[teqc] MultiPath with L1 GPS receiver
jjohnson at ucar.edu
Thu Feb 3 19:35:38 MST 2005
Ok, that's good to know. So all Hannan should have to do is compute
RMS values of these output files.
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
> to generate the .pl1 plot file (C/A - L1*lambda) -- but we never
> through with the running average, etc. At the time (and it's still
> true!) the most important qc aspect was whether we were getting
> data epochs or not -- what percentage of epochs was lost (due to
> or data collection problems).
> 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
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