pseudorange noise report

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I am triying to get confidence ellipse data from gpsd connected to my u-blox Neo-M8N.

I see that GPSD puts this information on the GST structure (called pseudorange noise report). But Actually I dont see it in my gpsd flow, so it would probably means that the necesary messages for this information are disabled. Can anyone give me an indication of which UBX/NMEA messages should I enable on my serial interface for gpsd to get the confidence ellipse data?.

Thank you
by gavilanes asked Apr 16
0 votes
Here is the protocol spec

Presume you're talking of Pseudo-Range Residuals (deviation from measurement vs solved solution)

Not super interested in digging into the GPSD expectations/requirements, I'm sure its documented well. I would expect you'd perhaps want to enable the GxGST and GxGRS NMEA sentences, this can be done using the UBX-CFG-MSG command or $PUBX

GRS breaks down the residuals at a satellite level, GST provides and overall error estimate
by clive1 answered Apr 16
Thank you Clive1 for your answer, I just enabled the GST messages. What I am trying to do is to get the major, minor and orientation of the axis of the confidence ellipse, present on the NMEA GST; the problem is that only those 3 values are empty on the NMEA strings. is there any way to make the receiver calculate them?
Are you sure you are parsing them correctly? I'm using a NEO-M8N and those values are always present in GST when I have a lock.
in fact,  I am sure, since I see the NMEA sentence like this:

those 3 values in the middle are empty. Perhaps a difference in configuration of both receivers.
The docs talk of  support in ADR 4.10, so assume you'd need a NEO-M8L or M8U
My mistake, I do not get the "Error ellipse semi-major axis 1 sigma error, in meters" fields either. I am using the last 3, the  "Latitude 1 sigma error, in meters" and "Longitude 1 sigma error, in meters", and "Height 1 sigma error, in meters". Not sure what the confidence ellipse is.
I'd imagine it is some blob of uncertainty, that is lemon shaped, roughly HDOP*CEP*2 high, and VDOP*CEP radius