[time-nuts] What position is measured?

[Pierpaolo Bernardi]

On Wed, Sep 8, 2010 at 02:16, jimlux <jimlux at earthlink.net> wrote:
> Mark J. Blair wrote:
>> On Sep 7, 2010, at 6:30 AM, jimlux wrote:

> Yes.. except that the cable's physical and electrical length *do* vary with
> temperature, so if you're looking at the gnat's eyelash sort of thing, you
> need to take that into account.  Maybe 10 ppm/degree, so a 20 meter run will
> change a bit less than a millimeter.  That's down in the fractional
> picoseconds time-wise.
>
> It's an issue if you're doing things like interferometry at higher
> frequencies..

Would be possible for the receiver to take into account automatically
the delay of the antenna cable, by measuring the delay of an echo of
a signal it sends towards the antenna?  Do such receivers exists?