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

Mon Jun 20 16:16:45 EDT 2011

OK, I was wondering about that.  The base is not actually moving, but 
this seems right.

How does it calculate E/N/U-Baseline without a base location?  The 
spatial orientation of the EN plane changes (rotates) with lat/long.

I assume it calculates an approximate lat/long solution and uses that to 
come up with the orientation of the ENU coordinate system?  Can it do 
this with SkyTraq-Raw, without a solution from the receiver itself?

BTW, I am very excited about RTKlib, and cannot thank you enough for 
making it available the way you have.  There is no shortage of practical 
uses for this.

Thanks,
Danny

On 6/20/2011 2:40 PM, Tomoji Takasu wrote:
> Dear Danny
>
>> 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.
>
> Collect receiver data in some period, process them in
> "Single" mode and average the results.
>
>> 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?
>
> You are right.
>
>> 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?
>
> Use "Moving-Base" mode and output "E/N/U-Baseline".
>
> regards,
>
> Tomoji TAKASU
>
> --------------------------------------------------
> From: "Danny Miller" <dannym at austin.rr.com>
> Sent: Tuesday, June 21, 2011 1:34 AM
> To: "Open Source GPS-related discussion and support" 
> <foss-gps at lists.osgeo.org>
> Subject: Re: [FOSS-GPS] Can't get Ambiguity Validation Ratio to move
>
>> 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
>>>>
>>>>
>>>> _______________________________________________
>>>> This message is sent to you from FOSS-GPS at lists.osgeo.org mailing 
>>>> list.
>>>> Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage 
>>>> your subscription
>>>> For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
>>>>
>>>>
>>>>
>>>
>>>
>>> _______________________________________________
>>> This message is sent to you from FOSS-GPS at lists.osgeo.org mailing list.
>>> Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage 
>>> your subscription
>>> For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
>>>
>>
>> _______________________________________________
>> This message is sent to you from FOSS-GPS at lists.osgeo.org mailing list.
>> Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your 
>> subscription
>> For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
>>
>>
>>
>
>
> _______________________________________________
> This message is sent to you from FOSS-GPS at lists.osgeo.org mailing list.
> Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your 
> subscription
> For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
>