IEEE - Aerospace and Electronic Systems - August 2022 - 43

Fr€anken et al.
Figure 11.
Some fusion input and output. Measured PSR (blue) and SSR
(purple) plots, radar/IFF tracks (magenta), fused tracks (green),
created Cartesian plots (orange and cyan), ADS-B (yellow).
codes from SSR. InHensoldt's passive radar system Twinvis,
a Funke RTH80 receiver delivers raw ADS-B messages that,
by default, are merely decoded and sent to the HMI in an
aggregated form. In APART-GAS, aggregated ADS-B data
have been used for comparison only. However, fusion with
aggregated ADS-B (internal or external) would be possible
too, depending on the configuration.
Figure 10 summarizes the overall data and fusion setup.
The two passive radar sensors from Hensoldt, the one from
PIT-RADWAR, as well as the two research sensors from
armasuisse and WUT, provided their bistatic plot data in
Hensoldt's proprietary input format (consisting of bistatic
range and range rate as well as, if reported by the sensor, azimuth).
Two active radars delivered PSR and SSR plots (only
one of themwas used in the upcoming results). As stated previously,
the active data were first processed by a standard
tracker, and the results were then sent to the data fusion.
Figure 11 shows PSR and SSR plots and the resulting radar/
IFF tracks, the fused tracks and the created Cartesian plots of
the two Hensoldt sensors, plus the ADS-B as reference. There
is a good match between the fused tracks and ADS-B, while
the active radar tracks exhibit some offset to the ADS-B here.
Apparently, the radar plots suffer from an imperfect northalignment
ofthe sensor.
MEASUREMENT RESULTS
In the following, some specific examples of fusion results
will be shown that have been achieved during the
measurement campaign conducted within APART-GAS.
Data from all participating sensors (active and passive)
was processed and fused. This way, an overall coverage
was achieved that ranged about 500 kilometers from
west to east and up to 560 kilometers from north to south.
Figure 12 shows the corresponding track data, accumulated
over one hour.
AUGUST 2022
Figure 13.
Survey ofhow the different passive radar sensors contribute to the
common fused tracks (gray). Hensoldt (top left, green), PITRADWAR
(top right, purple), armasuisse (bottom left, orange),
and WUT (bottom right, brown). Passive radar receiver locations
are shown as correspondingly colored squares, detailed in
Figure 15.
IEEE A&E SYSTEMS MAGAZINE
43
Figure 12.
Coverage achieved during APART-GAS. One hour of fused
tracks (green). Shorelines shown in gray and country borders in
light orange.
Figure 13 displays 20 minutes of accumulated track data
indicating the contributions of the different passive radar
systems. For each track update, it has been checked
whether the respective system has contributed bistatic plot
data to the track within the preceding 10 seconds. If so,
the track update has been marked with the corresponding
system's color and has been left gray otherwise. In particular,
it can be noted that the detection range of the commercial
systems exceeded that of the research systems by
far. This comes as no surprise, as the former use larger
numbers of high-power FM transmitters plus SFN
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