[teqc] TEC mesuarement

rocken rocken at ucar.edu
Wed Jan 2 15:16:08 MST 2008



This conversion comes from "Propagation Effects on Satellite
Systems at Frequencies Below 10 GHz, W.L. Flock, NASA Reference  
Publication
1108, 1983" (section 2.3.1).  The units should be in TECU (1 TECU is  
10**16 electrons / m**2)
The conversion teqc uses assumes that the values in the .ion file are
the ionospheric phase advance of the GPS L2 carrier in [m].

Negative TECU numbers are possible because the teqc *.ion values are  
based on phase
data and are biased by unknown carrier phase ambiguities.   Only the
rate of change of the TECU values from teqc are meaningful - except for
epochs when cycle slips affect the data.

Chris



On Jan 2, 2008, at 10:20 AM, Lou Estey wrote:

> Evgeny Brainin wrote:
>> Hi ALL
>> I want to know how teqc calculate TEC (total electron content), by  
>> which formula? and why sometimes i get negative data of TEC?
>
> This option was just an experiment that we tried 11 years ago.  The  
> data in
> the .tec file is just a simple rescaling of the .ion by:
>
> -(1227.6e6)^2/40.3e16
>
> where 1227.6e6 is the L2 carrier frequency in Hz.  I can't locate the
> reference that comes from, but Chris Rocken (who is on this list)  
> should
> know.
>
> At this point, the option should probably just be removed because I  
> think
> it causes more confusion that any good that comes from it.
>
> cheers,
> --lou
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
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>
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>                                                -- Leon Lederman
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