good phase stability is a combination of the two.  Some dielectrics and
construction have distinct bumps in the phase/temperature curve at
inconvenient temperatures (I'm looking at you Gore!) although they're
generally pretty good.  Some might have more variation over temperature, but
it's smooth and consistent.  Esp if you're measuring temperature or have it
controlled, the latter might be a better choice.

Then, you temperature cycle it a bunch of times with it formed in the final
shape, which relaxes the residual mechanical stresses.

Then, you try them all, and pick the best ones.



Jim