About the calculated position from gps measurement tools matlab source code

[mohamed fathi]

Why always the calculated position (lat long alt )from Weighted least square method by the matlab source  in gpsPvt.allLlaDegDegM different from the values from the txt file from GNSSLOGGER or GPSTEST 

From Fix message whether the provider is Fused location or GPS ?

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[mohamed fathi]

in other words, anyone works with the GPS measurement tools Matlab source code

[Sean Barbeau]

Each of those positions are calculated via different methods/sources:

* WLS is calculated using weighted least squares algorithm implemented in GNSSLogger or GNSS Analysis Tool

* Fused location comes from Google's fused location provider implemented in Google Play services

* GPS location comes from the GNSS chipset on the phone

Sean

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[mohamed fathi]

Dr sean thanks for your reply

But the wls is not accurate enough to compare with others  difference  is large sometimes reach hundred of meters 

Is it because the pseudorange and pseudorange rate calculated in Gnss logger without the ionosphere and troposphere delay ? 

And if yes or no

How to reduce the  difference between the calculated from wls and other from Gps and Fused location because the Gps and Fused location already have small difference between each other 

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From: Sean Barbeau <sjba...@gmail.com>
Sent: Friday, August 26, 2022 3:59:37 PM
To: mohamed fathi <mohammedf...@gmail.com>
Cc: GPSTest <gpstest...@googlegroups.com>
Subject: Re: About the calculated position from gps measurement tools MATLAB source code

 

[Sean Barbeau]

The fused provider and the GPS from the chipset are both post processed in proprietary ways, evidently with better accuracy than WLS alone. Here's the latest open source implementation of WLS for an older version of GnssLogger:

https://github.com/google/gps-measurement-tools/tree/master/GNSSLogger/pseudorange/src/main/java/com/google/location/lbs/gnss/gps/pseudorange

Check the Google Smartphone Decimeter Challenge for some ways that teams have accomplished better accuracy for positioning:

https://www.kaggle.com/competitions/smartphone-decimeter-2022/

Sean

[mohamed fathi]

Thanks Dr sean for your help 🙏

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From: Sean Barbeau <sjba...@gmail.com>
Sent: Saturday, August 27, 2022 12:38:39 AM