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

[Tomoji Takasu]

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
>>>
>>>
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>>
>>
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