[teqc] +QC report

Joe Sass joe_sass at spectraprecision.com
Tue Aug 14 10:40:26 MDT 2018

Hello Lou,

Thank you very much for this explanation and perspective.

Best Regards,  Joe Sass

On Tue, Aug 14, 2018 at 9:32 AM, Lou Estey <lou at unavco.org> wrote:

> hi Colleen,
> MP12 and MP21 are what (in UNAVCO's qc history) used to be called MP1 and
> MP2, respectively.
> MP12 is the rms of a linear combination of L1 pseudorange and phase with
> L2 phase, whereas MP2
> is the rms of a linear combination of L2 pseudorange and phase with L1
> phase.  (When there was
> just signals on GPS on L1 and L2 the older designations were enough to
> disambiguate the two
> possible combinations.)
> For the equipment at most sites, MP12 is often smaller than MP21 by
> 10-30%, but one can
> easily find situations where the reverse is the case.
> If you are looking at a long enough time period of data, say, hours, I'd
> say that one should
> see MP12 and MP21 having values of no more than a couple of meters -- as a
> general guideline.
> But due to the design of the algorithm, there is a trade-off between
> multipath slips and the
> rms values: as counts of detected multipath slips go up, the rms values go
> down.  (In the
> limit of multipath slips at every epoch, the rms is zero.)
> For 30- or 15-second sampling, I'd say that observations per slip should
> be something like
> 500 or higher, but there are certainly many cases where one can
> successfully process data where
> the observations per slip value is lower.   If there were the same number
> of slips per
> unit time in high rate data, then one might expect the observations per
> slip to go up
> by the factor of increased sampling rate, i.e. for 20-Hz sampling one
> might expect an
> observation per slip counts of 100000 - 200000 or even higher, but I
> somehow doubt you're
> actually going to see that.  You'll just have to experiment and see how
> your processing
> software does with different observation per slip values.
> Personally, I don't put too much stock in actual MP12 or MP21 values for
> setting hard-and-fast
> "good" vs. "bad" thresholds.  There are just too many exceptions.
> The utility of multipath rms, to me, is in monitoring these values over
> time and looking for
> significant degradations, i.e. multipath rms increases.
> --lou
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
> UNAVCO, 6350 Nautilus Drive
> <https://maps.google.com/?q=6350+Nautilus+Drive&entry=gmail&source=g>
>        FAX:  [+001] 303-381-7451
> Boulder, CO  80301-5554            e-mail:  lou  unavco.org
> "If the universe is the answer, what is the question?"
>                                                -- Leon Lederman
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> On 10-Aug-18 09:00 AM, Brooks, Colleen (GSFC-694.0)[SCIENCE SYSTEMS AND
>> Good Morning,
>> Im trying to find out some information about the QC report and what
>> certain things mean. Ive read through teh interperting teqc's qc Mode
>> output, and found a lot of useful information.  However im still missing
>> some information regarding MP12 and MP21.
>> first off the code that i used to create my filename.##S file is as
>> follows (its a 20hz file):
>>      teqc +qc -iod_jump 18000 -ion_jump 8 -mp_win 900 filename.##o
>> I am trying to determine the quality of the data we receive from the
>> receiver based on some of the information from the S file.  Im looking at
>> the tables under "MP12 RMS summary" and "MP21 RMS summary". I understand
>> the tables themselves, but my question is about what is MP12 and MP21 and
>> what is the difference between the two.  And also should one summary be
>> valued more heavily over the other?
>> And a second question, how many cycle slips is ok to see on a
>> receiver/satelleite before we should become concerned?
>> --
>> Colleen Brooks
>> SSAI - Science Systems and Applications Inc.
>> NASA/GSFC - Goddard Space Flight Center
>> LVIS (Land Vegetation Ice Sensor)
>> Bldg 22 Rm C135A
>> Phone 301-614-6505
>> e-mail:Colleen.Brooks at nasa.gov
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