Spectra Precision SP90m, Руководство пользователя

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This chart deserves a few more comments and explanations:
• Accuracy is inversely proportional to baseline length.
However a too long baseline can result in multipaths
between antennas and introduction of vehicle flexing into
the heading solution. These two factors are detrimental to
heading accuracy. In addition, the longer the baseline, the
longer the calibration sequence. That’s why baselines of
three to five meters are recommended. Baseline lengths
less than one meter are not advised.
• Accuracy figures given above are 1-sigma values, or RMS,
which means that 67% of the measurements are at or
below these figures.
• Heading accuracy will be about a factor of 2 better than
pitch or roll accuracy. Pitch and roll accuracies are the
same.
• The lower line (blue) represents accuracy achievable if no
multipath errors were present. In a normal environment,
this is not possible. Multipath effects from typical
environments are depicted by the upper line (red). For a
given baseline length, the performance of the SP90m
should lie somewhere near the upper line.
• A moving vehicle does not experience as many multipath
effects as when it is stationary. This is because multipath
is a correlated error. Correlated errors become more noise-
like under vehicle dynamics and therefore can be filtered
out. Therefore, accuracy results improve toward the lower
line (blue) when the vehicle is moving.
Elevation Offset
Ideally, the two antennas should be installed at the same
elevation. You may however be facing some installation
constraints on your vehicle compelling you to install the
antennas at different elevations. If that is the case, this is
how you should calculate the elevation offset between the two
0.1
0.1
0.01
0.001
1
1
10 100 1000
Baseline Length (m)
Heading A
ccur
a
c
y
(°)