[time-nuts] What position is measured?
rk at timing-consultants.com
Wed Sep 8 12:54:10 UTC 2010
It's usually a manual setting of antenna delay on receivers I've used, and based on assumed delay in the particular cable & connectors. You can tweak things closer if you have a good 1PPS to compare with.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Pierpaolo Bernardi
Sent: 08 September 2010 11:36 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] What position is measured?
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
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?
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