[teqc] MultiPath with L1 GPS receiver

Lou Estey lou at unavco.org
Thu Feb 3 19:39:57 MST 2005

... plus detect and remove slips when they occur.


> Ok, that's good to know.  So all Hannan should have to do is compute RMS 
> values of these output files.
> -Jim
> On Feb 3, 2005, at 7:21 PM, Lou Estey wrote:
>> James Johnson wrote:
>>> [...]  In principle, you can do this with single frequency data over 
>>> a short period of time, but after some time the L1 phase and C/A 
>>> measurements will diverge due to the ionosphere (phase advance on L1 
>>> and group delay on C/A).  What you want to look at is a running 
>>> average of C/A - L1*lambda where C/A is the pseudo range measurement, 
>>> L1 is the phase measurement in cycles, and lambda is the wavelength 
>>> of L1.  If you use a running average of a 10 min, you should be able 
>>> to see the multipath signal, an you could look at the RMS of this 
>>> value (with steps removed caused by possible cycle slips).  
>>> Unfortunately teqc does not do this.
>> Actually, Jim, if you remember: we started down this path some years
>> ago when we were researching L1-only receivers for the L1 project and
>> teqc got part way there.  You can still activate the +pl option during qc
>> to generate the .pl1 plot file (C/A - L1*lambda) -- but we never followed
>> through with the running average, etc.  At the time (and it's still
>> true!) the most important qc aspect was whether we were getting complete
>> data epochs or not -- what percentage of epochs was lost (due to 
>> transmission
>> or data collection problems).
>> 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
>>      WWW:  http://www.unavco.org   http://jules.unavco.org
>> "If the universe is the answer, what is the question?"
>>                                                -- Leon Lederman
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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