[time-nuts] OT: Far-out space navigation from sideways satnav signals

Attila Kinali attila at kinali.ch
Fri Apr 19 15:13:57 UTC 2013


On Thu, 18 Apr 2013 13:38:50 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> What's the adev of pulsars at long times?  How long is long?  Where is the 
> knee of the curve?

I remember reading something about 10^-18 long term (iirc 1year), but
cannot find where i read it.

But to acheive that level you have to compensate for a lot of stuff.
Not only the orbit and rotation of earth, but also solid earth tides
etc pp.

> How good a clock could you build with a pulsar-DO?
>(Assume you have a good crystal but no atomic clocks.)
> Would you have to watch multiple pulsars at the same time?
>  (Multiple antennas.)

I think you will have to watch the same pulsar from multiple antennas
placed strategically around the world to avoid cycle slips.. unless the
pulsar is up north (or south) in the sky so that you have a permanent
view of it.

And yes, i thought about that as well.. unfortunately, i neither have
the equipment nor the knowledge to engage in something like this ^^'

			Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
		-- Tirin, The Dispossessed, U. Le Guin



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