Yo All! u-blox has generously provide me with some EVKs of some newer u-blox receivers. That has directly led to updates to ubxtool, ubxtool-examples, and drivers/driver_ubx.c. Much more to come.
Out of curiosity I ran some new antenna tests using the UBX-MON-SPAN
command. These tests run on an F9T receiver in L1/L5 only mode. So
the results do not apply to L1/L2 mode or L1/L2/L5 mode.
Attached are 4 png images of the results. Not on the graph are the
automatic RF gains (psa).
f9t-generic-l5.png u-blox generic L1 only antenna
L1 psa 45 dB
L5 psa 39 dB
The generic only needed 3 dB more gain, and had a nice flat pass
band.
f9t-mb-l5.png u-blox MB-00-00 L1/l2 antenna
L1 psa 42 dB
L5 psa 54 dB
The MB needed a lot (18 dB) more gain, but otherwise the L5
pass-band looked OK.
f9t-mb1-l5.png u-blox MB1-00-00 L1/L5 antenna
L1 psa 42 dB
L5 psa 36 dB
The MB1 has slightly funcky L1 and L5 pass-bands. Similar to the
MB2.
f9t-mb2-l5.png u-blox MB2-00-00 L1/L2/L5/ antenna
L1 psa 42 dB
L5 psa 36 dB
The MB2 has roughest L1 and L5 pass-bands.
I'm not sure what it all means for final accuracy, but it
does point to some observations.
1. Don't use an L1/L2 antenna if you need L1/L6.
2. Sometimes a generic L1 antenna looks almost as good as and L1/L5
antenna. In this case flatter pass-bands but slightly less gain.
More details on doing your own antenna testing here:
https://gpsd.io/ubxtool-examples.html#_antenna_testing
RGDS
GARY
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Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
[email protected] Tel:+1 541 382 8588
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"If you can't measure it, you can't improve it." - Lord Kelvin
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