[time-nuts] What position is measured?

Bob Camp lists at rtty.us
Tue Sep 7 16:44:21 UTC 2010


Hi

If you are only interested in frequency, antenna feed line delay will not
matter to you.

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Mark J. Blair
Sent: Tuesday, September 07, 2010 12:25 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] What position is measured?


On Sep 7, 2010, at 6:30 AM, jimlux wrote:
> Another analogy is that if you had a machine that recorded all the
signals, mounted right at the antenna, and then carried the recording half
way around the world, and then ran the recording into a receiver, it would
give you the position of the antenna, not the receiver.  The cable is just a
time delay.

Does this mean that while the antenna feedline cable length does not
influence the measured position (at the phase center of the antenna), and it
does not influence the accuracy of a disciplined frequency reference output,
it does introduce an error into the absolute time output (i.e., adding a
delay to the PPS output)?

In other words, do I correctly assume that I may safely ignore the length of
my TBolt's antenna feedline if I am only interested in its 10 MHz OCXO
output, but I may want to compensate for it if I ever find a need to use its
PPS output as an absolute time marker?

-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.





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