[time-nuts] u-blox NEO-M8T GPS initial tracking test

MLewis mlewis000 at rogers.com
Thu Feb 9 22:03:12 EST 2017

Five M8Ts.
And here I was feeling extravagant having splurged for one...

I'm only seeing between 20 and 25 signals, but there's a bank of 
concrete&steel brick-clad buildings opposite. And typically with the 
majority of signals coming from north of my building, they're coming in 
off those buildings. Given the building orientation, the reported 
location during survey is interesting (attached).

With freezing rain yesterday, then a drop in temperature, one, the 
other, or both, resulted in last night's sats at 20 degrees and 35 
degrees on heading 320 showing a strong signal, likely off the 
freezing-rain coated office tower. I may throw a piece of RF foam in LOS 
from that building to the antenna to see if that can sufficiently block 
that one source. Isn't multipath fun.

I believe the M8T is supposed to be able to directly replace a M7T or 
M6T. By chance did you drop the M8T onto a M6T or M7T board?

The only thing I haven't been able to do is the GNSS configure and 
enable of GAL. Even with the assigned channels well under the 32 max, it 
won't accept GAL configurations. Seeing there was no GAL sequence in the 
text GNSS config file (others show their id an a sequence of zeros), I 
even configured Beidou as GAL, generated the GNSS config file and edited 
it to change the Beidou id from 3 to 2 for GAL. Loading the file 
populates with the text config file settings, except that it treats the 
2/GAL labelled sequence as its original Beidou as if the id is still 3.

Any tips on configuring/enabling for GAL?


On 09/02/2017 6:12 AM, David Witten wrote:
> I am doing similar tests, seeing similar results.  I have 5 x 
> NEO-M8T's, 3 M6T', 4 Skytrack Venus 838Lp-T's.  Mostly have Toaglas 
> triple band antennas on PCB groundplanes with LNA-SAW-LNA conditioning 
> in line.  I have built a three arm test rig (arm < =1.5 M) for testing 
> RTK measurments, etc. Hope to deploy it at local USGS office RTK 
> calibration/test range.
> So far the performance of the M8T's seems impressive. Usually 29 sats 
> in view from basement windowsill (inside) with woods 15 M away.  
> Facing south.

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