[FOSS-GPS] Can't get Ambiguity Validation Ratio to move

[Danny Miller]

OK- thank you so much!  I will try it out!

What is the best way to determine a location?  If I use a single unit's 
NMEA, I will not know the location with centimeter accuracy.

Am I correct in understanding that the small error in base location will 
not affect the relative accuracy of the base-to-rover difference?  Only 
that the absolute location of the rover will be off by an identical amount?

It might be useful to have a mode where the output is purely a relative 
distance vector might be useful.  Would that get rid of the need to fix 
exact coordinates for a base?

I was gonna say "maybe it should get an inaccurate base location from 
NMEA", but SkyTrak-Raw doesn't offer a calculated position fix at all.

Danny

On 6/20/2011 3:56 AM, Tomoji Takasu wrote:
> Dear Danny
>
>> In the data window of RTKNavi, I noticed the Lat/long/height of Base 
>> is not listed with real numbers (90deg 0m).  This isn't right- that 
>> GPS has a fine solution in NMEA.
>
> You have to set the base-station position properly in
> Options dialog for relative modes. RTKNAVI never uses
> receiver's NMEA.
>
> This is FAQ. So I will add FAQ in the support page.
>
> regards,
>
> ********
> Tomoji TAKASU
>
> --------------------------------------------------
> From: "Danny Miller" <dannym at austin.rr.com>
> Sent: Monday, June 20, 2011 5:07 PM
> To: <foss-gps at lists.osgeo.org>
> Subject: [FOSS-GPS] Can't get Ambiguity Validation Ratio to move
>
>> I'm new to RTK.  I have a pair of LEA-6T GPS units, one active 
>> Sarantel SL-1206 quadrafiliar helix ant.  There were supposed to be 
>> two of those but the second one was DOA so I'm making do with an 
>> active patch antenna for the second.  I don't have an antenna file 
>> for either of them.  I'm using 2.4.1.
>>
>> I have UBX RXM-RAW and RXM-SFRB reading out of both of them at 5Hz 
>> (tried this at 1Hz too).  I can get a fix out of either one of them.  
>> In Kinematic mode of RTKNavi, I get a position, but the "ratio factor 
>> of ambiguity validation" factor is stuck at 0.0.  I waited like an 
>> hour and it was still at 0.
>>
>> In the data window of RTKNavi, I noticed the Lat/long/height of Base 
>> is not listed with real numbers (90deg 0m).  This isn't right- that 
>> GPS has a fine solution in NMEA.  Both Base and Rover are showing 
>> strong (~45dbHz) signal bars in all colors.
>>
>> I looked under Solution 1 and Solution 2 and both have valid, similar 
>> solutions.
>>
>> I looked under errors and saw:
>> eight "outlier rejected" per sample period (5Hz)
>> one "no double-differenced residuals" message
>>
>> I tried switching the COM ports for Base and Rover, effectively 
>> switching which unit was which (neither is moving right now).  
>> Nothing changed, the "Base" unit channel still has no Lat/long/height 
>> and ambiguity validation is still 0.  That is, the problem is not 
>> tied to the GPS hardware unit.
>>
>> I tried disabling the Rover in RTKnavi.  There's still no solution 
>> under the Lat/Long/Height of Base.  The signal strength bars all turn 
>> gray.
>>
>> I tried the mkl version (I have an i7).  It didn't change anything.
>> I tried 2.4.0 rtknavi.  In that one, I can't get a rover solution to 
>> show up at all, it's blank on the main window and rtkplot shows nothing.
>>
>> Any ideas?
>>
>> Danny
>>
>>
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