6.2. AIM+: USING THE SPECTRUM ANALYSER TO
DETECT AND MITIGATE INTERFERENCE
6.2 AIM+: Using the spectrum analyser to
detect and mitigate interference
The AsteRx-U MARINE Fg is equipped with a sophisticated RF interference monitoring and
mitigation system (AIM+). To mitigate the effects of narrow-band interference, 3 notch
fi
lters
can be con
fi
gured either in auto or manual mode. These notch
fi
lters effectively remove a
narrow part of the RF spectrum around the interfering signal. The L2 band being open for
use by radio amateurs is particularly vulnerable to this type of interference. The effects of
wideband interference both intentional and unintentional can be mitigated by turning on
the WBI mitigation system. The WBI system also reduces, more effectively than traditionally
used pulse-blanking methods, the effects of pulsed interferers.
The spectrum view plot
In the Spectrum window of the GNSS menu, you can monitor the RF spectrum and con
fi
gure
three separate notch
fi
lters to cancel out narrowband interference. Figure 6-2 shows the L2
frequency band with the GPS L2P signal at 1227.60 indicated. Different bands can be viewed
by clicking on the
‘
Show table
’
button as shown. The spectrum is computed from baseband
samples taken at the output of the receiver
’
s analog to digital converters.
Figure 6-2:
The RF spectrum of the L2 Band
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