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INTRAC-305 TECHNICAL DESCRIPTION
© 2011 Advantech Wireless INTRAC-305 MANUAL - Issue 3.2 Page 55
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component of beam shift is not visible to the position
transducers. The mean of the reference shift is tracked by the
INTRAC algorithm in a similar way to a stationkeeping
manoeuvre.
The component of beam shift that is visible to the position
transducers is entirely tracked by INTRAC within a 10 MHz
noise bandwidth. When the position transducers accurately
reflect beam deflection in wind INTRAC continuously tracks
this antenna deflection at 16 sec updates. To support tracking
of visible wind-induced beam deflection between measurement
cycles the INTRAC servo control algorithm maintains a
short-term average of beam pointing. When deciding whether
to update beam pointing INTRAC references this average
rather than the current pointing. A further small deadband is
also applied to suppress unnecessary hunting.
The INTRAC tracking filter distinguishes received beacon
signal power fluctuations, fades and noise from the mean
component of windage-induced beam-pointing, orbit changes
and beam refraction. The effect of the fluctuations, fades and
noise on the INTRAC tracking filter is as if these were a zero
mean position random noise source. The variance of these is
brought within specification by tracking the position estimates
with a narrow noise bandwidth tracking filter. The mean
components of windage-induced beam-pointing, orbit changes
and refraction are seen as transients to be tracked by the
INTRAC relationship algorithm. The design of the relationship
algorithm is a carefully evolved working compromise between
transient performance and noise suppression which provides
high accuracy tracking under all conditions likely to be
encountered in practice.
THE MODES The INTRAC-305 has six major operational modes :-
Standby