[FOSS-GPS] U-blox LEA-M8T performance vs LEA-6T

[Maurolvs]

Hello FOSS GPS Community 

My name is Mauro Sierra.

One year ago, I realized an investigation that consisted of evaluating the
performance of the U-blox LEA-6T receiver + ANN-MS antenna, for Land
Surveying. The results were excellent as for static and kinematic
positioning (post-processing), but they were not very encouraging for RTK.

At present,  I am experimenting with the new LEA-M8T receiver + Tallysman
T2410 antenna, waiting for a significant improvement in the precision of the
measurements with regard to the LEA-6T. Unfortunately, the performance of
the receiver has not been the best (just GPS tracking). I have realized
several configurations (even the same ones that the LEA-6T) and do not
achieve stable measurements: sometimes it improves and others, it
deteriorates.

I have noticed that the LEA-M8T registers many losses of cycle. IMHO is due
to the fact that the receiver includes inside the raw information, the
rejected satellites by the RAIM feature (activated by default), and assigns
a value of 0 to the phase measurements. This may be degrading the
measurements.

<http://open-source-gps-related-discussion-and-support.1099874.n2.nabble.com/file/n7573228/Sin_t%C3%ADtulo2.png> 


RAWX messages in u-center (6T left, M8T right): signals below of 27 dBic are
rejected in LEA-M8T. Note the carrier phase (non zero values).


<http://open-source-gps-related-discussion-and-support.1099874.n2.nabble.com/file/n7573228/Sin_t%C3%ADtulo.png> 

RINEX taken at same time with LEA 6T (left) and M8T (right) receivers;
static positioning: 2 hr; separation between antennas: 20cm. Note that
rejected satellites are includes in raw data.

I am grateful to those who have experimented with the LEA-M8T, be able to
confirm to me this problem, in order to discard that my receiver is
defective. 

Thank you for your help... and sorry for my english, i´m working in that ;)

Kind regards,

Mauro S.















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