[teqc] TEC mesuarement

Lou Estey lou at unavco.org
Tue Jan 22 11:00:03 MST 2008


Yes.  .ted units should be the .tec units (10**16 electrons / m**2) per second.

--lou

> Thank you it was very helpful. Is the rate of change of TECU in time 
> present in *.ted files?
> 
> On Jan 3, 2008 12:16 AM, rocken <rocken at ucar.edu 
> <mailto:rocken at ucar.edu>> wrote:
> 
> 
> 
>     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
>      > UNAVCO, 6350 Nautilus Drive           FAX:  [+001] 303-381-7451
>      > Boulder, CO  80301-5554            e-mail:  lou   unavco.org
>     <http://unavco.org/>
>      >    WWW:  http://www.unavco.org <http://www.unavco.org/>  
>     http://jules.unavco.org <http://jules.unavco.org/>
>      >
>      > "If the universe is the answer, what is the question?"
>      >                                                -- Leon Lederman
>      > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


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