[time-nuts] Relationship of relative stability between distant locations using GPS and environmental factors

David Andersen dga+ at cs.cmu.edu
Fri Jun 30 15:31:11 EDT 2006

On Jun 30, 2006, at 3:20 PM, Magnus Danielson wrote:

> From: "Stephan Sandenbergh" <stephan at rrsg.ee.uct.ac.za>
> Subject: [time-nuts] Relationship of relative stability between  
> distant locations using GPS and environmental factors
> Date: Fri, 30 Jun 2006 14:36:30 +0200
> Message-ID: <002d01c69c41$d06f24f0$401c9e89 at Stephan>
>> Hi,
> Hi Stephan,
>> A number of recent entries to this list have mentioned topics  
>> relating to
>> GPS timing and environmental corrupting factors (e.g. Ionosphere,  
>> Temp.,
>> Humidity, etc.). Personally, I am very interested in setting up a  
>> very
>> precise relative time between locations (maybe 100s of meters to  
>> 10s of
>> kilometres apart) on time scales of (maybe 100s of seconds to 10s of
>> minutes). I noted some members referred to dual frequency  
>> receivers for
>> overcoming these effects. Can anyone point me to some literature,  
>> articles
>> or links to overcome these environmental factors?
> I can recommend the "Global Positioning System: Theory and  
> Application - Volume I" and also (naturally) Volume II, edited by  
> Parkinson & Spilker.
> The pair should be a natural extention to the "Understanding GPS  
> Principles
> and Applications" edited by Kaplan.

Also, note that you don't really need dual-frequency for short  
baseline synchronization.  Common-view carrier phase time transfer is  
designed for exactly that situation.  The ionospheric problems that  
dual frequency is designed to overcome are roughly equal when the two  
receivers are sitting that close, so you're able to get sub- 
nanosecond synchronization.

Environmental effects and system calibration (antenna length, etc)  
will be your big problems.  There's been lots of good discussion  
about heat/humidity/etc., and clocks on this list.  The usual  
solution for the national timing labs (and tvb. :) is to stick  
everything in a completely controlled room. :-)


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